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1

Interactions between soil structure and excess water formation on chernozem soils  

NASA Astrophysics Data System (ADS)

The main natural resource of Hungary is soil therefore its protection is a fundamental obligation for the state and the farmers too. The frequency of the weather extremeties have increased due to the global climate change which takes effect also on the soil properties. The hungarian agriculture was stricken with drought in the 1990's, whereas excess water has caused damages in the previous decade. According to multi-variable correlation tests, pedological parameters influence on the formation of excess water besides hydrometeorological, geological or relief factors. But not only the soil parameters can take effect on the formation of excess water, but also excess water can modify the soil parameters - causing appearance of hydromorfical characteristics or physical degradation. In our research the interactions between soil structure, excess water and land use were investigated in the aspects of changes in the structure of the upper soil, on a cultivated study area (located on the South Hungarian Great Plain). Three excess water patches were appointed with analysis of multitemporal Landsat images in the study area and were connected a southwest-west-nordeast-east line, forming a 700 meter-long catena. In July, 2011 soil samples were collected along this catena at each 50 meters from the depth of 0-5 cm, 10-15 cm and 20-25 cm to compare the agronomical structure and aggregates stability of soils covered temporally by excess water and without it. Furthermore, penetration resistance and relative moisture of soil were determined at the deep of 60 cm in definite points of a 25x25 m grid on the 45 hectares study field using 3T System hand penetrometer in order to create a multilayer-map from the soil compaction datas. The results call the attention both to the physical soil degradation caused by excess water and to the risk of erosion due to inadequate tillage or cultivation.

Gál, N.; Farsang, A.

2012-04-01

2

Interactions among Climate Forcing, Soil Water, and Groundwater for Enhanced Water Management Practices in Nebraska  

NASA Astrophysics Data System (ADS)

Water is one of the most valuable and vulnerable resources. The varying precipitation regimes together with the varying land use and land cover types over the state of Nebraska necessitate continuous monitoring and modeling of soil water, particularly in the root zone. Underlying the irrigated lands is the High Plains Aquifer, one of the largest in the world. The Ogallala Aquifer is hydrologically connected with streams in numerous river valleys and with rainfall/soil water at the surface. To sustain water reserves the net effect of groundwater pumping for irrigation and recharging the ground water system by precipitation/irrigation. If the net effect is zero or positive the reserves will not shrink. The Automated Weather Data Network (AWDN) of Nebraska has intensive soil water observation and critical weather measurements. Nebraska also has ground water wells, co-located with or near some of the AWDN stations. This work was conducted to continuously monitor the soil water and groundwater table and to model the surface and subsurface hydrologic processes as an integrated/linked system. The further task is to quantify the recharge under different initial conditions, land use practices, and to combine the new information with a surface hydrology model over various sites in Nebraska. To accomplish these objectives two weather stations were installed and enhanced at Shelton and Kearney and soil probes were buried directly under the crop lands. The newly installed soil water probes are co-located with the nearby weather stations and ground water wells. All the data recorded from the atmosphere, soil and aquifer will be incorporated into AWDN data archives and will be analyzed to examine the interactions between precipitation, soil moisture and groundwater.

You, J.; Hubbard, K. G.; Chen, X.

2009-12-01

3

A model for soil-vegetation-atmosphere interactions in water-limited ecosystems  

E-print Network

in water-limited environments with significant water recycling, and introduce a simple process modelA model for soil-vegetation-atmosphere interactions in water-limited ecosystems M. Baudena,1,2 F. D-vegetation-atmosphere interactions in water-limited ecosystems, Water Resour. Res., 44, W12429, doi:10.1029/2008WR007172. 1

D'Andrea, Fabio

4

Interactions between metal ions and biogeo-surfaces in soil and water  

Microsoft Academic Search

To provide the basis for an improved quantitative risk assessment of heavy metals in the environment, the interactions between the metal ions and the biogeo-surfaces in soil and water were studied using both experimental and modelling approaches.The Donnan membrane technique was developed and optimised for the measurement of metal speciation in soil solutions, in which a soil column was linked

L. Weng

2002-01-01

5

Gravel admix, vegetation, and soil water interactions in protective barriers: Experimental design, construction, and initial conditions  

SciTech Connect

The purpose of this study is to measure the interactive effects of gravel admix and greater precipitation on soil water storage and plant abundance. The study is one of many tasks in the Protective Barrier Development Program for the disposal of Hanford defense waste. A factorial field-plot experiment was set up at the site selected as the borrow area for barrier topsoil. Gravel admix, vegetation, and enhanced precipitation treatments were randomly assigned to the plots using a split-split plot design structure. Changes in soil water storage and plant cover were monitored using neutron probe and point intercept methods, respectively. The first-year results suggest that water extraction by plants will offset gravel-caused increases in soil water storage. Near-surface soil water contents were much lower in graveled plots with plants than in nongraveled plots without plants. Large inherent variability in deep soil water storage masked any effects gravel may have had on water content below the root zone. In the future, this source of variation will be removed by differencing monthly data series and testing for changes in soil water storage. Tests of the effects of greater precipitation on soil water storage were inconclusive. A telling test will be possible in the spring of 1988, following the first wet season during which normal precipitation is doubled. 26 refs., 9 figs., 9 tabs.

Waugh, W.J.

1989-05-01

6

Interacting vegetative and thermal contributions to water movement in desert soil  

USGS Publications Warehouse

Thermally driven water-vapor flow can be an important component of total water movement in bare soil and in deep unsaturated zones, but this process is often neglected when considering the effects of soil-plant-atmosphere interactions on shallow water movement. The objectives of this study were to evaluate the coupled and separate effects of vegetative and thermal-gradient contributions to soil water movement in desert environments. The evaluation was done by comparing a series of simulations with and without vegetation and thermal forcing during a 4.7-yr period (May 2001-December 2005). For vegetated soil, evapotranspiration alone reduced root-zone (upper 1 m) moisture to a minimum value (25 mm) each year under both isothermal and nonisothermal conditions. Variations in the leaf area index altered the minimum storage values by up to 10 mm. For unvegetated isothermal and nonisothermal simulations, root-zone water storage nearly doubled during the simulation period and created a persistent driving force for downward liquid fluxes below the root zone (total net flux ~1 mm). Total soil water movement during the study period was dominated by thermally driven vapor fluxes. Thermally driven vapor flow and condensation supplemented moisture supplies to plant roots during the driest times of each year. The results show how nonisothermal flow is coupled with plant water uptake, potentially influencing ecohydrologic relations in desert environments. ?? Soil Science Society of America 5585 Guilford Rd., Madison, WI 53711 USA. All rights reserved.

Garcia, C.A.; Andraski, B.J.; Stonestrom, D.A.; Cooper, C.A.; Simunek, J.; Wheatcraft, S.W.

2011-01-01

7

Interacting vegetative and thermal contributions to water movement in desert soil  

USGS Publications Warehouse

Thermally driven water-vapor flow can be an important component of total water movement in bare soil and in deep unsaturated zones, but this process is often neglected when considering the effects of soil–plant–atmosphere interactions on shallow water movement. The objectives of this study were to evaluate the coupled and separate effects of vegetative and thermal-gradient contributions to soil water movement in desert environments. The evaluation was done by comparing a series of simulations with and without vegetation and thermal forcing during a 4.7-yr period (May 2001–December 2005). For vegetated soil, evapotranspiration alone reduced root-zone (upper 1 m) moisture to a minimum value (25 mm) each year under both isothermal and nonisothermal conditions. Variations in the leaf area index altered the minimum storage values by up to 10 mm. For unvegetated isothermal and nonisothermal simulations, root-zone water storage nearly doubled during the simulation period and created a persistent driving force for downward liquid fluxes below the root zone (total net flux ~1 mm). Total soil water movement during the study period was dominated by thermally driven vapor fluxes. Thermally driven vapor flow and condensation supplemented moisture supplies to plant roots during the driest times of each year. The results show how nonisothermal flow is coupled with plant water uptake, potentially influencing ecohydrologic relations in desert environments.

Garcia, C.A.; Andraski, B.J.; Stonestrom, D.A.; Cooper, C.A.; Šim?nek, J.; Wheatcraft, S.W.

2011-01-01

8

Water flow path interactions with soil hydraulic properties in till soil at Gĺrdsjön, Sweden  

NASA Astrophysics Data System (ADS)

In 1989, in a hydrological research programme within a deacidification project in the Gĺrdsjön area in southwest Sweden, flow paths and residence times of soil water and groundwater in microcatchments were examined to support the interpretation of the hydrochemical changes. Saturated hydraulic conductivity and soil water retention were analysed on more than 100 cylinder samples. The catchments have shallow sandy-silty till soil with a mean depth in the main catchment of 43 cm. Porosity of the mineral soil in the main catchment was high and ranged from 38 to 85%. The samples from the B-horizon had generally higher porosity. Porosity and the content of organic matter were correlated. The soil water retention was relatively high at all tensions, likely owing to the high content of organic matter. Dissolved organic substances were most probably transported from the shallow soil on the steep sides of the catchment down to the valley where it precipitated. The high porosities could be a consequence of long-term weathering, provided that the organic substances present have increased the leaching of the weathering products. Measured values of saturated hydraulic conductivity were close to log-normally distributed with a mean for all samples of 3 × 10 -5 m s -1. There was a significant increase in conductivity toward the ground surface with the mean conductivity of the samples in the uppermost 10 cm of the mineral soil of 4 × 10 -5 m s -1, which was about 13 times higher than the conductivity of 3 × 10 -6 m s -1 at 1 m depth. From the relationship between runoff at the catchment outlet and groundwater levels, the conductivity was estimated to be 15-200 times higher in the upper soil layer than in the deeper ones. In one profile, 44-64% of the yearly lateral flow was estimated to occur above 30 cm depth. The conductivity was correlated with the content of drainable water, which indicated the importance of the largest pores for the saturated hydraulic conductivity.

Nyberg, Lars

1995-08-01

9

Dynamics of the water-pipeline-soil interaction  

Microsoft Academic Search

A design engineer-oriented approach to determining the pipeline dynamic response to ocean forces accounting for complex environmental and pipeline conditions is presented. The described analysis yields time histories of pipeline motion and steel pipe stresses induced by water motion. Sinusoidal variation of normal water particle motion in time and along the pipeline, waves, flexural rigidity of pipe, damaged concrete coating,

K. Karal; S. A. Halvorsen

1982-01-01

10

Future African Water Resources: Interactions between Soil Degradation and Global Warming  

Microsoft Academic Search

This study uses a well-established water balance methodology to evaluate the relative impact of global warming and soil degradation due to desertification on future African water resources. Using a baseline climatology, a GCM global warming scenario, a newly derived soil water-holding capacity data set, and a worldwide survey of soil degradation between 1950 and 1980, four climate and soil degradation

Johannes J. Feddema

1999-01-01

11

Barrier erosion control test plan: Gravel mulch, vegetation, and soil water interactions  

SciTech Connect

Soil erosion could reduce the water storage capacity of barriers that have been proposed for the disposal of near-surface waste at the US Department of Energy's Hanford Site. Gravel mixed into the top soil surface may create a self-healing veneer that greatly retards soil loss. However, gravel admixtures may also enhance infiltration of rainwater, suppress plant growth and water extraction, and lead to the leaching of underlying waste. This report describes plans for two experiments that were designed to test hypotheses concerning the interactive effects of surface gravel admixtures, revegetation, and enhanced precipitation on soil water balance and plant abundance. The first experiment is a factorial field plot set up on the site selected as a soil borrow area for the eventual construction of barriers. The treatments, arranged in a a split-split-plot design structure, include two densities of gravel admix, a mixture of native and introduced grasses, and irrigation to simulate a wetter climate. Changes in soil water storage and plant cover are monitored with neutron moisture probes and point intercept sampling, respectively. The second experiment consists of an array of 80 lysimeters containing several different barrier prototypes. Surface treatments are similar to the field-plot experiment. Drainage is collected from a valve at the base of each lysimeter tube, and evapotranspiration is estimated by subtraction. The lysimeters are also designed to be coupled to a whole-plant gas exchange system that will be used to conduct controlled experiments on evapotranspiration for modeling purposes. 56 refs., 6 figs., 8 tabs.

Waugh, W.J.; Link, S.O. (Pacific Northwest Lab., Richland, WA (USA))

1988-07-01

12

Soil heat and water movement  

Technology Transfer Automated Retrieval System (TEKTRAN)

The interrelation between heat and water flow in soil is complex. Temperature gradients can induce vapor and liquid water transfer within the soil; in turn, water movement carries heat with it, thus altering the thermal regime of soil. These interactions are often neglected to simplify analysis of t...

13

Soil nutrients and water availability interact to influence willow growth and chemistry but not leaf beetle performance  

Microsoft Academic Search

We investigated the effects of soil nutrient and water availability on the growth and chemistry of the silky willow ( Salix sericea Marshall), and on the performance of the imported willow leaf beetle ( Plagiodera versicolora Laichartig). Our major aims were to determine whether there are nutrient-water interactions on plant traits and whether this leads to parallel interactions for herbivore

Steven S. Lower; Colin M. Orians

2003-01-01

14

Oxygen isotope fractionation effects in soil water via interaction with cations (Mg, Ca, K, Na) adsorbed to phyllosilicate clay minerals  

NASA Astrophysics Data System (ADS)

In isotope-enabled hydrology, soil and vadose zone sediments have been generally considered to be isotopically inert with respect to the water they host. This is inconsistent with knowledge that clay particles possessing an electronegative surface charge and resulting cation exchange capacity (CEC) interact with a wide range of solutes which, in the absence of clays, have been shown to exhibit ?18O isotope effects that vary in relation to the ionic strength of the solutions. To investigate the isotope effects caused by high CEC clays in mineral-water systems, we created a series of monominerallic-water mixtures at gravimetric water contents ranging from 5% to 32%, consisting of pure deionized water of known isotopic composition with homoionic (Mg, Ca, Na, K) montmorillonite. Similar mixtures were also created with quartz to determine the isotope effect of non-, or very minimally-, charged mineral surfaces. The ?18O value of the water in these monominerallic soil analogs was then measured by isotope ratio mass spectrometry (IRMS) after direct headspace CO2 equilibration. Mg- and Ca-exchanged homoionic montmorillonite depleted measured ?18O values up to 1.55‰ relative to pure water at 5% water content, declining to 0.49‰ depletion at 30% water content. K-montmorillonite enriched measured ?18O values up to 0.86‰ at 5% water content, declining to 0.11‰ enrichment at 30% water. Na-montmorillonite produces no measureable isotope effect. The isotope effects observed in these experiments may be present in natural, high-clay soils and sediments. These findings have relevance to the interpretation of results of direct CO2-water equilibration approaches to the measurement of the ?18O value of soil water. The adsorbed cation isotope effect may bear consideration in studies of pedogenic carbonate, plant-soil water use and soil-atmosphere interaction. Finally, the observed isotope effects may prove useful as molecular scale probes of the nature of mineral-water interactions.

Oerter, Erik; Finstad, Kari; Schaefer, Justin; Goldsmith, Gregory R.; Dawson, Todd; Amundson, Ronald

2014-07-01

15

Trees, Soil and Water  

NSDL National Science Digital Library

Trees, soil and water: Journey to Forever - health care for mountains, trees for deserts, trees for people, forest, forestry, deforestation, erosion, soil conservation, water conservation, desertification.

Keith Addison

2010-01-01

16

Seismic evaluation of a cooling water reservoir facility including fluid-structure and soil-structure interaction effects  

SciTech Connect

Seismic analyses and structural evaluations were performed for a cooling water reservoir of a nuclear reactor facility. The horizontal input seismic motion was the NRC Reg. Guide 1.60 spectrum shape anchored at 0.20 g zero period acceleration. Vertical input was taken as two-thirds of the horizontal input. Soil structure interaction and hydrodynamic effects were addressed in the seismic analyses. Uncertainties in the soil properties were accounted for by considering three soil profiles. Two 2-dimensional SSI models and a 3-dimensional static model, representing different areas of the reservoir structures were developed and analyzed to obtain seismic forces and moments, and accelerations at various locations. The results indicated that both hydrodynamic and soil-structure interaction effects are significant contributors to the seismic responses of the water-retaining walls of the reservoir.

Kabir, A.F. [Advanced Engineering Consultants, Inc., San Francisco, CA (United States); Maryak, M.E.; Bandyopadhyay, R. [Westinghouse Savannah River Co., Aiken, SC (United States)

1991-12-31

17

Seismic evaluation of a cooling water reservoir facility including fluid-structure and soil-structure interaction effects  

SciTech Connect

Seismic analyses and structural evaluations were performed for a cooling water reservoir of a nuclear reactor facility. The horizontal input seismic motion was the NRC Reg. Guide 1.60 spectrum shape anchored at 0.20 g zero period acceleration. Vertical input was taken as two-thirds of the horizontal input. Soil structure interaction and hydrodynamic effects were addressed in the seismic analyses. Uncertainties in the soil properties were accounted for by considering three soil profiles. Two 2-dimensional SSI models and a 3-dimensional static model, representing different areas of the reservoir structures were developed and analyzed to obtain seismic forces and moments, and accelerations at various locations. The results indicated that both hydrodynamic and soil-structure interaction effects are significant contributors to the seismic responses of the water-retaining walls of the reservoir.

Kabir, A.F. (Advanced Engineering Consultants, Inc., San Francisco, CA (United States)); Maryak, M.E.; Bandyopadhyay, R. (Westinghouse Savannah River Co., Aiken, SC (United States))

1991-01-01

18

4, 407437, 2007 Fitting of soil water  

E-print Network

Interactive Discussion EGU Abstract The soil hydraulic parameters for analyzing soil water movement can be determined by fitting a soil water retention curve to a certain function, i.e., a soil hydraulic model of matric potential), is the volumetric water content, and K is the unsaturated hydraulic conductivity

Boyer, Edmond

19

CHEMFLO-2000: INTERACTIVE SOFTWARE FOR PREDICTING AND VISUALIZING TRANSIENT WATER AND CHEMICAL MOVEMENT IN SOILS AND ASSOCIATED UNCERTAINTIES  

EPA Science Inventory

An interactive Java applet and a stand-alone application program will be developed based on the CHEMFLO model developed in the mid-1980s and published as an EPA report (EPA/600/8-89/076). The model solves Richards Equation for transient water movement in unsaturated soils, and so...

20

Plant interactions with changes in coverage of biological soil crusts and water regime in Mu Us Sandland, China.  

PubMed

Plant interactions greatly affect plant community structure. Dryland ecosystems are characterized by low amounts of unpredictable precipitation as well as by often having biological soil crusts (BSCs) on the soil surface. In dryland plant communities, plants interact mostly as they compete for water resources, and the direction and intensity of plant interaction varies as a function of the temporal fluctuation in water availability. Since BSCs influence water redistribution to some extent, a greenhouse experiment was conducted to test the hypothesis that the intensity and direction of plant interactions in a dryland plant community can be modified by BSCs. In the experiment, 14 combinations of four plant species (Artemisia ordosica, Artemisia sphaerocephala, Chloris virgata and Setaria viridis) were subjected to three levels of coverage of BSCs and three levels of water supply. The results show that: 1) BSCs affected plant interaction intensity for the four plant species: a 100% coverage of BSCs significantly reduced the intensity of competition between neighboring plants, while it was highest with a 50% coverage of BSCs in combination with the target species of A. sphaerocephala and C. virgata; 2) effects of the coverage of BSCs on plant interactions were modified by water regime when the target species were C. virgata and S. viridis; 3) plant interactions were species-specific. In conclusion, the percent coverage of BSCs affected plant interactions, and the effects were species-specific and could be modified by water regimes. Further studies should focus on effects of the coverage of BSCs on plant-soil hydrological processes. PMID:24498173

Gao, Shuqin; Pan, Xu; Cui, Qingguo; Hu, Yukun; Ye, Xuehua; Dong, Ming

2014-01-01

21

Plant Interactions with Changes in Coverage of Biological Soil Crusts and Water Regime in Mu Us Sandland, China  

PubMed Central

Plant interactions greatly affect plant community structure. Dryland ecosystems are characterized by low amounts of unpredictable precipitation as well as by often having biological soil crusts (BSCs) on the soil surface. In dryland plant communities, plants interact mostly as they compete for water resources, and the direction and intensity of plant interaction varies as a function of the temporal fluctuation in water availability. Since BSCs influence water redistribution to some extent, a greenhouse experiment was conducted to test the hypothesis that the intensity and direction of plant interactions in a dryland plant community can be modified by BSCs. In the experiment, 14 combinations of four plant species (Artemisia ordosica, Artemisia sphaerocephala, Chloris virgata and Setaria viridis) were subjected to three levels of coverage of BSCs and three levels of water supply. The results show that: 1) BSCs affected plant interaction intensity for the four plant species: a 100% coverage of BSCs significantly reduced the intensity of competition between neighboring plants, while it was highest with a 50% coverage of BSCs in combination with the target species of A. sphaerocephala and C. virgata; 2) effects of the coverage of BSCs on plant interactions were modified by water regime when the target species were C. virgata and S. viridis; 3) plant interactions were species-specific. In conclusion, the percent coverage of BSCs affected plant interactions, and the effects were species-specific and could be modified by water regimes. Further studies should focus on effects of the coverage of BSCs on plant-soil hydrological processes. PMID:24498173

Gao, Shuqin; Pan, Xu; Cui, Qingguo; Hu, Yukun; Ye, Xuehua; Dong, Ming

2014-01-01

22

CHEMFLO-2000: INTERACTIVE SOFTWARE FOR SIMULATING WATER AND CHEMICAL MOVEMENT IN UNSATURATED SOILS  

EPA Science Inventory

The movement of water and chemicals into and through soils has a large impact upon our environment and the entire ecosystem. Understanding these processes is of great importance in managing, utilizing, and protecting our natural resources. This software was written to enhance our...

23

BIOLOGICAL EFFECTS AND INTERACTIONS OF PESTICIDES IN A SOIL-PLANT-WATER MICROCOSM  

EPA Science Inventory

A Soil-plant-water microcosm was used to develop a data base for pesticide transport and metabolism and to determine the effects of varying environmental conditions and/or components on chemical movement in a terrestrial ecosystem. The system was used in a comparative transport s...

24

Coupled soil heat and water movement  

Technology Transfer Automated Retrieval System (TEKTRAN)

The interrelation between heat and water flow in soil is complex. Temperature gradients can induce vapor and liquid water transfer within the soil; in turn, water movement carries heat with it, thus altering the thermal regime of soil. These interactions are often neglected to simplify analysis of t...

25

Interactions of soil water content heterogeneity and species diversity patterns in semi-arid steppes on the Loess Plateau of China  

NASA Astrophysics Data System (ADS)

Soil water is a major driving force for plant community succession in semi-arid area. Many studies have focused on the relationships of species diversity-productivity, but few studies have paid attentions to the effects of soil water content heterogeneity on the plant species diversity in the semi-arid loess regions. To determine relationship of soil water content heterogeneity and plant community structure properties a semi-arid steppe on the Loess Plateau, we conducted a gradient analysis of soil water content variation and above- and below-ground properties of plant communities. Results showed that community coverage, above- and below-ground biomass were significantly and positively related to the surface soil water contents (0-5 cm). Plant diversity (Shannon index and Richness index) were closely correlated to soil water content at the soil depth of 0-10 cm. But plant height, litter biomass and root/shoot ratio were not related to soil water content. These results showed that there is an positive interaction effects for plant diversity and soil water content in the semi-arid grassland communities. Our observations indicate that change of plant species diversity is also an important community responses to soil water content heterogeneity in the semi-arid grassland ecosystem.

Wu, Gao-Lin; Zhang, Zhi-Nan; Wang, Dong; Shi, Zhi-Hua; Zhu, Yuan-Jun

2014-11-01

26

Space-Time Dynamics of Soil Water and Process Interactions in Semi-Arid Terrain, Colorado, USA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil water is a dominant control of plant growth and hydrologic response in dryland (rainfed) agriculture. In agricultural fields, soil water is typically assumed to move vertically with no differential subsurface lateral flow in semi-arid regions. However, soil water dynamics in the profile can v...

27

Soil Erosion by Water  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil erosion by water, the wearing away of the earth's surface by the forces of water and gravity, consists of rock or soil particle dislodgement, entrainment, transport, and deposition. This sequence of events occurs over a wide range of temporal and spatial scales, from raindrop splash moving par...

28

Trench water-soil chemistry and interactions at the Maxey Flats Site  

SciTech Connect

This report is part of an overall program designed to provide an understanding of and to monitor the behavior of existing low-level sites. This investigation will provide source term data for radionuclides and other solutes in trench waters and will describe the physical, chemical, and biological properties of the geochemical system that controls radionuclide movement. General conclusions can be made from the data in terms of source term information to be used in modeling efforts, as well as processes which may affect radionuclide migration. Trench waters are complex anoxic chemical systems which require more extensive investigation to assess their role in radionuclide retention and mobilization. No overall systematic changes in the disposal site trenches were observed during the brief sampling interval. However, changes in some radionuclide and cation concentrations were observed in several trenches. Numerous organic compounds were identified in trench waters at Maxey Flats, some of which have the potential for chelation with radionuclides. The presence of radionuclides and organic compounds in wells UB1 and UB1-A and in nearby trenches indicates communication between the wells and trench water leachates by subsurface migration. Radionuclides were also measured in the new experimental trench dug parallel to trench 27. Aerobic, anaerobic, sulfate reducing, denitrifying, and methanogenic bacteria are present in the leachate samples, and are able to grow anaerobically in trench leachates. Experimental results indicate that the observed sorption K/sub d/ is a function of both solid and liquid phase compositional variations as well as contact time. The observation that e lowest K/sub d/ results are observed with anoxic trench waters and ultrasonicated soils points to the need to use site specific materials and experimental conditions which simulate in situ conditions as closely as possible.

Weiss, A. J.; Czyscinski, K. S.

1980-01-01

29

SOIL WATER ENERGY CONCEPTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The soil water hydraulic pressure head is composed of matric, overburden, and hydrostatic pressures. The soil solution will flow from higher hydraulic pressure heads to lower hydraulic pressure heads. Piezometers are used to measure the hydrostatic pressure head, and tensiometers are used to measu...

30

7 Phosphorus Modeling in Soil and Water  

E-print Network

163 7 Phosphorus Modeling in Soil and Water Assessment Tool (SWAT) Model Indrajeet Chaubey...........................................................................164 7.2 Phosphorus Modeling in SWAT: Soil Phosphorus Interactions..................167 7.2.1 Initialization of Soil Phosphorus Levels......................................... 168 7.2.2 Mineralization

31

MANE: A MULTIPHASE, AQUEOUS, NON-STEADY STATE EQUILIBRIUM MODEL FOR SIMULATING SOIL-WATER INTERACTIONS  

EPA Science Inventory

A variety of chemical equilibrium models have been developed to help assess environmental chemistry problems, but few were specifically developed as research and teaching tools for use in conjunction with soil chemistry experiments. MANE model was developed to calculate equilibri...

32

Exchange of greenhouse gases between soil and atmosphere: interactions of soil physical factors and biological processes  

Microsoft Academic Search

Summary This review examines the interactions between soil physical factors and the biological processes respon- sible for the production and consumption in soils of greenhouse gases. The release of CO2 by aerobic respiration is a non-linear function of temperature over a wide range of soil water contents, but becomes a function of water content as a soil dries out. Some

K. A. S MITH; F. C ONEN; K. E. D OBBIE; A. R EY

2003-01-01

33

The interaction of water vapor with a lunar soil, a compacted soil, and a cinder-like rock fragment  

NASA Technical Reports Server (NTRS)

A volumetric adsorption system incorporating a pressure gauge was employed to determine nitrogen adsorption and evaluate surface areas. The water adsorption of the lunar samples was measured with the aid of a gravimetric adsorption system including a microbalance. The results obtained in the investigation for the three samples are discussed in detail, giving attention to aspects of dehydroxylation and rehydroxylation.

Cadenhead, D. A.; Stetter, J. R.

1974-01-01

34

SOIL WATER SENSING FOR PLANT WATER UPTAKE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Of the many ways to deduce plant water uptake, the soil water balance is the most frequently used, with plant water uptake determined as the residual of other terms in the equation. Extensive work with weighing lysimeters and soil water sensing methods allows us to contrast the effectiveness of and ...

35

Triazine Soil Interactions  

Technology Transfer Automated Retrieval System (TEKTRAN)

The fate of triazine herbicides in soils is controlled by three basic processes: transformation, retention, and transport. Sorption of triazines on surfaces of soil particles is the primary means by which triazines are retained in soils. Soils are very complex mixtures of living organisms, various t...

36

CO2 and CH4 Exchange in Interior Alaska: Interactions Between Fire, Water, Soils and Vegetation.  

NASA Astrophysics Data System (ADS)

The Alaskan interior contains large carbon reserves stored in poorly drained ecosystems. With warming, these areas of the boreal forest may experience more frequent or extensive stand replacing fires, and thus change the primary factors controlling carbon emissions. In 2001, a low-lying area of the Tanana Flood Plain adjacent to the Bonanza Creek LTER burned. Historical changes in vegetation, hydrology and fire at this site were tracked through macrofossil, charcoal and diatom analysis of peat cores. Dating the charcoal layers in the peat cores indicate four fire events in the past 800 years. The paleoecological record reveals a pattern of expansion of the bog after fire. After the most recent fire, a 30m transect was established along a moisture gradient from the center of a sphagnum dominated collapse feature into the surrounding burn. Thermocarst and subsiding soils were observed on the margin of the sphagnum bog in the three years since the fire. This has increased the anaerobic fraction of the soil profile. CO2 flux data suggest that both the dry and wet ends of the moisture gradient are sinks for CO2, with a growing season average daytime NEE of -2 ? mol CO2 m-2 s^{-1}. The moat is a CH^{4} source with an average growing season flux of 30 mg CH^{4} m^{-2} d^{-1} in the abnormally dry summer of 2004. We hypothesize that, after fire, lowland areas become wetter. This leads to high NEP, greater inputs of labile carbon, and increased CH^{4}$ efflux. However, if interior Alaska experiences more abnormally warm and dry summers like that of 2004, future CH4 production may be suppressed by the changing climate.

Myers-Smith, I. H.; McGuire, A. D.; Chapin, F. S.; Harden, J. W.

2004-12-01

37

Crop Residue and Soil Water  

Technology Transfer Automated Retrieval System (TEKTRAN)

Crop yield is greatly influenced by the amount of water that moves from the soil, through the plant, and out into the atmosphere. Winter wheat yield responds linearly to available soil water content at planting (bu/a = 5.56 + 5.34*inches). Therefore, storing precipitation in the soil during non-crop...

38

Soils - Part 2: Physical Properties of Soil and Soil Water  

NSDL National Science Digital Library

This lesson will help you understand the major components of the physical properties of soil. You will learn such terms as texture, aggregation, soil structure, bulk density, and porosity as it relates to soils. You will learn how soil holds and transmits water and cultural practices that enhance or degrade physical properties of the soil.[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.

39

Semiarid soil and water conservation  

Microsoft Academic Search

This book provides an overview of soil and water conservation and emphasizes practical control measures. Contents include surface hydrology, analysis of the erosion process, and practical control measures through: correct land use; crop rotations; shifting cultivation; contour farming; and strip cropping; Water harvesting, recently developed systems now in use, and rangeland management for soil and water conservation in semi-arid regions

1986-01-01

40

soils.ifas.ufl.edu Soil & Water Science Department  

E-print Network

soils.ifas.ufl.edu UF/IFAS Soil & Water Science Department DISTANCE EDUCATION GRADUATE PROGRAMS #12;SOIL AND WATER SCIENCE DEPARTMENT The Soil and Water Science Department at the University of Florida in agricultural science. #12;CERTIFICATE PROGRAMS The Soil and Water Science Department also offers several

Watson, Craig A.

41

Field study of gravel admix, vegetation, and soil water interactions: Protective Barrier Program Status Reprt - FY 1989  

SciTech Connect

Pacific Northwest Laboratory (PNL) and Westinghouse Hanford Company (Westinghouse Hanford) are collaborating on a field study of the effects of gravel admixtures on plant growth and soil water storage in protective barriers. Protective barriers are engineered earthern covers designed to prevent water, plants, and animals from contacting buried waste and transporting contaminants to groundwater or the land surface. Some of the proposed designs include gravel admixtures or gravel mulches on the barrier surface to control soil loss by wind and runoff. The purpose of this study is to measure, in a field setting, the influence of surface gravel additions on soil water storage and plant cover. The study plots are located northwest of the Yakima Gate in the McGee Ranch old field. Here we report the status of work completed in FY 1989 on the creation of a data management system, a test of water application uniformity, field calibration of neutron moisture gages, and an analysis of the response of plants to various combinations of gravel admixtures and increased rainfall. 23 refs., 11 figs., 6 tabs.

Waugh, W.J.; Thiede, M.E.; Kemp, C.J.; Cadwell, L.L. Link, S.O.

1990-08-01

42

Sources, interactions, and ecological impacts of organic contaminants in water, soil, and sediment: an introduction to the special series.  

PubMed

Agricultural and urban activities result in the release of a large number of organic compounds that are suspected of impacting human health and ecosystems: herbicides, insecticides, human and veterinary pharmaceuticals, natural and synthetic hormones, personal care products, surfactants, plasticizers, fire retardants, and others. Sorbed reservoirs of these compounds in soil represent a potentially chronic source of water contamination. This article is an introduction to a series of technical papers stemming from a symposium at the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America 2008 Annual Meeting, which was held jointly with The Geological Society of America, The Gulf Coast Association of Geological Scientists, and the Houston Geological Society, under one of the Joint Meeting's overarching themes: Emerging Trace Contaminants in Surface and Ground Water Generated from Waste Water and Solid Waste Application. The symposium emphasized the role of soils as sources, sinks, and reaction catalysts for these contaminants and the occurrence and fate of these contaminants in surface and underground water supplies. Topics covered included novel advances in analytical techniques, transport of infectious agents, occurrence and fate of veterinary pharmaceuticals, characterization of sorption mechanism, biotic and abiotic transformation reactions, the role of soil components, occurrence and fate in wastewater treatment systems, transport of engineered nanoparticles, groundwater contamination resulting from urban runoff, and issues in water reuse. Overviews of the reports, trends, gaps in our knowledge, and topics for further research are presented in this special series of papers. The technical papers in this special series reflect current gains in knowledge and simultaneously underscore how poorly we are able to predict the fate and, hence, the associated risk to ecological and human receptors of these contaminants. PMID:20830899

Pignatello, Joseph J; Katz, Brian G; Li, Hui

2010-01-01

43

Quantitative simulation tools to analyze up- and downstream interactions of soil and water conservation measures: supporting policy making in the Green Water Credits program of Kenya.  

PubMed

Upstream soil and water conservation measures in catchments can have positive impact both upstream in terms of less erosion and higher crop yields, but also downstream by less sediment flow into reservoirs and increased groundwater recharge. Green Water Credits (GWC) schemes are being developed to encourage upstream farmers to invest in soil and water conservation practices which will positively effect upstream and downstream water availability. Quantitative information on water and sediment fluxes is crucial as a basis for such financial schemes. A pilot design project in the large and strategically important Upper-Tana Basin in Kenya has the objective to develop a methodological framework for this purpose. The essence of the methodology is the integration and use of a collection of public domain tools and datasets: the so-called Green water and Blue water Assessment Toolkit (GBAT). This toolkit was applied in order to study different options to implement GWC in agricultural rainfed land for the pilot study. Impact of vegetative contour strips, mulching, and tied ridges were determined for: (i) three upstream key indicators: soil loss, crop transpiration and soil evaporation, and (ii) two downstream indicators: sediment inflow in reservoirs and groundwater recharge. All effects were compared with a baseline scenario of average conditions. Thus, not only actual land management was considered but also potential benefits of changed land use practices. Results of the simulations indicate that especially applying contour strips or tied ridges significantly reduces soil losses and increases groundwater recharge in the catchment. The model was used to build spatial expressions of the proposed management practices in order to assess their effectiveness. The developed procedure allows exploring the effects of soil conservation measures in a catchment to support the implementation of GWC. PMID:22922092

Hunink, J E; Droogers, P; Kauffman, S; Mwaniki, B M; Bouma, J

2012-11-30

44

Soil and Human Interactions in Maya Wetlands  

NASA Astrophysics Data System (ADS)

Since the early 1990s, we have studied Maya interaction with soils in Mexico, Belize, Guatemala, and elsewhere. We studied upland and lowland soils, but here we focus on seasonal or 'Bajo' wetlands and perennial wetlands for different reasons. Around the bajos, the ancient Maya focused on intensive agriculture and habitation despite the difficulties their Vertisol soils posed. For the perennial wetlands, small populations spread diffusely through Mollisol and Histisol landscapes with large scale, intensive agro-ecosystems. These wetlands also represent important repositories for both environmental change and how humans responded in situ to environmental changes. Work analyzing bajo soils has recorded significant diversity but the soil and sediment record shows two main eras of soil instability: the Pleistocene-Holocene transition as rainfall fluctuated and increased and tropical forest pulsed through the region, and the Maya Preclassic to Classic 3000 to 1000 BP as deforestation, land use intensity, and drying waxed and waned. The ancient Maya adapted their bajo soil ecosystems successfully through agro-engineering but they also withdrew in many important places in the Late Preclassic about 2000 BP and Terminal Classic about 1200 BP. We continue to study and debate the importance of perennial wetland agro-ecosystems, but it is now clear that Maya interaction with these soil landscapes was significant and multifaceted. Based on soil excavation and coring with a broad toolkit of soil stratigraphy, chemistry, and paleoecology from 2001 to 2013, our results show the ancient Maya interacted with their wetland soils to maintain cropland for maize, tree crops, arrow root, and cassava against relative sea level rise, increased flooding, and aggradation by gypsum precipitation and sedimentation. We have studied these interactions across an area of 2000 km2 in Northern Belize to understand how Maya response varied and how these soil environments varied over time and distance. Most areas dealt with water table rise and gypsum aggradation from extremely sulfur- and calcium-rich water sources. Thus far we have evidence for Archaic to Classic aggradation (5000 BP to the present) and Classic period fields and canals as mostly piecemeal attempts by the Maya to adapt to these and other environmental changes. Wetland fields were mainly Classic period systems (1500 to 1000 BP) but varied from long- to short-lived. We found one example of a very Late/Terminal Classic (c. 1200 BP), preplanned reclamation project on a floodplain. One system had some reoccupation in the Postclassic about 800 BP. These findings and a recent discovery in Campeche, MX display the burgeoning evidence for intricate Maya connections with tropical wetland soils.

Beach, Timothy; Luzzadder-Beach, Sheryl

2013-04-01

45

Alkali Soils, Irrigation Waters.  

E-print Network

for sev- eral Tears been collecting data in regard to the occurrence, and nature of alkali soils in Texas. It appears time for us to gi ~ort of pro'gresq containing informntion concerning alkali. Alks imp0 r- tant matter in some portions of the State... of cjt? of Pecus. Grass grows where irrigated; otherwise, almost bzre, 5 inches. RTater d~es not penetrate this soil, but flows off on other soils and injures them. 1799-Soil from near Pecos and partly washed from ap hills and !lot regarded as good...

Fraps, G. S. (George Stronach)

1910-01-01

46

Profiling soil water content sensor  

Technology Transfer Automated Retrieval System (TEKTRAN)

A waveguide-on-access-tube (WOAT) sensor system based on time domain reflectometry (TDR) principles was developed to sense soil water content and bulk electrical conductivity in 20-cm (8 inch) deep layers from the soil surface to depths of 3 m (10 ft) (patent No. 13/404,491 pending). A Cooperative R...

47

Estimating soil water retention using soil component additivity model  

NASA Astrophysics Data System (ADS)

Soil water retention is a major soil hydraulic property that governs soil functioning in ecosystems and greatly affects soil management. Data on soil water retention are used in research and applications in hydrology, agronomy, meteorology, ecology, environmental protection, and many other soil-related fields. Soil organic matter content and composition affect both soil structure and adsorption properties; therefore water retention may be affected by changes in soil organic matter that occur because of both climate change and modifications of management practices. Thus, effects of organic matter on soil water retention should be understood and quantified. Measurement of soil water retention is relatively time-consuming, and become impractical when soil hydrologic estimates are needed for large areas. One approach to soil water retention estimation from readily available data is based on the hypothesis that soil water retention may be estimated as an additive function obtained by summing up water retention of pore subspaces associated with soil textural and/or structural components and organic matter. The additivity model and was tested with 550 soil samples from the international database UNSODA and 2667 soil samples from the European database HYPRES containing all textural soil classes after USDA soil texture classification. The root mean square errors (RMSEs) of the volumetric water content estimates for UNSODA vary from 0.021 m3m-3 for coarse sandy loam to 0.075 m3m-3 for sandy clay. Obtained RMSEs are at the lower end of the RMSE range for regression-based water retention estimates found in literature. Including retention estimates of organic matter significantly improved RMSEs. The attained accuracy warrants testing the 'additivity' model with additional soil data and improving this model to accommodate various types of soil structure. Keywords: soil water retention, soil components, additive model, soil texture, organic matter.

Zeiliger, A.; Ermolaeva, O.; Semenov, V.

2009-04-01

48

A new model for humic materials and their interactions with hydrophobic organic chemicals in soil-water or sediment-water systems  

USGS Publications Warehouse

A generalized model of humic materials in soils and sediments, which is consistent with their observed properties, is presented. This model provides a means of understanding the interaction of hydrophobic pollutants with humic materials. In this model, it is proposed that the humic materials in soils and sediments consist of a number of different oligomers and simple compounds which result from the partial degradation of plant remains. These degradation products are stabilized by incorporation into humic aggregates bound together by weak bonding mechanisms, such as hydrogen bonding, pi bonding, and hydrophobic interactions. The resulting structures are similar to micelles or membranes, in which the interiors of the structures are hydrophobic and the exteriors are hydrophilic. Hydrophobic compounds will partition into the hydrophobic interiors of the humic micelles or "membrane-like" structures. ?? 1986.

Wershaw, R.L.

1986-01-01

49

The Effects of Microbiotic Soil Crustson Soil Water Loss  

Microsoft Academic Search

Microbiotic soil crusts play several important roles in many arid and semiarid ecosystems around the world. Their effects on soil hydrology, however, are poorly understood. It has been speculated that crusts (1) improve soil water availability by \\

D. B. George; B. A. Roundy; L. L. S. T. CLAIR; J. R. Johansen; G. B. Schaalje; B. L. Webb

2003-01-01

50

Soil and Water Conservation Spring 2014  

E-print Network

SWS 4233 Soil and Water Conservation Spring 2014 Instructor Susan Curry scurry@ufl.edu 352 equations and reduction practices, government conservation programs; water conservation, irrigation students with an understanding of the interconnectedness of soil and water conservation. The course

Ma, Lena

51

Can the soil properties affect the O and H isotopic composition of the soil water?  

NASA Astrophysics Data System (ADS)

Understanding the dynamic of the soil water content is of primary importance since it is the vector of the matter exchange between soil and the other compartments of watersheds. The soil water is the phase, which is best suited to characterize the current dynamics in the soil and to provide information on mid- to long-term soil processes. Oxygen and Hydrogen stable isotopes of water are now currently used in hydrological studies to inform on water mixing and residence time in the soil and greatly contribute to improve our understanding of soil-water interactions. However, as of today the influence of biogeochemical processes on the spatio-temporal variability of ?18O and ?D of the soil solutions was rarely quantified. The Oxygen and Hydrogen exchanges between the soil water and the other soil compartments (living organisms, mineral, exchange capacity, organic matter) are still poorly studied and require deeper investigations. For instance, the weathering of silicate minerals produces O2+ in the soil solution, exchange capacity in acidic soils releases quantity of H+ in the soil solution and the degradation of the organic matter could also impact the Oxygen and Hydrogen isotope ratios of the soil water. But, are we able to quantify the contribution of these different processes to the Oxygen and Hydrogen isotopic composition of the soil water? In order to address this question, we set up a laboratory experiment with one liter soil columns of a 2mm-sieved and air-dried soil. The goal of the experiment was to observe the variation of the water Oxygen and Hydrogen isotopic composition at two different depths of these soil columns starting from the field capacity to the complete drying of the soil. Water with a known isotopic composition was used to saturate the soil matrix and we observed the deviation from this initial composition at the different depths during the drying of the soil using ceramic cup lysimeters. Three steps of saturation were applied during the entire experiment. The deviation from the initial isotopic composition becomes significant in the soil waters at the different depths after two weeks of experiment and increases until reaching a threshold at the end of the experiment. After each new saturation step, the isotopic composition of the input water is not conserved anymore in the collected solutions and increases instantaneously. This observation may illustrate the potential for the soil bio-physico-chemical activities to contribute to the O and H composition of the soil water. These preliminary results allowed us to evaluate the contribution of the evaporation process in the Oxygen and Hydrogen isotopic fractionation and to deduce the potential contribution of soil compartments.

Hissler, Christophe; Legout, Arnaud; Barnich, François; Stoll, Martine; Klaus, Julian

2014-05-01

52

The effect of soil water upon soil albedo  

E-print Network

THE EFFECT OF SOIL WATER UPON SOIL ALBEDO A Thesis by ELIZABETH ANNETTE GRASER Submitted to the Graduate College of Texas A/M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 19S1 Major Sub...]ect: Soil Science THE EFFECT OF SOIL WATER UPON SOIL ALBEDO A Thesis by ELI ZABETH ANNETTE GRASER Approved as to style and content by: arrman of Committee Mem er Rem er ea o epar nt August 1981 The Effect of Soil Water upon Soil Albedo. (August...

Graser, Elizabeth Annette

1981-01-01

53

Soil and Water Conservation Spring 2014  

E-print Network

1 SWS 4233 Soil and Water Conservation 3 Credits Spring 2014 Instructor Susan Curry scurry, government conservation programs; water conservation, irrigation, drainage and salinity; stormwater of the interconnectedness of soil and water conservation. The course focusses on soil and water management as it relates

Ma, Lena

54

Irrigation Monitoring with Soil Water Sensors  

E-print Network

Monitoring soil water content is essential if growers want to optimize production, conserve water, reduce environmental impacts and save money. This publication illustrates how soil moisture monitoring can improve irrigation decisions and how...

Enciso, Juan; Porter, Dana; Peries, Xavier

2007-01-19

55

Nature of water molecular bridging of the soil organic matter  

NASA Astrophysics Data System (ADS)

Soil is a complex anisotropic and porous system consisting of both inorganic and organic parts, air and water, inhabited and successively transformed by soil biota. Processes of soil formation are influenced by several factors. Among the most important factors belong the inorganic and organic input materials, which are mixed and transformed during soil formation. As a result, specific interactions and interrelationships develop between soil compartments. Although, they are important for soil function and its stability, they are still not well understood. This work deals with water molecule bridges (WaMB), as one of those interactions, and their relation to organic matter functioning. Differential scanning calorimetry (DSC) belongs to the family of methods of thermal analysis, i.e. it uses heat as a probe of the sample's nature. In soil science, the application of this common method is quite rare. In our previous works, DSC revealed a physical stabilization of organic matter segments in soils by development of WaMB. Results suggested the development of those bridges at ambient temperature accompanied with condensation of water into small nanodroplets. In another work, we found out that water, evaporating at the same temperature as WaMB transition occurs, correlates with the activity of soil microorganisms measured via CO2respiration. In this work, the enthalpy and kinetic parameters of water evaporation are studied in two kinds of soil: in clay-rich chernozem soils originating from Siberia and a histosol collected in Germany. We discuss the details of application of DSC, experimental arrangement and advantages and disadvantages of this approach. It is shown that enthalpy of evaporation can be used for understanding the nature of water binding in soils with well-developed aggregates. In contrast, the evaporation of water from histosol, without a typical soil texture, is more complicated because of diffusion processes. Further, the connection between enthalpy of evaporation and soil microbiological activity is discussed.

Kucerik, Jiri; Siewert, Christian; Quilesfogel-Esparza, Claudia; Schaumann, Gabriele E.

2014-05-01

56

SOIL PHYSICAL PROPERTIES, PROCESSES AND ASSOCIATED ROOT-SOIL INTERACTIONS  

Microsoft Academic Search

The soil is the most upper part of the vadose zone, subject to fluctuations in water and chemical content by infiltration\\u000a and leaching, water uptake by plant roots, and evaporation from the soil surface. It is the most dynamic, as changes occur\\u000a at increasingly smaller time and spatial scales when moving from the groundwater towards the soil surface. Scientists are

Jan W. HOPMANS

57

Macroscopic modeling of plant water uptake: soil and root resistances  

NASA Astrophysics Data System (ADS)

The macroscopic physically-based plant root water uptake (RWU) model, based on water-potential-gradient formulation (Vogel et al., 2013), was used to simulate the observed soil-plant-atmosphere interactions at a forest site located in a temperate humid climate of central Europe and to gain an improved insight into the mutual interplay of RWU parameters that affects the soil water distribution in the root zone. In the applied RWU model, the uptake rates are directly proportional to the potential gradient and indirectly proportional to the local soil and root resistances to water flow. The RWU algorithm is implemented in a one-dimensional dual-continuum model of soil water flow based on Richards' equation. The RWU model is defined by four parameters (root length density distribution, average active root radius, radial root resistance, and the threshold value of the root xylem potential). In addition, soil resistance to water extraction by roots is related to soil hydraulic conductivity function and actual soil water content. The RWU model is capable of simulating both the compensatory root water uptake, in situations when reduced uptake from dry layers is compensated by increased uptake from wetter layers, and the root-mediated hydraulic redistribution of soil water, contributing to more natural soil moisture distribution throughout the root zone. The present study focusses on the sensitivity analysis of the combined soil water flow and RWU model responses in respect to variations of RWU model parameters. Vogel T., M. Dohnal, J. Dusek, J. Votrubova, and M. Tesar. 2013. Macroscopic modeling of plant water uptake in a forest stand involving root-mediated soil-water redistribution. Vadose Zone Journal, 12, 10.2136/vzj2012.0154.

Vogel, Tomas; Votrubova, Jana; Dohnal, Michal; Dusek, Jaromir

2014-05-01

58

A review on temporal stability of soil water contents  

Technology Transfer Automated Retrieval System (TEKTRAN)

Temporal stability of soil water content (TS SWC) has been observed across a wide range of soil types, landscapes, climates and scales. A better understanding of TS SWC controls and their interactions needs to be developed. The objective of this work is to develop a comprehensive inventory of publis...

59

INTERACTION OF METHYL-TERT BUTYL ETHER AND WATER STRESS ON SEED GERMINATION AND SEEDLING GROWTH IN SOIL MICROCOSMS  

EPA Science Inventory

Methyl tert-butyl ether (MTBE) is a widespread contaminant in surface and ground water in the United States. Frequently irrigation is used to water fields to germinate planted seeds and sustain plant growth. A likely possibility exists that water used may have some MTBE. Our s...

60

The moisture response of soil heterotrophic respiration: interaction with soil properties  

NASA Astrophysics Data System (ADS)

Soil moisture is of primary importance for predicting the evolution of soil carbon stocks and fluxes, both because it strongly controls organic matter decomposition and because it is predicted to change at global scales in the following decades. However, the soil functions used to model the heterotrophic respiration response to moisture have limited empirical support and introduce an uncertainty of at least 4% in global soil carbon stock predictions by 2100. The necessity of improving the representation of this relationship in models has been highlighted in recent studies. Here we present a data-driven analysis of soil moisture-respiration relations based on 90 soils. With the use of linear models we show how the relationship between soil heterotrophic respiration and different measures of soil moisture is consistently affected by soil properties. The empirical models derived include main effects and moisture interaction effects of soil texture, organic carbon content and bulk density. When compared to other functions currently used in different soil biogeochemical models, we observe that our results can correct biases and reconcile differences within and between such functions. Ultimately, accurate predictions of the response of soil carbon to future climate scenarios will require the integration of soil-dependent moisture-respiration functions coupled with realistic representations of soil water dynamics.

Moyano, F. E.; Vasilyeva, N.; Bouckaert, L.; Cook, F.; Craine, J.; Curiel Yuste, J.; Don, A.; Epron, D.; Formanek, P.; Franzluebbers, A.; Ilstedt, U.; Kätterer, T.; Orchard, V.; Reichstein, M.; Rey, A.; Ruamps, L.; Subke, J.-A.; Thomsen, I. K.; Chenu, C.

2012-03-01

61

The moisture response of soil heterotrophic respiration: interaction with soil properties  

NASA Astrophysics Data System (ADS)

Soil moisture is of primary importance for predicting the evolution of soil carbon stocks and fluxes, both because it strongly controls organic matter decomposition and because it is predicted to change at global scales in the following decades. However, the soil functions used to model the heterotrophic respiration response to moisture have limited empirical support and introduce an uncertainty of at least 4 % in global soil carbon stock predictions by 2100. The necessity of improving the representation of this relationship in models has been highlighted in recent studies. Here we present a data-driven analysis of soil moisture-respiration relations based on 90 soils. With the use of linear models we show how the relationship between soil heterotrophic respiration and different measures of soil moisture is consistently affected by soil properties. The empirical models derived include main and moisture interaction effects of soil texture, organic carbon content and bulk density. When compared to other functions currently used in different soil biogeochemical models, we observe that our results can correct biases and reconcile differences within and between such functions. Ultimately, accurate predictions of the response of soil carbon to future climate scenarios will require the integration of soil-dependent moisture-respiration functions coupled with realistic representations of soil water dynamics.

Moyano, F. E.; Vasilyeva, N.; Bouckaert, L.; Cook, F.; Craine, J.; Curiel Yuste, J.; Don, A.; Epron, D.; Formanek, P.; Franzluebbers, A.; Ilstedt, U.; Kätterer, T.; Orchard, V.; Reichstein, M.; Rey, A.; Ruamps, L.; Subke, J.-A.; Thomsen, I. K.; Chenu, C.

2011-12-01

62

Phosphorus transfer from soil to surface waters  

Microsoft Academic Search

The release of phosphate ions (PO4–P) from soils to surface waters and overland flow was examined in this study. Sand and undisturbed soil cores were ponded in beakers and the surface waters were subjected to a gentle swirling action by a paddle agitator. Slabs of soil were also placed in a flume, saturated and subjected to overland flow. A comparison

J Mulqueen; M Rodgers; P Scally

2004-01-01

63

How soil organic matter composition controls hexachlorobenzene-soil-interactions: adsorption isotherms and quantum chemical modeling.  

PubMed

Hazardous persistent organic pollutants (POPs) interact in soil with the soil organic matter (SOM) but this interaction is insufficiently understood at the molecular level. We investigated the adsorption of hexachlorobenzene (HCB) on soil samples with systematically modified SOM. These samples included the original soil, the soil modified by adding a hot water extract (HWE) fraction (soil+3 HWE and soil+6 HWE), and the pyrolyzed soil. The SOM contents increased in the order pyrolyzed soilsoil+3 HWE<soil+6 HWE. For the latter three samples this order was also valid for the HCB adsorption. The pyrolyzed soil adsorbed more HCB than the other samples at low initial concentrations, but at higher concentrations the HCB adsorption became weaker than in the samples with HWE addition. This adsorption combined with the differences in the chemical composition between the soil samples suggested that alkylated aromatic, phenol, and lignin monomer compounds contributed most to the HCB adsorption. To obtain a molecular level understanding, a test set has been developed on the basis of elemental analysis which comprises 32 representative soil constituents. The calculated binding energy for HCB with each representative system shows that HCB binds to SOM stronger than to soil minerals. For SOM, HCB binds to alkylated aromatic, phenols, lignin monomers, and hydrophobic aliphatic compounds stronger than to polar aliphatic compounds confirming the above adsorption isotherms. Moreover, quantitative structure-activity relationship (QSAR) of the binding energy with independent physical properties of the test set systems for the first time indicated that the polarizability, the partial charge on the carbon atoms, and the molar volume are the most important properties controlling HCB-SOM interactions. PMID:24463030

Ahmed, Ashour A; Kühn, Oliver; Aziz, Saadullah G; Hilal, Rifaat H; Leinweber, Peter

2014-04-01

64

iSOIL: Interactions between soil related sciences - Linking geophysics, soil science and digital soil mapping  

NASA Astrophysics Data System (ADS)

High-resolution soil property maps are one major prerequisite for the specific protection of soil functions and restoration of degraded soils as well as sustainable land use, water and environmental management. To generate such maps the combination of digital soil mapping approaches and remote as well as proximal soil sensing techniques is most promising. However, a feasible and reliable combination of these technologies for the investigation of large areas (e.g. catchments and landscapes) and the assessment of soil degradation threats is missing. Furthermore, there is insufficient dissemination of knowledge on digital soil mapping and proximal soil sensing in the scientific community, to relevant authorities as well as prospective users. As one consequence there is inadequate standardization of techniques. At the poster we present the EU collaborative project iSOIL within the 7th framework program of the European Commission. iSOIL focuses on improving fast and reliable mapping methods of soil properties, soil functions and soil degradation risks. This requires the improvement and integration of advanced soil sampling approaches, geophysical and spectroscopic measuring techniques, as well as pedometric and pedophysical approaches. The focus of the iSOIL project is to develop new and to improve existing strategies and innovative methods for generating accurate, high resolution soil property maps. At the same time the developments will reduce costs compared to traditional soil mapping. ISOIL tackles the challenges by the integration of three major components: (i)high resolution, non-destructive geophysical (e.g. Electromagnetic Induction EMI; Ground Penetrating Radar, GPR; magnetics, seismics) and spectroscopic (e.g., Near Surface Infrared, NIR) methods, (ii)Concepts of Digital Soil Mapping (DSM) and pedometrics as well as (iii)optimized soil sampling with respect to profound soil scientific and (geo)statistical strategies. A special focus of iSOIL lies on the sustainable dissemination of technologies and concepts developed in the projects through workshops for stakeholders and the publication of a handbook "Methods and Technologies for Mapping of Soil Properties, Function and Threat Risks". Besides, the CEN Workshop offers a new mechanism and approach to standardization. During the project we decided that the topic of the CEN Workshop should focus on a voluntary standardization of electromagnetic induction measurement to ensure that results can be evaluated and processed under uniform circumstances and can be comparable. At the poster we will also present the idea and the objectives of our CEN Workshop "Best Practice Approach for electromagnetic induction measurements of the near surface"and invite every interested person to participate.

Dietrich, Peter; Werban, Ulrike; Sauer, Uta

2010-05-01

65

Soil Water and Temperature System (SWATS) Handbook  

SciTech Connect

The soil water and temperature system (SWATS) provides vertical profiles of soil temperature, soil-water potential, and soil moisture as a function of depth below the ground surface at hourly intervals. The temperature profiles are measured directly by in situ sensors at the Central Facility and many of the extended facilities of the SGP climate research site. The soil-water potential and soil moisture profiles are derived from measurements of soil temperature rise in response to small inputs of heat. Atmospheric scientists use the data in climate models to determine boundary conditions and to estimate the surface energy flux. The data are also useful to hydrologists, soil scientists, and agricultural scientists for determining the state of the soil.

Bond, D

2005-01-01

66

Data assimilation with soil water content sensors and pedotransfer functions in soil water flow modeling  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil water flow models are based on a set of simplified assumptions about the mechanisms, processes, and parameters of water retention and flow. That causes errors in soil water flow model predictions. Soil water content monitoring data can be used to reduce the errors in models. Data assimilation (...

67

A minimalist probabilistic description of root zone soil water  

USGS Publications Warehouse

The probabilistic response of depth-integrated soil water to given climatic forcing can be described readily using an existing supply-demand-storage model. An apparently complex interaction of numerous soil, climate, and plant controls can be reduced to a relatively simple expression for the equilibrium probability density function of soil water as a function of only two dimensionless parameters. These are the index of dryness (ratio of mean potential evaporation to mean precipitation) and a dimensionless storage capacity (active root zone soil water capacity divided by mean storm depth). The first parameter is mainly controlled by climate, with surface albedo playing a subsidiary role in determining net radiation. The second is a composite of soil (through moisture retention characteristics), vegetation (through rooting characteristics), and climate (mean storm depth). This minimalist analysis captures many essential features of a more general probabilistic analysis, but with a considerable reduction in complexity and consequent elucidation of the critical controls on soil water variability. In particular, it is shown that (1) the dependence of mean soil water on the index of dryness approaches a step function in the limit of large soil water capacity; (2) soil water variance is usually maximized when the index of dryness equals 1, and the width of the peak varies inversely with dimensionless storage capacity; (3) soil water has a uniform probability density function when the index of dryness is 1 and the dimensionless storage capacity is large; and (4) the soil water probability density function is bimodal if and only if the index of dryness is <1, but this bimodality is pronounced only for artificially small values of the dimensionless storage capacity.

Milly, P.C.D.

2001-01-01

68

Thresholds of biotic/abiotic interactions in soil carbon storage  

NASA Astrophysics Data System (ADS)

Thresholds of biotic/abiotic interactions during soil development are linked to the spatial proximity of biological inputs and chemical weathering. On stable landforms, the downward transport of water and weathering products through soils give rise to vertical biogeochemical and mineralogical gradients, and the shape of these gradients change through time as the soil development proceeds. The weathering-zone, where rates of mineral dissolution and precipitation are greatest, typically migrates downward through the soil profile with increased duration of soil development. As the weathering-zone moves deeper in the soil profile, away from the zone of maximum biological inputs, abiotic/biotic interactions controlling the formation of secondary minerals and the stabilization of carbon may shift toward new stable states. Here we explore the relationship between soil development and organic carbon storage and stability and evaluate the existence of threshold behavior in soil carbon sequestration. We compare depth profiles of soil mineralogy, geochemistry and surface area with carbon stocks and radiocarbon content for a soil chronosequence spanning 1200 kyr. Results show a strong inverse correlation between radiocarbon content and mineral surface area and indicate the possible existence of a threshold behavior in soil carbon stabilization. Increases in surface area appear to arise from increasing amounts of secondary clay precipitation. Such thresholds have been previously observed in systems where short-range order minerals are prevalent but we demonstrate they may also be important in other soils. We use the reactive transport model CrunchFlow to evaluate the relationship of organic inputs and chemical weathering and to explore the influence of climate (specifically water flux) on soil threshold behavior.

Lawrence, C. R.; Harden, J. W.; Schulz, M. S.; Maher, K.

2013-12-01

69

Hyphal interactions among some soil fungi  

Microsoft Academic Search

Summary  Hyphal interactions amongRhizopus oryzae, a dominant soil inhabiting fungus and soil fungi with potential antagonistic characters, were studiedin vitro. Results depict that diameter of the hyphae of interacting fungi plays an important role in hyperparasitic interactions.\\u000a None of the hyphae with wide diam. could penetrate inside and coil around the hyphae ofR. oryzae, while most of the hyphae with narrow

R. S. Dwivedi; D. K. Arora

1978-01-01

70

The influence of water, land, energy and soil-nutrient resource interactions on the food system in Uganda  

E-print Network

and woodlands. Particularly disconcerting is the estimated 4.7 TgC of the tropical forest biomass, which contributes to Uganda’s serious 2% deforestation rate (UBOS, 2012, p.2). 4.3 Energy Sankey 2012 Figure 10 illustrates Uganda’s 2012 Energy Flows... .3.1 Water Stress According to FAO statistics (FAOSTAT, 2013), over 90% of the agriculture in Sub-Saharan Africa is rain-fed. This leads to perennial food shortages on account of failing rains, as reported in the USAID monthly surveillance report...

Mukuve, Feriha Mugisha; Fenner, Richard A.

2014-12-31

71

Phosphorus in Soil and Water  

NSDL National Science Digital Library

Many waterways are considered polluted due, at least in part, to excessive amounts of phosphorus. This topic-in-depth delves into the issues surrounding phosphorus in the environment. First, Larry G. Bundy at the University of Wisconsin - Madison provides a slide show about phosphorus's presence in soils (1). Students can discover the agronomic need for phosphorus, its effects on water quality and management issues. The second web site, created by the University of Florida Cooperative Extension Service, offers a great overview of how wetlands affect the retention, cycling, and release of phosphorus in wetlands (2). Users will find a straightforward diagram of the phosphorus cycle in wetlands. Next, Manitoba Agriculture, Food, and Rural Initiatives present the reasons for careful management of phosphorus in fertilizers, manure, detergents, sewage, and industrial waste (3). The web site effectively summarizes how phosphorus gets into the surface water and negatively influences the environment. Developed by the USGS, the fourth web site addresses the pollution concerns surrounding agricultural landscapes (4). Visitors can learn about the amounts and effects of the erosion of phosphorus, as well as nitrogen and pesticides, on nearby streams and lakes. Next, the Minnesota Environmental Partnership discusses why Minnesota has restricted the use of phosphorus-containing fertilizers on lawns (5). Visitors can discover tips for buying fertilizers and how to deal with the leftovers. The sixth web site describes the USDA's Agricultural Research Service's findings that residue from water-treatment processes may increase soil's capacity to adsorb phosphorus (6). Users can discover how this may help reduce the transport of phosphorus into the watershed, especially in sandy soils. Next, the Australian Government's National Eutrophication Management Program presents its research examining phosphorus erosion, external things that affect its movement, predictive capabilities, and ways to reduce its movement (7). Visitors can learn about the researchers' discoveries that phosphorus can enter waterways through the subsoil. Lastly, the Minnesota Department of Agriculture describes the concept of a watershed and how they influence water quality (8). Users can find out how to reduce the amount of phosphorus entering nearby streams and lakes and how to help their watershed.

72

On water vapor transport in field soils  

Microsoft Academic Search

Measurements of soil volumetric moisture content and temperature were made at 2, 4, 7, 10, and 15 cm below the surface of a bare field soil, over a 1-week period at 20-min intervals. The conductive heat and liquid moisture fluxes were calculated for the soil layer 7-10 cm below the surface, and the water vapor flux was then determined from

Anthony T. Cahill; Marc B. Parlange

1998-01-01

73

DIVISION S-6--SOIL & WATER MANAGEMENT & CONSERVATION  

E-print Network

DIVISION S-6--SOIL & WATER MANAGEMENT & CONSERVATION Soil Organic Carbon Sequestration Rates soil column within 20 yr following culti- Carbon sequestration rates, with a change from CT to NT, can in approximately 40 to and returning to the original land cover or other peren- 60 yr. Carbon sequestration rates

74

SOIL WATER ESTIMATION USING ELECTROMAGNETIC INDUCTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Two published salinity models (designated the Rhoades and Mualem - Friedman models) were examined for application to real-time soil water estimation using apparent soil electrical conductivity. Field data were collected at two sites representing a range of soil types in Central Texas: high shrinkin...

75

Plant Water Uptake in Drying Soils1  

PubMed Central

Over the last decade, investigations on root water uptake have evolved toward a deeper integration of the soil and roots compartment properties, with the goal of improving our understanding of water acquisition from drying soils. This evolution parallels the increasing attention of agronomists to suboptimal crop production environments. Recent results have led to the description of root system architectures that might contribute to deep-water extraction or to water-saving strategies. In addition, the manipulation of root hydraulic properties would provide further opportunities to improve water uptake. However, modeling studies highlight the role of soil hydraulics in the control of water uptake in drying soil and call for integrative soil-plant system approaches. PMID:24515834

Lobet, Guillaume; Couvreur, Valentin; Meunier, Félicien; Javaux, Mathieu; Draye, Xavier

2014-01-01

76

Plant water uptake in drying soils.  

PubMed

Over the last decade, investigations on root water uptake have evolved toward a deeper integration of the soil and roots compartment properties, with the goal of improving our understanding of water acquisition from drying soils. This evolution parallels the increasing attention of agronomists to suboptimal crop production environments. Recent results have led to the description of root system architectures that might contribute to deep-water extraction or to water-saving strategies. In addition, the manipulation of root hydraulic properties would provide further opportunities to improve water uptake. However, modeling studies highlight the role of soil hydraulics in the control of water uptake in drying soil and call for integrative soil-plant system approaches. PMID:24515834

Lobet, Guillaume; Couvreur, Valentin; Meunier, Félicien; Javaux, Mathieu; Draye, Xavier

2014-04-01

77

Soil Water and Shallow Groundwater Relations in an Agricultural Hillslope  

Technology Transfer Automated Retrieval System (TEKTRAN)

Shallow water tables contribute to soil water variations under rolling topography, and soil properties contribute to shallow water table fluctutations. Preferential flow through large soil pores can cause a rise in the water table with little increase in soil water except near the soil surface. Late...

78

Porosity and Water Flow in Soils  

NSDL National Science Digital Library

Three different types of sediments will be taken and the porosity and water flow rate for each type will be determined. From this activity, students will understand concepts of porosity and water flow through soil material.

Tej Gautam

79

Stochastic analysis of soil-structure interaction  

E-print Network

This study investigates the effect of soil structure interaction on the response of a building subjected to an earthquake motion. Spectra consisting of the auto and cross spectral densities of three components of free-field earthquake motion at all...

Chan, Charles Cheuk Lap

1994-01-01

80

IRRIGATION OPTIMIZATION BY MODELING OF PLANT-SOIL INTERACTION  

E-print Network

IRRIGATION OPTIMIZATION BY MODELING OF PLANT-SOIL INTERACTION Zhongping Li Laboratory of Applied UMR G-EAU Cemagref Montpellier, France ABSTRACT Irrigation scheduling is an important issue for crop agricultural productivity. Methods to optimize crop irrigation should take into ac- count the impact of water

Boyer, Edmond

81

America's Soil and Water: Condition and Trends.  

ERIC Educational Resources Information Center

A review of conditions and trends regarding soil and water resources of rural nonfederal lands of the United States is presented in this publication. Maps, charts, and graphs illustrate the data collected on various aspects of soil and water use and practice. Topic areas considered include: (1) land use patterns; (2) classes of land; (3)…

1981

82

SOIL AND WATER ASSESSMENT TOOL 2000  

EPA Science Inventory

The Soil and Water Assessment Tool (SWAT), is a river basin, or watershed, scale model developed to predict the impact of land management practices on water, sediment and agricultural chemical yields in large complex watersheds with varying soils, land use and management conditio...

83

Water as a Reagent for Soil Remediation  

SciTech Connect

SRI International conducted experiments in a two-year, two-phase process to develop and evaluate hydrothermal extraction technology, also known as hot water extraction (HWE) technology, for remediating petroleum-contaminated soils. The bench-scale demonstration of the process has shown great promise, and the implementation of this technology will revolutionize the conventional use of water in soil remediation technologies and provide a standalone technology for removal of both volatile and heavy components from contaminated soil.

Jayaweera, Indira S.; Marti-Perez, Montserrat; Diaz-Ferrero, Jordi; Sanjurjo, Angel

2003-03-06

84

Variation of Water Retention in Various Soils of Kuwait  

Microsoft Academic Search

Soil properties varied in water retention; due to soil texture and organic matter content. Variations of texture in many soils are effected mostly to soil forming factors of parent materials of the soil; biological activities; climactic variation; and duration of soil reaction. While the organic matter contents are affected totally by the environmental conditions of the soils. Water holding capacity

M. Abdal; M. Suleiman; M. Albaho

2002-01-01

85

Variation Of Water Retention In Various Soils Of Kuwait  

Microsoft Academic Search

Soil properties varied in water retention; due to soil texture and organic matter content. Variations of texture in many soils are effected mostly to soil forming factors of parent materials of the soil, biological activities, climactic variation, and duration of soil reaction. While the organic matter contents are affected totally by the environmental conditions of the soils. Water holding capacity

M. Abdal; M. Suleiman; S. Al-Ghawas

2002-01-01

86

Seasonal and long-term effects of CO2 and O3 on water loss in ponderosa pine and their interaction with climate and soil moisture.  

PubMed

Evapotranspiration (ET) is driven by evaporative demand, available solar energy and soil moisture (SM) as well as by plant physiological activity which may be substantially affected by elevated CO2 and O3. A multi-year study was conducted in outdoor sunlit-controlled environment mesocosm containing ponderosa pine seedlings growing in a reconstructed soil-litter system. The study used a 2 x 2 factorial design with two concentrations of CO2 (ambient and elevated), two levels of O3 (low and high) and three replicates of each treatment. The objective of this study was to assess the effects of chronic exposure to elevated CO2 and O3, alone and in combination, on daily ET. This study evaluated three hypotheses: (i) because elevated CO2 stimulates stomatal closure, O3 effects on ET will be less under elevated CO2 than under ambient CO2; (ii) elevated CO2 will ameliorate the long-term effects of O3 on ET; and (iii) because conductance (g) decreases with decreasing SM, the impacts of elevated CO2 and O3, alone and in combination, on water loss via g will be greater in early summer when SM is not limiting than to other times of the year. A mixed-model covariance analysis was used to adjust the daily ET for seasonality and the effects of SM and photosynthetically active radiation when testing for the effects of CO2 and O3 on ET via the vapor pressure deficit gradient. The empirical results indicated that the interactive stresses of elevated CO2 and O3 resulted in a lesser reduction in ET via reduced canopy conductance than the sum of the individual effects of each gas. CO2-induced reductions in ET were more pronounced when trees were physiologically most active. O3-induced reductions in ET under ambient CO2 were likely transpirational changes via reduced conductance because needle area and root biomass were not affected by exposures to elevated O3 in this study. PMID:19748912

Lee, E Henry; Tingey, David T; Waschmann, Ronald S; Phillips, Donald L; Olszyk, David M; Johnson, Mark G; Hogsett, William E

2009-11-01

87

Increasing Efficiency of Water Use in Agriculture through Management of Soil Water Repellency to Optimize Soil and Water Productivity  

NASA Astrophysics Data System (ADS)

Water's ability to infiltrate and disperse in soils, and soil's ability to receive, transport, retain, filter and release water are important factors in the efficient use of water in agriculture. Deteriorating soil conditions, including development of soil water repellency, negatively impact hydrological processes and, consequently, the efficiency of rainfall and irrigation. Soil water repellency is increasingly being identified in diverse soils and cropping systems. Recently research has been conducted on the use of novel soil surfactants (co-formulations of alkyl polyglycoside and block copolymer surfactants) to avoid or overcome soil water repellency and enhance water distribution in soils. Results indicate that this is an effective and affordable approach to maintaining or restoring soil and water productivity in irrigated cropping systems. Results from studies conducted in Australia and the United States to determine how this technology modifies soil hydrological behavior and crop yields will be presented. A range of soils and various crops, including potatoes, corn, apples and grapes, were included. Several rates were compared to controls for effect on soil moisture levels, soil water distribution, and crop yield. An economic analysis was also conducted in some trials. Treatments improved rootzone water status, significantly increased crop yield and quality, and in some cases allowed significant reductions in water requirements. Where assessed, a positive economic return was generated. This technology holds promise as a strategy for increasing efficiency of water use in agriculture.

Moore, Demie; Kostka, Stan; McMillan, Mica; Gadd, Nick

2010-05-01

88

Interactive effects of ozone and climate on water use, soil moisture content and streamflow in a southern Applachian forest in the USA  

SciTech Connect

Documentation of the degree and direction of effects of ozone on transpiration of canopies of mature forest trees is critically needed to model ozone effects on forest water use and growth in a warmer future climate. Patterns of sap flow in stems and soil moisture in the rooting zones of mature trees, coupled with late-season streamflow in three forested watersheds in east Tennessee, USA, were analyzed to determine relative influences of ozone and other climatic variables on canopy physiology and streamflow patterns. Statistically significant increases in whole-tree canopy conductance, depletion of soil moisture in the rooting zone, and reduced late-season streamflow in forested watersheds were detected in response to increasing ambient ozone levels. Short-term changes in canopy water use and empirically modeled streamflow patterns over a 23-yr observation period suggest that current ambient ozone exposures may exacerbate the frequency and level of negative effects of drought on forest growth and stream health.

McLaughlin, Samuel B. [Oak Ridge National Laboratory (Retired); Wullschleger, Stan D [ORNL; Sun, G. [USDA Forest Service; Nosal, M. [University of Calgary, ALberta, Canada

2007-01-01

89

Hygrometric Measurement of Soil Water Potential  

NASA Astrophysics Data System (ADS)

Knowledge of soil water potential as a function of water content is required to make unsaturated flow and transport predictions. Although numerous methods are available to measure soil water potential, they are largely difficult and time consuming procedures. The goal of the research is to develop a hygrometric method that will perform satisfactorily with minimal required hardware or technician time. The volume of a drop of saline water will change due to evaporation or condensation until its salinity, and hence osmotic potential, is equal to the water potential in the adjacent gas phase. This relationship is exploited by our method to measure soil moisture potential. To begin, a drop of KCl solution with known mass and KCL concentration is placed adjacent to a soil sample with known water content inside a hermetically sealed container. The mass of the KCl drop is recorded over time with an electronic balance. As thermodynamic equilibrium is achieved, the mass of water within the KCl drop changes until its osmotic potential is equal to the capillary potential of water within the soil sample. After the mass of the KCl drop reaches equilibrium, the KCl concentration is calculated, which enables direct determination of the water potential within the soil sample. Unlike transient hygrometric measurements of water potential using psychrometers, no calibration is required.

Butler, C. D.; Tyner, J. S.

2004-12-01

90

Performance evaluation of TDT soil water content and watermark soil water potential sensors  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study evaluated the performance of digitized Time Domain Transmissometry (TDT) soil water content sensors (Acclima, Inc., Meridian, ID) and resistance-based soil water potential sensors (Watermark 200, Irrometer Company, Inc., Riverside, CA) in two soils. The evaluation was performed by compar...

91

mySoil: Crowd-Sourcing Soil Water Repellency Data to Create a Global Assessment  

NASA Astrophysics Data System (ADS)

Soil water repellency (SWR) alters the way water interacts with soil by impacting hydrological and biogeochemical cycling to an extent which is not yet fully understood. Most studies have focused on SWR in specific environments and habitats, mostly in Mediterranean climates, but SWR has been increasingly observed in a range of habitats from the tropics to the northern latitudes. To better assess the distribution of this phenomenon, we propose using citizen science to create a means of crowd-sourcing SWR data from around the globe using the mySoil app. The water drop penetration time (WDPT) test, in which the length of time a drop of water remains on the soil surface is measured and a corresponding qualitative water repellency class is assigned to the soil, provides useful data and is easy to use. We propose adding a simple, standardised WDPT protocol to the mySoil app and web portal so both academics and non-scientists can contribute to the collection of SWR data from around the world. The protocol would include guidelines on drop size and the number of drops to apply, and would encourage inclusion of details such as vegetation cover, soil moisture conditions, last rainfall, and broad habitat. By initially engaging with researchers to create a back bone of respondents, we believe we can develop a global assessment that will reveal the distribution of the SWR phenomenon.

Hallin, Ingrid; Robinson, David A.; Doerr, Stefan H.; Douglas, Peter; Lawley, Russell; Shelley, Wayne; Urbanek, Emilia

2014-05-01

92

Pesticide interactions with soils affected by olive oil mill wastewater  

NASA Astrophysics Data System (ADS)

Soil pesticide sorption is well known to affect the fate of pesticides, their bioavailability and the potential to contaminate air and water. Soil - pesticide interactions may be strongly influenced by soil organic matter (SOM) and organic matter (OM)-rich soil amendments. One special OM source in soils is related to olive oil production residues that may include both solid and liquid wastes. In the Mediterranean area, the olive oil production is considered as an important field in the agricultural sector. Due to the significant rise in olive oil production, the amount of wastes is growing respectively. Olive oil mill waste water (OMWW) is the liquid byproduct in the so-called "three phase" technological process. Features of OMWW include the high content of fatty aliphatic components and polyphenols and their often-considered toxicity. One way of OMWW disposal is the land spreading, e.g., in olive orchards. The land application of OMWW (either controlled or not) is supposed to affect the multiple soil properties, including hydrophobicity and the potential of soils to interact with pesticides. Therefore, there is both basic and applied interest in elucidating the interactions between organic compounds and soils affected by OMWW. However, little is known about the impact of OMWW - soil interactions on sorption of organic compounds, and specifically, on sorption of agrochemicals. This paper reports an experimental study of sorption interactions of a series of organic compounds including widely used herbicides such as diuron and simazine, in a range of soils that were affected by OMWW (i) historically or (ii) in the controlled land disposal experiments. It is demonstrated that there is a distinct increase in apparent sorption of organic chemicals in soils affected by OMWW. In selected systems, this increase may be explained by increase in SOM content. However, the SOM quality places a role: the rise in organic compound - soil interactions may both exceed the SOM content increase and be less than that. Sorption interactions of herbicides with soils demonstrate a strong hysteresis (which is not expected to be related to a biodegradation). The data suggests that the OMWW - soil interaction seems to change the shape of the apparent sorption isotherms of organic sorbates, and, possibly, their sorption mechanisms: from a Langmuir-like sorption isotherm (describing the adsorptive interactions with a saturation of sorption sites) in the native soils to the sigmoidal or linear isotherms (expected for a partitioning into the bulk OM phases and their swelling) in the OMWW-amended soils. These results may have a significant impact on multiple agricultural and hydrological aspects, e.g., such as the application rate of herbicides in the field, and their possible release and the long term effect on groundwater. The authors acknowledge the support from the OLIVEOIL project (SCHA849/13) funded by DFG.

Keren, Yonatan; Bukhanovsky, Nadezhda; Borisover, Mikhail

2013-04-01

93

Water retention, hydraulic conductivity of hydrophilic polymers in sandy soil as affected by temperature and water quality  

NASA Astrophysics Data System (ADS)

SummaryHydrophilic polymers can swell by absorbing huge volumes of water or aqueous solutions. This property has led to many practical applications of these new materials, particularly in arid regions for improving water retention in sandy soils and the water supply to plants grown on them. The effects of two hydrophilic polymers, carboxymethylcellulose (RF) and isopropyl acrylamide (BF) on the water holding capacity and saturated hydraulic conductivity ( KS) of a sandy soil at varying soil temperature and water quality were evaluated. The RF was less efficient in absorbing water than BF, but the efficiency of BF in retaining water was negatively affected by its thermo-sensitivity and the quality of water. The temperature dependence of the water absorption was not clear for the soils treated with RF, whereas, the efficiency of BF treatment in absorbing water decreased significantly ( P < 0.05) with increasing soil temperature. The dependence of the KS on soil temperature differed with the type of hydrophilic polymer used. The KS of the control soil remained nearly constant as the soil temperature increased. The KS of the BF treated soil increased significantly ( P < 0.05) and linearly with increasing soil temperature, while that of soil treated with RF showed a quadratic response. The soil-absorbent mixtures exhibited different water retention characteristics under different soil temperature conditions. The increase in soil temperature did not affect the water retention characteristics curve of the control. The effect of soil temperature on the water potential curve of the soil treated with RF was not clear particularly when the temperature increased from 25 to 35 °C. The water potential curve for soil-BF mixtures showed that the water content value at field capacity shifted from 0.21 to 0.10 cm 3 cm -3 for 0.1% and from 0.27 to 0.12 cm 3 cm -3 for 0.2%, as the soil temperature increased from 15 to 35 °C. This implies that the soil-BF absorbent mixtures would release some moisture as the soil temperature would increase from 15 to 35 °C, and this water could be lost by percolation or taken up by plant. It was found that available water content increased up to four times with RF as compared to control soil whereas it increased up to five times with BF treatment. At high temperature, the difference was much reduced except for RF at 0.2%. This understanding of the characteristics of the absorbents and the interactions among absorbents, soil, and temperature would be of help in water management in sandy soil.

Andry, H.; Yamamoto, T.; Irie, T.; Moritani, S.; Inoue, M.; Fujiyama, H.

2009-06-01

94

The soil water balance in a mosaic of clumped vegetation  

NASA Astrophysics Data System (ADS)

The spatio-temporal distribution of soil moisture influences the plant growth and the distribution of terrestrial vegetation. This effect is more evident in arid and semiarid ecosystems where the interaction between individuals and the water limited conditions play a fundamental role, providing environmental conditions which drive a variety of non-linear ecohydrological response functions (such as transpiration, photosynthesis, leakage). In this context, modeling vegetation patterns at multiple spatial aggregation scales is important to understand how different vegetation structures can modify the soil water distribution and the exchanged fluxes between soil and atmosphere. In the present paper, the effect of different spatial vegetation patterns, under different climatic scenarios, is investigated in a patchy vegetation mosaic generated by a random process of individual tree canopies and their accompanying root system. Vegetation pattern are generated using the mathematical framework proposed by Caylor et al. (2006) characterized by a three dimensional stochastic vegetation structure, based on the density, dispersion, size distribution, and allometry of individuals within a landscape. A Poisson distribution is applied to generate different distribution of individuals paying particular attention on the role of clumping on water distribution dynamics. The soil water balance is evaluated using the analytical expression proposed by Laio et al. (2001) to explore the influence of climate and vegetation patterns on soil water balance steady-state components (such as the average rates of evaporation, the root water uptake and leakage) and on the stress-weighted plant water uptake. Results of numerical simulations show that clumping may be beneficial for water use efficiency at the landscape scale. References Caylor, Kelly K., P. D'Odorico and I. Rodriguez Iturbe: On the ecohydrology of structurally heterogeneous semiarid landscape. Water Resour. Res., 28, W07424, 2006. Laio, F., A. Porporato, L., Ridolfi and I. Rodriguez Iturbe: Plants in water controlled ecosystems: Active role in hydrological processes and response to water stress, II. Probabilistic soil moisture dynamics, Adv. Water Resour., 24(7), 707-723,2001.

Pizzolla, Teresa; Manfreda, Salvatore; Caylor, Kelly; Gioia, Andrea; Iacobellis, Vito

2014-05-01

95

Water Drainage from Unsaturated Soils in a Centrifuge Permeameter  

NASA Astrophysics Data System (ADS)

This study involves an analysis of water drainage from an initially saturated silt layer in a centrifuge permeameter to evaluate the hydraulic properties of the soil layer in unsaturated conditions up to the point where the water phase becomes discontinuous. These properties include the soil water retention curve (SWRC) and the hydraulic conductivity function (HCF). The hydraulic properties of unsaturated silt are used in soil-atmosphere interaction models that take into account the role of infiltration and evaporation of water from soils due to atmospheric interaction. These models are often applied in slope stability analyses, landfill cover design, aquifer recharge analyses, and agricultural engineering. The hydraulic properties are also relevant to recent research concerning geothermal heating and cooling, as they can be used to assess the insulating effects of soil around underground heat exchangers. This study employs a high-speed geotechnical centrifuge to increase the self-weight of a compacted silt specimen atop a filter plate. Under a centrifuge acceleration of N times earth's gravity, the concept of geometric similitude indicates that the water flow process in a small-scale soil layer will be similar to those in a soil layer in the field that is N times thicker. The centrifuge acceleration also results in an increase in the hydraulic gradient across the silt specimen, which causes water to flow out of the pores following Darcy's law. The drainage test was performed until the rate of liquid water flow out of the soil layer slowed to a negligible level, which corresponds to the transition point at which further water flow can only occur due to water vapor diffusion following Fick's law. The data from the drainage test in the centrifuge were used to determine the SWRC and HCF at different depths in the silt specimen, which compared well with similar properties defined using other laboratory tests. The transition point at which liquid water flow stopped (and Darcy's law is no longer valid) was at a relatively high degree of saturation of 0.8. This finding is important as many water flow analyses in the literature assume that Darcy's law is valid over a much wider range of degrees of saturation, an error that potentially may lead to overestimates of water flow in unsaturated soil layers.

Ornelas, G.; McCartney, J.; Zhang, M.

2013-12-01

96

Soil/Structure Interactions in Earthquakes  

NASA Technical Reports Server (NTRS)

In effort to improve design of Earthquake-resistant structures, mathematical study undertaken to simulate interactions among soil, foundation, and superstructure during various kinds of vibrational excitation. System modeled as three lumped masses connected vertically by springs, with lowest mass connected to horizontal vibrator (representing ground) through springs and dashpot. Behavior of springs described by elastic or elastoplastic force/deformation relationships. Relationships used to approximate nonlinear system behavior and soil/foundation-interface behavior.

Ramey, G. W.; Moore, R. K.; Yoo, C. H.; Bush, Thomas D., Jr.; Stallings, J. M.

1986-01-01

97

Closing the loop of the soil water retention curve  

USGS Publications Warehouse

The authors, to their knowledge for the first time, produced two complete principal soil water retention curves (SWRCs) under both positive and negative matric suction regimes. An innovative testing technique combining the transient water release and imbibition method (TRIM) and constant flow method (CFM) was used to identify the principal paths of SWRC in the positive pore-water pressure regime under unsaturated conditions. A negative matric suction of 9.8 kPa is needed to reach full saturation or close the loop of the SWRC for a silty soil. This work pushes the understanding of the interaction of soil and water into new territory by quantifying the boundaries of the SWRC over the entire suction domain, including both wetting and drying conditions that are relevant to field conditions such as slope wetting under heavy rainfall or rapid groundwater table rise in earthen dams or levees.

Lu, Ning; Alsherif, N; Wayllace, Alexandra; Godt, Jonathan W.

2015-01-01

98

Soil water evaporation and crop residues  

Technology Transfer Automated Retrieval System (TEKTRAN)

Crop residues have value when left in the field and also when removed from the field and sold as a commodity. Reducing soil water evaporation (E) is one of the benefits of leaving crop residues in place. E was measured beneath a corn canopy at the soil suface with nearly full coverage by corn stover...

99

Intrusion of Soil Water through Pipe Cracks  

EPA Science Inventory

This report describes a series of experiments conducted at U.S. EPA?s Test and Evaluation Facility in 2013-2014 to study the intrusion of contaminated soil water into a pipe crack during simulated backflow events. A test rig was used consisting of a 3? x 3? x 3? acrylic soil bo...

100

Soil Chapter-Soils as Sponges: How Much Water does Soil Hold?  

NSDL National Science Digital Library

Students determine the moisture content of a sponge after squeezing the water out of the sponge, and allowing water to evaporate from the sponge. Students also measure the amount of water that has evaporated from the soil samples. This learning resource is part of the Soils chapter of the GLOBE Teacher's Guide, and is supported by the GLOBE soils protocols. GLOBE (Global Learning and Observation to Benefit the Environment) is a worldwide, hands-on, K-12 school-based science education program.

2012-08-03

101

Transient soil moisture profile of a water-shedding soil cover in north Queensland, Australia  

NASA Astrophysics Data System (ADS)

In current agricultural and industrial applications, soil moisture determination is limited to point-wise measurements and remote sensing technologies. The former has limitations on spatial resolution while the latter, although has greater coverage in three dimensions, but may not be representative of real-time hydrologic conditions of the substrate. This conference paper discusses the use of elongated soil moisture probes to describe the transient soil moisture profile of water-shedding soil cover trial plots in north Queensland, Australia. Three-metre long flat ribbon cables were installed at designed depths across a soil cover with substrate materials from mining activities comprising of waste rocks and blended tailings. The soil moisture measurement is analysed using spatial time domain reflectometry (STDR) (Scheuermann et al., 2009) Calibration of the flat ribbon cable's soil moisture measurement in waste rocks is undertaken in a glasshouse setting. Soil moisture retention and outflows are monitored at specific time interval by mass balance and water potential measurements. These data sets together with the soil hydrologic properties derived from laboratory and field measurements are used as input in the numerical code on unsaturated flow, Hydrus2D. The soil moisture calculations of the glasshouse calibration using this numerical method are compared with results from the STDR soil moisture data sets. In context, the purpose of the soil cover is to isolate sulphide-rich mine wastes from atmospheric interaction as oxidation and leaching of these materials may result to acid and metalliferous drainage. The long term performance of a soil cover will be described in terms of the quantities and physico-chemical characteristics of its outflows. With the soil moisture probes set at automated and pre-determined measurement time intervals, it is expected to distinguish between macropore and soil moisture flows during high intensity rainfall events and, also continuously update data sets on soil moisture retention, especially during long periods of drought. As such, description of the soil cover water balance will be more elaborate as the soil moisture profile will be described in terms of temporal and spatial variability. Moreover, this field data set can lend support on the evaluation of the potential use of mine wastes as cover materials with respect to their hydrologic and geochemical properties.

Gonzales, Christopher; Baumgartl, Thomas; Scheuermann, Alexander

2014-05-01

102

Acid-base characteristics of the Grass Pond watershed in the Adirondack Mountains of New York State, USA: interactions between soil, vegetation and surface waters  

NASA Astrophysics Data System (ADS)

Grass Pond watershed is located within the Southwestern Adirondack Mountain region of New York State, USA. This region receives some of the highest rates of acidic deposition in North America and is particularly sensitive to acidic inputs due to many of its soils having shallow depths and being generally base-poor. Differences in soil chemistry and tree species between seven subwatersheds were examined in relation to acid-base characteristics of the seven major streams that drain into Grass Pond. Mineral soil pH, stream water BCS and pH exhibited a positive correlation with sugar maple basal area (p = 0.055; 0.48 and 0.39, respectively). Black cherry basal area was inversely correlated with stream water BCS, ANCc and NO3- (p = 0.23; 0.24 and 0.20, respectively). Sugar maple basal areas were positively correlated with watershed characteristics associated with the neutralization of atmospheric acidic inputs while in contrast, black cherry basal areas showed opposite relationships to these same watershed characteristics. Canonical Correspondence Analysis indicated that black cherry had a distinctive relationship with forest floor chemistry apart from the other tree species, specifically a strong positive association with forest floor NH4 while sugar maple had a distinctive relationship with stream chemistry variables, specifically a strong positive association with stream water ANCc, BCS and pH. Our results provide evidence that sugar maple is acid-intolerant or calciphilic tree species and also demonstrate that black cherry is likely an acid-tolerant tree species.

McEathron, K. M.; Mitchell, M. J.; Zhang, L.

2012-09-01

103

Acid-base characteristics of the Grass Pond watershed in the Adirondack Mountains of New York State, USA: interactions among soil, vegetation and surface waters  

NASA Astrophysics Data System (ADS)

Grass Pond watershed is located within the southwestern Adirondack Mountain region of New York State, USA. This region receives some of the highest rates of acidic deposition in North America and is particularly sensitive to acidic inputs due to many of its soils having shallow depths and being generally base poor. Differences in soil chemistry and tree species between seven subwatersheds were examined in relation to acid-base characteristics of the seven major streams that drain into Grass Pond. Mineral soil pH, stream water BCS (base-cation surplus) and pH exhibited a positive correlation with sugar maple basal area (p = 0.055; 0.48 and 0.39, respectively). Black cherry basal area was inversely correlated with stream water BCS, ANC (acid neutralizing capacity)c and NO3- (p = 0.23; 0.24 and 0.20, respectively). Sugar maple basal areas were positively associated with watershed characteristics associated with the neutralization of atmospheric acidic inputs while in contrast, black cherry basal areas showed opposite relationships to these same watershed characteristics. Canonical correspondence analysis indicated that black cherry had a distinctive relationship with forest floor chemistry apart from the other tree species, specifically a strong positive association with forest floor NH4, while sugar maple had a distinctive relationship with stream chemistry variables, specifically a strong positive association with stream water ANCc, BCS and pH. Our results provide evidence that sugar maple is acid-intolerant or calciphilic tree species and also demonstrate that black cherry is likely an acid-tolerant tree species.

McEathron, K. M.; Mitchell, M. J.; Zhang, L.

2013-07-01

104

Applicability of CS616 Soil Water Sensors for South  

E-print Network

Applicability of CS616 Soil Water Sensors for South Florida Urban Soils Kevin Koryto Water: Determine if CS616 soil water sensors are functioning adequately at field site. Hypothesis: Presence of air pockets is causing soil water sensors to give low readings. Field site: Urban environment, grass

Migliaccio, Kati White

105

GRAVIMETRIC AND VOLUMETRIC DIRECT MEASUREMENT OF SOIL WATER CONTENT  

Technology Transfer Automated Retrieval System (TEKTRAN)

Accurate soil water content measurements to considerable depth are required for investigations of crop water use, water use efficiency, irrigation efficiency, and the hydraulic properties of soils. Many indirect methods have been proposed for sensing soil water content with minimal soil disturbance....

106

WATER AS A REAGENT FOR SOIL REMEDIATION  

SciTech Connect

SRI International conducted experiments in a two-year, two-phase process to develop and evaluate hydrothermal extraction technology, also known as hot water extraction (HWE) technology, to separate petroleum-related contaminants and other hazardous pollutants from soil and sediments. In this process, water with added electrolytes (inexpensive and environmentally friendly) is used as the extracting solvent under subcritical conditions (150-300 C). The use of electrolytes allows us to operate reactors under mild conditions and to obtain high separation efficiencies that were hitherto impossible. Unlike common organic solvents, water under subcritical conditions dissolves both organics and inorganics, thus allowing opportunities for separation of both organic and inorganic material from soil. In developing this technology, our systematic approach was to (1) establish fundamental solubility data, (2) conduct treatability studies with industrial soils, and (3) perform a bench-scale demonstration using a highly contaminated soil. The bench-scale demonstration of the process has shown great promise. The next step of the development process is the successful pilot demonstration of this technology. Once pilot tested, this technology can be implemented quite easily, since most of the basic components are readily available from mature technologies (e.g., steam stripping, soil washing, thermal desorption). The implementation of this technology will revolutionize the conventional use of water in soil remediation technologies and will provide a stand-alone technology for removal of both volatile and heavy components from contaminated soil.

Indira S. Jayaweera; Montserrat Marti-Perez; Jordi Diaz-Ferrero; Angel Sanjurjo

2001-11-12

107

SW—Soil and Water  

Microsoft Academic Search

The overgrowing population and the recent droughts are putting water resources under pressure and calling for new approaches for water planning and management if escalating conflicts are to be avoided and environmental degradation is to be reversed. As countries are using their water resources with growing intensity, poor rainfall increasingly leads to national water crises as water tables fall and

Ragab Ragab; Christel Prudhomme

2002-01-01

108

Passive Microwave Observation of Soil Water Infiltration  

NASA Technical Reports Server (NTRS)

Infiltration is a time varying process of water entry into soil. Experiments were conducted here using truck based microwave radiometers to observe small plots during and following sprinkler irrigation. Experiments were conducted on a sandy loam soil in 1994 and a silt loam in 1995. Sandy loam soils typically have higher infiltration capabilities than clays. For the sandy loam the observed brightness temperature (TB) quickly reached a nominally constant value during irrigation. When the irrigation was stopped the TB began to increase as drainage took place. The irrigation rates in 1995 with the silt loam soil exceeded the saturated conductivity of the soil. During irrigation the TB values exhibited a pattern that suggests the occurrence of coherent reflection, a rarely observed phenomena under natural conditions. These results suggested the existence of a sharp dielectric boundary (wet over dry soil) that was increasing in depth with time.

Jackson, Thomas J.; Schmugge, Thomas J.; Rawls, Walter J.; ONeill, Peggy E.; Parlange, Marc B.

1997-01-01

109

Interaction between Diclofenac and Soil Humic Acids  

Microsoft Academic Search

The interaction between the non-steroidal anti-inflammatory drug diclofenac and standard humic acids (HAs) in bulk solution was studied using two complementary analytical methods: UV-Visible spectroscopy and square wave voltammetry. The observed UV-Vis spectra and Ip\\/V curves suggested that, at our experimental conditions, albeit both substances being negatively charged at pH 6.5, interaction between the pharmaceutical and the soil humic acids

Alja Margon; Arnold Pastrello; Davide Mosetti; Pierpaolo Cantone; Liviana Leita

2009-01-01

110

INVESTIGATING SOIL MICROBIAL INTERACTIONS OF PORTULACARIA AFRA  

E-print Network

a symbiotic relationship with mycorrhizal fungi and the interaction with rhizobacteria may enhance and improve a survey of the arbuscular mycorrhizal (AM) fungal populations associated with spekboom, determination mycorrhizal fungi and selected rhizobacteria to enhance establishment and growth of spekboom. Soil and root

111

Investigation of indigenous water, salt and soil for solar ponds  

NASA Technical Reports Server (NTRS)

The existence of salt-gradient solar ponds in nature is a strong indication that the successful exploitation of this phenomenon must account adequately for the influences of the local setting. Sun, weather and other general factors are treated elsewhere. This paper deals with water, salt, and soil. A general methodology for evaluating and, where feasible, adjusting the effects of these elements is under development. Eight essential solar pond characteristics have been identified, along with a variety of their dependencies upon properties of water, salt and soil. The comprehensive methodology, when fully developed, will include laboratory investigation in such diverse areas as brine physical chemistry, light transmission, water treatment, brine-soil interactions, sealants, and others. With the Salton Sea solar pond investigation as an example, some methods under development will be described.

Marsh, H. E.

1983-01-01

112

Influence of soil pH on properties of the soil-water interface  

NASA Astrophysics Data System (ADS)

Surface characteristics of soils are one of the main factors controlling processes at the soil-water interface like wetting, sorption or dissolution processes and, thereby, have a high impact on natural soil functions like habitat, filter, buffer, storage and transformation functions. Since surface characteristics, like wettability or repellency, are not static soil properties but continuously changing, the relevant processes and mechanisms are in the focus of the presented study. These mechanisms help to gain further insight into the behaviour of soil and its dynamics under changing environmental conditions. The influence of water content, relative air humidity and drying temperature on soil water repellency has been investigated in many studies. In contrast, few studies have systematically investigated the relationship between soil water repellency (SWR) and soil pH. Several studies found alkaline soils to be less prone to SWR compared to acidic soils (e.g., Cerdŕ, and Doerr 2007; Mataix-Solera et al. 2007). Furthermore, SWR has been successfully reduced in acidic soils by increasing soil pH via liming (e.g., Karnok et al. 1993; Roper 2005). However, SWR has also been reported in calcareous soils in the Netherlands (Dekker and Jungerius 1990), California, USA (Holzhey 1968) and Spain (Mataix-Solera and Doerr 2004). The hypothesis that the pH may control repellency via changes in the variable surface charge of soil material has not yet been tested. Previously it has been shown that it is necessary to eliminate the direct influence of changes in soil moisture content so that the unique relationship between pH and SWR can be isolated (Bayer and Schaumann 2007). A method has been developed which allows adjustment of the pH of soils with low moisture content via the gas phase with minimal change in moisture content. The method was applied to 14 soil samples from Germany, Netherlands, the UK and Australia, using the water drop penetration time (WDPT) as the indicator of SWR. Sessile drop and Wilhelmy plate contact angles (CAsess and CAwpm resp.) were measured on the four samples from Germany and the data correlated with those of WDPT. The titratable surface charge of these four soils was measured at selected pH values using a particle charge detector (PCD). Changes in SWR with soil pH were found to be influenced by the density and type of sites able to interact with protons at the available surfaces of organic and mineral materials in soil. The maximum SWR occurred for soil at natural pH and where the charge density was minimal. As pH increased, negative surface charge increased due to deprotonation of sites and WDPT decreased. Two types of behaviour were observed: Those in which (i) WDPT shortened with decreasing pH and ii) WDPT was sensibly constant with decreasing pH. The data suggest that the availability and relative abundance of proton active sites at mineral surfaces, and those at organic functional groups influence the behaviour. Bayer, J. V. and G. E. Schaumann (2007). Hydrological processes 21(17): 2266 - 2275. Cerdŕ, A. and S. H. Doerr (2007). Hydrological Processes 21(17): 2325-2336. Dekker, L. W. and P. D. Jungerius (1990). Dunes of the European coasts, Catena-Verlag. 18: 173-183. Holzhey, C. S. (1968). Symposium on water repellent soils, Riverside, California. Karnok, K. A., E. J. Rowland, et al. (1993). Agronomy Journal 85(5): 983-986. Mataix-Solera, J., V. Arcenegui, et al. (2007). Hydrological Processes 21(17): 2300-2309. Mataix-Solera, J. and S. H. Doerr (2004). Geoderma 118(1-2): 77-88. Roper, M. M. (2005). Australian Journal of Soil research 43: 803-810.

Diehl, Doerte

2010-05-01

113

Interaction of fecal coliforms with soil aggregates  

Technology Transfer Automated Retrieval System (TEKTRAN)

Land-applied manures may contain various contaminants that cause water pollution and concomitant health problems. Some of these pollutants are bacteria, and fecal coliforms (FC) have been widely used as an indicator of bacterial contamination. Experiments on bacteria attachment to soil are tradition...

114

Black Carbon - Soil Organic Matter abiotic and biotic interactions  

NASA Astrophysics Data System (ADS)

Wildfires, prescribed burns and the use of char as a soil amendment all add large quantities of black carbon to soils, with profound, yet poorly understood, effects on soil biology and chemical-physical structure. We will present results emerging from our black carbon program, which addresses questions concerning: 1) black carbon-soil organic matter interactions, 2) char decomposition and 3) impacts on microbial community structure and activities. Our understanding derives from a complementary set of post-fire black carbon field surveys and laboratory and field experiments with grass and wood char amendments, in which we used molecular (i.e., BPCA, PLFA) and isotopic (i.e., 13C and 15N labelled char) tracers. Overall, emerging results demonstrate that char additions to soil are prone to fast erosion, but a fraction remains that increases water retention and creates a better environment for the microbial community, particularly favoring gram negative bacteria. However, microbial decomposition of black carbon only slowly consumes a small fraction of it, thus char still significantly contributes to soil carbon sequestration. This is especially true in soils with little organic matter, where black carbon additions may even induce negative priming.

Cotrufo, Francesca; Boot, Claudia; Denef, Karolien; Foster, Erika; Haddix, Michelle; Jiang, Xinyu; Soong, Jennifer; Stewart, Catherine

2014-05-01

115

Analysis of the response of soil water to climate change  

SciTech Connect

We used a daily time step soil water model to investigate the potential effects of changes in temperature and precipitation on soil water dynamics in the central grassland region of the U.S.. We collected 20-years of driving variable data from each of 300 USGS weather stations throughout the region. Simulations were run for each station and the results were entered into a GIS database for analysis and display. Soil water patterns under current climatic conditions reflected the large scale west-east precipitation and south-north temperature gradients. Bare soil evaporation accounted for a large proportion of water loss in the driest areas and was replaced by canopy interception in the wettest areas. Transpiration water loss reflected the regional pattern of net primary production, highest in the warm and wet areas and lowest in the warm and dry areas. Increased temperature affected both evaporation and transpiration losses largely by increasing the length of time when evaporative demand of the atmospheric was high. Increases and decreases in precipitation affected water supply directly. Interactions between changes in elevated temperature and increased or decreased precipitation depended upon the balance of changes in water supply and demand.

Lauenroth, W.K.I.; Burke, K.I.C.; Coffin, D.P. (Colorado State Univ., Fort Collins, CO (United States))

1994-06-01

116

Measured and simulated soil water evaporation from four Great Plains soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

The amount of soil water lost during stage one and stage two soil water evaporation is of interest to crop water use modelers. The ratio of measured soil surface temperature (Ts) to air temperature (Ta) was tested as a signal for the transition in soil water evaporation from stage one to stage two d...

117

Modeling, estimation, and control of robot-soil interactions  

E-print Network

This thesis presents the development of hardware, theory, and experimental methods to enable a robotic manipulator arm to interact with soils and estimate soil properties from interaction forces. Unlike the majority of ...

Hong, Won, 1971-

2001-01-01

118

Using soil water sensors to improve irrigation management  

Technology Transfer Automated Retrieval System (TEKTRAN)

Irrigation water management has to do with the appropriate application of water to soils, in terms of amounts, rates, and timing to satisfy crop water demands while protecting the soil and water resources from degradation. In this regard, sensors can be used to monitor the soil water status; and som...

119

Effect of corn or soybean row position on soil water  

Technology Transfer Automated Retrieval System (TEKTRAN)

Crop plants can funnel water to the soil and increase water content more in the row relative to the interrow. Because the row intercepts more soil water after rains and higher root density, the soil may also dry out more between rains than does soil in the interrow. The purpose of this study was to ...

120

Predicting soil-water and soil-air transport properties and their effects on soil-vapor extraction efficiency  

Microsoft Academic Search

Accurate prediction of water and air transport parameters in variably saturated soil is necessary for modeling of soil-vapor extraction (SVE) at soil sites contaminated with volatile organic chemicals (VOCs). An expression for predicting saturated water permeability (k{sub 1,s}) in undisturbed soils from the soil total porosity and the field capacity soil-water content was developed by fitting a tortuous-tube fluid flow

Tjalfe G. Poulsen; Per Moldrup; Toshiko Yamaguchi; P. Schjoenning; Jens Aage Hansen

1999-01-01

121

Water repellency and critical soil water content in a dune sand  

Microsoft Academic Search

Assessments of water repellency of soils are commonly made on air-dried or oven-dried samples, without considering the soil water content. The objectives of this study were to examine the spatial and temporal variability of soil water content, actual water repellency over short distances, and the variations in critical soil water contents. Between 22 April and 23 November 1999, numerous samples

Louis W. Dekker; Stefan H. Doerr; Klaas Oostindie; Apostolos K. Ziogas; Coen J. Ritsema

2001-01-01

122

Soil Water: Advanced Crop and Soil Science. A Course of Study.  

ERIC Educational Resources Information Center

The course of study represents the fourth of six modules in advanced crop and soil science and introduces the agriculture student to the topic of soil water. Upon completing the three day module, the student will be able to classify water as to its presence in the soil, outline the hydrological cycle, list the ways water is lost from the soil,…

Miller, Larry E.

123

Water conductivity of arctic zone soils (Spitsbergen)  

NASA Astrophysics Data System (ADS)

The water conductivity of arctic zone soils derived in different micro-relief forms was determined. The greatest water conductivity at the 0-5 cm depth for the higher values of water potentials (> -7 kJ m-3) was shown by tundra polygons (Brunic-Turbic Cryosol, Arenic) - 904-0.09 cm day-1, whereas the lowest were exhibited by Turbic Cryosols - 95-0.05 cm day-1. Between -16 and -100 kJ m-3, the water conductivity for tundra polygons rapidly decreased to 0.0001 cm day-1, whereas their decrease for the other forms was much lower and in consequence the values were 0.007, 0.04, and 0.01 cm day-1 for the mud boils (Turbic Cryosol (Siltic, Skeletic)), cell forms (Turbic Cryosol (Siltic, Skeletic)), and sorted circles (Turbic Cryosol (Skeletic)), respectively. In the 10-15 cm layer, the shape of water conductivity curves for the higher values of water potentials is nearly the same as for the upper layer. Similarly, the water conductivity is the highest - 0.2 cm day-1 for tundra polygons. For the lower water potentials, the differences in water conductivity increase to the decrease of soil water potential. At the lowest potential the water conductivity is the highest for sorted circles - 0.02 cm day-1 and the lowest in tundra polygons - 0.00002 cm day-1.

Witkowska-Walczak, Barbara; S?awi?ski, Cezary; Bartmi?ski, Piotr; Melke, Jerzy; Cymerman, Jacek

2014-10-01

124

An overview of soil water sensors for salinity & irrigation management  

Technology Transfer Automated Retrieval System (TEKTRAN)

Irrigation water management has to do with the appropriate application of water to soils, in terms of amounts, rates, and timing to satisfy crop water demands while protecting the soil and water resources from degradation. Accurate irrigation management is even more important in salt affected soils ...

125

Enhancing Green Water in Soils of South Asia  

Microsoft Academic Search

Enhancing green water (GW) in soils has vast significance with respect to depleting water resources, especially in South Asia (SA). The water stored in soil that's productively used for transpiration is called GW. The enhancement of GW includes all those techniques and approaches that lead to increased soil-water storage and infiltration, reduced runoff, and decreased evaporation, such as minimum tillage,

M. S. Kahlon; R. Lal

2011-01-01

126

The Impact of Soil Water Repellency on Hydrological Properties of Soil, the Plant Growing Environment, Irrigation Efficiency and Water Consumption  

NASA Astrophysics Data System (ADS)

Soil water repellency causes at least temporal changes in the hydrological properties of a soil. These changes, among other things, often result in suboptimal growing conditions, reduced crop performance, and/or increased irrigation requirements. Water repellency in soil is more wide spread than previously thought and has been identified in many soil types under a wide array of climatic conditions and cropping systems worldwide. (Dekker et al., 2005) The reduction or loss of soil wettability caused by soil water repellency leads to drastically different hydrological behavior (Dekker et al. 2009), and reduces the ability of the soil to function as expected. Consequences of soil water repellency include increased runoff and preferential flow, reduced plant available water, reduced irrigation efficiency, suboptimal crop performance, increased requirement for water and other inputs, and increased potential for non-point source pollution. (Dekker et al., 2001) This presentation consolidates information on basic hydrological and soil system functions as they relate to the plant growth environment, irrigation efficiency and water conservation, and shows the differences between what happens in soils affected by varying levels of soil water repellency compared to wettable soils or soils where soil surfactants have been used to restore/optimize wettability. The impact on irrigation efficiency and the plant growth environment is also discussed. The conclusion is that the impact of soil water repellency compromises hydrological properties and the plant growth environment in a wider range of conditions than previously recognized and, therefore, deserves consideration in the management of soil and water in crop systems.

Moore, Demie; Kostka, Stanley; Boerth, Thomas; McMillan, Mica; Ritsema, Coen; Dekker, Louis; Oostindie, Klaas; Stoof, Cathelijne; Wesseling, Jan

2010-05-01

127

CHEMFLO: ONE-DIMENSIONAL WATER AND CHEMICAL MOVEMENT IN UNSATURATED SOILS  

EPA Science Inventory

An interactive software system was developed to enable decision-makers, regulators, policy-makers, scientists, consultants, and students to simulate the movement of waterand chemicals in unsaturated soils. Water movement is modeled using Richards (1931) - equation. Chemical trans...

128

Soil and Water Conservation Activities for Scouts.  

ERIC Educational Resources Information Center

The purpose of the learning activities outlined in this booklet is to help Scouts understand some conservation principles which hopefully will lead to the development of an attitude of concern for the environment and a commitment to help with the task of using and managing soil, water, and other natural resources for long range needs as well as…

Soil Conservation Service (USDA), Washington, DC.

129

SOIL AND WATER ASSESSMENT TOOL (SWAT)  

EPA Science Inventory

Soil and Water Assessment Tool (SWAT) is the continuation of a long-term effort of nonpoint source pollution modeling with the US Department of Agriculture -Agricultural Research Service (ARS). SWAT is a continuous time model that operates on a daily time step. The objective in ...

130

Selenium in Oklahoma ground water and soil  

SciTech Connect

Selenium with a consumption of 2 liters per day (5). The objectives of this study are: (1) to determine the concentrations of Se in Oklahoma ground water and soil samples. (2) to map the geographical distribution of Se species in Oklahoma. (3) to relate groundwater depth, pH and geology with concentration of Se.

Atalay, A.; Vir Maggon, D.

1991-03-30

131

Mathematics: Food, Soil, Water, Air, Free Speech  

E-print Network

Chapter 5 Mathematics: Food, Soil, Water, Air, Free Speech As I write there are reports of yet another outbreak of food borne disease with some hospitalizations and deaths. This time it is Escherichia.cdc.gov in 1999, more than 75 million Americans get sick each year from food, of which about 325,000 require

Russo, Bernard

132

Effect of soil water table on soil respiration in a riparian forest of northeast Spain.  

NASA Astrophysics Data System (ADS)

Soil respiration is a major component in ecosystem carbon cycle and is strongly affected by soil water content. Soil respiration consists of autotrophic and heterotrophic respiration, which may have different sensitivities toward soil water content. The objectives of this study are: (1) to analyze the seasonal variation in soil water table and soil respiration in a Mediterranean riparian forest. (2) To examine difference in soil respirations of tree species. We measured the soil respiration rate along the soil water table with 5 transects of three tree species. Soil respiration rate decreased significantly from riverside to middle hill and showed clearly seasonality. Soil respiration rate also showed significantly different among tree species. Heterotrophic respiration rate contributed to the soil respiration rate from 48% to 95% depends on season and species.

Chang, Chao-Ting; Sperlich, Dominik; Gracia, Carlos; Sabaté, Santiago

2013-04-01

133

Linking Soil and Water Quality in Conservation Agricultural Systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil and water resources are fundamental components of agriculture. Soil quality can be determined by observing the functionality of soil after being subjected to different types of management. Some key functions of soil are to: supply nutrients to plants, allow rainfall to penetrate soil and prov...

134

Soil, Water and Forage Testing Laboratory Phosphorus recommendations applicable for  

E-print Network

Soil, Water and Forage Testing Laboratory Phosphorus recommendations applicable for methods used #12;Soil, Water and Forage Testing Laboratory Phosphorus recommendations applicable for methods used Laboratory Phosphorus recommendations applicable for methods used by laboratory. Mehlich III by ICP only

135

Effects of Estimating Soil Hydraulic Properties and Root Growth Factor on Soil Water Balance and Crop Production  

Technology Transfer Automated Retrieval System (TEKTRAN)

Increasing water use efficiency (WUE) is one of the oldest goals in agricultural sciences, yet it is still not fully understood and achieved due to the complexity of soil-weather-management interactions. System models that quantify these interactions are increasingly used for optimizing crop WUE, es...

136

River regulation and interactions groundwater - surface water  

NASA Astrophysics Data System (ADS)

The determination of a minimum acceptable flow in a river affected by regulation is a major task in management of hydropower development. The Norwegian Water Resources and Energy Directorate (NVE), responsible for administrating the nation's water resources, requires an objective system that takes into account the needs of the developer and the rivers environment such as water quality, river biota, landscape, erosion and groundwater. A research project has been initiated with focus on interactions between groundwater and surface water. The purpose of the project is to provide the licensing authorities with tools for quantitative assessment of the effects of regulation on groundwater resources and at the same time the effect of groundwater abstraction on river flows. A small, urbanised alluvial plain (2 km^2) by the river Glomma in Central Southern Norway is used as a case study. The local aquifer consists of heterogeneous glaciofluvial and fluvial deposit, mainly sand and gravel. Two three-dimensional numerical models (Visual Modflow 3.0 and Feflow 5.0) have been used for this study. The models were calibrated with hydro-geological data collected in the field. Aquifer and river sediment has been examined by use of Ground Penetrating Radar (GPR) and soil samples collection. Preferential flow has been examined by tracer tests. Water level, temperature and electric conductivity have been recorded in both aquifer and river. Hydro-climatic regime has been analysed by statistical tools. The first task of the project is to carry out water balance studies in order to estimate the change in rate of groundwater recharge from and to the river along a normal hydrologic year with snowmelting, flood, and baseflow. The second task is to analyse the potential effect of change in the river water regime (due to regulation and consecutive clogging) on groundwater resources and their interaction with stream water.

Colleuille, H.; Wong, W. K.; Dimakis, P.; Pedersen, T. S.

2003-04-01

137

The Impact of Soil Water Repellency on Hydrological Properties of Soil, the Plant Growing Environment, Irrigation Efficiency and Water Consumption  

Microsoft Academic Search

Soil water repellency causes at least temporal changes in the hydrological properties of a soil. These changes, among other things, often result in suboptimal growing conditions, reduced crop performance, and\\/or increased irrigation requirements. Water repellency in soil is more wide spread than previously thought and has been identified in many soil types under a wide array of climatic conditions and

Demie Moore; Stanley Kostka; Thomas Boerth; Mica McMillan; Coen Ritsema; Louis Dekker; Klaas Oostindie; Cathelijne Stoof; Jan Wesseling

2010-01-01

138

Impact of soil compaction upon soil water balance and maize yield estimated by the SIMWASER model  

Microsoft Academic Search

The capability of the soil water balance model SIMWASER to predict the impact of soil compaction upon the yield of maize (Zea mays L.) is tested, using the results of a field experiment on the influence of soil compaction by wheel pressure upon soil structure, water regime and plant growth. The experimental site was located on an Eutric Cambisol with

E Stenitzer; E Murer

2003-01-01

139

Response of three soil water sensors to variable solution electrical conductivity in different soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Commercial dielectric soil water sensors may improve management of irrigated agriculture by providing continuous field soil water information. Use of these sensors is partly limited by sensor sensitivity to variations in soil salinity and texture, which force expensive, time consuming, soil specific...

140

Saturated hydraulic conductivity and soil water retention properties across a soil-slope transition  

E-print Network

Saturated hydraulic conductivity and soil water retention properties across a soil-slope transition measured saturated hydraulic conductivity (Ksat) and soil water retention functions at two (15 and 30 cm Area Research and Extension Center, Santa Clara, California Abstract. The hydraulic properties of soil

Mohanty, Binayak P.

141

Soil erodibility and processes of water erosion on hillslope  

NASA Astrophysics Data System (ADS)

The importance of the inherent resistance of soil to erosional processes, or soil erodibility, is generally recognized in hillslope and fluvial geomorphology, but the full implications of the dynamic soil properties that affect erodibility are seldom considered. In Canada, a wide spectrum of soils and erosional processes has stimulated much research related to soil erodibility. This paper aims to place this work in an international framework of research on water erosion processes, and to identify critical emerging research questions. It focuses particularly on experimental research on rill and interrill erosion using simulated rainfall and recently developed techniques that provide data at appropriate temporal and spatial scales, essential for event-based soil erosion prediction. Results show that many components of erosional response, such as partitioning between rill and interrill or surface and subsurface processes, threshold hydraulic conditions for rill incision, rill network configuration and hillslope sediment delivery, are strongly affected by spatially variable and temporally dynamic soil properties. This agrees with other recent studies, but contrasts markedly with long-held concepts of soil credibility as an essentially constant property for any soil type. Properties that determine erodibility, such as soil aggregation and shear strength, are strongly affected by climatic factors such as rainfall distribution and frost action, and show systematic seasonal variation. They can also change significantly over much shorter time scales with subtle variations in soil water conditions, organic composition, microbiological activity, age-hardening and the structural effect of applied stresses. Property changes between and during rainstorms can dramatically affect the incidence and intensity of rill and interrill erosion and, therefore, both short and long-term hillslope erosional response. Similar property changes, linked to climatic conditions, may also significantly influence the stability and resilience of plant species and vegetation systems. Full understanding of such changes is essential if current event-based soil erosion models such as WEPP and EUROSEM are to attain their full potential predictive precision. The complexity of the interacting processes involved may, however, ultimately make stochastic modelling more effective than physically based modelling in predicting hillslope response to erodibility dynamics.

Bryan, Rorke B.

2000-03-01

142

[Evaluation on soil anti-erodibility of soil and water conservation forest].  

PubMed

Indexes including organic matter content, water stable aggregate content, mean weight diameter of water stable aggregate, aggregate degree and disperse coefficient were selected to evaluate soil anti-erodibility of soil and water conservation forests component of different tree species at different ages. The results showed that soil and water conservation forest played an important role in improving soil anti-erodibility, especially to the topsoil. Compared with that of Chinese pine pure forests, Chinese pine-broadleaved mixed forests had higher soil organic matter content, and water stable aggregate content increased by 1.71%-38.53%, and soil anti-erodibility was also increased with increasing stand age. PMID:11767629

Shen, H; Jiang, F; Du, X; Lu, T

2000-06-01

143

SOIL WATER SENSING - FOCUS on VARIABLE RATE IRRIGATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Irrigation scheduling using soil water sensors is an exercise in maintaining the water content of the crop root zone soil above a lower limit defined by the management allowed depletion (MAD) for that soil and crop, but not so wet that too much water is lost to deep percolation. The management allow...

144

Agricultural Grassland, Soil and Water Research Laboratory, Temple, TX  

E-print Network

Agricultural Research Service Grassland, Soil and Water Research Laboratory, Temple, TX Monitoring monitoring, modeling, and decision- making #12;Agricultural Research Service Grassland, Soil and Water(6):667-674. #12;Agricultural Research Service Grassland, Soil and Water Research Laboratory, Temple, TX Small

145

Agricultural Grassland, Soil and Water Research Laboratory, Temple, TX  

E-print Network

Agricultural Research Service Grassland, Soil and Water Research Laboratory, Temple, TX Monitoring(6):667-674. Agricultural Research Service Grassland, Soil and Water Research Laboratory, Temple, TX Small Watershed Monitoring Agricultural Research Service Grassland, Soil and Water Research Laboratory, Temple, TX Discharge

146

NEZ PERCE SOIL AND WATER CONSERVATION DISTRICT CULDESAC, IDAHO 83524  

E-print Network

NEZ PERCE SOIL AND WATER CONSERVATION DISTRICT PO BOX 131 CULDESAC, IDAHO 83524 208-843-2931 PHONE AVENUE, SUITE 1100 PORTLAND, OREGON 97204-1348 FROM: NEZ PERCE SOIL AND WATER CONSERVATION DISTRICT PROJECTS DATE: 10/4/06 Dear Council Members: The Nez Perce Soil and Water Conservation District (District

147

Post-doctoral Fellow Soil and Water Conservation Position specification  

E-print Network

Post-doctoral Fellow Soil and Water Conservation Position specification Internationally Recruited and soil and water conservation in the context of watershed management - Identify, verify and implement and evaluate soil and water conservation measures at farm and watershed levels in cooperation with various

148

Sensible heat observations reveal soil-water evaporation dynamics  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil water evaporation is important at scales ranging from microbial ecology to large-scale climate. Yet, routine measurments are unable to capture rapidly shifting near-surface soil heat and water processes involved in soil-water evaporation. The objective of this study was to determine the depth a...

149

Modelling for planning soil and water conservation: a critical review  

Microsoft Academic Search

Degradation of soil and water resources, which is increasing throughout the World, is affecting directly and indirectly all the vital processes on the Earth's surface. This is partially due to non-appropriate land use planning, where soil and water conservation must be the most important components. Global climate changes may contribute to accelerate some soil and water degradation processes and their

SENTÍS Ildefonso

150

College of Agricultural and Life Sciences Soil and Water Science Department  

E-print Network

College of Agricultural and Life Sciences Soil and Water Science Department at the University OPTIONS IN SOIL & WATER SCIENCE Water Science Specialization Environmental Management in Agriculture of Florida SOIL SCIENCE SPECIALIZATION soil and water science major undergraduate UNDERGRADUATE DEGREE

Watson, Craig A.

151

Temporal patterns of infiltration into a water repellent soil under field conditions  

NASA Astrophysics Data System (ADS)

Water repellency causes substantial economic losses for farmers in southern Australia through impacts on crop growth and weed germination. However, recent research has demonstrated that laboratory measurements of water repellency may not be a reliable indicator of the severity of symptoms experienced in the field. In particular, crop residue retention and minimal soil disturbance led to increased water repellency, but was also associated with higher soil water contents measured at strategic times of the year. Little is known about the temporal patterns of soil water storage close to the soil surface in a water repellent sand. In this research we measured soil water content at a depth of 0.05 m at 15-minute intervals from June 2011 to October 2012, under various treatment combinations of residue retention and soil disturbance. Measurements were made in both 'crop row' and 'crop inter-row' positions. For a rainfall event (9.2 mm) in March 2012, prior to crop seeding, plots previously established with no-till absorbed significantly more water (increase in soil water content of 0.074 v/v) than plots conventionally cultivated (0.038 v/v). In June 2012 (12.6 mm), 4 weeks after crop seeding, tillage was again significant, and there was a significant interaction between tillage and 'row' or 'inter-row' position. These results demonstrate the importance of crop management in modifying the response of water repellent soils to rainfall in the field.

Ward, Phil; Roper, Margaret; Micin, Shayne; Jongepier, Ramona

2014-05-01

152

A Review on Temporal Stability of Soil Water Contents  

NASA Astrophysics Data System (ADS)

Temporal stability of soil water content (TS SWC) has been observed across a wide range of soil types, landscapes, climates and scales. A better understanding of TS SWC controls and their interactions needs to be developed. The objective of this work is to develop a comprehensive inventory of published data on TC SWC and to determine knowledge gaps. Mean relative difference (MRD) values and associated standard deviations (SDRD) were digitized from 157 graphs in 37 publications and analyzed. The MRD followed generally a Gaussian distribution with the determination coefficient R2 > 0.84. The standard deviation of MRD (SDMRD) showed a trend of increase with scale. No relationship between SDMRD and R2 was observed. The smallest R2 values were mostly found for negatively skewed and platykurtic MRD distributions. An analysis of seven measurement-, terrain-, and climate-related TS SWC controls suggested strong interactions and showed that combined effects are typically observed. Many of the existing datasets on TS WCS are mostly byproducts of soil water dynamics studies in agronomic or environmental projects. Future research should include more focused TS SWC studies tailored to understand interactions of controls, underlying mechanisms, and efficiency of applications.

Vanderlinden, Karl; Vereecken, Harry; Hardelauf, Horst; Herbst, Michael; Martínez, Gonzalo; Cosh, Michael H.; Pachepsky, Yakov A.

2013-04-01

153

Soil organic carbon covariance with soil water content; a geostatistical analysis in cropland fields  

NASA Astrophysics Data System (ADS)

Soil texture has traditionally represented the rate of soil water drainage influencing soil water content (WC) in the soil characteristic curves, hydrological models and remote sensing field studies. Although soil organic carbon (OC) has been shown to significantly increase the water holding capacity of soil in individual field studies, evidence is required to consider soil OC as a significant factor in soil WC variability at the scale of a remote sensing footprint (25 km2). The relationship of soil OC to soil WC was evaluated over 50 fields during the Soil Moisture Active Passive (SMAP) soil WC field sampling campaign over southern Manitoba, Canada. On each field, soil WC was measured at 16 sample points, at 100 m spacing to 5 cm depth with Stevens hydra probe sensors on 16 sampling dates from June 7 to July 19, 2012. Soil cores were also taken at sampling sites on each field, each sampling day, to determine gravimetric moisture, bulk density and particle size distribution. On 4 of the sampling dates, soil OC was also determined by loss on ignition on the dried soil samples from all fields. Semivariograms were created from the field mean soil OC and field mean surface soil WC sampled at midrow, over all cropland fields and averaged over all sampling dates. The semivariogram models explained a distinct relationship of both soil OC and WC within the soil over a range of 5 km with a Gaussian curve. The variance in soil that soil OC and WC have in common was a similar Gaussian curve in the cross variogram. Following spatial interpolation with Kriging, the spatial maps of soil OC and WC were also very similar with high covariance over the majority of the sampling area. The close correlation between soil OC and WC suggests they are structurally related in the soil. Soil carbon could thus assist in improving downscaling methods for remotely sensed soil WC and act as a surrogate for interpolation of soil WC.

Manns, H. R.; Berg, A. A.; von Bertoldi, P.

2013-12-01

154

Root effects on soil water and hydraulic properties  

Microsoft Academic Search

Plants can affect soil moisture and the soil hydraulic properties both directly by root water uptake and indirectly by modifying\\u000a the soil structure. Furthermore, water in plant roots is mostly neglected when studying soil hydraulic properties. In this\\u000a contribution, we analyze effects of the moisture content inside roots as compared to bulk soil moisture contents and speculate\\u000a on implications of

Horst H. Gerke; Rolf O. Kuchenbuch

2007-01-01

155

USE OF LIMITED SOIL PROPERTY DATA AND MODELING TO ESTIMATE ROOT ZONE SOIL WATER CONTENT.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Modeling root zone soil water content at watershed scales is important for both the strategic and tactical management of water resources, but detailed soil physical and hydraulic property data required by most physically-based soil water models are generally not available over large land areas. Wit...

156

Evaluation and Targeting of Soil and Water Conservation Practices in the Goodwater Creek Watershed  

Technology Transfer Automated Retrieval System (TEKTRAN)

The objective of our research was to identify how conservation practices, their biophysical settings, and the socio/economic constraints interact to affect water quality in the Goodwater Creek Experimental Watershed. Analysis of fifteen years of flow and water quality data showed that soil and water...

157

Carbon dioxide and water vapor exchange in response to drought in the atmosphere and in the soil  

Microsoft Academic Search

This review describes the current hypotheses of how humidity and plant and soil water status may interact and regulate stomatal conductance and photosynthesis. This review will focus on the effects of 1. humidity, 2. leaf water potential and leaf turgor, and of 3. soil water status on leaf conductance, transpiration, and COâ assimilation.

E D Schulze

1986-01-01

158

Water movement through an experimental soil liner  

USGS Publications Warehouse

A field-scale soil liner was constructed to test whether compacted soil barriers in cover and liner systems could be built to meet the U.S. EPA saturated hydraulic conductivity requirement (???1 x 10-7 cm s-1). The 8 x 15 x 0.9m liner was constructed in 15 cm compacted lifts using a 20,037 kg pad-foot compactor and standard engineering practices. Water infiltration into the liner has been monitored for one year. Monitoring will continue until water break through at the base of the liner occurs. Estimated saturated hydraulic conductivities were 2.5 x 10-9, 4.0 x 10-8, and 5.0 x 10-8 cm s-1 based on measurements of water infiltration into the liner by large- and small-ring infiltrometers and a water balance analysis, respectively. Also investigated in this research was the variability of the liner's hydraulic properties and estimates of the transit times for water and tracers. Small variances exhibited by small-ring flux data suggested that the liner was homogeneous with respect to infiltration fluxes. The predictions of water and tracer breakthrough at the base of the liner ranged from 2.4-12.6 y, depending on the method of calculation and assumptions made. The liner appeared to be saturated to a depth between 18 and 33 cm at the end of the first year of monitoring. Transit time calculations cannot be verified yet, since breakthrough has not occurred. The work conducted so far indicates that compacted soil barriers can be constructed to meet the saturated hydraulic conductivity requirement established by the U.S. EPA.A field-scale soil liner was constructed to test whether compacted soil barriers in cover and liner systems could be built to meet the U.S. EPA saturated hydraulic conductivity requirement (??? 1 ?? 10-7 cm s-1). The 8 ?? 15 ?? 0.9 m liner was constructed in 15 cm compacted lifts using a 20.037 kg pad-foot compactor and standard engineering practices. Water infiltration into the liner has been monitored for one year. Monitoring will continue until water break through at the base of the liner occurs. Estimated saturated hydraulic conductivities were 2.5 ?? 10-9, 4.0 ?? 10-8, and 5.0 ?? 10-8 cm s-1 based on measurements of water infiltration into the liner by large- and small-ring infiltrometers and a water balance analysis, respectively. Also investigated in this research was the variability of the liner's hydraulic properties and estimates of the transit times for water and tracers. Small variances exhibited by small-ring flux data suggested that the liner was homogeneous with respect to infiltration fluxes. The predictions of water and tracer breakthrough at the base of the liner ranged from 2.4-12.6 y, depending on the method of calculation and assumptions made. The liner appeared to be saturated to a depth between 18 and 33 cm at the end of the first year of monitoring. Transit time calculations cannot be verified yet, since breakthrough has not occurred. The work conducted so far indicates that compacted soil barriers can be constructed to meet the saturated hydraulic conductivity requirement established by the U.S. EPA.

Krapac, I.G.; Cartwright, K.; Panno, S.V.; Hensel, B.R.; Rehfeldt, K.R.; Herzog, B.L.

1991-01-01

159

Nitrogen in Desert Grasses as Affected by Biosolids, their Time of Application, and Soil Water Content  

Microsoft Academic Search

This study evaluated the interactive effect of biosolids, time of application, and soil water on plant N concentration and uptake by Bouteloua gracilis (blue grama) and Hilaria mutica (tobosagrass) grown in pots. Biosolids were surface-applied to the soil of the pots either in the spring or the summer at rates of 0, 7, 18, 34, and 90 dry Mg ha.

RICARDO MATA-GONZÁLEZ; RONALD E. SOSEBEE; CHANGGUI WAN

2004-01-01

160

Ad Hoc Modeling of Root Zone Soil Water with Landsat Imagery and Terrain and Soils Data  

PubMed Central

Agricultural producers require knowledge of soil water at plant rooting depths, while many remote sensing studies have focused on surface soil water or mechanistic models that are not easily parameterized. We developed site-specific empirical models to predict spring soil water content for two Montana ranches. Calibration data sample sizes were based on the estimated variability of soil water and the desired level of precision for the soil water estimates. Models used Landsat imagery, a digital elevation model, and a soil survey as predictor variables. Our objectives were to see whether soil water could be predicted accurately with easily obtainable calibration data and predictor variables and to consider the relative influence of the three sources of predictor variables. Independent validation showed that multiple regression models predicted soil water with average error (RMSD) within 0.04 mass water content. This was similar to the accuracy expected based on a statistical power test based on our sample size (n = 41 and n = 50). Improved prediction precision could be achieved with additional calibration samples, and range managers can readily balance the desired level of precision with the amount of effort to collect calibration data. Spring soil water prediction effectively utilized a combination of land surface imagery, terrain data, and subsurface soil characterization data. Ranchers could use accurate spring soil water content predictions to set stocking rates. Such management can help ensure that water, soil, and vegetation resources are used conservatively in irrigated and non-irrigated rangeland systems.

Sankey, Joel B.; Lawrence, Rick L.; Wraith, Jon M.

2008-01-01

161

How can climate, soil, and monitoring schedule affect temporal stability of soil water contents?  

NASA Astrophysics Data System (ADS)

Temporal stability (TS) of soil water content (SWC) reflects the spatio-temporal organization of soil water. The TS SWC was originally recognized as a phenomenon that can be used to provide temporal average SWC of an area of interest from observations at a representative location(s). Currently application fields of TS SWC are numerous, e.g. up- and downscaling SWC, SWC monitoring and data assimilation, precision farming, and sensor network design and optimization. However, the factors that control the SWC organization and TS SWC are not completely understood. Among these factors are soil hydraulic properties that are considered as local controls, weather patterns, and the monitoring schedule. The objective of this work was to use modeling to assess the effect of these factors on the spatio-temporal patterns of SWC. We ran the HYDRUS6 code to simulate four years of SWC in 4-m long soil columns. The columns were assumed homogeneous, soil hydraulic conductivity was drawn from lognormal distributions. Sets of columns were generated separately for sandy loam and loamy soils, soil water retention was set to typical values for those soil textures. Simulations were carried out for four climates present at the continental US. The climate-specific weather patterns were obtained with the CLIGEN code using climate-specific weather observation locations that were humid subtropical from College Station (TX), humid continental from Indianapolis (IN), cold semiarid from Moscow (ID) and hot semiarid from Tucson (AZ). We evaluated the TS and representative location (RL) selections by comparing i) different climates; ii) for the same climates different years; iii) different time intervals between samplings; iv) one year duration surveys vs. one month summer campaigns; and v) different seasons of the same year. Spatial variability of the mean relative differences (MRD) differed among climates for both soils, as the probability of observing the same variance in the MRD was lower than 29%. These differences were smaller for the loamy soils than for the sandy loam and may be related to more inertia to changes in SWC in the loam soil. The probability that the variance in MRD depended on sampling frequency was always higher than 89% in the sandy loam soil and was above 97% in the loamy soil. Same variability of MRD with July and the whole year SWC was generally low probable and depended on the soil type and climate. Different variability of the MRD with season was found with at least a 55% probability. Larger differences were observed for the robustness of the MRD than for its spatial variability. The inter-annual difference in MRD variation from short and intensive summer campaigns was highly probable for all climates. There were more coincidences under the different scenarios analyzed in the RL selected for the sandy loam soil than for the loamy soil. Among the methods used for selection of RL, those that are based on a minimum difference with MRD of zero showed more consistency than others. The TS appears to be the result of the interplay between climate, soil properties, and survey protocols. One implication of this factor interaction effect on TS SWC is that a simulation study can be useful to decide on the feasibility of including a search for the representative location based on TS for a specific site.

Martinez, G.; Pachepsky, Y. A.; Vereecken, H.

2012-12-01

162

[Dynamics of soil water under Eucommia ulmodes plantation in hilly red soil region of southern China].  

PubMed

By using time domain reflectometry (TDR), a fixed-position monitoring research on the dynamics of soil water under Eucommia ulmoides plantation was conducted in a hilly red soil region of southern China. The results showed that there was a significant difference in the soil water storage among different months, and the dynamics of soil water could be divided into the phases of reduction, increase, and more reduction. Soil water varied significantly in its vertical distribution, and the variation pattern also differed with seasons. The vertical distribution of soil water could be divided into two phases, i.e., accumulation and depletion based on the seasonal variation of soil water, or rainy season and dry season based on the monthly variation of rainfall. Soil water was correlated significantly (P < 0.05) with relative humidity (RH), air temperature (t), vapor pressure deficit (VPD) and rainfall (R), and regulated by these meteorological factors synthetically, among which, rainfall was the most important factor, followed by air temperature. The soil water loss rate after rain had a significant hyperbolic relationship with durative droughty days, while soil water storage had a significant linear negative relationship with this duration (P < 0.05). With the extension of drought duration after rain, soil water loss tended to vary gently with increasing soil depth. PMID:18062293

Huang, Zhi-Gang; Li, Feng-Rui; Cao, Yun; Wang, Zhong-Jian; Ouyang, Zhi-Yun; Zheng, Hua; Li, Xi-Quan; Tian, Yu-Xin

2007-09-01

163

Climate change impacts on soil and water conservation  

Technology Transfer Automated Retrieval System (TEKTRAN)

A 2003 report of the Soil and Water Conservation Society concluded that changes in long-term precipitation may substantial impact runoff and soil erosion. These findings call for a review of current approaches to estimating runoff and soil erosion from agricultural lands, enhancements to soil and wa...

164

Biological and Environmental Engineering Soil & Water Research Group  

E-print Network

for generating maps of soil topographic index (STI) from TI maps and soil data. The procedure for generating a topographic index (TI) map from DEM is described in "Creating TI map". #12;Biological and Environmental Engineering Soil & Water Research Group ·STI grids are soil topographic index grids, derived from digital

Walter, M.Todd

165

Managing pine straw harvests to minimize soil and water losses  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pine straw is a valuable landscape mulch because it conserves soil moisture, moderates soil temperature, inhibits weed growth, and protects the soil surface against erosion, while retaining a loose structure that allows water, air, and fertilizer to easily reach the soil surface. As a result, marke...

166

Harmful soil changes in storm water infiltration devices  

Microsoft Academic Search

The investigation of chemical soil properties in storm water infiltration devices is based on the concern that these soils accumulate harmful substances like heavy metals more than normal soils. In case of confirmation of this concern, this investigation is to prove the dimension of the harmful soil changes and to see if there is a transgression of trigger values of

HILLER Dieter; DORNAUF Christine; WINZIG Guido

1999-01-01

167

EFFECT OF SOIL AGGREGATE SIZE DISTRIBUTION ON WATER RETENTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Quantitative information on soil water retention is in demand in hydrology, agrometeorology, agronomy, contaminant transport, and other soil-related disciplines of earth and environmental sciences. Soil aggregate composition is an important characteristic of soil structure and, as such, has been exp...

168

USING WINTER COVER CROPS TO IMPROVE SOIL AND WATER QUALITY  

Microsoft Academic Search

This article reviews literature about the impacts of cover crops in cropping systems that affect soil and water quality and presents limited new information to help fill knowledge gaps. Cover crops grow during periods when the soil might otherwise be fallow. While actively growing, cover crops increase solar energy harvest and carbon flux into the soil, providing food for soil

S. M. Dabney; J. A. Delgado; D. W. Reeves

2001-01-01

169

Soil erosion by water - model concepts and application  

NASA Astrophysics Data System (ADS)

Soil erosion is not a continuous process but the result of isolated surface runoff events, whose erosional effects are determined by numerous temporally and spatially varying variables. Thus the monitoring of soil loss by direct observation is extremely limited with respect to space and time. Usually observation plots cover an area of less than 100 m2 and the observation period is less than 10 years. In order to estimate soil losses by water erosion for others than empirically observable conditions, mathematical models are needed, which are able to describe the interaction of the different physical mechanisms involved either statistically or on the basis of physical algorithms. Such models are absolutely essential for risk prognoses on catchment and regional scale. Besides the aspect of soil conservation the delivery of sediments and sediment bound pollutants into surface water bodies are of increasing relevance in this context. Based on an exemplary selection of existing water erosion models this contribution aims to give an overview over different mathematical approaches used for the description of particle detachment, transport and deposition of soil particles. According to the chronology in the development of soil erosion models empirical algorithms will be presented first based on the USLE approach. However, since purely empirical models like USLE are limited to the estimation of annual soil loss further attempts in soil erosion modelling are focussed on event based estimations considering the fact that soil erosion is not a continuous process but the result of isolated runoff events. One of the first models of this type was CREAMS using physically based algorithms in combination with empirical ones in order to describe the basic erosion processes. Today there are diverse soil erosion models available following in principle the CREAMS concept but using different algorithms in detail. Concerning particle detachment, transport and deposition alternative approaches will be discussed taking account of the models WEPP, EUROSEM, IISEM and EROSION 3D. In order to provide a better representation of spatially heterogeneous catchments in terms of landuse, soil, slope, and rainfall most of recently developed models operate on a grid-cell basis or other kinds of sub-units, each having uniform characteristics. These so-called "Distributed Models" accepts inputs from raster based geographic information system (GIS). The cell-based structure of the models also allows to generate drainage paths by which water and sediment can be routed from the top to the bottom of the respective watershed. One of the open problems in soil erosion modelling refers to the spontaneous generation of erosion rills without the need for pre-existing morphological contours. A promising approach to handle this problem was realized first in the RILLGROW model, which uses a cellular automaton system in order to generate realistic rill patterns. With respect to the above mentioned models selected applications will be presented and discussed regarding their usability for soil and water conservation purposes.

Schmidt, Juergen

2010-05-01

170

Water status of soil and vegetation in a shortgrass steppe  

Microsoft Academic Search

In an attempt to describe some major relationships between soil and plant compartments in a shortgrass steppe, the process of water loss from the system and plant water relations throughout a drying cycle were studied. The water supply was manipulated and some soil and plant variables monitored throughout a drying cycle. Leaf conductance and leaf water potential of blue grama

O. E. Sala; W. K. Lauenroth; W. J. Parton; M. J. Trlica

1981-01-01

171

Seismic behavior of bridge piers including soil-structure interaction  

Microsoft Academic Search

As a rule, widely used practices do not consider soil-structure interaction (SSI) in the seismic design of bridges. This study attempts to assess the significance of SSI for the design of bridge piers placed on either a homogeneous deep soil stratum or a shallow soil stratum overlying a rigid bedrock. The objective is pursued through a simple, yet capable to

C Spyrakos

1992-01-01

172

Centrifuge modelling of seismic soil structure interaction effects  

Microsoft Academic Search

Proper understanding of the role of unbounded soil in the evaluation of dynamic soil structure interaction (SSI) problem is very important for structures used in the nuclear industry. In this paper, the results from a series of dynamic centrifuge tests are reported. These tests were performed on different types of soil stratifications supporting a rigid containment structure. Test results indicate

B. Ghosh; S. P. G. Madabhushi

2007-01-01

173

Mucilage exudation facilitates root water uptake in dry soils  

NASA Astrophysics Data System (ADS)

As plant roots take up water and the soil dries, water depletion is expected to occur in the rhizosphere. However, recent experiments showed that the rhizosphere of lupines was wetter than the bulk soil during root water uptake. On the other hand, after irrigation the rhizosphere remained markedly dry and it rewetted only after one-two days. We hypothesize that: 1) drying/wetting rates of the rhizosphere are controlled by mucilage exuded by roots; 2) mucilage alters the soil hydraulic conductivity: in particular, wet mucilage increases the soil hydraulic conductivity and dry mucilage makes the soil water repellent; 3) mucilage exudation favors root water uptake in dry soil; and 4) dry mucilage limits water loss from roots to dry soils. We used a root pressure probe to measure the hydraulic conductance of artificial roots sitting in soils. As an artificial root we employed a suction cup with a diameter of 2 mm and a length of 45 mm. The root pressure probe gave the hydraulic conductance of the soil-root continuum during pulse experiments in which water was injected into or sucked from the soil. First, we performed experiments with roots in a relatively dry soil with a volumetric water content of 0.03. Then, we repeated the experiment with artificial roots covered with mucilage and then placed into the soil. As a model for mucilage, we collected mucilage from Chia seeds. The water contents (including that of mucilage) in the experiments with and without mucilage were equal. The pressure curves were fitted with a model of root water that includes rhizosphere dynamics. We found that the artificial roots covered with wet mucilage took up water more easily. In a second experimental set-up we measured the outflow of water from the artificial roots into dry soils. We compared two soils: 1) a sandy soil and 2) the same soil wetted with mucilage from Chia seeds and then let dry. The latter soil became water repellent. Due to the water repellency, the outflow of water from the root in this soil was significantly reduced. The experiments demonstrated that mucilage increased the hydraulic conductance of the root-soil continuum and facilitated the extraction of water from dry soils. The increase in conductivity resulted from the higher water content of the soil near the roots. Mucilage has a lower surface tension than pure water and a higher viscosity, resulting in a slower penetration of mucilage into the soil. After mucilage was placed into the soil, it did not spread into the bulk soil, but it remained near the roots, maintaining the rhizosphere wetter and more conductive than the bulk soil. However, as mucilage dried, it turned water repellent and reduced the back flow of water from the root to soil. We hypothesize that mucilage exudation is a plant strategy to locally and temporally facilitate water uptake from dry soils. After drying, mucilage becomes water repellent and may limit the local uptake of water after irrigation. On the other hand, mucilage water repellency may as well be a strategy to reduce water loss from roots to dry soils.

Ahmed, Mutez; Kroener, Eva; Holz, Maire; Zarebanadkouki, Mohsen; Carminati, Andrea

2014-05-01

174

Ecohydrology of root zone water fluxes and soil development in complex semiarid rangelands  

NASA Astrophysics Data System (ADS)

In semiarid complex terrain, the landscape creates spatial niches for different types of vegetation through the effects of aspect, slope and curvature on the water and energy balance at the soil surface. The ecohydrology of rangelands is defined by the interaction of soils, plants and climate occurring on a topographic surface. While these interactions have been studied for subtle terrain, little is known about the controls exerted by terrain position, in particular terrain aspect, on ecosystem processes. Furthermore, differential plant establishment can lead to measurable differences in rates of soil development, which in turn can affect soil hydraulic properties and the surface water balance. In this study, we outline the physical mechanisms affecting plant establishment, soil development and hydrologic fluxes in semiarid complex terrain. We illustrate the interactions between vegetation, root zone water fluxes and soil development using, as an example, a small drainage basin in the Sevilleta National Wildlife Refuge (SNWR), New Mexico. In the study basin, opposing hillslopes are characterized by marked differences in ecosystem composition and soil profile properties, with the north-facing hillslope dominated by one seed juniper (Juniperus monosperma) and the south-facing slope consisting of creosote bush (Larrea tridentata). We assess the effect of terrain aspect on root zone hydrologic fluxes and soil development in the two ecosystems by using soil observations, hydraulic properties from pedotransfer functions (PTFs), and numerical modelling of vadose zone fluxes. Modelling results show marked differences in root zone fluxes in the north-facing juniper and south-facing creosote ecosystems. Differences in the amplitude and frequency of soil water content and pressure correspond to changes in soil profile and vegetation characteristics. For example, soil properties of the calcium carbonate (CaCO3) horizons and differential plant water uptake impact the simulated soil water pressure over an 8-year period in the opposing ecosystems. It is believed that these variations in water fluxes reinforce the development of CaCO3 horizons present in the soil profiles, leading to a feedback between vegetation establishment, soil water fluxes and geomorphic processes in the catchment. Our results also indicate that soil properties and water fluxes compensate for large differences in evaporative demand and lead to similar actual evapotranspiration (AET) in the opposing slopes.

Gutiérrez-Jurado, Hugo A.; Vivoni, Enrique R.; Harrison, J. Bruce J.; Guan, Huade

2006-10-01

175

Determining the least limiting water range using limited soil data  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Least Limiting Water Range (LLWR) is a useful tool to evaluate changes in soil physical condition caused by changing soil management. It incorporates limitations to plant growth based on limiting aeration, water holding capacity and soil strength. A disadvantage of the LLWR is the need to determ...

176

Soil Water Trends During the 2005 - 2006 Drought in Oklahoma  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil water depletion is an early consequence of a meteorological drought, with the latter defined as a precipitation deficit lasting a few months to several years. Soil water in the upper soil profile (approximately first meter) is limited and highly variable because of its rapid response to precipi...

177

Willie Harris Address: Soil and Water Science Department  

E-print Network

1 Willie Harris Address: Soil and Water Science Department 2169 McCarty Hall University of Florida Fellow, Soil Science Society of America, 2005 UF College of Agriculture and Life Sciences (CALS) Graduate in Graduate Research, 2005 Soil and Water Science Department Outstanding Teacher/Advisor of the Year, 2003

Jawitz, James W.

178

Soil, Water and Forage Testing Laboratory Phosphorus recommendations applicable for  

E-print Network

Soil, Water and Forage Testing Laboratory Phosphorus recommendations applicable for methods used 20 15 5 0 #12;Soil, Water and Forage Testing Laboratory Phosphorus recommendations applicable by laboratory. Mehlich III by ICP only. Phosphorus Soil Fertility Recommendations for Oil Crops 0 5 10 15 20 25

179

Simulation of Water Transport in the Soil-Plant - System.  

NASA Astrophysics Data System (ADS)

The objective of this dissertation is to develop a mechanistic model of water transport in the soil-plant -atmosphere system that describes the plant's physical expression of water stress to study the effects of environmental factors, and plant hydraulic and physical properties on plant water transport. The model includes soil moisture uptake, soil heat and water transfer, evapotranspiration, and energy partitioning in the canopy and at the soil surface. The model inputs are: daily weather data (air temperature, dew point temperature, wind speed, and solar radiation); initial soil moisture and temperature profiles; plant characteristics; root density; and soil hydraulic properties. The model user may select from a number of outputs. Principal outputs include: leaf resistance, leaf temperature, soil moisture profile and evapotranspiration rate. The model describes a feedback mechanism by which transpiration controls leaf water potential, leaf water potential influences leaf resistance, and leaf resistance which, in turn, controls transpiration. The simulation runs represented the energy partitioning in the canopy and at the soil surface, and the diurnal variation of temperatures and vapor pressures of the leaf, the canopy air, and the soil surface. The relationships of leaf water potential to soil water potential, leaf resistance and transpiration were also presented. In addition, results show that root water extraction is related to the root length density profile and the soil moisture profile. The model mechanistically describes the water transport in the soil-plant-atmosphere system. The results of model validation indicated that the model is capable of simulating plant water transport under natural conditions with reasonable accuracy. Results show that the model simulates the basic features of the system including feedback processes. The sensitivity studies show that the model may be used to study plant water response to environmental factors and plant properties. The model is also useful for estimating evapotranspiration and the soil moisture profile and may provide information for irrigation and soil water management. (Abstract shortened with permission of author.).

Guo, Yimei

1992-01-01

180

Dynamic aspects of soil water availability for isohydric plants: Focus on root hydraulic resistances  

NASA Astrophysics Data System (ADS)

Soil water availability for plant transpiration is a key concept in agronomy. The objective of this study is to revisit this concept and discuss how it may be affected by processes locally influencing root hydraulic properties. A physical limitation to soil water availability in terms of maximal flow rate available to plant leaves (Qavail) is defined. It is expressed for isohydric plants, in terms of plant-centered variables and properties (the equivalent soil water potential sensed by the plant, ?s eq; the root system equivalent conductance, Krs; and a threshold leaf water potential, ?leaf lim). The resulting limitation to plant transpiration is compared to commonly used empirical stress functions. Similarities suggest that the slope of empirical functions might correspond to the ratio of Krs to the plant potential transpiration rate. The sensitivity of Qavail to local changes of root hydraulic conductances in response to soil matric potential is investigated using model simulations. A decrease of radial conductances when the soil dries induces earlier water stress, but allows maintaining higher night plant water potentials and higher Qavail during the last week of a simulated 1 month drought. In opposition, an increase of radial conductances during soil drying provokes an increase of hydraulic redistribution and Qavail at short term. This study offers a first insight on the effect of dynamic local root hydraulic properties on soil water availability. By better understanding complex interactions between hydraulic processes involved in soil-plant hydrodynamics, better prospects on how root hydraulic traits mitigate plant water stress might be achieved.

Couvreur, V.; Vanderborght, J.; Draye, X.; Javaux, M.

2014-11-01

181

Measuring and modeling water-related soil-vegetation feedbacks in a fallow plot  

NASA Astrophysics Data System (ADS)

Land fallowing is one possible response to shortage of water for irrigation. Leaving the soil unseeded implies a change of the soil functioning that has an impact on the water cycle. The development of a soil crust in the open spaces between the patterns of grass weed affects the soil properties and the field-scale water balance. The objectives of this study are to test the potential of integrated non-invasive geophysical methods and ground-image analysis and to quantify the effect of the soil-vegetation interaction on the water balance of fallow land at the local- and plot scale. We measured repeatedly in space and time local soil saturation and vegetation cover over two small plots located in southern Sardinia, Italy, during a controlled irrigation experiment. One plot was left unseeded and the other was cultivated. The comparative analysis of ERT maps of soil moisture evidenced a considerably different hydrologic response to irrigation of the two plots. Local measurements of soil saturation and vegetation cover were repeated in space to evidence a positive feedback between weed growth and infiltration at the fallow plot. A simple bucket model captured the different soil moisture dynamics at the two plots during the infiltration experiment and was used to estimate the impact of the soil vegetation feedback on the yearly water balance at the fallow site.

Ursino, N.; Cassiani, G.; Deiana, R.; Vignoli, G.; Boaga, J.

2014-03-01

182

Measuring and modelling water related soil-vegetation feedbacks in a fallow plot  

NASA Astrophysics Data System (ADS)

Land fallowing is one possible response to shortage of water for irrigation. Leaving the soil unseeded implies a change of the soil functioning that has an impact on the water cycle. The development of a soil crust in the open spaces between the patterns of grass weed affects the soil properties and the field scale water balance. The objectives of this study are to test the potential of integrated non invasive geophysical methods and ground-image analysis and to quantify the effect of the soil vegetation interaction on the water balance of a fallow land at the local and plot scale. We measured repeatedly in space and time local soil saturation and vegetation cover over two small plots located in southern Sardinia, Italy, during a controlled irrigation experiment. One plot was left unseeded and the other was cultivated. The comparative analysis of ERT maps of soil moisture evidenced a considerably different hydrologic response to irrigation of the two plots. Local measurements of soil saturation and vegetation cover were repeated in space to evidence a positive feedback between weed growth and infiltration at the fallow plot. A simple bucket model captured the different soil moisture dynamics at the two plots during the infiltration experiment and was used to estimate the impact of the soil vegetation feedback on the yearly water balance at the fallow site.

Ursino, N.; Cassiani, G.; Deiana, R.; Vignoli, G.; Boaga, J.

2013-08-01

183

Investigation of Soil Moisture - Vegetation Interactions in Oklahoma  

E-print Network

and-atmosphere interactions are an important component of climate, especially in semi-arid regions such as the Southern Great Plains. Interactions between soil moisture and vegetation modulate land-atmosphere coupling and thus represent a crucial...

Ford, Trenton W.

2013-03-06

184

Soil water availability for plants as quantified by conventional available water, least limiting water range and integral water capacity  

Microsoft Academic Search

There are different approaches to define the soil available water (SAW) for plants. The objectives of this study are to evaluate\\u000a the SAW values of 12 arable soils from Hamadan province (western Iran) calculated by plant available water (PAW), least limiting\\u000a water range (LLWR) and integral water capacity (IWC) approaches and to explore their relations with Dexter’s index of soil

Hossein Asgarzadeh; Mohammad Reza Mosaddeghi; Ali Akbar Mahboubi; Akram Nosrati; Anthony Roger Dexter

2010-01-01

185

Soil-Water Characteristic Curve Modeling at Low Water Content: Empirical and Semi-Empirical Approaches  

E-print Network

Soil-Water Characteristic Curve Modeling at Low Water Content: Empirical and Semi model, the Modified Kovacs (MK) model for the determination of soil-water characteristic curve at the low water contents of two horizons of a soil from Burkina Faso. Combining terms from capillary state

Paris-Sud XI, Université de

186

The redistribution of soil water by tree root systems  

Microsoft Academic Search

Plant roots transfer water between soil layers of different water potential thereby significantly affecting the distribution\\u000a and availability of water in the soil profile. We used a modification of the heat pulse method to measure sap flow in roots\\u000a of Grevillea robusta and Eucalyptus camaldulensis and demonstrated a redistribution of soil water from deeper in the profile to dry surface

Stephen S. O. Burgess; Mark A. Adams; Neil C. Turner; Chin K. Ong

1998-01-01

187

Surface water and groundwater interactions in coastal wetlands  

NASA Astrophysics Data System (ADS)

Salt marshes are an important wetland system in the upper intertidal zone, interfacing the land and coastal water. Dominated by salt-tolerant plants, these wetlands provide essential eco-environmental services for maintaining coastal biodiversity. They also act as sediment traps and help stabilize the coastline. While they play an active role in moderating greenhouse gas emissions, these wetlands have become increasingly vulnerable to the impact of global climate change. Salt marshes are a complex hydrological system characterized by strong, dynamic interactions between surface water and groundwater, which underpin the wetland's eco-functionality. Bordered with coastal water, the marsh system undergoes cycles of inundation and exposure driven by the tide. This leads to dynamic, complex pore-water flow and solute transport in the marsh soil. Pore-water circulations occur at different spatial and temporal scales with strong link to the marsh topography. These circulations control solute transport between the marsh soil and the tidal creek, and ultimately affect the overall nutrient exchange between the marsh and coastal water. The pore-water flows also dictate the soil aeration conditions, which in turn affect marsh plant growth. This talk presents results and findings from recent numerical and experimental studies, focusing on the pore-water flow behaviour in the marsh soil under the influence of tides and density-gradients.

Li, Ling; Xin, Pei; Shen, Chengji

2014-05-01

188

Soil Water Thermodynamic to Unify Water Retention Curve by Pressure Plates and Tensiometer  

NASA Astrophysics Data System (ADS)

The pressure plate method is a standard method for measuring the pF curves, also called soil water retention curves, in a large soil moisture range from saturation to a dry state corresponding to a tension pressure of near 1500 kPa. However, the pressure plate can only provide discrete water retention curves represented by a dozen measured points. In contrast, the measurement of the soil water retention curves by tensiometer is direct and continuous, but limited to the range of the tensiometer reading: from saturation to near 70-80 kPa. The two methods stem from two very different concepts of measurement and the compatibility of both methods has never been demonstrated. The recently established thermodynamic formulation of the pedostructure water retention curve, will allow the compatibility of the two curves to be studied, both theoretically and experimentally. This constitutes the object of the present article. We found that the pressure plate method provides accurate measurement points of the pedostructure water retention curve h(W), conceptually the same as that accurately measured by the tensiometer. However, contrarily to what is usually thought, h is not equal to the applied air pressure on the sample, but rather, is proportional to its logarithm, in agreement with the thermodynamic theory developed in the article. The pF curve and soil water retention curve, as well as their methods of measurement are unified in a same physical theory. It is the theory of the soil medium organization (pedostructure) and its interaction with water. We show also how the hydrostructural parameters of the theoretical curve equation can be estimated from any measured curve, whatever the method of measurement. An application example using published pF curves is given.

Braudeau, Erik; Hovhannissian, Gaghik; Assi, Amjad; Mohtar, Rabi

2014-10-01

189

Seasonal and long-term effects of CO2 and O3 and their interaction with climate and soil moisture on water loss in ponderosa pine  

EPA Science Inventory

Evapotranspiration (ET) is driven by evaporative demand, available solar energy and soil moisture as well as by physiological plant activity which may be substantially affected by elevated CO2 and O3. A multi-year study was conducted in outdoor sun-lit controlled-environment cha...

190

Seasonal and long-term effects of CO2 and O3 on water loss in ponderosa pine and their interaction with climate and soil moisture  

EPA Science Inventory

Evapotranspiration (ET) is driven by evaporative demand, available solar energy and soil moisture (SM) as well as by plant physiological activity which may be substantially affected by elevated CO2 and O3. A multi-year study was conducted in outdoor sunlit-controlled environment ...

191

Determination of Martian soil mineralogy and water content using the Thermal Analyzer for Planetary Soils (TAPS)  

NASA Technical Reports Server (NTRS)

Physical and chemical interactions between the surface and atmosphere of Mars can be expected to embody a strong cause-and-effect relationship with the minerals comprising the martian regolith. Many of the minerals in soils and sediments are probably products of chemical weathering (involving surface/atmosphere or surface/hydrosphere reactions) that could be expected to subsequently influence the sorption of atmospheric gases and water vapor. Therefore, identification of the minerals in martian surface soils and sediments is essential for understanding both past and present interactions between the Mars surface and atmosphere. Clearly, the most definitive mineral analyses would be achieved with well-preserved samples returned to Earth-based laboratories. In advance of a Mars sample return mission, however, significant progress could be made with in situ experiments that fill current voids in knowledge about the presence or abundance of key soil minerals such as clays (layered-structured silicates), zeolites, and various salts, including carbonates. TAPS is intended to answer that challenge by providing first-order identification of soil and sediment minerals.

Gooding, James L.; Ming, Douglas W.; Allton, Judith H.; Byers, Terry B.; Dunn, Robert P.; Gibbons, Frank L.; Pate, Daniel B.; Polette, Thomas M.

1992-01-01

192

PERMEABILITY OF SOILS TO FOUR ORGANIC LIQUIDS AND WATER  

EPA Science Inventory

Saturated hydraulic conductivities and intrinsic permeabilities were evaluated for eight contrasting soils with four organic liquids and water. The organic liquids were kerosene, ethylene glycol, isopropyl alcohol and xylene. Intrinsic permeability for any given soil varied inver...

193

Review of soil water models with respect to savanna hydrology   

E-print Network

Effective management leading towards sustainable rangeland production in arid and semi-arid regions will stem from effective soil water management and comprehension of the hydrological properties of the soil in relation to pastoralism. However...

Derry, Julian F; Russell, Graham; Liedloff, Adam C

2006-07-21

194

DEVELOPING JOINT PROBABILITY DISTRIBUTIONS OF SOIL WATER RETENTION CHARACTERISTICS  

EPA Science Inventory

A method is presented for developing probability density functions for parameters of soil moisture relationships of capillary head and hydraulic conductivity. These soil moisture parameters are required for the assessment of water flow and solute transport in unsaturated media. T...

195

Characterization of Soil Water Content Variability and Soil Texture using GPR Groundwave Techniques  

E-print Network

Characterization of Soil Water Content Variability and Soil Texture using GPR Groundwave Techniques. In this study, ground penetrating radar (GPR) methods were used to characterize the spatial correlation of water content in a three acre field as a function of sampling depth, season, vegetation, and soil texture. GPR

Hubbard, Susan

196

Verification of Ground Penetrating Radar for Soil Water Content Measuring  

NASA Astrophysics Data System (ADS)

Spatially distributed water at the land surface is a vital natural resource for human being and ecosystems. Soil water content at vadose zone at regional scale controls exchange of moisture and energy between Earth surface and atmosphere, at the catchment scale - the separation of precipitation into infiltration, runoff and evapotranspiration, at the field scale - plant growing, at the small plot scale - pathway of water flow through soil profile. Hydrologist, agronomists, soil scientists and others looking for technology providing soil water content measurements across a range of spatial range. Ground penetrating radar is not destructive method of measurement for diverse application was tested in the field for mapping a spatial distribution of soil water content during infiltration event at chestnut soil of Saratov Region, Russia. A Common-MidPoint method was used to calibrate GPR OKO with a 400 MHz antenna. At experimental plot of 50x50 m a range of 36 boreholes equipped by vertical access tubes (10 distance between) for TDR PR2 with 4 predefined depths of soil moisture measurements was prepared. TDR PR2 equipment used for measurements was calibrated on special experimental setup with soil from plot. Data sets of parallel measurements of soil water content by TDR at 4 depths of borehole locations and GPR at trace lines along ranges of boreholes were used to produce soil water content maps with geo-statistical methods. Keywords: GPR, TDR, soil water content

Ermolaeva, O.; Zeiliguer, A.

2009-04-01

197

Surface soil water content regimes: opportunities in soil science  

Microsoft Academic Search

With the qualities and properties of soil not being uniformly distributed across continents, soils are classified according to their morphological features, genesis and soil-forming processes. Because properties of soils vary across the landscape, a relationship observed at one location may not be applicable for other locations. Hence, measured data and deduced relationships are location specific and should be interpreted with

Donald R. Nielsen; Miroslav Kutílek; Marc B. Parlange

1996-01-01

198

Distribution of the genus Leptospira in soil and water.  

PubMed Central

The distribution of the aerobic spirochetes Leptospira in surface waters, soil, and aquatic animals was investigated. Isolates from water and soil exhibited physiological characteristics common to members of the "biflexa complex," none were capable of infecting experimental animals, and leptospires could not be isolated from the eight genera of aquatic animals examined. The isolation frequencies from surface waters were: stream, 100%; lake, 65%; spring, 28%; bog lake, 5%; and marsh, 0%. With the exception of the stream, more isolations were obtained from the soil adjacent to the water than from the water. Leptospires were most frequently associated with soils of high moisture and organic matter content. PMID:637546

Henry, R A; Johnson, R C

1978-01-01

199

Estimation of tree water relationships using a Soil-Tree-Atmosphere Continuum model  

NASA Astrophysics Data System (ADS)

To better understand root-soil water interactions, a mature white fir (Abies concolor) and the surrounding root zone were continuously monitored (sap flow, canopy stem water potential, soil moisture, and temperature), to characterize tree hydrodynamics. We present a hydrodynamic flow model, simulating unsaturated flow in the soil and tree with stress functions controlling spatially distributed root water uptake and canopy transpiration. Using the van Genuchten functions, we parameterize the effective retention and unsaturated hydraulic conductivity functions of the tree sapwood and soil, soil and canopy stress functions, and radial root zone distribution. To parameterize the in-situ tree water relationships, we combine a numerical model with observational data in an optimization framework, minimizing residuals between simulated and measured observational data of soil and tree canopy. Using the MCMC method, the HYDRUS model is run in an iterative process that adjusts parameters until residuals are minimized. Using these optimized parameters, the HYDRUS model simulates diurnal tree water potential and sap flow as a function of tree height, in addition to spatially distributed changes in soil water storage and soil water potential.

Hopmans, Jan; Hartsough, Peter; Rings, Joerg; Kandalous, Maziar; Kamai, Tamir; Vrugt, Jasper; Simunek, Jirka

2014-05-01

200

Influence of soil porosity on water use in Pinus taeda  

Microsoft Academic Search

We analyzed the hydraulic constraints imposed on water uptake from soils of different porosities in loblolly pine (Pinus taeda L.) by comparing genetically related and even-aged plantations growing in loam versus sand soil. Water use was evaluated\\u000a relative to the maximum transpiration rate (E\\u000a crit) allowed by the soil-leaf continuum. We expected that trees on both soils would approach E

U. G. Hacke; J. S. Sperry; B. E. Ewers; D. S. Ellsworth; K. V. R. Schäfer; R. Oren

2000-01-01

201

WATER AS A REAGENT FOR SOIL REMEDIATION  

SciTech Connect

SRI International is conducting experiments to develop and evaluate hydrothermal extraction technology or hot water extraction (HWE) technology for remediating petroleum-contaminated soils. Most current remediation practices either fail to remove the polycyclic aromatic hydrocarbons (PAHs) found in petroleum-contaminated sites, are too costly, or require the use of organic solvents at the expense of additional contamination and with the added cost of recycling solvents. Hydrothermal extraction offers the promise of efficiently extracting PAHs and other kinds of organics from contaminated soils at moderate temperatures and pressures, using only water and inorganic salts such as carbonate. SRI has conducted experiments to measure the solubility and rate of solubilization of selected PAHs (fluoranthene, pyrene, chrysene, 9,10-dimethylanthracene) in water using SRI's hydrothermal optical cell with the addition of varying amounts of sodium carbonate to evaluate the efficiency of the technology for removing PAHs from the soil. SRI data shows a very rapid increase in solubility of PAHs with increase in temperature in the range 25-275 C. SRI also measured the rate of solubilization, which is a key factor in determining the reactor parameters. SRI results for fluoranthene, pyrene, chrysene, and 9,10-dimethylanthracene show a linear relationship between rate of solubilization and equilibrium solubility. Also, we have found the rate of solubilization of pyrene at 275 C to be 6.5 ppm/s, indicating that the equilibrium solubilization will be reached in less than 3 min at 275 C; equilibrium solubility of pyrene at 275 C is 1000 ppm. Also, pyrene and fluoranthene appear to have higher solubilities in the presence of sodium carbonate. In addition to this study, SRI studied the rate of removal of selected PAHs from spiked samples under varying conditions (temperature, pore sizes, and pH). We have found a higher removal of PAHs in the presence of sodium carbonate in both sand and bentonite systems. Also, sodium carbonate greatly reduces the possible reactor corrosion under hydrothermal conditions. Our results show that a water-to-sand ratio of at least 3:1 is required to efficiently remove PAH from soil under static conditions.

Indira S. Jayaweera; Montserrat Marti-Perez; Jordi Diaz-Ferrero; Angel Sanjurjo

2001-03-29

202

Water repellent soils as they occur on UK golf greens  

Microsoft Academic Search

Water repellent soils have been identified as a major problem in the management of golf greens in the UK for over 60years. The cause of this problem has provoked much speculation, but prior to this work, no research into the possible cause of water repellent soils in the UK had been completed. One of the commonly believed links with water

C. A York; P. M Canaway

2000-01-01

203

Soil water sensor response to bulk electrical conductivity  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil water monitoring using electromagnetic (EM) sensors can facilitate observations of water content at high temporal and spatial resolutions. These sensors measure soil dielectric permittivity (Ka) which is largely a function of volumetric water content. However, bulk electrical conductivity BEC c...

204

Can surfactants affect management of non-water repellent soils?  

Technology Transfer Automated Retrieval System (TEKTRAN)

Surfactants affect the water relations of water repellent soils but may or may not affect those of wettable soils. We studied the effects of three surfactants, Aquatrols IrrigAid Gold®, an ethylene oxide/propylene oxide block copolymer, and an alkyl polyglycoside, along with untreated tap water as ...

205

Improved interpretation of water content reflectometer measurements in soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Water content reflectometers use time domain reflectometry (TDR) to estimate the apparent permittivity of soil, which in turn can be related to the soil water content. The objective of this study is to develop a physical model for water content reflectometers. The length of the sensor rods and the d...

206

STABLE ISOTOPES AS INDICATORS OF SOIL WATER DYNAMICS IN WATERSHEDS  

EPA Science Inventory

Stream water quality and quantity depend on discharge rates of water and nutrients from soils. However, soil-water storage is very dynamic and strongly influenced by plants. We analyzed stable isotopes of oxygen and hydrogen to quantify spatial and temporal changes in evaporati...

207

Hydrologic modeling of soil water storage in landfill cover systems  

SciTech Connect

The accuracy of modeling soil water storage by two hydrologic models, CREAMS and HELP, was tested by comparing simulation results with field measurements of soil moisture in eight experimental landfill cover systems having a range of well-defined soil profiles and vegetative covers. Regression analysis showed that CREAMS generally represented soil moisture more accurately than HELP simulations. Soil profiles that more closely resembled natural agricultural soils were more accurately modeled than highly artificial layered soil profiles. Precautions for determining parameter values for model input and for interpreting simulation results are discussed.

Barnes, F.J.; Rodgers, J.C.

1987-01-01

208

The effect of soil surfactants on soil hydrological behavior, the plant growth environment, irrigation efficiency and water conservation  

Microsoft Academic Search

Soil water repellency causes at least temporal changes in the hydrological properties of a soil which result in, among other things, suboptimal growing conditions and increased irrigation requirements. Water repellency in soil is more widespread than previously thought and has been identified in many soil types under a wide array of climatic conditions worldwide. Consequences of soil water repellency include

D. Moore; S. J. Kostka; T. J. Boerth; M. A. Franklin; C. J. Ritsema; L. W. Dekker; K. Oostindie; C. R. Stoof; J. G. Wesseling

2010-01-01

209

Distribution of soil and leaf water potentials of mature grapefruit trees under three soil moisture regimes  

E-print Network

DISTRIBUTION OF SOIL AND LEAF WATER POTENTIALS OF MATURE GRAPEFRUIT TREES UNDER THREE SOIL MOISTURE REGIMES A Thesis by SANMUGAM AHEMBARANATHAN PRATHAPAP, Submitted to the Graduate College of Texas A&M University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE May 1982 Major Subject; Agricultural Engineering DISTRIBUTION OF SOIL AND LEAF WATER POTENTIALS OF MATURE GRAPEFRUIT TREES UNDER THREE SOIL MOISTURE REGIMES A Thesis by SANMUGAM AHEMBARANATHAN PRATHAPAR...

Prathapar, Sanmugam Ahembaranathan

1982-01-01

210

Soil CO? dynamics in a tree island soil of the Pantanal: the role of soil water potential.  

PubMed

The Pantanal is a biodiversity hotspot comprised of a mosaic of landforms that differ in vegetative assemblages and flooding dynamics. Tree islands provide refuge for terrestrial fauna during the flooding period and are particularly important to the regional ecosystem structure. Little soil CO? research has been conducted in this region. We evaluated soil CO? dynamics in relation to primary controlling environmental parameters (soil temperature and soil water). Soil respiration was computed using the gradient method using in situ infrared gas analyzers to directly measure CO? concentration within the soil profile. Due to the cost of the sensors and associated equipment, this study was unreplicated. Rather, we focus on the temporal relationships between soil CO? efflux and related environmental parameters. Soil CO? efflux during the study averaged 3.53 µmol CO? m?˛ s?ą, and was equivalent to an annual soil respiration of 1220 g C m?˛ y?ą. This efflux value, integrated over a year, is comparable to soil C stocks for 0-20 cm. Soil water potential was the measured parameter most strongly associated with soil CO? concentrations, with high CO? values observed only once soil water potential at the 10 cm depth approached zero. This relationship was exhibited across a spectrum of timescales and was found to be significant at a daily timescale across all seasons using conditional nonparametric spectral Granger causality analysis. Hydrology plays a significant role in controlling CO? efflux from the tree island soil, with soil CO? dynamics differing by wetting mechanism. During the wet-up period, direct precipitation infiltrates soil from above and results in pulses of CO? efflux from soil. The annual flood arrives later, and saturates soil from below. While CO? concentrations in soil grew very high under both wetting mechanisms, the change in soil CO? efflux was only significant when soils were wet from above. PMID:23762259

Johnson, Mark S; Couto, Eduardo Guimarăes; Pinto, Osvaldo B; Milesi, Juliana; Santos Amorim, Ricardo S; Messias, Indira A M; Biudes, Marcelo Sacardi

2013-01-01

211

Soil CO2 Dynamics in a Tree Island Soil of the Pantanal: The Role of Soil Water Potential  

PubMed Central

The Pantanal is a biodiversity hotspot comprised of a mosaic of landforms that differ in vegetative assemblages and flooding dynamics. Tree islands provide refuge for terrestrial fauna during the flooding period and are particularly important to the regional ecosystem structure. Little soil CO2 research has been conducted in this region. We evaluated soil CO2 dynamics in relation to primary controlling environmental parameters (soil temperature and soil water). Soil respiration was computed using the gradient method using in situ infrared gas analyzers to directly measure CO2 concentration within the soil profile. Due to the cost of the sensors and associated equipment, this study was unreplicated. Rather, we focus on the temporal relationships between soil CO2 efflux and related environmental parameters. Soil CO2 efflux during the study averaged 3.53 µmol CO2 m?2 s?1, and was equivalent to an annual soil respiration of 1220 g C m?2 y?1. This efflux value, integrated over a year, is comparable to soil C stocks for 0–20 cm. Soil water potential was the measured parameter most strongly associated with soil CO2 concentrations, with high CO2 values observed only once soil water potential at the 10 cm depth approached zero. This relationship was exhibited across a spectrum of timescales and was found to be significant at a daily timescale across all seasons using conditional nonparametric spectral Granger causality analysis. Hydrology plays a significant role in controlling CO2 efflux from the tree island soil, with soil CO2 dynamics differing by wetting mechanism. During the wet-up period, direct precipitation infiltrates soil from above and results in pulses of CO2 efflux from soil. The annual flood arrives later, and saturates soil from below. While CO2 concentrations in soil grew very high under both wetting mechanisms, the change in soil CO2 efflux was only significant when soils were wet from above. PMID:23762259

Johnson, Mark S.; Couto, Eduardo Guimarăes; Pinto Jr, Osvaldo B.; Milesi, Juliana; Santos Amorim, Ricardo S.; Messias, Indira A. M.; Biudes, Marcelo Sacardi

2013-01-01

212

[Impact of biological soil crusts on soil water repellence in the hilly Loess Plateau region, China].  

PubMed

By using water drop penetration time (WDPT) and molarity of ethanol droplet (MED) methods, the soil water repellence of undisturbed biological soil crusts (biocrusts) in five successional stages, from the hilly Loess Plateau region of China was tested. The five stages of biocrusts were light cyanobacterial crust, dark cyanobacterial crust, cyanobacterial with sparse moss crust, moss and tiny cyanobacteria patches crust and moss dominated crust. The results showed that 1) the soil water repellence was markedly increased both in the intensity and persistence since the formation of biocrusts. 2) The soil water repellence showed a decrease trend along with the successional stages of biocrusts. The soil water repellence of the biocrusts with the moss coverage above 20% was significantly lower than that of the cyanobacterial crusts. 3) The soil water repellence of the biocrusts was closely related to soil moisture and the dominant organism. The soil water repellence increased with the decrease of soil water content for the moss dominated biocrusts, while changed in a bimodal curve with the decrease of soil water content for the cyanobacterial biocrusts. PMID:24984480

Zhang, Pei-Pei; Zhao, Yun-Ge; Wang, Yuan; Yao, Chun-Zhu

2014-03-01

213

Reflectance of vegetation, soil, and water  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. The ability to read the 24-channel MSS CCT tapes, select specified agricultural land use areas from the CCT, and perform multivariate statistical and pattern recognition analyses has been demonstrated. The 5 optimum channels chosen for classifying an agricultural scene were, in the order of their selection the far red visible, short reflective IR, visible blue, thermal infrared, and ultraviolet portions of the electromagnetic spectrum, respectively. Although chosen by a training set containing only vegetal categories, the optimum 4 channels discriminated pavement, water, bare soil, and building roofs, as well as the vegetal categories. Among the vegetal categories, sugar cane and cotton had distinctive signatures that distinguished them from grass and citrus. Acreages estimated spectrally by the computer for the test scene were acceptably close to acreages estimated from aerial photographs for cotton, sugar cane, and water. Many nonfarmable land resolution elements representing drainage ditch, field road, and highway right-of-way as well as farm headquarters area fell into the grass, bare soil plus weeds, and citrus categories and lessened the accuracy of the farmable acreage estimates in these categories. The expertise developed using the 24-channel data will be applied to the ERTS-1 data.

Wiegand, C. L. (principal investigator)

1973-01-01

214

Physical and chemical effects of biochar on natural and artificial water repellent soils  

NASA Astrophysics Data System (ADS)

Water repellency (WR) affects soils worldwide. Hydrophobic compounds accumulate in soil through organic matter decomposition, microbial activity, condensation of organic compounds during vegetation fires, or through anthropogenic impacts such as oil spills. WR hinders vegetation establishment, which can lead to soil erosion and increased runoff. Biochar is currently being evaluated for its potential to increase soil carbon and as a soil amendment. To date, the effect of biochar on water repellent soils has remained largely undetermined. This study considered the potential of biochar as both a physical and chemical amendment for water repellent soils by asking two questions: does adding biochar reduce the observed degree of soil water repellency; and does biochar remove hydrophobic compounds from soil? The potential of biochar as a physical amendment to water repellent soils was evaluated by mixing 5, 10, 25 and 40% (by weight) each of coarse and fine ground biochar with two naturally water repellent soils and measuring the water drop penetration time (WDPT) for each mixture. Biochar particles beyond the range of existing soil particle diameters increased WDPT variability, which could be explained by increased surface roughness and the resulting enhancement of water repellency effects through Cassie-Baxter interactions. Overall, fine biochar was more effective at reducing water repellency: 25% w/w rendered both soils studied wettable. Removal of hydrophobic compounds by biochar was tested by mixing 1, 5, 10, 25 and 40% biochar with acid washed sand (AWS) coated with 1.2x10-5 mol octadecane and octadecanoic acid (per gram AWS, which corresponds to approximately 50 monolayers hydrophobic compound per gram AWS). Each mix stood for 1 to 30 days in a solution of pH 3, 6 or 9 before the AWS was extracted and the quantity of hydrophobic compound remaining determined by infrared spectroscopy and/or gas chromatography. Biochar successfully removed the hydrophobic compounds, even in dry conditions and independent of pH and exposure time. Results varied with the quantity of biochar added: some removal was evident with 1% and 5% biochar additions, approximately 50% of material initially deposited onto AWS was removed by 10% biochar, and ? 25% biochar removed 100% of the material present. These results suggest that biochar can reduce WR effects in soils by creating wettable pathways through water repellent soil and by removing hydrophobic compounds from soil particles.

Hallin, Ingrid; Douglas, Peter; Doerr, Stefan H.; Bryant, Rob; Matthews, Ian; Charbonneau, Cecile

2014-05-01

215

Water and temperature relations of soil Actinobacteria.  

PubMed

Actinobacteria perform essential functions within soils, and are dependent on available water to do so. We determined the water-activity (aw ) limits for cell division of Streptomyces albidoflavus, Streptomyces rectiviolaceus, Micromonospora grisea and Micromonospora (JCM 3050) over a range of temperatures, using culture media supplemented with a biologically permissive solute (glycerol). Each species grew optimally at 0.998 aw (control; no added glycerol) and growth rates were near-optimal in the range 0.971-0.974 (1?M glycerol) at permissive temperatures. Each was capable of cell division at 0.916-0.924 aw (2?M glycerol), but only S.?albidoflavus grew at 0.895 or 0.897 aw (3?M glycerol, at 30 and 37°C respectively). For S.?albidoflavus, however, no growth occurred on media at ??0.870 (4?M glycerol) during the 40-day assessment period, regardless of temperature, and a theoretical limit of 0.877 aw was derived by extrapolation of growth curves. This level of solute tolerance is high for non-halophilic bacteria, but is consistent with reported limits for the growth and metabolic activities of soil microbes. The limit, within the range 0.895-0.870 aw , is very much inferior to those for obligately halophilic bacteria and extremely halophilic or xerophilic fungi, and is inconsistent with earlier reports of cell division at 0.500 aw . These findings are discussed in relation to planetary protection policy for space exploration and the microbiology of arid soils. PMID:25132485

Stevenson, Andrew; Hallsworth, John E

2014-12-01

216

Modeling as a tool for management of saline soils and irrigation waters  

Technology Transfer Automated Retrieval System (TEKTRAN)

Optimal management of saline soils and irrigation waters requires consideration of many interrelated factors including, climate, water applications and timing, water flow, plant water uptake, soil chemical reactions, plant response to salinity and solution composition, soil hydraulic properties and ...

217

Predicting and mapping soil available water capacity in Korea  

PubMed Central

The knowledge on the spatial distribution of soil available water capacity at a regional or national extent is essential, as soil water capacity is a component of the water and energy balances in the terrestrial ecosystem. It controls the evapotranspiration rate, and has a major impact on climate. This paper demonstrates a protocol for mapping soil available water capacity in South Korea at a fine scale using data available from surveys. The procedures combined digital soil mapping technology with the available soil map of 1:25,000. We used the modal profile data from the Taxonomical Classification of Korean Soils. The data consist of profile description along with physical and chemical analysis for the modal profiles of the 380 soil series. However not all soil samples have measured bulk density and water content at ?10 and ?1500 kPa. Thus they need to be predicted using pedotransfer functions. Furthermore, water content at ?10 kPa was measured using ground samples. Thus a correction factor is derived to take into account the effect of bulk density. Results showed that Andisols has the highest mean water storage capacity, followed by Entisols and Inceptisols which have loamy texture. The lowest water retention is Entisols which are dominated by sandy materials. Profile available water capacity to a depth of 1 m was calculated and mapped for Korea. The western part of the country shows higher available water capacity than the eastern part which is mountainous and has shallower soils. The highest water storage capacity soils are the Ultisols and Alfisols (mean of 206 and 205 mm, respectively). Validation of the maps showed promising results. The map produced can be used as an indication of soil physical quality of Korean soils. PMID:23646290

Hong, Suk Young; Han, Kyung Hwa; Kim, Yihyun; Lee, Kyungdo

2013-01-01

218

The use of soil electrical resistivity to monitor plant and soil water relationships in vineyards  

NASA Astrophysics Data System (ADS)

Soil water availability deeply affects plant physiology. In viticulture it is considered as a major contributor to the "terroir" expression. The assessment of soil water in field conditions is a difficult task especially over large surfaces. New techniques, are therefore required to better explore variations of soil water content in space and time with low disturbance and with great precision. Electrical Resistivity Tomography (ERT) meets these requirements, for applications in plant sciences, agriculture and ecology. In this paper, possible techniques to develop models that allow the use of ERT to spatialise soil water available to plants are reviewed. An application of soil water monitoring using ERT in a grapevine plot in Burgundy (north-east of France) during the vintage 2013 is presented. We observed the lateral heterogeneity of ERT derived Fraction of Transpirable Soil Water (FTSW) variations, and differences in water uptake depending on grapevine water status (leaf water potentials measured both at predawn and at solar noon and contemporary to ERT monitoring). Active zones in soils for water movements were identified. The use of ERT in ecophysiological studies, with parallel monitoring of plant water status, is still rare. These methods are promising because they have the potential to reveal a hidden part of a major function of plant development: the capacity to extract water from the soil.

Brillante, L.; Mathieu, O.; Bois, B.; van Leeuwen, C.; Lévęque, J.

2014-10-01

219

The use of soil electrical resistivity to monitor plant and soil water relationships in vineyards  

NASA Astrophysics Data System (ADS)

Soil water availability deeply affects plant physiology. In viticulture it is considered a major contributor to the "terroir" effect. The assessment of soil water in field conditions is a difficult task, especially over large surfaces. New techniques are therefore required in order to better explore variations of soil water content in space and time with low disturbance and with great precision. Electrical resistivity tomography (ERT) meets these requirements for applications in plant sciences, agriculture and ecology. In this paper, possible techniques to develop models that allow the use of ERT to spatialise soil water available to plants are reviewed. An application of soil water monitoring using ERT in a grapevine plot in Burgundy (north-east France) during the vintage 2013 is presented. We observed the lateral heterogeneity of ERT-derived fraction of transpirable soil water (FTSW) variations, and differences in water uptake depend on grapevine water status (leaf water potentials measured both at predawn and at solar noon and contemporary to ERT monitoring). Active zones in soils for water movements were identified. The use of ERT in ecophysiological studies, with parallel monitoring of plant water status, is still rare. These methods are promising because they have the potential to reveal a hidden part of a major function of plant development: the capacity to extract water from the soil.

Brillante, L.; Mathieu, O.; Bois, B.; van Leeuwen, C.; Lévęque, J.

2015-03-01

220

Interactive biotic and abiotic regulators of soil carbon cycling: evidence from controlled climate experiments on peatland and boreal soils.  

PubMed

Partially decomposed plant and animal remains have been accumulating in organic soils (i.e. >40% C content) for millennia, making them the largest terrestrial carbon store. There is growing concern that, in a warming world, soil biotic processing will accelerate and release greenhouse gases that further exacerbate climate change. However, the magnitude of this response remains uncertain as the constraints are abiotic, biotic and interactive. Here, we examined the influence of resource quality and biological activity on the temperature sensitivity of soil respiration under different soil moisture regimes. Organic soils were sampled from 13 boreal and peatland ecosystems located in the United Kingdom, Ireland, Spain, Finland and Sweden, representing a natural resource quality range of C, N and P. They were incubated at four temperatures (4, 10, 15 and 20 °C) at either 60% or 100% water holding capacity (WHC). Our results showed that chemical and biological properties play an important role in determining soil respiration responses to temperature and moisture changes. High soil C : P and C : N ratios were symptomatic of slow C turnover and long-term C accumulation. In boreal soils, low bacterial to fungal ratios were related to greater temperature sensitivity of respiration, which was amplified in drier conditions. This contrasted with peatland soils which were dominated by bacterial communities and enchytraeid grazing, resulting in a more rapid C turnover under warmer and wetter conditions. The unexpected acceleration of C mineralization under high moisture contents was possibly linked to the primarily role of fermented organic matter, instead of oxygen, in mediating microbial decomposition. We conclude that to improve C model simulations of soil respiration, a better resolution of the interactions occurring between climate, resource quality and the decomposer community will be required. PMID:24687903

Briones, María Jesús I; McNamara, Niall P; Poskitt, Jan; Crow, Susan E; Ostle, Nicholas J

2014-09-01

221

Predicting Soil-Water Partition Coefficients for Cadmium  

E-print Network

understand the mechanism of adsorption, the experimental results for the adsorption of Cd by the 15 soils with natural soil particles is complex, involving multiple mechanisms. Much of the work relating to trace metalPredicting Soil-Water Partition Coefficients for Cadmium S U E N - Z O N E L E E Department

Sparks, Donald L.

222

University of Florida Soil and Water Science Department  

E-print Network

.......................................................................................... 16 #12;3 Abstract The loss of soil on the land surface by wind and water erosion has been identified-Highlands: Its soils and land resources...........................................5 3. Vertisols on soil resources. As a result, land use has seen tremendous changes in the past 50 years. The population

Ma, Lena

223

Linking soil and water quality in conservation agricultural systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil and water resources are fundamental components of agriculture. Successful utilization of these resources for sustainable agricultural production is partly dependent upon how they are conserved. Soil quality is generally defined by how well soil functions under a given set of environmental con...

224

Teaching Soil and Water Conservation: A Classroom and Field Guide.  

ERIC Educational Resources Information Center

Compiled in this booklet are 22 activities designed to develop awareness of the importance of conservation and the wise use of soil and moisture on croplands, grasslands, and woodlands. They have been selected by Soil Conservation Service (SCS) personnel and consultants to show that the way we manage our basic natural resources, soil and water,…

Foster, Albert B.; Fox, Adrian C.

225

Nonequilibrium water dynamics in the rhizosphere: How mucilage affects water flow in soils  

NASA Astrophysics Data System (ADS)

The flow of water from soil to plant roots is controlled by the properties of the narrow region of soil close to the roots, the rhizosphere. In particular, the hydraulic properties of the rhizosphere are altered by mucilage, a polymeric gel exuded by the roots. In this paper we present experimental results and a conceptual model of water flow in unsaturated soils mixed with mucilage. A central hypothesis of the model is that the different drying/wetting rate of mucilage compared to the bulk soil results in nonequilibrium relations between water content and water potential in the rhizosphere. We coupled this nonequilibrium relation with the Richards equation and obtained a constitutive equation for water flow in soil and mucilage. To test the model assumptions, we measured the water retention curve and the saturated hydraulic conductivity of sandy soil mixed with mucilage from chia seeds. Additionally, we used neutron radiography to image water content in a layer of soil mixed with mucilage during drying and wetting cycles. The radiographs demonstrated the occurrence of nonequilibrium water dynamics in the soil-mucilage mixture. The experiments were simulated by numerically solving the nonequilibrium model. Our study provides conceptual and experimental evidences that mucilage has a strong impact on soil water dynamics. During drying, mucilage maintains a greater soil water content for an extended time, while during irrigation it delays the soil rewetting. We postulate that mucilage exudation by roots attenuates plant water stress by modulating water content dynamics in the rhizosphere.

Kroener, Eva; Zarebanadkouki, Mohsen; Kaestner, Anders; Carminati, Andrea

2014-08-01

226

Experimental and mathematical modeling of soil water and heat regime in selected soils  

NASA Astrophysics Data System (ADS)

Knowledge of soil thermal (heat) properties is essential when assessing heat transport in soils. Heat regime in soils associates with many other soil processes (like water evaporation and diffusion, plant transpiration, contaminants behavior etc.). Thermal properties are needed when assessing affectivity of energy gathering from soil profiles using horizontal ground heat exchangers, which is a main goal of this study. Study is focused on measuring of thermal properties (heat capacity and heat conductivity) in representative soils of the Czech Republic. Measurements were performed on soil samples taken from the surface horizons of 11 representative soil types and from 2 soil substrates (sand and loess). The measured relationships between the heat conductivity and volumetric soil-water content were described by non-linear equations (Chung and Horton, 1987). The measured relationships between the heat capacity and volumetric soil-water content were expressed using the linear equations. The greatest values of the heat conductivity were measured in sandy soils (sandy and gravely sand substrates). The average values were obtained in soils on loess substrates. Lower values were obtained for all Cambisols (variable substrates). The lowest values were measured in Stagnic Chernozem Siltic on marlite. Opposite trend was observed for the maximal heat capacity, which was mostly impacted by water content. A soil water and heat regime within the soil profile was monitored at one location. In addition the impact of various soil cover at the soil top on soil water content and temperature was measured. Soil hydraulic properties were measured using the multistep-outflow technique. The saturated hydraulic conductivities were also measured using the Guelph permeameter. Programs HYDRUS-1D and 2D/3D were used for a mathematical interpretation of the observed soil water and heat regime. Acknowledgment: Authors acknowledge the financial support of the Technology Agency of the Czech Republic (TA02020991). Work was also partly supported by the Ministry of Agriculture of the Czech Republic (QJ1230319). Literature Chung, S.O., Horton, R. 1987. Soil heat and water flow with a partial surface mulch, Water Resour. Res., 23(12), 2175-2186, 1987.

Kodesova, Radka; Fer, Miroslav; Klement, Ales; Nikodem, Antonin; Vlasakova, Mirka; Tepla, Daniela; Jaksik, Ondrej

2013-04-01

227

Difficulties in the evaluation and measuring of soil water infiltration  

NASA Astrophysics Data System (ADS)

Soil water infiltration is the most important hydrological parameter for the evaluation and diagnosis of the soil water balance and soil moisture regime. Those balances and regimes are the main regulating factors of the on site water supply to plants and other soil organisms and of other important processes like runoff, surface and mass erosion, drainage, etc, affecting sedimentation, flooding, soil and water pollution, water supply for different purposes (population, agriculture, industries, hydroelectricity), etc. Therefore the evaluation and measurement of water infiltration rates has become indispensable for the evaluation and modeling of the previously mentioned processes. Infiltration is one of the most difficult hydrological parameters to evaluate or measure accurately. Although the theoretical aspects of the process of soil water infiltration are well known since the middle of the past century, when several methods and models were already proposed for the evaluation of infiltration, still nowadays such evaluation is not frequently enough accurate for the purposes being used. This is partially due to deficiencies in the methodology being used for measuring infiltration, including some newly proposed methods and equipments, and in the use of non appropriate empirical models and approaches. In this contribution we present an analysis and discussion about the main difficulties found in the evaluation and measurement of soil water infiltration rates, and the more commonly committed errors, based on the past experiences of the author in the evaluation of soil water infiltration in many different soils and land conditions, and in their use for deducing soil water balances under variable and changing climates. It is concluded that there are not models or methods universally applicable to any soil and land condition, and that in many cases the results are significantly influenced by the way we use a particular method or instrument, and by the alterations in the soil conditions by the land management, but also due to the manipulation of the soil before and during the measurement. Direct "in situ" field evaluations have to be preferred in any case to indirect deductions from other soil characteristics measured under laboratory conditions in the same soils, or in other soils, through the so called "pedo-transfer" functions, or through the use of stochastic models such as the SCS Curve Number Method, or of other models using empirical or physical approaches, which have demonstrated to be of limited value in most of the cases. References Philip, J. R., 1954., An infiltration equation with physical significance: Soil Sci..,v. 77, p. 153-157. Philip, J. R., 1958. The theory of infiltration, pt. 7: Soil Sci., v. 85, no. 6, p. 333-337. Pla, I.1981. Simuladores de lluvia para el estudio de relaciones suelo-agua bajo agricultura de secano en los trópicos. Rev. Fac. Agron. XII(1-2):81-93.Maracay (Venezuela) Pla, I. 1986. A routine laboratory index to predict the effects of soil sealing on soil and water conservation. En "Assesment of Soil Surface Sealing and Crusting". 154-162.State Univ. of Ghent.Gante (Bélgica Pla, I., 1997. A soil water balance model for monitoring soil erosion processes and effects on steep lands in the tropics. Soil Technology. 11(1):17-30. Elsevier Pla, I., M.C. Ramos, S. Nacci, F. Fonseca y X. Abreu. 2005. Soil moisture regime in dryland vineyards of Catalunya (Spain) as influenced by climate, soil and land management. "Integrated Soil and Water Management for Orchard Development". FAO Land and Water Bulletin 10. 41-49. Roma (Italia). Pla, I., 2006. Hydrological approach for assessing desertification processes in the Mediterranean region. In W.G. Kepner et al. (Editors), Desertification in the Mediterranean Region. A Security Issue. 579-600 Springer. Heidelberg (Germany) Pla, I. 2011. Evaluación y Modelización Hidrológica para el Diagnóstico y Prevención de "Desastres Naturales". Gestión y Ambiente 14 (3): 17-22. UN-Medellín (Colombia). ISSN 0124.177X

Pla-Sentís, Ildefonso

2013-04-01

228

Interactions between soil and tree roots accelerate long-term soil carbon decomposition.  

PubMed

Decomposition of soil organic carbon (SOC) is the main process governing the release of CO(2) into the atmosphere from terrestrial systems. Although the importance of soil-root interactions for SOC decomposition has increasingly been recognized, their long-term effect on SOC decomposition remains poorly understood. Here we provide experimental evidence for a rhizosphere priming effect, in which interactions between soil and tree roots substantially accelerate SOC decomposition. In a 395-day greenhouse study with Ponderosa pine and Fremont cottonwood trees grown in three different soils, SOC decomposition in the planted treatments was significantly greater (up to 225%) than in soil incubations alone. This rhizosphere priming effect persisted throughout the experiment, until well after initial soil disturbance, and increased with a greater amount of root-derived SOC formed during the experiment. Loss of old SOC was greater than the formation of new C, suggesting that increased C inputs from roots could result in net soil C loss. PMID:17910623

Dijkstra, Feike A; Cheng, Weixin

2007-11-01

229

Measuring and Modelling water related soil - vegetation feedbacks in a fallow plot  

NASA Astrophysics Data System (ADS)

Land fallowing is one possible response to shortage of water for irrigation. Leaving the soil unseeded implies a change of the soil functioning that has an impact on the water cycle. The development of a soil crust in the open spaces between the patterns of grass weed affects the soil properties and the field scale water balance. The objective of this study was to test the potential of integrated non invasive geophysics and ground-image analysis and to quantify the effect of the soil vegetation interaction on the water balance of a fallow land at the local and plot scale. We measured repeatedly in space and time local soil saturation and vegetation cover over two small plots located in southern Sardinia, Italy, during an infiltration experiment. One plot was left unseeded and the other was cultivated. The comparative analysis of the experimental data evidenced a positive feedback between weed growth and infiltration at the fallow plot. A simple bucket model captured the different soil moisture dynamics at the two plots during the infiltration experiment and was used to estimate the impact of the soil vegetation feedback on the yearly water balance at the site.

Ursino, Nadia; Cassiani, Giorgio; Deiana, Rita; Vignoli, Giulio; Boaga, Jacopo

2013-04-01

230

EFFECTIVENESS OF SOIL AND WATER CONSERVATION PRACTICES FOR POLLUTION CONTROL  

EPA Science Inventory

The potential water quality effects and economic implications of soil and water conservation practices (SWCPs) are identified. Method for estimating the effects of SWCPs on pollutant losses from croplands are presented. Mathematical simulation and linear programming models were u...

231

Monitoring soil-vegetation interactions using non-invasive geophysical techniques  

NASA Astrophysics Data System (ADS)

The understanding of soil-vegetation-atmosphere interactions is of utmost importance in the solution of a number of hydrological questions and practical issues, including flood control, agricultural best practice, slope stability and impacts of climatic changes. Geophysical time-lapse monitoring can greatly contribute to the understanding of these interactions particularly for its capability to map in space and time the effects of vegetation on soil moisture content. In this work we present the results of two case studies showing the potential of hydro-geophysics in this context. The first example refers to the long term monitoring of the soil static and dynamic characteristics in an experimental site located in Sardinia (Italy). The main objective of this study is to understand the effects of soil - water - plants interactions on soil water balance. A combination of time-lapse electromagnetic induction (EMI) monitoring over wide areas and localized irrigation tests monitored by electrical resistivity tomography (ERT) and TDR soil moisture measurements is here used, in order to achieve quantitative field-scale estimates of moisture content from topsoil layer. Natural gamma-ray emission mapping, texture analysis and laboratory calibration of an electrical constitutive relationship on soil samples complete the dataset. We therefore observed that the growth of vegetation, with the associated below ground allocation of biomass, has a significant impact on the soil moisture dynamics. In particular vegetation extracts a large amount of water from the soil in the hot season, but it also reduces evaporation by shadowing the soil surface. In addition, vegetation enhances the soil wetting process as the root system facilitates water infiltration, thus creating a positive feedback system. The second example regards the time-lapse monitoring of soil moisture content in an apple orchard located in the Alpine region of Northern Italy (Trento). A three-dimensional cross-hole ERT setup was created using four small-scale boreholes and a 2D array of surface electrodes. The soil response to irrigation and evapo-transpiration evidences the location of tree roots, including the influence of irrigation patterns on the root growth, and their efficiency at removing soil moisture.

Perri, M.; Cassiani, G.; Boaga, J.; Rossi, M.; Vignoli, G.; Deiana, R.; Ursino, N.; Putti, M.; Majone, B.; Bellin, A.; Blaschek, M.; Duttmann, R.; Meyer, S.; Ludwig, R.; Soddu, A.; Dietrich, P.; Werban, U.

2012-12-01

232

Coupled Oxygen and Hydrogen Isotope Analysis of Water Along the Soil-Plant- Atmosphere Continuum  

NASA Astrophysics Data System (ADS)

The oxygen and hydrogen isotope compositions of water within a plant vary with transpiration rates and the isotopic composition of soil water. Both of these parameters are affected by temperature and relative humidity. A controlled-temperature, growth-chamber experiment was conducted to determine the relationships among temperature, relative humidity, soil water evaporation and plant-water isotope composition in cattails and horsetails. Typha, a cattail species that grows in wetland conditions, and Equisetum, a horsetail species that prefers dry soils, were each grown in four chambers at 15, 20, 25 and 30 degrees Celsius. The oxygen and hydrogen isotope compositions of watering water, soil water, vapour in the growth chambers and plant water from the leaves and stems were analyzed throughout the eight-month long artificial growing season. Although the oxygen isotope composition of the watering water remained constant, the soil water, atmospheric vapour and plant water were progressively enriched in oxygen-18 and deuterium in each of the four chambers from low to high temperatures as a result of increasing evaporation. The oxygen isotope composition of plant water along the length of a single stem or leaf was increasingly enriched in the heavier isotopes towards the apex. There was no significant difference in the magnitude of this trend between species. These results indicate that the isotopic composition of plant water is primarily controlled by environmental conditions. The oxygen isotope composition of the water vapour in the growing chamber increased with temperature, consistent with equilibration between the vapour and the oxygen-18 enriched soil and plant water reservoirs. The magnitude and interaction of these variables, as measured for these modern samples of cattails and horsetails, should be useful in calibrating paleoclimate proxies based on fossilized plant materials (e.g., cellulose, phytoliths).

Huang, Z.; Webb, E. A.; Longstaffe, F. J.

2008-12-01

233

Character of interactions of saprophytic soil microflora via gaseous metabolites  

Microsoft Academic Search

The character of interaction between saprophytic soil bacteria via gaseous metabolites was studied. It was established that,\\u000a at the metabolic level, a diverse character of interspecies interrelationships between bacteria exist, directly influencing\\u000a their reproduction and preservation in soil. Volatile compounds produced by bacteria are able to act as both intra-and interspecies\\u000a regulators of microbial communities. The soil microbiocenosis composition may

M. L. Sidorenko; L. S. Buzoleva

2008-01-01

234

Soil water content and infiltration in agroforestry buffer strips  

Microsoft Academic Search

Agroforestry practices are receiving increased attention in temperate zones due to their environmental and economic benefits.\\u000a To test the hypothesis that agroforestry buffers reduce runoff by increased infiltration, water use, and water storage; profile\\u000a water content and soil water infiltration were measured for a Putnam soil (fine, smectitic, mesic Vertic Albaqualf). The watershed\\u000a was under no-till management with a corn

Stephen H. Anderson; Ranjith P. Udawatta; Tshepiso Seobi; Harold E. Garrett

2009-01-01

235

Subsurface And Surface Water Flow Interactions  

EPA Science Inventory

In this chapter we present basic concepts and principles underlying the phenomena of groundwater and surface water interactions. Fundamental equations and analytical and numerical solutions describing stream-aquifer interactions are presented in hillslope and riparian aquifer en...

236

Moditored unsaturated soil transport processes as a support for large scale soil and water management  

NASA Astrophysics Data System (ADS)

The current societal demand for sustainable soil and water management is very large. The drivers of global and climate change exert many pressures on the soil and water ecosystems, endangering appropriate ecosystem functioning. The unsaturated soil transport processes play a key role in soil-water system functioning as it controls the fluxes of water and nutrients from the soil to plants (the pedo-biosphere link), the infiltration flux of precipitated water to groundwater and the evaporative flux, and hence the feed back from the soil to the climate system. Yet, unsaturated soil transport processes are difficult to quantify since they are affected by huge variability of the governing properties at different space-time scales and the intrinsic non-linearity of the transport processes. The incompatibility of the scales between the scale at which processes reasonably can be characterized, the scale at which the theoretical process correctly can be described and the scale at which the soil and water system need to be managed, calls for further development of scaling procedures in unsaturated zone science. It also calls for a better integration of theoretical and modelling approaches to elucidate transport processes at the appropriate scales, compatible with the sustainable soil and water management objective. Moditoring science, i.e the interdisciplinary research domain where modelling and monitoring science are linked, is currently evolving significantly in the unsaturated zone hydrology area. In this presentation, a review of current moditoring strategies/techniques will be given and illustrated for solving large scale soil and water management problems. This will also allow identifying research needs in the interdisciplinary domain of modelling and monitoring and to improve the integration of unsaturated zone science in solving soil and water management issues. A focus will be given on examples of large scale soil and water management problems in Europe.

Vanclooster, Marnik

2010-05-01

237

Iron clad wetlands: Soil iron-sulfur buffering determines coastal wetland response to salt water incursion  

NASA Astrophysics Data System (ADS)

Coastal freshwater wetland chemistry is rapidly changing due to increased frequency of salt water incursion, a consequence of global change. Seasonal salt water incursion introduces sulfate, which microbially reduces to sulfide. Sulfide binds with reduced iron, producing iron sulfide (FeS), recognizable in wetland soils by its characteristic black color. The objective of this study is to document iron and sulfate reduction rates, as well as product formation (acid volatile sulfide (AVS) and chromium reducible sulfide (CRS)) in a coastal freshwater wetland undergoing seasonal salt water incursion. Understanding iron and sulfur cycling, as well as their reduction products, allows us to calculate the degree of sulfidization (DOS), from which we can estimate how long soil iron will buffer against chemical effects of sea level rise. We show that soil chloride, a direct indicator of the degree of incursion, best predicted iron and sulfate reduction rates. Correlations between soil chloride and iron or sulfur reduction rates were strongest in the surface layer (0-3 cm), indicative of surface water incursion, rather than groundwater intrusion at our site. The interaction between soil moisture and extractable chloride was significantly related to increased AVS, whereas increased soil chloride was a stronger predictor of CRS. The current DOS in this coastal plains wetland is very low, resulting from high soil iron content and relatively small degree of salt water incursion. However, with time and continuous salt water exposure, iron will bind with incoming sulfur, creating FeS complexes, and DOS will increase.

Schoepfer, Valerie A.; Bernhardt, Emily S.; Burgin, Amy J.

2014-12-01

238

EFFICIENCY OF SOIL CORE AND SOIL-PORE WATER SAMPLING SYSTEMS  

EPA Science Inventory

A laboratory column and field lysimeter study were conducted to evaluate the efficiency of soil core and soil-pore water samples to detect the migration of the organic components of land treated wastes through soil. In the laboratory, column leaching studies were performed by pac...

239

Soil water dynamics inside and outside of lysimeters  

NASA Astrophysics Data System (ADS)

Lysimeters are the one and only instrument to directly measure water fluxes through the upper an lower boundary of soil profiles. This allows to close the water balance including soil water storage, deep seepage and evapotranspiration. However, lysimeters force the water flow to the vertical direction while in reality lateral water movement is deemed to play an important role in soil water dynamics especially along hillslopes. We present an approach where we monitor soil water dynamics in lysimeters and in the field at the same location of a gentle hillslope. A cylindrical soil monolith is taken leaving the surrounding soil undisturbed. The monolith is used as a weighable lysimeter while the pit in the field is equipped with the same sensors (moisture, water potential, temperature) as the lysimeter. Based on this set up, we can evaluate in how far water flow inside the lysimeter corresponds to the situation in the field. The results demonstrate that lateral flow becomes important when the water content is close to saturation. This is true at the soil surface in case of surface runoff but also at the depth of a compacted plow pan where interflow is initiated. Under unsaturated conditions, the limitation of lysimeters to 1D flow seems to be an acceptable approximation even in slopy areas.

Vogel, Hans-Joerg; Rupp, Holger; Köhne, Max; Wollschläger, Ute

2014-05-01

240

Soil community composition drives aboveground plantherbivoreparasitoid interactions  

Microsoft Academic Search

Soil organisms can influence higher trophic level aboveground organisms, but only very few studies have considered such effects. We manipulated soil community composition of model grassland ecosystems by introducing nematode communities, microorganisms, neither or both groups. Above ground, aphids (Rhopalosiphum padi) and parasitoids (Aphidius colemani) were introduced, and we measured individual performance and population dynamics of plants, aphids and parasitoids.

T. M. Bezemer; G. B. De Deyn; T. M. Bossinga; N. M. Van Dam; J. A. Harvey; W. H. Van der Putten

2005-01-01

241

Soil Water Use by Ceanothus velutinus and Two Grasses  

Microsoft Academic Search

Seasonal trends of soil water content in plots of snowbrush (Ceanothus velutinus Dougl.), orchard grass (Dactylis glomerata L), and pinegrass {Calamagrostis rubes- cens Buckl.) and in bare plots were measured on a burned-over forest watershed in north-central Washington. A comparison of soil water contents at depths of 12, 24, 36, and 48 inches indicated that the grasses and snowbrush generally

W. Lopushinsky; G. O. Klock

242

Comparison of corn transpiration, eddy covariance, and soil water loss  

Technology Transfer Automated Retrieval System (TEKTRAN)

Stem flow gages are used to estimate plant transpiration, but only a few studies compare transpiration with other measures of soil water loss. The purpose of this study was to compare transpiration from stem flow measurements with soil water changes estimated by daily neutron probe readings. Monitor...

243

Soil and Water Challenges for Pacific Northwest Agriculture  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil and water conservation has been a major concern in the Inland Pacific Northwest since the onset of farming 125 years ago. Some of the highest historic water erosion rates in the USA have occurred on steep slopes in the Palouse region where soil loss averaged 45 Mg ha-1 yr-1 and could reach 450 ...

244

POLYACRYLAMIDE EFFECTS ON WATER INFILTRATION IN SANDY LOAM SOILS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Some sandy soils of the California San Joaquin Valley have low water infiltration. Electrical conductivity (EC) and sodium adsorption ratio (SAR) of irrigation water greatly affect infiltration rate and hydraulic conductivity of soils. High molecular weight polyacrylamides (PAM) have been shown to i...

245

TILLAGE EFFECTS ON NEAR SURFACE SOIL WATER DYNAMICS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tillage modifies the soil physical properties near the surface which in turn can influence evaporation rates and how water is redistributed within the profile during and after precipitation. The objective of this study was to evaluate the effects of sweep tillage on near surface soil water dynamics....

246

Management of Irrigation with Saline Water in Cracking Clay Soils  

Microsoft Academic Search

Management scenarios aimed at optimizing irrigation in a Sicilian vineyard characterized by a cracking clay soil irrigated with saline wa- ter were explored for seven soil profiles (Baglio 1-Baglio 7), by using the simulation model soil-water-atmosphere-plant environment (SWAP), which accounts for shrinkage and cracking. Accurate pre- diction of water content, u, was obtained for the seven profiles by expressing the

Giuseppina Crescimanno; Paolo Garofalo

2006-01-01

247

Water table fluctuations and soil biogeochemistry: An experimental approach using an automated soil column system  

NASA Astrophysics Data System (ADS)

Water table fluctuations significantly affect the biological and geochemical functioning of soils. Here, we introduce an automated soil column system in which the water table regime is imposed using a computer-controlled, multi-channel pump connected to a hydrostatic equilibrium reservoir and a water storage reservoir. The potential of this new system is illustrated by comparing results from two columns filled with 45 cm of the same homogenized riparian soil. In one soil column the water table remained constant at -20 cm below the soil surface, while in the other the water table oscillated between the soil surface and the bottom of the column, at a rate of 4.8 cm d-1. The experiment ran for 75 days at room temperature (25 ± 2 °C). Micro-sensors installed at -10 and -30 cm below the soil surface in the stable water table column recorded constant redox potentials on the order of 600 and -200 mV, respectively. In the fluctuating water table column, redox potentials at the same depths oscillated between oxidizing (?700 mV) and reducing (?-100 mV) conditions. Pore waters collected periodically and solid-phase analyses on core material obtained at the end of the experiment highlighted striking geochemical differences between the two columns, especially in the time series and depth distributions of Fe, Mn, K, P and S. Soil CO2 emissions derived from headspace gas analysis exhibited periodic variations in the fluctuating water table column, with peak values during water table drawdown. Transient redox conditions caused by the water table fluctuations enhanced microbial oxidation of soil organic matter, resulting in a pronounced depletion of particulate organic carbon in the midsection of the fluctuating water table column. Denaturing Gradient Gel Electrophoresis (DGGE) revealed the onset of differentiation of the bacterial communities in the upper (oxidizing) and lower (reducing) soil sections, although no systematic differences in microbial community structure between the stable and fluctuating water table columns were detected.

Rezanezhad, F.; Couture, R.-M.; Kovac, R.; O'Connell, D.; Van Cappellen, P.

2014-02-01

248

Effect of single Quercus ilex trees upon spatial and seasonal changes in soil water content in dehesas of central western Spain  

Microsoft Academic Search

The spatial and temporal evolution of soil water content (?) in Quercus ilex dehesas has been investigated to determine how trees modify the soil water dynamics and the nature of tree-grass interactions\\u000a in terms of soil water use in these ecosystems. Soil physical parameters and ? were measured at different distances from the\\u000a tree trunk (2–30 m) in the upper

Elena Cubera; Gerardo Moreno

2007-01-01

249

Centrifuge modelling of lateral pipeline/soil interaction -- Phase 2  

SciTech Connect

An ongoing research program is investigating the load transfer behavior of buried pipelines subjected to lateral soil movement in cohesive soil. Phase 1 of this study, reported to OMAE `92, demonstrated that the centrifuge technique was appropriate for this application in determining the interaction conditions for the lateral loading of pipelines. Limited control of the shear strength masked geometric effects (trench width and burial depth) on the interaction factors and desiccation affected the interpretation of some of the interaction factors. The Phase 2 study investigated the geometric effects of pipeline soil cover, ditch width and also displacement rate. The study included a ``modelling of models`` test to verify the reliability of the centrifuge modelling technique. This paper addresses two issues: (1) The Phase 1 soil strength profiles and interaction factors were reanalyzed based on an improved understanding of the soil conditions at the time of testing; (2) A selection of the Phase 2 results are presented for a 0.95m diameter pipeline subjected to lateral soil movement. The program results are discussed and compared with current pipeline/soil interaction analysis methods.

Paulin, M.J.; Phillips, R. [Memorial Univ. of Newfoundland, St. John`s, Newfoundland (Canada). Centre for Cold Ocean Resources Engineering; Boivin, R. [NOVA Corp., Calgary, Alberta (Canada). NOVA Gas Transmission Limited Division

1995-12-31

250

Relation of soil-, surface-, and ground-water distributions of inorganic nitrogen with  

E-print Network

Relation of soil-, surface-, and ground-water distributions of inorganic nitrogen with topographic in subsurface soils. Spatial distributions of soil inorganic nitrogen (N) concentrations were not explained

Macdonald, Ellen

251

Onset of water stress, hysteresis in plant conductance, and hydraulic lift: Scaling soil water dynamics  

E-print Network

Onset of water stress, hysteresis in plant conductance, and hydraulic lift: Scaling soil water hysteresis in canopy conductance, hydraulic lift, and compensatory root water uptake during extended drying effective is dictated by soil hydraulic properties and surrogates for atmospheric water vapor demand

Katul, Gabriel

252

Water and methyl isothiocyanate distribution in soil after drip fumigation.  

PubMed

Methyl isothiocyanate (MITC) generators, such as metam sodium (Met-Na), are used for soil fumigation of agricultural land. The ban on the fumigant methyl bromide has resulted in greater use of MITC generators. To understand the efficacy of MITC, it is necessary to assess its generation and disappearance kinetics when Met-Na is applied to soil. This study evaluated the movement of water and distribution and dissipation of MITC in soil after application of Met-Na through surface drip irrigation systems. The effects of varying water application volume (25, 50, and 75 mm) and rate (1.9, 5.0, and 7.5 L h m) were evaluated in a sandy loam soil. Good fumigant distribution within the sandy loam soil was observed under medium water application amount (50 mm) with slow to intermediate drip application rates (1.9-5.0 L h m). Low water application amount (25 mm) or high application rate (7.5 L h m) did not provide adequate MITC distribution throughout the soil bed width and rooting depth. Dissipation patterns of MITC in soil in all water application amounts and rates followed first-order kinetics, with a rate constant of 0.025 ± 0.004 h and a half-life of 27 ± 3 h. Simulated water distribution through the soil profile using HYDRUS 2D/3D fitted measured field data well, and the model accurately simulated MITC fumigant distribution in the soil. PMID:24216433

Nelson, Shad D; Ajwa, Husein A; Trout, Tom; Stromberger, Mary; Yates, Scott R; Sharma, Shankar

2013-09-01

253

Marked differences between van Genuchten soil water-retention parameters for temperate and tropical soils: a new water-retention pedo-transfer functions developed for tropical soils  

Microsoft Academic Search

All of the physical, chemical and soil water-retention data suitable for the derivation of a Pedo-Transfer Functions (PTF) for water retention for tropical soils (771 suitable horizons) were extracted from the IGBP-DIS soil database. The parameters ?s, ?r, ? and n of the van Genuchten (vG) [Soil Sci. Soc. Am. J. 44 (1980) 892] equation were derived and compared with

M. G. Hodnett; J. Tomasella

2002-01-01

254

Improving Water Quality and Conserving Soil Using Soil Amendments.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Conservation tillage such a no-tillage has widely been shown to control soil erosion compared to other forms of management that involved some extent of tillage. However, in no-tillage most if not all the chemicals are placed near or on the soil surface which makes their movement more likely to occu...

255

US-Japan Workshop on Soil-Structure Interaction, Tsukuba, Japan, March 2007 COMMENTS ON SOIL-STRUCTURE INTERACTION  

E-print Network

). Properly speaking, the theory of SSI began in the 1930's with the publication of Reissner [14th US-Japan Workshop on Soil-Structure Interaction, Tsukuba, Japan, March 2007 1 COMMENTS ON SOIL in general, and from the vast accumulation of earthquake records obtained by seismological stations as well

Entekhabi, Dara

256

26 CFR 1.175-2 - Definition of soil and water conservation expenditures.  

Code of Federal Regulations, 2012 CFR

...false Definition of soil and water conservation expenditures. 1.175-2...175-2 Definition of soil and water conservation expenditures. (a) Expenditures...for the purpose of soil or water conservation in respect of...

2012-04-01

257

26 CFR 1.175-2 - Definition of soil and water conservation expenditures.  

Code of Federal Regulations, 2014 CFR

...false Definition of soil and water conservation expenditures. 1.175-2...175-2 Definition of soil and water conservation expenditures. (a) Expenditures...for the purpose of soil or water conservation in respect of...

2014-04-01

258

26 CFR 1.175-2 - Definition of soil and water conservation expenditures.  

Code of Federal Regulations, 2011 CFR

...false Definition of soil and water conservation expenditures. 1.175-2...175-2 Definition of soil and water conservation expenditures. (a) Expenditures...for the purpose of soil or water conservation in respect of...

2011-04-01

259

26 CFR 1.175-2 - Definition of soil and water conservation expenditures.  

Code of Federal Regulations, 2013 CFR

...false Definition of soil and water conservation expenditures. 1.175-2...175-2 Definition of soil and water conservation expenditures. (a) Expenditures...for the purpose of soil or water conservation in respect of...

2013-04-01

260

26 CFR 1.175-1 - Soil and water conservation expenditures; in general.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 false Soil and water conservation expenditures; in general... § 1.175-1 Soil and water conservation expenditures; in general...farmer may deduct his soil or water conservation expenditures which...

2014-04-01

261

26 CFR 1.175-1 - Soil and water conservation expenditures; in general.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Soil and water conservation expenditures; in general... § 1.175-1 Soil and water conservation expenditures; in general...farmer may deduct his soil or water conservation expenditures which...

2012-04-01

262

26 CFR 1.175-1 - Soil and water conservation expenditures; in general.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Soil and water conservation expenditures; in general... § 1.175-1 Soil and water conservation expenditures; in general...farmer may deduct his soil or water conservation expenditures which...

2011-04-01

263

26 CFR 1.175-1 - Soil and water conservation expenditures; in general.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Soil and water conservation expenditures; in general... § 1.175-1 Soil and water conservation expenditures; in general...farmer may deduct his soil or water conservation expenditures which...

2013-04-01

264

26 CFR 1.175-2 - Definition of soil and water conservation expenditures.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 false Definition of soil and water conservation expenditures...continued) § 1.175-2 Definition of soil and water conservation expenditures...expenditures paid or incurred for the purpose of soil or water conservation in...

2010-04-01

265

77 FR 35323 - National Environmental Policy Act: Categorical Exclusions for Soil and Water Restoration Activities  

Federal Register 2010, 2011, 2012, 2013, 2014

...Policy Act: Categorical Exclusions for Soil and Water Restoration Activities AGENCY...the potential environmental effects of soil and water restoration projects that are...exclusions for activities that achieve soil and water restoration objectives....

2012-06-13

266

Soil surfactant products for improving hydrologic function in post-fire water repellent soil  

Technology Transfer Automated Retrieval System (TEKTRAN)

There are a wide range of soil surfactant chemistries on the market today that are primarily designed for the treatment of water repellent soils in cropping and turfgrass systems. These chemicals may also have potential in treating the deleterious effects associated with post-fire water repellent so...

267

Tillage effects on soil water redistribution and bare soil evaporation throughout a season  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tillage-induced changes in soil properties are difficult to predict, yet can influence evaporation, infiltration, and how water is redistributed within the profile after precipitation. We evaluated the effects of sweep tillage (ST) on near surface soil water dynamics as compared with an untilled (UT...

268

Wood chip mulch thickness effects on soil water, soil temperature, weed growth, and landscape plant growth  

Technology Transfer Automated Retrieval System (TEKTRAN)

Wood chip mulches are used in landscapes to reduce soil water evaporation and competition from weeds. A study was conducted over a three-year period to determine soil water content at various depths under four wood chip mulch treatments and to evaluate the effects of wood chip thickness on growth of...

269

Tillage effects on soil water redistribution and bare soil evaporation throughout a season  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tillage-induced changes in soil properties are difficult to predict, yet can influence how water is redistributed within the profile after precipitation and subsequent evaporation rates. We evaluated the effects of sweep tillage (ST) on near surface soil water dynamics as compared with an untilled (...

270

Effect of soil water content on soil thermal conductivity under field conditions  

NASA Astrophysics Data System (ADS)

Knowledge of the thermal properties of soils is required in many areas of engineering, meteorology, agronomy, and ecosystem and soil science. Soil thermal conductivity varies in time and space, since it is influenced by soil properties as well as soil temperature and moisture conditions. We use the one dimensional heat conduction equation in conjunction with two-year data measured in a grass-covered field in North Carolina Piedmont to estimate soil thermal conductivity and to investigate how it is impacted by water content. In agreement with laboratory experiments reported in the literature, our results suggest that under dry conditions soil thermal conductivity increases across a relatively narrow range of soil water contents, above which a further increase in water content does not significantly change thermal conductivity. However, when soil approaches saturation, heat transfer is further improved, a fact not previously noted. This nonlinear behavior is consistent with the formation at high water contents of a continuous film of liquid water in soil aggregates of mineral and organic matter.

Vico, G.; Daly, E.; Manzoni, S.; Porporato, A.

2008-12-01

271

Original article Scaling xylem sap flux and soil water  

E-print Network

Original article Scaling xylem sap flux and soil water balance and calculating variance: a method transpiration, we quantified water flux in a forest using three approaches: 1) measuring water flux in xylem of EC and ET. Diurnal 'patterns' in water uptake were similar using direct measurements in stem xylem

Boyer, Edmond

272

Subcritical water extraction of polychlorinated biphenyls from soil and sediment  

Microsoft Academic Search

Two certified reference materials, an industrial soil (CRM 481) and a river sediment (NIST 1939), were extracted by subcritical water at 50 atm and temperatures ranging from 50 to 300°C. The extraction efficiency of PCBs is extremely dependent on water temperature, since the polarity (dielectric constant) of water can be dramatically lowered by raising the water temperature. While only traces

Yu. Yang; S. Bewadt; Steven B. Hawthorne; David J. Miller

1995-01-01

273

Soil Moisture-Ecosystem-Climate Interactions in a Changing Climate  

NASA Astrophysics Data System (ADS)

Soil moisture is a key variable of the climate system. It constrains plant transpiration and photosynthesis in several regions of the world, with consequent impacts on the water, energy and biogeochemical cycles (e.g. Seneviratne et al. 2010). Moreover it is a storage component for precipitation and radiation anomalies, inducing persistence in the climate system. Finally, it is involved in a number of feedbacks at the local, regional and global scales, and plays a major role in climate-change projections. This presentation will provide an overview on these interactions, based on several recent publications (e.g. Seneviratne et al. 2006, Orlowsky and Seneviratne 2010, Teuling et al. 2010, Hirschi et al. 2011). In particular, it will highlight possible impacts of soil moisture-ecosystem coupling for climate extremes such as heat waves and droughts, and the resulting interconnections between biophysical and biogeochemical feedbacks in the context of climate change. Finally, it will also address recent regional- to global-scale trends in land hydrology and ecosystem functioning, as well as issues and potential avenues for investigating these trends (e.g. Jung et al. 2010, Mueller et al. 2011). References Hirschi, M., S.I. Seneviratne, V. Alexandrov, F. Boberg, C. Boroneant, O.B. Christensen, H. Formayer, B. Orlowsky, and P. Stepanek, 2011: Observational evidence for soil-moisture impact on hot extremes in southeastern Europe. Nature Geoscience, 4, 17-21, doi:10.1038/ngeo1032. Jung, M., et al., 2010: Recent decline in the global land evapotranspiration trend due to limited moisture supply. Nature, 467, 951-954. doi:10.1038/nature09396 Mueller, B., S.I. Seneviratne, et al.: Evaluation of global observations-based evapotranspiration datasets and IPCC AR4 simulations, Geophys. Res. Lett., 38, L06402, doi:10.1029/2010GL046230 Orlowsky, B., and S.I. Seneviratne, 2010: Statistical analyses of land-atmosphere feedbacks and their possible pitfalls. J. Climate, 23(14), 3918-3932 Seneviratne, S.I., T. Corti, E.L. Davin, M. Hirschi, E.B. Jaeger, I. Lehner, B. Orlowsky, and A.J. Teuling, 2010: Investigating soil moisture-climate interactions in a changing climate: A review. Earth-Science Reviews, 99, 3-4, 125-161, doi:10.1016/j.earscirev.2010.02.004 Seneviratne, S.I., D. Lüthi, M. Litschi, and C. Schär, 2006: Land-atmosphere coupling and climate change in Europe. Nature, 443, 205-209. Teuling, A.J., S.I. Seneviratne, et al. 2010: Contrasting response of European forest and grassland energy exchange to heatwaves. Nature Geoscience, 3, 722-727, doi:10.1038/ngeo950.

Seneviratne, S. I.; Davin, E.; Hirschi, M.; Mueller, B.; Orlowsky, B.; Teuling, A.

2011-12-01

274

An experimental investigation into lateral pipeline/soil interaction  

SciTech Connect

In 1991, Nova Gas Transmission Limited began an experimental research program using centrifuge modeling to study the load transfer behavior of buried pipelines subjected to lateral soil movement. Phase 2 of this research program continued to examine laterally displacing pipeline/soil interaction. The six main objectives of this phase were to investigate: (1) the effect of pipeline soil cover; (2) the effect of ditch width; (3) the effect of interaction rate; (4) a modeling of models to verify the centrifuge modeling technique; (5) the effect of preconsolidation stress of the soil; and (6) the effect of different backfills. The data and preliminary analysis of objectives 1--4 were presented at OMAE `95. This paper addresses two issues: (1) the authors present new experimental test results obtained since the last OMAE meeting for a prototype pipeline (0.95m diameter) subjected to lateral soil movement under a 0.8m pipeline cover depth. These test results were obtained for interaction rates ranging from approximately 0.35 to 275m/year, in soil subjected to one dimensional preconsolidation stresses of 160 and 400 kPa, and for pipelines with a variety of backfills; (2) the authors discuss the phase 2 results through comparison with current pipeline/soil interaction analysis methods, through comparison with conventional geotechnical analysis results, and through observed trends in the data.

Paulin, M.J.; Phillips, R. [Memorial Univ. of Newfoundland, St. John`s, Newfoundland (Canada). Centre for Cold Ocean Resources Engineering; Boivin, R. [Nova Gas Transmission Ltd., Calgary, Alberta (Canada)

1996-12-01

275

Protection of ground water by immobilization of heavy metals in industrial-waste-impacted soil systems  

SciTech Connect

Immobilization processes in soil/waste systems impacted by hazardous wastes containing heavy metals were investigated. Samples of contaminated material (soil and/or waste) from nine sites in the Intermountain West and California included milling, electroplating, cement kiln dust, petroleum, and tailing and waste rock from mining operations. A sequential extraction procedure, originally developed to fractionate metals in sludge-amended soils into water soluble, mobile, and plant-available forms, was used to obtain preliminary identification of the leachable-metal fraction for the hazardous-waste-contaminated soils studied. Sorption kinetics and batch sorption/desorption studies were performed to determine the interaction of Cu and Cd, from an acidic leachate of a mine waste, with calcareous soils. Solid phase diagrams, exchange models, and GEOCHEM were used to define the mechanisms of metal attenuation of these soils.

McLean, J.E.; Dudley, L.M.; Sims, R.C.

1986-09-01

276

COMPARISON AND EVALUATION OF FIELD METHODS (DIRECT AND INDIRECT) TO ESTIMATE SOIL WATER FLUXES.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Knowledge of soil water fluxes is critical for evaluating efficiency and environmental effects of soil and crop management. Indirect methods commonly used to estimate soil water fluxes estimates are currently based on (a) soil water balance, (b) soil water potential measurements with the Darcy-Bucki...

277

Interaction of leaf traits and soil fauna and their role for carbon sequestration in soil  

NASA Astrophysics Data System (ADS)

Litter traits are assumed as one of the most important factor true which plants affect biogeochemisty of the stand where they grow including soil formation and nutrient dynamic which affect substantially function of whole ecosystem. Relationships between potential decomposition and leaf litter traits were extensively studied. Despite importance of potential decomposition, we believe that effect of leaf traits on litter quality is more complex: 1) litter potential decomposability affect litter processing by soil fauna and intensity of consequent fragmentation bioturbation and incorporation into soil aggregates. 2) litter, when supplied into soil for longer period of time affect also soil formation and composition of decomposer community which consequently affect dynamic of litter decomposition. In addition interactions between leaf traits and litter trait may nod be also quite complex. We will demonstrate several examples showing that litter with higher potential decomposability may sequeterr more in soil that les decomposable litter because is in larger extend stabilized by soil fauna.

Frouz, J.

2012-04-01

278

Citrus orchards management and soil water repellency in Eastern Spain  

NASA Astrophysics Data System (ADS)

Water repellent soils are found around the world, although originally was found on fire affected soil (DeBano, 1981). However, for decades, water repellency was found to be a rare soil property. One of the pioneer research that shown that water repellency was a common soil property is the Wander (1949) publication in Science. Wander researched the water repellency on citrus groves, and since then, no information is available about the water repellency on citrus plantations. The Mediterranean soils are prone to water repellency due to the summer dry conditions (Cerdŕ and Doerr, 2007). And Land Use and Land Management are key factors (Harper et al., 2000; Urbanek et al., 2007) to understand the water repellency behaviour of agriculture soils. Valencia region (Eastern Spain) is the largest exporter in the world and citrus plantations located in the alluvial plains and fluvial terraces are moving to alluvial fans and slopes where the surface wash is very active (Cerdŕ et al., 2009). This research aims to show the water repellency on citrus orchards located on the sloping terrain (< 15 % angle slope). Measurement were conducted in four experimental plots located in the Canyoles River watershed to assess the soil water repellency in citrus orchards under different managements: annual addition of plant residues and manure with no tilling and no fertilizer (MNT), annual addition of plant residues with no tillage (NT), application of conventional herbicides and no tilling (HNT) and conventional tillage in June (CT). The period for each type of management ranged from 2 and 27 (MNT), 1 and 25 (NT), 2 and 27 (HNT) and 3 and 29 years (CT). At each plot, a ten points were selected every 10 cm along inter-rows and water drop penetration time test (WDTP; DeBano, 1981) was performed. The results show that the MNT treatment induced slight water repellency in citrus-cropped soils compared to other treatments. Small but significant soil water repellency was observed under NT and HNT treatments (mean WDTP 4 ± 4 s and 2 ± 2 s, respectively), which may be regarded as subcritical soil water repellency. Slight water repellency observed in soils under MNT treatment may be attributed to the input of hydrophobic organic compounds as a consequence of the addition of plant residues and organic manure. A further issue to be achieved is the study of geomorphological processes associated to sub-critical soil water repellency. The experimental setup within the citrus plantation is being supported by the research project CGL2008-02879/BTE

Cerdŕ, A.; González Peńaloza, F. A.; Jordán, A.; Zavala, L. M.

2012-04-01

279

pH-dependent ciprofloxacin sorption to soils: Interaction mechanisms and soil factors influencing sorption  

Microsoft Academic Search

A study of ciprofloxacin sorption to 30 soils from the eastern United States revealed a statistically significant effect of pH on the solid–water distribution coefficient (Kd). Cation exchange capacity was the key soil factor influencing the extent of sorption at all pH values (3–8), with soil metal oxide content playing a smaller role at higher pH. Although, cation exchange, cation

Dharni Vasudevan; Gregory L. Bruland; Brendan S. Torrance; Virginia G. Upchurch; Allison A. MacKay

2009-01-01

280

Estimation of water saturated permeability of soils, using 3D soil tomographic images and pore-level transport phenomena modelling  

NASA Astrophysics Data System (ADS)

There are some important macroscopic properties of the soil porous media such as: saturated permeability and water retention characteristics. These soil characteristics are very important as they determine soil transport processes and are commonly used as a parameters of general models of soil transport processes used extensively for scientific developments and engineering practise. These characteristics are usually measured or estimated using some statistical or phenomenological modelling, i.e. pedotransfer functions. On the physical basis, saturated soil permeability arises from physical transport processes occurring at the pore level. Current progress in modelling techniques, computational methods and X-ray micro-tomographic technology gives opportunity to use direct methods of physical modelling for pore level transport processes. Physically valid description of transport processes at micro-scale based on Navier-Stokes type modelling approach gives chance to recover macroscopic porous medium characteristics from micro-flow modelling. Water microflow transport processes occurring at the pore level are dependent on the microstructure of porous body and interactions between the fluid and the medium. In case of soils, i.e. the medium there exist relatively big pores in which water can move easily but also finer pores are present in which water transport processes are dominated by strong interactions between the medium and the fluid - full physical description of these phenomena is a challenge. Ten samples of different soils were scanned using X-ray computational microtomograph. The diameter of samples was 5 mm. The voxel resolution of CT scan was 2.5 µm. Resulting 3D soil samples images were used for reconstruction of the pore space for further modelling. 3D image threshholding was made to determine the soil grain surface. This surface was triangulated and used for computational mesh construction for the pore space. Numerical modelling of water flow through the sample was performed. Steady-state Navier-Stokes equations for incompressible laminar flows were used for that purpose. Resulting from modelling values of the soil saturated permeabilities were compared with results from measurements, made using constant head permeameter. Differences in this results were discussed. The study was partially funded from the National Science Centre (Poland) upon the contract: UMO-2011/01/B/ST10/07544.

Lamorski, Krzysztof; S?awi?ski, Cezary; Barna, Gyöngyi

2014-05-01

281

On-Farm Soil Monitoring for Water  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Plant and crop residue cover generations and other species. Improving and protecting soil quality can help support sustainable crop in your field and cropping practices affect the soil. This publication will present quick

Holland, Jeffrey

282

Scaling Infiltration and Other Soil Water Processes Across Diverse Soil textural Classes  

NASA Astrophysics Data System (ADS)

Our studies showed that the pore-size distribution index (lambda) can scale Brooks-Corey (B-C) formulation of the soil-water retention curves below the air-entry pressure head across dissimilar (Sandy to clayey) soils, and other key B-C hydraulic parameters ( Ksat, air-entry pressure head, and dependant) were also strongly related to lambda. We then examined how these relationships to lambda led to relationships for infiltration across soil textural classes using three different approaches, as well as the subsequent soil water contents during redistribution, evaporation, and transpiration. The Root Zone Water Quality Model was used to generate data for infiltration under four rainfall intensities, redistribution for four initial wetting depths, and evaporation and transpiration under different potential rates in eleven textural class mean soils. Cumulative infiltration could be scaled quite well across textural classes based on knowledge of lamda using the Green-Ampt normalization equations. There were also strong empirical functional relationships between cumulative infiltration at fixed times across soils and the soils' lamda, and between the parameters of the empirical Kostiakov (Lewis) infiltration equation and lamda as well as Ksat. The Kostiakov parameters vs. lamda or Ksat (Ksat was better) provided more compact and explicit relationships across diverse soil classes both for instantaneous ponding and non-instantaneous ponding (e.g., rainfall) infiltration conditions, and could be used to scale and estimate infiltration across these classes. Similar strong relations were found between lamda (and by inference Ksat) and soil water contents across soil types during redistribution, and for evapotranspiration and transpiration. This study is a breakthrough in our understanding of the soil water relationships and scaling among soil textural classes, that could serve as a basis for describing spatial variability of soil water on the landscape for site-specific management and for scaling up results in modeling from plots to fields to watersheds.

Kozak, J.; Ahuja, L.; Green, T.

2005-12-01

283

Perchlorate levels in soil and waters from the Atacama Desert.  

PubMed

Perchlorate is an anion that originates as a contaminant in ground and surface waters. The presence of perchlorate in soil and water samples from northern Chile (Atacama Desert) was investigated by ion chromatography-electrospray mass spectrometry. Results indicated that perchlorate was found in five of seven soils (cultivated and uncultivated) ranging from 290 ± 1 to 2,565 ± 2 ?g/kg. The greatest concentration of perchlorate was detected in Humberstone soil (2,565 ± 2 ?g/kg) associated with nitrate deposits. Perchlorate levels in Chilean soils are greater than those reported for uncultivated soils in the United States. Perchlorate was also found in superficial running water ranging from 744 ± 0.01 to 1,480 ± 0.02 ?g/L. Perchlorate water concentration is 30-60 times greater than levels established by the United States Environmental Protection Agency (24.5 ?g/L) for drinking. PMID:24165784

Calderón, R; Palma, P; Parker, D; Molina, M; Godoy, F A; Escudey, M

2014-02-01

284

Soil-tool interaction theories as they apply to lunar soil simulant  

NASA Astrophysics Data System (ADS)

With the establishment of a lunar base, excavation of the lunar soil will be a necessary and time-critical activity. It is the intent of this paper to establish the importance of certain excavation parameters and how they interrelate. With this approach, an overall efficiency of an excavating system can be determined and used as a basis for comparing several excavating systems. This structured approach requires knowledge of the mechanical properties of the lunar soil in its utilization. So, the mechanical properties of the lunar soil and a terrestrial analog are also presented. The analysis of excavating parameters demonstrates that force is a parameter derived from constants. With this parameter the force required to fail the dense lunar soil is investigated. There exists some soil-tool interaction theories developed for finding the force required to fail soil with a blade, given the appropriate parameters of the blade, the soil, and their interaction. These predictive models are used to predict the force required to fail the lunar soil simulant with a flat blade. An apparatus is developed to fail the prepared lunar soil simulant while measuring the required force. Given this data, the validity of the predictive models for use in comparing alternative excavating techniques in this dense lunar soil is determined.

Willman, Brian M.; Boles, Walter W.

1995-04-01

285

Rock fragments induce patchy distribution of soil water repellency in burned soils  

NASA Astrophysics Data System (ADS)

Forest fires are recurrent phenomena in the Mediterranean area and are one of the main causes of changes in the Mediterranean ecosystems, increasing the risk of soil erosion and desertification. Fire is an important agent which can induce important changes in the chemical and physical characteristics of soils. During wildfires, only a small part of the heat generated is transmitted to the first centimetres of the soil profile. The intensity of the changes produced in the physical and chemical characteristics of the soil depends on the temperatures reached at different soil depths, the time of residence of temperature peaks, and the stability of the different soil components. One of the soil physical properties strongly affected by fire is soil water repellency (WR). Depending on temperature, time of heating, type of soil and fuel, fire can induce, enhance or destroy soil WR. Soil WR is a key factor in controlling soil hydrology and water availability in burnt soils together with other factors as texture or aggregation. Although the occurrence and consequences of fire-induced soil WR have been deeply studied, some gaps still exist, as the influence of rock fragment cover during burning. During combustion of litter and aerial biomass, the soil surface under rock fragments is heated and reachs temperature peaks after a certain delay respect to exposed areas. In contrast, temperature peaks are longer, increasing the time of residence of high temperature. In consequence, rock fragments may change the expected spatial distribution of soil WR. Up to date, very scarce research concerns the effect of rock fragments at the soil surface on the fire-induced pattern of soil water repellency. METHODS Two experiments were carried out in this research. In the first case, an experiment was conducted in an experimental farm in Sevilla (southern Spain). The effect of a low severity prescribed fire was studied in soil plots under different rock fragment covers (0, 15, 30, 45 and 60%). Soil WR was assessed in soil samples (0-10 cm) collected monthly during 6 monhts after burning. In the second case, a fire-affected forest soil from Calańas (Huelva, southweastern Spain) was studied. Soil plots under different fire severities (low, medium and high severity burning) and rock fragment cover classes (20-40 and 60-80%) were analyzed. Soil WR was assessed in the soil surface immediately under the vertical projection of randomly selected stones and in the middle point between these and the nearest stones. Unburned adjacent soils under similar rock fragment cover classes were used as control. All soil WR assessments were carried out using the WDPT method. RESULTS In both cases, soil WR was induced in the soil surface contacting rock fragments after burning. Severity of WR ranged between subcritical or slight (low severity burning) and strong (high severity burning). Soil WR was also found to increase with rock fragment cover, especially after moderate or high severity burning, both under and between rock fragments. It is suggested that high density of rock fragments on the soil surface create a continuous surface of high residence of temperature peaks (in agreement with García-Moreno et al., 2013). Combustion of plant residues in oxygen depletion conditions between adjacent nearby rock fragments contributes to heat transfer to the soil surface and consequent enhanced soil WR. REFERENCES García-Moreno, J., Gordillo-Rivero, A.J., Gil, J., Jiménez-Morillo, N.T., Mataix-Solera, J., González-Peńaloza, F.A., Granged, A.J.P., Bárcenas-Moreno, G., Jiménez-Pinilla, P., Lozano, E., Jordán, A., Zavala, L.M. 2013. Do stones modify the spatial distribution of fire-induced soil water repellency? Preliminary data. Flamma, 4:76-80.

Gordillo-Rivero, Ángel; García-Moreno, Jorge; Bárcenas-Moreno, Gema; Jiménez-Morillo, Nicasio T.; Mataix-Solera, Jorge; Jordán, Antonio; Zavala, Lorena M.

2013-04-01

286

Measuring Low Concentrations of Liquid Water in Soil  

NASA Technical Reports Server (NTRS)

An apparatus has been developed for measuring the low concentrations of liquid water and ice in relatively dry soil samples. Designed as a prototype of instruments for measuring the liquidwater and ice contents of Lunar and Martian soils, the apparatus could also be applied similarly to terrestrial desert soils and sands. The apparatus is a special-purpose impedance spectrometer: Its design is based on the fact that the electrical behavior of a typical soil sample is well approximated by a network of resistors and capacitors in which resistances decrease and capacitances increase (and, hence, the magnitude of impedance decreases) with increasing water content.

Buehler, Martin

2009-01-01

287

Environmental Implications of Soil Properties and Essential Nutrient Interactions, Under the Effect of Treated Municipal Wastewater  

Microsoft Academic Search

An experiment of randomized block design was conducted during 2005 in a green-house, Agrinion Greece. The effect of two variables\\u000a was studied on the interactions between essential nutrients and the soil physical and chemical properties, i.e. treated municipal\\u000a waste water (TMWW), and fresh irrigation water, denoted as “control”. The experiment was done in six replications with a total\\u000a of 2?×?6?=?12

I. K. Kalavrouziotis; P. H. Koukoulakis

2009-01-01

288

Evaluation of different field methods for measuring soil water infiltration  

NASA Astrophysics Data System (ADS)

Soil infiltrability, together with rainfall characteristics, is the most important hydrological parameter for the evaluation and diagnosis of the soil water balance and soil moisture regime. Those balances and regimes are the main regulating factors of the on site water supply to plants and other soil organisms and of other important processes like runoff, surface and mass erosion, drainage, etc, affecting sedimentation, flooding, soil and water pollution, water supply for different purposes (population, agriculture, industries, hydroelectricity), etc. Therefore the direct measurement of water infiltration rates or its indirect deduction from other soil characteristics or properties has become indispensable for the evaluation and modelling of the previously mentioned processes. Indirect deductions from other soil characteristics measured under laboratory conditions in the same soils, or in other soils, through the so called "pedo-transfer" functions, have demonstrated to be of limited value in most of the cases. Direct "in situ" field evaluations have to be preferred in any case. In this contribution we present the results of past experiences in the measurement of soil water infiltration rates in many different soils and land conditions, and their use for deducing soil water balances under variable climates. There are also presented and discussed recent results obtained in comparing different methods, using double and single ring infiltrometers, rainfall simulators, and disc permeameters, of different sizes, in soils with very contrasting surface and profile characteristics and conditions, including stony soils and very sloping lands. It is concluded that there are not methods universally applicable to any soil and land condition, and that in many cases the results are significantly influenced by the way we use a particular method or instrument, and by the alterations in the soil conditions by the land management, but also due to the manipulation of the surface soil before and during the measurement. Due to the commonly found high variability, natural or induced by land management, of the soil surface and subsurface hydrological properties, and to the limitations imposed by the requirements of water for the measurements, there is proposed a simple and handy method, which do not use high volumes of water, adaptable to very different soil and land conditions, and that allow many repeated measurements with acceptable accuracy for most of the purposes. References Pla, I., 1997. A soil water balance model for monitoring soil erosion processes and effects on steep lands in the tropics. Soil Technology. 11(1):17-30. Elsevier Pla, I., 2006. Hydrological approach for assessing desertification processes in the Mediterranean region. In W.G. Kepner et al. (Editors), Desertification in the Mediterranean Region. A Security Issue. 579-600 Springer. Heidelberg (Germany) Reynolds W.D., B.T. Bowman, R.R. Brunke, C.F. Drury and C.S. Tan. 2000. Comparison of Tension Infiltrometer, Pressure Infiltrometer, and Soil Core Estimates of Saturated Hydraulic Conductivity . Soil Science Society of America Journal 64:478-484 Segal, E., S.A.Bradford, P. Shouse; N. Lazarovich, and D. Corwin. 2008. Integration of Hard and Soft Data to Characterize Field-Scale Hydraulic Properties for Flow and Transport Studies. Vadose Zone J 7:878-889 Young, E. 1991. Infiltration measurements, a review. Hydrological processes 5: 309-320.

Pla-Sentís, Ildefonso; Fonseca, Francisco

2010-05-01

289

Running heading: Water retention properties of the clay in clayey soils Water retention properties of the clay in soils developed  

E-print Network

1 Running heading: Water retention properties of the clay in clayey soils Water retention. E-mail: ary.bruand@orleans.inra.fr Summary We have investigated the water retention properties retention properties have been studied from -10 hPa to -15 000 hPa water potential using small clods

Paris-Sud XI, Université de

290

The effect of soil: water ratios on the mineralisation of phenanthrene: LNAPL mixtures in soil.  

PubMed

Contamination of soil by polycyclic aromatic hydrocarbons is frequently associated with non-aqueous-phase liquids. Measurement of the catabolic potential of a soil or determination of the biodegradable fraction of a contaminant can be done using a slurried soil respirometric system. This work assessed the impact of increasing the concentration of transformer oil and soil:water ratio on the microbial catabolism of [(14)C]phenanthrene to (14)CO(2) by a phenanthrene-degrading inoculum. Slurrying (1:1, 1:2, 1:3 and 1:5 soil:water ratios) consistently resulted in statistically higher rates and extents of mineralisation than the non-slurried system (2:1 soil:water ratio; P<0.01). The maximum extents of mineralisation observed occurred in the 1:2-1:5 soil:water ratio microcosms irrespective of transformer oil concentration. Transformer oil concentrations investigated displayed no statistically significant effect on total mineralisation (P>0.05). Soil slurries 1:2 or greater, but less than 1:5 (soil:water), are recommended for bioassay determinations of total contaminant bioavailability due to greater overall mineralisation and improved reproducibility. PMID:12644224

Doick, Kieron J; Semple, Kirk T

2003-03-14

291

The interactive effects of soil transplant into colder regions and cropping on soil microbiology and biogeochemistry.  

PubMed

Soil transplant into warmer regions has been shown to alter soil microbiology. In contrast, little is known about the effects of soil transplant into colder regions, albeit that climate cooling has solicited attention in recent years. To address this question, we transplanted bare fallow soil over large transects from southern China (subtropical climate zone) to central (warm temperate climate zone) and northern China (cold temperate climate zone). After an adaptation period of 4 years, soil nitrogen components, microbial biomass and community structures were altered. However, the effects of soil transplant on microbial communities were dampened by maize cropping, unveiling a negative interaction between cropping and transplant. Further statistical analyses with Canonical correspondence analysis and Mantel tests unveiled annual average temperature, relative humidity, aboveground biomass, soil pH and NH4 (+) -N content as environmental attributes closely correlated with microbial functional structures. In addition, average abundances of amoA-AOA (ammonia-oxidizing archaea) and amoA-AOB (ammonia-oxidizing bacteria) genes were significantly (P?soil nitrification capacity, hence both AOA and AOB contributed to the soil functional process of nitrification. These results suggested that the soil nitrogen cycle was intimately linked with microbial community structure, and both were subjected to disturbance by soil transplant to colder regions and plant cropping. PMID:24548455

Liu, Shanshan; Wang, Feng; Xue, Kai; Sun, Bo; Zhang, Yuguang; He, Zhili; Van Nostrand, Joy D; Zhou, Jizhong; Yang, Yunfeng

2015-03-01

292

Water repellent soils as they occur on UK golf greens  

NASA Astrophysics Data System (ADS)

Water repellent soils have been identified as a major problem in the management of golf greens in the UK for over 60 years. The cause of this problem has provoked much speculation, but prior to this work, no research into the possible cause of water repellent soils in the UK had been completed. One of the commonly believed links with water repellent soils on UK golf greens was the activity of basidiomycete fungi. This was proposed as a possible causal factor because the symptoms expressed on the turf above affected soils, were similar in many instances to those symptoms expressed by the activity of superficial fairy rings. Since it was impractical to study superficial fairy rings, it was decided to observe other basidiomycete fairy rings (Type 1 fairy rings) to see if any water-repellence could be identified as being associated with them. Three of these rings, caused by the fungus Marasmius oreades (Bolt ex. Fr) Fr., were studied on each of the two different sites. Soil samples were removed at intervals from the centre of the rings, across the obvious symptoms of the rings (i.e. the zone of dead grass bordered on both sides by a zone of stimulated grass growth) and beyond, into the uncolonised soil. These samples were taken to the laboratory, allowed to air dry and were then tested to determine relative levels of water repellence. It was found that on the 'outside' of the fairy rings where the fungus had not yet colonised, the soils were less water repellent than they were in the other zones of the rings (i.e. the dead zone and the inner zone). In the region of the dead zone of these fairy rings, the soil was very water repellent. This may have been expected because the fungus was present in this area in large quantities and the fungus itself repels water. However, of particular interest, were the results from the inner part of the ring where the fungus had been present in the past, but where it no longer colonised the soil. In these soil samples, the rootzone soil was still very water repellent. It was concluded from the study that it was possible for basidiomycete-type fungi to effect water repellence on soils through which they have passed. Thus, this may be at least a contributory factor to the development of severely water repellent soils on UK golf greens.

York, C. A.; Canaway, P. M.

2000-05-01

293

Comparison of bioassays by testing whole soil and their water extract from contaminated sites.  

PubMed

The harmful effects of contaminants on the ecosystems and humans are characterised by their environmental toxicity. The aim of this study was to assess applicability and reliability of several environmental toxicity tests, comparing the result of the whole soils and their water extracts. In the study real contaminated soils were applied from three different inherited contaminated sites of organic and inorganic pollutants. The measured endpoints were the bioluminescence inhibition of Vibrio fischeri (bacterium), the dehydrogenase activity inhibition of Azomonas agilis (bacterium), the reproduction inhibition of Tetrahymena pyriformis (protozoon), and Panagrellus redivivus (nematode), the mortality of Folsomia candida (springtail), the root and shoot elongation inhibition of Sinapis alba (plant: white mustard) and the nitrification activity inhibition of an uncontaminated garden soil used as "test organism". Besides the standardised or widely used methods some new, direct contact ecotoxicity tests have been developed and introduced, which are useful for characterisation of the risk of contaminated soils due to their interactive nature. Soil no. 1 derived from a site polluted with transformer oil (PCB-free); Soil no. 2 originated from a site contaminated with mazout; Soil no. 3 was contaminated with toxic metals (Zn, Cd, Cu, Pb, As). In most cases, the interactive ecotoxicity tests indicated more harmful effect of the contaminated soil than the tests using soil extracts. The direct contact environmental toxicity tests are able to meet the requirements of environmental toxicology: reliability, sensibility, reproducibility, rapidity and low cost. PMID:16860849

Leitgib, Laura; Kálmán, Judit; Gruiz, Katalin

2007-01-01

294

Field-measured, hourly soil water evaporation stages in relation to reference evapotranspiration rate and soil air temperature ratio  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil water evaporation takes critical water supplies away from crops, especially in areas where both rainfall and irrigation water are limited. This study measured bare soil water evaporation from clay loam, silt loam, sandy loam, and fine sand soils. It found that on average almost half of the ir...

295

Hydraulic lift: Substantial nocturnal water transport between soil layers by Artemisia tridentata roots  

Microsoft Academic Search

Diel soil water potential fluctuations reflected daytime depletion and nocturnal resupply of water in upper soil layers. Transpiration suppression experiments demonstrated that water absorption by roots caused the daytime depletion. The soil water potential data and experimental results suggest that at night water absorbed from moist soil by deeper roots is transported to and lost from roots into drier upper

J. H. Richards; M. M. Caldwell

1987-01-01

296

Interaction of water with epoxy.  

SciTech Connect

The chemistries of reactants, plasticizers, solvents and additives in an epoxy paint are discussed. Polyamide additives may play an important role in the absorption of molecular iodine by epoxy paints. It is recommended that the unsaturation of the polyamide additive in the epoxy cure be determined. Experimental studies of water absorption by epoxy resins are discussed. These studies show that absorption can disrupt hydrogen bonds among segments of the polymers and cause swelling of the polymer. The water absorption increases the diffusion coefficient of water within the polymer. Permanent damage to the polymer can result if water causes hydrolysis of ether linkages. Water desorption studies are recommended to ascertain how water absorption affects epoxy paint.

Powers, Dana Auburn

2009-07-01

297

Integrated use of soil physical and water isotope methods for ecohydrological characterization of desertified areas  

NASA Astrophysics Data System (ADS)

Measures for monitoring desertification and soil degradation require a thorough understanding of soil physical properties and of the water balance in order to guide restoration efforts (Costantini et al. 2009). It is hypothesized that long term restoration success on degraded land depends on a series of interacting factors such as exposition, soil type, soil hydrology including lateral flow on hill-slope catenae. Recently, new soil water isotope measurement techniques have been developed (Garvelmann et al. 2012) that provide much faster and reliable stable water isotope profiles in soils. This technique yield information on groundwater recharge, soil water balance and on the origin of water available for plants, which in combination with conservative chemical tracers (chloride) can be validated. A multidisciplinary study including ecologists, soil physicists and hydrologists of the COST Action Desert Restoration Hub was carried out on four semi-arid sites in Portugal. A comparative characterization of soil physical parameters, soil water isotope and chloride profiles was performed in order to estimate pedoclimate, soil aridity, soil water balance and groundwater recharge. In combination with soil physical data a comprehensive and cross-validated characterization of pedoclimate and soil aridity was obtained. These indicators were then integrated and related to plant cover. The long-term rainfall of the four sites ranges from 512 to 638 mm, whereas air temperature is from 15.8 to 17.0°C. The De Martonne index of aridity spans from 19.3 to 24.6, pointing to semiarid to moderately arid climatic conditions. The long-term average number of days when the first 0.50 m of soil is dry ranges from 110 to 134, while the mean annual soil temperature at 0.50 m spans from 15.8 and 19.1°C. The studied profiles show different hydrological characteristics, in particular, the estimated hydraulic conductivity ranges from 0.1-1 to 10-100 µm/s. Three out of four profiles show a marked decrease in water permeability at 0.04, 0.20, or 0.40 m depth. Soil isotope profiles indicated that percolation beneath the root zone and groundwater recharge ranges from 21.7 mm/y to 29.7 mm/y. The recharge rate was positively related to mean annual rainfall and soil organic matter, and interestingly, increased with aridity and desertification. The difference between mean annual rainfall and percolation was positively related to plant cover and in inverse proportion to the aridity index. Our results highlight the importance of combining different methods of site characterization by soil physics, soil water isotopes and soil water chemistry (chloride) with vegetation data, providing a more specific analysis of ecohydrological conditions and their relation to ecosystem functioning and recovery potential. The field protocol applied can provide relevant information for guiding restoration strategies. Costantini, E. A. C., Urbano, F., Aramini, G., Barbetti, R., Bellino, F., Bocci, M., & Tascone, F. (2009). Rationale and methods for compiling an atlas of desertification in Italy. Land Degradation & Development, 20(3), 261-276. Garvelmann, J., Külls, C., & Weiler, M. (2012). A porewater-based stable isotope approach for the investigation of subsurface hydrological processes. Hydrology and Earth System Sciences, 16(2), 631-640.

Külls, Christoph; Nunes, Alice; Köbel-Batista, Melanie; Branquinho, Cristina; Bianconi, Nadja; Costantini, Eduardo

2014-05-01

298

[Behavior of HTO in simulated rice-water-soil ecosystem].  

PubMed

The behavior of transportation, accumulation and disappearance of HTO (tritium water) in a simulated rice-water-soil ecosystem was studied by using isotope-tracer techniques for simulated pollutants, and the fitting equation was confirmed by application of the open three-compartment system model and nonlinear regression method. The results showed that HTO in water was not only transferred to other compartments in the ecosystem, but also vaporized into atmosphere rapidly. Both free water tritium and bound tritium were found in the rice, and tritium of hygroscopic and crystalline water was consisted in the soil. The specific activity of free water tritium (or tritium of hygroscopic water) was stronger than that of bound tritium (or tritium of crystalline water). The specific activity of total tritium reduced after reaching the maximum in the rice and soil, and the bound tritium increased slowly. The specific activity of total tritium in stem was the strongest in the rice, and reached equipoise each other in the later stage gradually. The regression equations of accumulation and disappearance for the specific activity of total tritium in the water, soil and rice were given by analyzing the obtained data with exponential regression method. The analysis results of variance showed that each regression equation could describe the behavior of accumulation and disappearance of HTO in the rice-water-soil ecosystems preferably. PMID:12827885

Shi, Jianjun; Guo, Jiangfeng

2003-02-01

299

Water dynamics and interactions in water-polyether binary mixtures.  

PubMed

Poly(ethylene) oxide (PEO) is a technologically important polymer with a wide range of applications including ion-exchange membranes, protein crystallization, and medical devices. PEO's versatility arises from its special interactions with water. Water molecules may form hydrogen-bond bridges between the ether oxygens of the backbone. While steady-state measurements and theoretical studies of PEO's interactions with water abound, experiments measuring dynamic observables are quite sparse. A major question is the nature of the interactions of water with the ether oxygens as opposed to the highly hydrophilic PEO terminal hydroxyls. Here, we examine a wide range of mixtures of water and tetraethylene glycol dimethyl ether (TEGDE), a methyl-terminated derivative of PEO with 4 repeat units (5 ether oxygens), using ultrafast infrared polarization selective pump-probe measurements on water's hydroxyl stretching mode to determine vibrational relaxation and orientational relaxation dynamics. The experiments focus on the dynamical interactions of water with the ether backbone because TEGDE does not have the PEO terminal hydroxyls. The experiments observe two distinct subensembles of water molecules: those that are hydrogen bonded to other waters and those that are associated with TEGDE molecules. The water orientational relaxation has a fast component of a few picoseconds (water-like) followed by much slower decay of approximately 20 ps (TEGDE associated). The two decay times vary only mildly with the water concentration. The two subensembles are evident even in very low water content samples, indicating pooling of water molecules. Structural change as water content is lowered through either conformational changes in the backbone or increasing hydrophobic interactions is discussed. PMID:19323522

Fenn, Emily E; Moilanen, David E; Levinger, Nancy E; Fayer, Michael D

2009-04-22

300

Soil warming, carbon-nitrogen interactions, and forest carbon budgets.  

PubMed

Soil warming has the potential to alter both soil and plant processes that affect carbon storage in forest ecosystems. We have quantified these effects in a large, long-term (7-y) soil-warming study in a deciduous forest in New England. Soil warming has resulted in carbon losses from the soil and stimulated carbon gains in the woody tissue of trees. The warming-enhanced decay of soil organic matter also released enough additional inorganic nitrogen into the soil solution to support the observed increases in plant carbon storage. Although soil warming has resulted in a cumulative net loss of carbon from a New England forest relative to a control area over the 7-y study, the annual net losses generally decreased over time as plant carbon storage increased. In the seventh year, warming-induced soil carbon losses were almost totally compensated for by plant carbon gains in response to warming. We attribute the plant gains primarily to warming-induced increases in nitrogen availability. This study underscores the importance of incorporating carbon-nitrogen interactions in atmosphere-ocean-land earth system models to accurately simulate land feedbacks to the climate system. PMID:21606374

Melillo, Jerry M; Butler, Sarah; Johnson, Jennifer; Mohan, Jacqueline; Steudler, Paul; Lux, Heidi; Burrows, Elizabeth; Bowles, Francis; Smith, Rose; Scott, Lindsay; Vario, Chelsea; Hill, Troy; Burton, Andrew; Zhou, Yu-Mei; Tang, Jim

2011-06-01

301

Soil warming, carbon–nitrogen interactions, and forest carbon budgets  

PubMed Central

Soil warming has the potential to alter both soil and plant processes that affect carbon storage in forest ecosystems. We have quantified these effects in a large, long-term (7-y) soil-warming study in a deciduous forest in New England. Soil warming has resulted in carbon losses from the soil and stimulated carbon gains in the woody tissue of trees. The warming-enhanced decay of soil organic matter also released enough additional inorganic nitrogen into the soil solution to support the observed increases in plant carbon storage. Although soil warming has resulted in a cumulative net loss of carbon from a New England forest relative to a control area over the 7-y study, the annual net losses generally decreased over time as plant carbon storage increased. In the seventh year, warming-induced soil carbon losses were almost totally compensated for by plant carbon gains in response to warming. We attribute the plant gains primarily to warming-induced increases in nitrogen availability. This study underscores the importance of incorporating carbon–nitrogen interactions in atmosphere–ocean–land earth system models to accurately simulate land feedbacks to the climate system. PMID:21606374

Melillo, Jerry M.; Butler, Sarah; Johnson, Jennifer; Mohan, Jacqueline; Steudler, Paul; Lux, Heidi; Burrows, Elizabeth; Bowles, Francis; Smith, Rose; Scott, Lindsay; Vario, Chelsea; Hill, Troy; Burton, Andrew; Zhou, Yu-Mei; Tang, Jim

2011-01-01

302

WATER REPELLENT SOILS AND THEIR RELATION TO WILDFIRE TEMPERATURES  

Microsoft Academic Search

A naturally occurring water resistant soil was exposed to different burning times and temperatures after which the soil samples were tested for non-wettability. The less intense treatments produced an extremely non-wettable condition. Temperatures of 800 and 900 degrees applied for 20 minutes completely destroyed the non-wettable property. Heat treatments within the realm of soil temperatures existing during wildfires were capable

L. F. DEBANO; J. S. KRAMMES

1966-01-01

303

Arsenic Enrichment in Surface Water and Soil in Tibetan Plateau  

Microsoft Academic Search

Corresponding author: yan.zheng@qc.cuny.edu The average soil arsenic concentration was reported to be 18.7 mg\\/kg based on a survey of 205 samples in Tibet. This is considerably higher than the commonly cited crustal background value of 10 mg\\/kg of As for soil, and is unlikely due to anthropogenic pollution. To investigate the origin of this geochemical anomaly in soil arsenic, water

S. Li; M. Wang; B. Zheng; Y. Zheng

2008-01-01

304

Soil Water Retention as Indicator for Soil Physical Quality - Examples from Two SoilTrEC European Critical Zone Observatories  

NASA Astrophysics Data System (ADS)

Soil water retention is of primary importance for majority of soil functions. The characteristics derived from Soil Water Retention Curve (SWRC) are directly related to soil structure and soil water regime and can be used as indicators for soil physical quality. The aim of this study is to present some parameters and relationships based on the SWRC data from the soil profiles characterising the European SoilTrEC Critical Zone Observatories Fuchsenbigl and Koiliaris. The studied soils are representative for highly productive soils managed as arable land in the frame of soil formation chronosequence at "Marchfeld" (Fuchsenbigl CZO), Austria and heavily impacted soils during centuries through intensive grazing and farming, under severe risk of desertification in context of climatic and lithological gradient at Koiliaris, Crete, Greece. Soil water retention at pF ? 2.52 was determined using the undisturbed soil cores (100 cm3 and 50 cm3) by a suction plate method. Water retention at pF = 4.2 was determined by a membrane press method and at pF ? 5.6 - by adsorption of water vapour at controlled relative humidity, both using ground soil samples. The soil physical quality parameter (S-parameter) was defined as the slope of the water retention curve at its inflection point (Dexter, 2006), determined with the obtained parameters of van Genuhten (1980) water retention equation. The S-parameter values were categorised to assess soil physical quality as follows: S < 0.020 very poor, 0.020 ? S < 0.035 poor, 0.035 ? S < 0.050 good, S ? 0.050 very good (Dexter, 2004). The results showed that most of the studied topsoil horizons have good physical quality according to both the S-parameter and the Plant-Available Water content (PAW), with the exception of the soils from croplands at CZO Fuxenbigl (F4, F5) which are with poor soil structure. The link between the S-parameter and the indicator of soil structure stability (water stable soil aggregates with size 1-3 mm) is not well defined. The scattering is due to high values of S in subsoil, which does not always coincide with favourable physical properties, as it can be seen from the relationship with the PAW content. It was found that values of S ? 0.05 correspond to PAW > 20 % vol. in the topsoil horizons. The high values of S in subsoil horizons are due to the low PAW and restrict the application of the S categories in these cases. Well defined links are found between the PAW content and the S-parameter when the data from the topsoil horizons are grouped in 2 groups according to the ratio between air-filled pores (at pF 2.52) and plant available water: <2 and ? 2. The authors acknowledge gratefully the European Commission Research Directorate-General for funding the SoilTrEC project (Contract No 244118) under its 7th Framework Programme.

Rousseva, Svetla; Kercheva, Milena; Shishkov, Toma; Dimitrov, Emil; Nenov, Martin; Lair, Georg J.; Moraetis, Daniel

2014-05-01

305

Corn yield response to nitrogen and soil water content variability along a hillslope  

Technology Transfer Automated Retrieval System (TEKTRAN)

A better understanding of the interaction of corn response to N fertilizer and soil water availability should improve N fertilizer use efficiency in corn (Zea mays L.) through spatially variable N applications. The objective of this study was to determine whether the within-field spatial variability...

306

Optimum nitrogen rate for corn related to hillslope variability in soil water redistribution  

Technology Transfer Automated Retrieval System (TEKTRAN)

Improving site-specific N recommendations for corn (Zea mays L.) will depend on an improved understanding of the interactive effects of yield response to N and other independent variables. The objective of this study was to determine in-season soil water content redistribution (dW) for ten locations...

307

Observed soil moisture-atmosphere interactions in the contiguous US from the Soil Climate Analysis Network (SCAN)  

NASA Astrophysics Data System (ADS)

The interactions of water and energy between the land and atmosphere are important in many aspects such as understanding the role of the land in weather and climate, improving seasonal forecasts, and evaluating climate models and their projections. Past studies on land-atmosphere interactions over large regions have generally been carried out with reanalysis, satellite remote sensing and model data. This study focuses on observational data from the Soil Climate Analysis Network (SCAN) to investigate the coupling of air temperature, precipitation and soil moisture at different time scales across the contiguous United States. SCAN data from over 80 sites across the U.S. with data between 2002 and 2012 are quality controlled to remove measurement errors and spurious values. Two main hypotheses regarding land-atmosphere interactions are explored: 1) precipitation is the main driver of soil moisture variation with the strength of coupling dependent on location, soil depth and time scale; 2) lack of soil moisture is related to high temperatures through sensible heating with relationships also dependent on location and scale. The statistical correlation between precipitation and soil moisture at daily, sub-monthly, and monthly scales is examined, and a positive relationship is prominent. Daily and monthly air temperature and soil moisture observations suggest that a control of air temperature by soil moisture exists. Further analysis shows significant negative relationships between the number of hot days (NHD) in summer months and soil moisture. The extent of this relationship (quantified by the slope of linear regression) varies across the U.S., with stronger relationships moving from the humid east to the drier central U.S.. In order to differentiate the sources of temperature changes between local coupling and advection, temperature advection is estimated using data from the North American Land Data Assimilation System-2 (NLDAS-2). The results suggest that local feedbacks may account for up to about 50% of local temperature changes in dry periods. This study shows that coupling between the land and atmosphere can be seen in observations, and regions of strongest coupling between soil moisture and temperature extremes tend to occur in the drier central U.S..

Xu, R.; Sheffield, J.

2013-12-01

308

Non-isothermal soil water transport and evaporation  

Microsoft Academic Search

A detailed model was formulated to describe the non-isothermal transport of water in the unsaturated soil zone. The model consists of the coupled equations of mass conservation for the liquid phase, gas phase and water vapor and the energy conservation equation. The water transport mechanisms considered are convection in the liquid phase, and convection, diffusion and dispersion of vapor in

Jordi Grifoll; Josep Ma. Gastoa; Yoram Cohen

2005-01-01

309

Water holding of biochar amended SE Coastal Plain soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Because southeastern Coastal Plain soils are sandy, poorly aggregated, and low in organic matter, they have low water holding capacities. Water holding can be improved with biochar amendments that have the potential to increase aggregation and provide a medium of water storage in the char. Changes i...

310

Toward improving global estimates of field soil water capacity  

Technology Transfer Automated Retrieval System (TEKTRAN)

Field capacity or field water capacity (FC) is defined as the water content of a soil after having been wetted with water and after free drainage is negligible. Different recommendations exist world-wide on which, if any, pressure head should be used in laboratory measurements to approximate the FC ...

311

[Characteristics of water infiltration in urban soils of Nanjing City].  

PubMed

By using dual-ring method, this paper measured the water infiltration rate in urban soils under representative land use patterns in Nanjing City, and studied the characteristics of water infiltration in the soils with different compaction degree. The results showed that there was a great difference in the infiltration rate among the soils with different compactness. Soil infiltration rate decreased with increasing bulk density and decreasing porosity, and the water-transport-limiting layer existed in heavily compacted soils resulted in a dramatic decrease of final stabilized infiltration rate. There was a significant linear relationship between the initial and final infiltration rates in the same soil though their absolute values had a great difference. The urban soils in Nanjing City had a wide range of final infiltration rate varied from 1 mm X h(-1) to 679 mm X h(-1), which was highly related to the soil compactness, structural status, and skeleton grain contents. The decrease of urban soil infiltration rate could induce the increase of runoff and of the probability and intensity of flooding. PMID:18464644

Yang, Jin-Ling; Zhang, Gan-Lin; Yuan, Da-Gang

2008-02-01

312

Cooperative water-SOM interactions derived from the organic compound effect on SOM hydration  

NASA Astrophysics Data System (ADS)

Interactions of water molecules with soil organic matter (SOM) may affect the ability of SOM to participate in multiple physical, chemical and biological processes. Specifically, water-SOM interactions may have a profound effect on interactions of organic compounds with SOM which is often considered as a major natural sorbent controlling the environmental fate of organic pollutants in the soil environment. Quantification of water - SOM interactions may be carried out by using water vapor sorption isotherms. However, water sorption isotherms providing macroscopic thermodynamic data do not allow examining water-SOM interactions on a microenvironment scale. The examination of water-SOM interactions in a local SOM environment may be carried out by determining the response of the SOM hydration to sorption of probe organic compounds. Recently, the model-free approach was proposed which allows quantifying effects of sorbing organic molecules on water - SOM interactions, by using relatively more available data on the effect of water activity on organic compound - SOM interactions. Therefore, this thermodynamic approach was applied to the experimental data describing sorption of organic compounds by SOM, both from the vapor and liquid phases, at various water activities. Hence, the response of water interactions with the model SOM materials such as a humic acid and an organic matter-rich peat soil to the presence of various organic sorbates was evaluated. Depending on a molecular structure of organic sorbates probing various molecular environments in SOM, the SOM-bound water may be driven in or out of the SOM sorbents. Organic compounds containing the atoms of oxygen, nitrogen or sulfur and preferring a relatively "polar" SOM microenvironment demonstrate the distinct enhancing effect on water-SOM interactions. In contrast, the "low-polarity" organic compounds, e.g., hydrocarbons or their halogen-substituted derivatives, produce a weakening effect on water-SOM interactions. Importantly, the changes in water-SOM interactions induced by the presence of organic compounds may demonstrate the cooperative behavior: (1) several water molecules may be involved in an enhanced hydration of SOM, (2) at the presence of an organic sorbate, interactions of water molecules with SOM enhance the uptake of the following water molecules. The proposed cooperative water-SOM interactions may result from a perturbation of the SOM matrix due to a sorption of organic and water molecules where a partial disrupting of molecular contacts in SOM makes easier the following SOM-water interactions thus promoting the enhanced SOM hydration.

Borisover, Mikhail

2014-05-01

313

UNCORRECTEDPROOF Soil carbon losses by water erosion: Experimentation  

E-print Network

delivery 1. Introduction The carbon cycle in soils is a key component of global and national carbon budgetsUNCORRECTEDPROOF DTD 5 Soil carbon losses by water erosion: Experimentation and modeling at field, Bedfordshire, United Kingdom, show that the total amount of carbon removed as particulate organic matter from

Quinton, John

314

A soil lysimeter system with water table and temperature control  

Microsoft Academic Search

Summary  A soil lysimeter system especially built for Histosoils, has been in operation since 1974. The individual cell has preset\\u000a levels of water table and simulated temperature gradients. The system has functioned satisfactory in studies on plant-soil\\u000a relationships.

1982-01-01

315

Precipitates Suppress Mobility Of Metals in Soil and Water  

E-print Network

and water with hazardous metals ­ such as cadmium, copper, lead, and nickel ­ is a national environ- mental. Natural soil concentrations of nickel are normally less than 50 parts per mil- lion (ppm), but they have. Also, the disposal of sewage sludge may increase nickel concentrations in soils to more than 2,500 ppm

Sparks, Donald L.

316

Remediation of soil contaminated with dioxins by subcritical water extraction  

Microsoft Academic Search

The effectiveness of subcritical water extraction (SCWE) was examined for removing dioxins from contaminated soil. Most dioxins in the soil sample were reduced at 300 °C or more, but decreased dioxin concentrations were also observed at 150 °C. After 4 h of extraction, 99.4%, 94.5% and 60% of PCDDs were removed from samples at 350, 300 and 150 °C, respectively.

Shunji Hashimoto; Kiyohiko Watanabe; Kazutoshi Nose; Masatoshi Morita

2004-01-01

317

Soil and water conservation: Productivity and environmental protection. 3. edition  

SciTech Connect

This book is a revision of a landmark book offering a broad coverage of the field of soil and water conservation while fully exploring the hazards posed by erosion, sedimentation, and pollution. Scope includes agriculture, engineering, mining, and other uses of land along with the techniques needed to conserve soil while maintaining environmental quality.

Troeh, F.R.; Hobbs, J.A.; Donahue, R.L.

1999-08-01

318

The chemistry of salt-affected soils and waters  

Technology Transfer Automated Retrieval System (TEKTRAN)

Knowledge of the chemistry of salt affected soils and waters is necessary for management of irrigation in arid and semi-arid regions. In this chapter we review the origin of salts in the landscape, the major chemical reactions necessary for prediction of the soil solution composition, and the use of...

319

Measurement of soil water content with dielectric dispersion frequency  

Technology Transfer Automated Retrieval System (TEKTRAN)

Frequency domain reflectometry (FDR) is an inexpensive and attractive methodology for repeated measurements of soil water content (SWC). Although there are some known measurement limitations for dry soil and sand, a fixed-frequency method is commonly employed using commercially available FDR probes....

320

Modelling and simulation of explosions in soil interacting with deformable structures  

NASA Astrophysics Data System (ADS)

A detonating explosive interacting with a deformable structure is a highly transient and non-linear event. In field blast trials of military vehicles, a standard procedure is often followed in order to reduce the uncertainties and increase the quality of the test. If the explosive is buried in the ground, the state of the soil must meet specific demands. In the present work, laboratory experiments have been performed to characterize the behaviour of a soil material. Soil may be considered a three-phase medium, consisting of solid grains, water and air. Variations between the amounts of these phases affect the mechanical properties of the soil. The experimental outcome has formed input data to represent the soil behaviour included in a three-phase elastic-plastic cap model. This unified constitutive model for soil has been used for numerical simulations representing field blast trials, where the explosive load is interacting with a deformable structure. The blast trials included explosive buried at different depths in wet or dry sand. A dependence of the soil initial conditions can be shown, both in the past field trials along with the numerical simulations. Even though some deviations exist, the simulations showed in general acceptable agreement with the experimental results.

Zakrisson, Björn; Häggblad, Hans-Áke; Jonsén, Pär

2012-12-01

321

Microcosmic study of soil microarthropod and earthworm interaction in litter decomposition and nutrient turnover  

Microsoft Academic Search

A microcosm experiment was set up under laboratory conditions and verified under field conditions with the objective of investigating the interaction of soil microarthropods and earthworms in litter decomposition, nutrient release, and uptake by maize crop. The treatments included: soil alone (control), soil with leaf litter (Senna siamea leaves), soil with leaf litter and soil microarthropods, soil with leaf litter

C. O. Adejuyigbe; G. Tian; G. O. Adeoye

2006-01-01

322

Survey of Microbial Enzymes in Soil, Water, and Plant Microenvironments  

PubMed Central

Detection of microbial enzymes in natural environments is important to understand biochemical activities and to verify the biotechnological potential of the microorganisms. In the present report, 346 isolates from soil, water, and plants were screened for enzyme production (caseinase, gelatinase, amylase, carboxymethyl cellulase, and esterase). Our results showed that 89.6% of isolates produced at least one tested enzyme. A predominance of amylase in soil samples, carboxymethyl cellulase in plants, as well as esterase and gelatinase in water was observed. Interesting enzymatic profiles were found in some microenvironments, suggesting specificity of available nutrients and/or natural selection. This study revealed the potential of microorganisms present in water, soil, and plant to produce important enzymes for biotechnological exploration. A predominance of certain enzymes was found, depending on the type of environmental sample. The distribution of microbial enzymes in soil, water and plants has been little exploited in previous reports. PMID:24847390

Alves, Priscila Divina Diniz; Siqueira, Flávia de Faria; Facchin, Susanne; Horta, Carolina Campolina Rebello; Victória, Júnia Maria Netto; Kalapothakis, Evanguedes

2014-01-01

323

Supercritical extraction of organic mixtures from soil-water slurries  

E-print Network

Supercritical C02was used to extract orgamc rruxtures from soil-water slurries. The extent of extraction and the equilibrium distribution of the mixture and of the individual components were determined. A single stage batch vessel was used...

Green, Lynda Ann

1994-01-01

324

Water and Solute Flow in a Highly-Structured Soil  

E-print Network

Prevention of groundwater contamination by agricultural activities is a high priority in the United States. Water and contaminants often follow particular flow paths through the soil that lead to rapid movement of pesticides out of the rootzone...

Hallmark, C. Tom; Wilding, Larry P.; McInnes, Kevin J.; Heuvelman, Willem J.

325

Influence of water table level and soil properties on emissions of greenhouse gases from cultivated peat soil  

Microsoft Academic Search

A lysimeter method using undisturbed soil columns was used to investigate the effect of water table depth and soil properties on soil organic matter decomposition and greenhouse gas (GHG) emissions from cultivated peat soils. The study was carried out using cultivated organic soils from two locations in Sweden: Örke, a typical cultivated fen peat with low pH and high organic

Ö. Berglund; K. Berglund

2011-01-01

326

Mediterranean shrub vegetation: soil protection vs. water availability  

NASA Astrophysics Data System (ADS)

Soil Erosion and Land Degradation are closely related to the changes in the vegetation cover (Zhao et al., 2013). Although other factors such as rainfall intensiy or slope (Ziadat and Taimeh, 2013) the plant covers is the main factor that controls the soil erosion (Haregeweyn, 2013). Plant cover is the main factor of soil erosion processes as the vegetation control the infiltration and runoff generation (Cerdŕ, 1998a; Kargar Chigani et al., 2012). Vegetation cover acts in a complex way in influencing on the one hand on runoff and soil loss and on the other hand on the amount and the way that rainfall reaches the soil surface. In arid and semiarid regions, where erosion is one of the main degradation processes and water is a scant resource, a minimum percentage of vegetation coverage is necessary to protect the soil from erosion, but without compromising the availability of water (Belmonte Serrato and Romero Diaz, 1998). This is mainly controlled by the vegetation distribution (Cerdŕ, 1997a; Cammeraat et al., 2010; Kakembo et al., 2012). Land abandonment is common in Mediterranean region under extensive land use (Cerdŕ, 1997b; García-Ruiz, 2010). Abandoned lands typically have a rolling landscape with steep slopes, and are dominated by herbaceous communities that grow on pasture land interspersed by shrubs. Land abandonment use to trigger an increase in soil erosion, but the vegetation recovery reduces the impact of the vegetation. The goal of this work is to assess the effects of different Mediterranean shrub species (Dorycnium pentaphyllum Scop., Medicago strasseri, Colutea arborescens L., Retama sphaerocarpa, L., Pistacia Lentiscus L. and Quercus coccifera L.) on soil protection (runoff and soil losses) and on rainfall reaching soil surface (rainfall partitioning fluxes). To characterize the effects of shrub vegetation and to evaluate their effects on soil protection, two field experiments were carried out. The presence of shrub vegetation reduced runoff by at least 45% and soil loss by at least 59% in relation to an abandoned and degraded soil (bare soil) (Garcia-Estringana et al., 2010a). D. pentaphyllum, M. strasseri and C. arborescens were more effective in reducing runoff and soil loss (at least 83% and 97% respectively) than R. sphaerocarpa (45% and 59% respectively). Pisctacia Lentiscus L reduced the soil losses in 87% and the runoff rates (68%) meanwhile Quercus coccifera L reached a larger reduction (95% and 88 %) in comparison to herbicide treated agriculture soil. So, all shrub species protected the soil, but not in the same way. In relation to rainfall reaching the soil surface, great differences were observed among species, with interception losses varying between 10% for R. sphaerocarpa to greater than 36% for D. pentaphyllum and M. strasseri, and with stemflow percentages changing between less than 11% for D. pentaphyllum and M. strasseri and 20% for R. sphaerocarpa (Garcia-Estringana et al., 2010b). Rainfall interception on Pistacia Lentiscus and Quercus coccifera were 24% and 34% respectively for the two years of measurements. The integration of the effects of Mediterranean shrub vegetation on soil protection and rainfall partitioning fluxes facilitates understanding the effects of changes in vegetation type on soil and water resources. From this perspective, the interesting protective effect of D. pentpahyllum and M. strasseri, reducing intensely runoff and soil loss contrasts with the dangerous reduction in rainfall reaching the soil surface. Soil protection is essential in semiarid and arid environments, but a proper assessment of the effects on water availability is critical because of water is a scant resource in these kinds of environments. Pistacia Lentiscus and Quercus coccifera shown both a high capacity to intercept rainfall, increase infiltration and reduce the soil losses. We suggest to apply similar research programs into recently fire affected land as the role of vegetation after the fire is very dynamic (Cerdŕ 1998b). Acknowledgements The research projects 07 M/0077/1998, 07 M/0023/

García Estringana, Pablo; Nieves Alonso-Blázquez, M.; Alegre, Alegre; Cerdŕ, Artemi

2014-05-01

327

Predicting subgrid variability of soil water content from basic soil information  

NASA Astrophysics Data System (ADS)

Knowledge of unresolved soil water content variability within model grid cells (i.e., subgrid variability) is important for accurate predictions of land-surface energy and hydrologic fluxes. Here we derived a closed-form expression to describe how soil water content variability depends on mean soil water content (??()) using stochastic analysis of 1-D unsaturated gravitational flow based on the van Genuchten-Mualem (VGM) model. A sensitivity analysis showed that the n parameter strongly influenced both the shape and magnitude of the maximum of ??(). The closed-form expression was used to predict ??() for eight data sets with varying soil texture using VGM parameters obtained from pedotransfer functions that rely on available soil information. Generally, there was good agreement between observed and predicted ??() despite the obvious simplifications that were used to derive the closed-form expression. Furthermore, the novel closed-form expression was successfully used to inversely estimate the variability of hydraulic properties from observed ??() data.

Qu, W.; Bogena, H. R.; Huisman, J. A.; Vanderborght, J.; Schuh, M.; Priesack, E.; Vereecken, H.

2015-02-01

328

Soil Moisture and Vegetation Water Content Retrieval Using QuikSCAT data  

NASA Astrophysics Data System (ADS)

Future water resources are a critical societal impact of climate change and hydrological cycles. Current climate models uncertainties result in disagreement on whether there will be more or less water. On a global scale, there are important gaps in knowledge of where water is stored, where it is going, and how fast it is moving. Soil moisture and vegetation water content are key environmental variables on evaporation and transpiration at the land-atmosphere boundary. Radar remote sensing helps to improve our estimate of water resources globally and temporally. SMAP (Soil Moisture Active Passive) and SWOT (Surface Water Ocean Topography) are the two future NASA missions to monitor water resources and their variation spatially and temporally. Li et al. (Li. Et al. 2010) developed a physically based six-channel algorithm, which uses dual-polarization Windsat passive microwave data to retrieve soil moisture and vegetation water content. We use the retrieved soil moisture and vegetation water content using Windsat descending pass (around 6AM), and also simultaneous collocated QuikSCAT dual-polarization backscattered power to estimate different parameters of the land. The backscattered power can be written as ?pi = fbare ?grp(smi,m) + (1-fbare){ Ap ( 1-exp(-Bp Wi) ) + Cp Wi? exp(-Bp Wi) } where ?pi is the ith QuikSCAT backscatter power with polarization p, fbare is the bare surface fraction, m is soil rms. slope, ?grp is the ground backscattered power with polarization p, and smi and Wi are the retrieved soil moisture and vegetation water content using Windsat data. Ap, Cp, and Bp are the backscattering contributions from vegetation volume, canopy ground interaction, and attenuation of the canopy with polarization p, respectively. We assume all parameters remain constant for each month of different years compared to soil moisture and vegetation water content. Therefore for each point, we have 10 unknowns for HH and VV polarizations. We collect all observations of simultaneous QuikSCAT and retrieved smi and Wi for each location during the summer season and retrieve all those 10 parameters. We show how the retrieved global bare surface fraction compares well with the existing maps. These parameters are then used to estimate the soil moisture and vegetation water content for summer days of a different year using QuikSCAT backscattered power and formula above. Although QuikSCAT satellite is designed to capture sea-winds, it also collects data over land globally almost every day. Therefore, we can generate a global map of soil moisture and vegetation water content daily. We compare the retrieved values with Li et al.'s retrieval values.

Oveisgharan, S.; Haddad, Z. S.; Turk, J.; Li, L.; Rodriguez, E.

2013-05-01

329

Water Infiltration and Permeability of Selected Urban Soils as Affected by Salinity and Sodicity  

E-print Network

Soil sodicity is known to affect soil structural stability and permeability. However, the impact differs depending on salinity of irrigation water, soil types as well as irrigation management practices. This study examined water infiltration...

Miyamoto, S.

2012-10-05

330

Fates and transport of PPCPs in soil receiving reclaimed water irrigation.  

PubMed

Fates and transport of 9 commonly found PPCPs of the reclaimed water were simulated based on the HYDRUS-1D software that was validated with data generated from field experiments. Under the default scenario in which the model parameters and input data represented the typical conditions of turf grass irrigation in southern California, the adsorption, degradation, and volatilization of clofibric acid, ibuprofen, 4-tert-octylphenol, 4-n-nonylphenol, naproxen, triclosan, diclofenac sodium, bisphenol A and estrone in the receiving soils were tracked for 10 years. At the end, their accumulations in the 90 cm soil profile varied from less than 1 ng g(-1) to about 140 ng g(-1) and their concentrations in the drainage water in the 90 cm soil depth varied from nil to ?g L(-1) levels. The adsorption and microbial degradation processes interacted to contain the PPCPs entirely within surface 40 cm of the soil profiles. Leaching and volatilization were not significant processes governing the PPCPs in the soils. The extent of accumulations in the soils did not appear to produce undue ecological risks to the soil biota. PPCPs did not represent any potential environmental harm in reclaimed water irrigation. PMID:24148973

Chen, Weiping; Xu, Jian; Lu, Sidan; Jiao, Wentao; Wu, Laosheng; Chang, Andrew C

2013-11-01

331

Presence and distribution of wastewater-derived pharmaceuticals in soil irrigated with reclaimed water  

USGS Publications Warehouse

Three sites in the Front Range of Colorado, USA, were monitored from May through September 2003 to assess the presence and distribution of pharmaceuticals in soil irrigated with reclaimed water derived from urban wastewater. Soil cores were collected monthly, and 19 pharmaceuticals, all of which were detected during the present study, were measured in 5-cm increments of the 30-cm cores. Samples of reclaimed water were analyzed three times during the study to assess the input of pharmaceuticals. Samples collected before the onset of irrigation in 2003 contained numerous pharmaceuticals, likely resulting from the previous year's irrigation. Several of the selected pharmaceuticals increased in total soil concentration at one or more of the sites. The four most commonly detected pharmaceuticals were erythromycin, carbamazepine, fluoxetine, and diphenhydramine. Typical concentrations of the individual pharmaceuticals observed were low (0.02-15 ??g/kg dry soil). The existence of subsurface maximum concentrations and detectable concentrations at the lowest sampled soil depth might indicate interactions of soil components with pharmaceuticals during leaching through the vadose zone. Nevertheless, the present study demonstrates that reclaimed-water irrigation results in soil pharmaceutical concentrations that vary through the irrigation season and that some compounds persist for months after irrigation. ?? 2006 SETAC.

Kinney, C.A.; Furlong, E.T.; Werner, S.L.; Cahill, J.D.

2006-01-01

332

Soil water repellency characteristic curves for soil profiles with natural organic carbon gradients  

NASA Astrophysics Data System (ADS)

Soil water repellency (SWR) is a phenomenon that influences many soil hydrologic processes such as reduction of infiltration, increase in overland flow, and enhanced preferential flow. SWR has been observed in various soil types and textures, and the degree of SWR is greatly controlled by soil moisture content and levels of organic matter and clay. One of the key topics in SWR research is how to describe accurately the seasonal and temporal variation of SWR with the controlling factors such as soil moisture, organic matter, and clay contents for soil profiles with natural organic carbon gradients. In the present study, we summarize measured SWR data for soil profiles under different land uses and vegetation in Japan and New Zealand, and compared these with literature data. We introduce the contact angle-based evaluation of SWR and predictive models for soil water repellency characteristic curves, in which the contact angle is a function of the moisture content. We also discuss a number of novel concepts, including i) the reduction in the contact angle with soil-water contact time to describe the time dependence of SWR, ii) the relationship between the contact angles from the measured scanning curves under controlled wetting and drying cycles, and iii) the initial contact angles measured by the sessile drop method.

Kawamoto, Ken; Müller, Karin; Moldrup, Per; de Jonge, Lis; Clothier, Brent; Hiradate, Syuntaro; Komatsu, Toshiko

2014-05-01

333

Soil permittivity response to bulk electrical conductivity for selected soil water sensors  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bulk electrical conductivity can dominate the low frequency dielectric loss spectrum in soils, masking changes in the real permittivity and causing errors in estimated water content. We examined the dependence of measured apparent permittivity (Ka) on bulk electrical conductivity in contrasting soil...

334

Comparison of available soil water capacity estimated from topography and soil series information  

Microsoft Academic Search

We present a simple and generalized method to predict Available Soil Water Capacity (ASWC-TOP) for a given area using a topographic index, defined as ln(?\\/tan?), where ? is the upslope area draining past a certain point per unit width of slope, and ? is the local surface slope angle. The estimated results (ASWC-TOP) were then compared with the available soil

Daolan Zheng; E. R. Hunt; Steven W. Running

1996-01-01

335

Influence of rocks on soil temperature, soil water potential, and rooting patterns for desert succulents  

Microsoft Academic Search

At a site in the Sonoran Desert, subterranean rocks and exposed boulders affected soil water potential as well as root morphology and distribution. For Agave deserti, the number of lateral roots per unit length of main root was 11 times higher under rocks and six times higher alongside rocks than in rock-free regions. Total root length per unit soil volume

Park S. Nobel; Patsy M. Miller; Eric A. Graham

1992-01-01

336

MULTIMODEL ENSEMBLE PREDICTION OF SOIL HYDRAULIC PROPERTIES TO SIMULATE FIELD-SCALE SOIL WATER FLOW  

Technology Transfer Automated Retrieval System (TEKTRAN)

Using pedotransfer functions (PTF) to estimate soil hydraulic properties may be necessary in soil water flow simulations for large-scale projects or in a pilot studies. The accuracy of a PTF outside of its development dataset is unknown. Existence of several models that are developed and tested in o...

337

Effect of soil water repellency on soil hydraulic properties estimated under dynamic conditions  

NASA Astrophysics Data System (ADS)

SummarySoil research done over the past decades has proven that water repellent soils are widespread in all climates. Water repellency enhances the leaching of contaminants in the unsaturated zone by introducing preferential flow. In order to predict soil water fluxes in the unsaturated zone the accurate knowledge of the soil hydraulic properties (SHP) is mandatory. In this study the effect of water repellency on both imbibition and drainage SHP was studied. Inflow/outflow experiments were conducted in the laboratory for two soils and two artificially created hydrophobic mixtures. In the inflow/outflow experiments the pressure head at the bottom of the soil column was increased/decreased and the estimated SHP functions were obtained by means of inverse modeling. Inflow/outflow experiments were also conducted using ethanol instead of water in order to estimate the effect of liquid wetting properties on the estimated characteristic curves of the materials under study. The results showed that the water retention functions and the unsaturated hydraulic conductivity functions estimated from the dynamic experiments are strongly dependent on the degree of water repellency and the wetting/drying process.

Diamantopoulos, E.; Durner, W.; Reszkowska, A.; Bachmann, J.

2013-04-01

338

Climate regime and soil storage capacity interact to effect evapotranspiration in western United States mountain catchments  

NASA Astrophysics Data System (ADS)

In the winter-wet, summer-dry forests of the western United States (US), total annual evapotranspiration (ET) is largely a function of three separate but interacting properties: (1) climate, especially magnitude of precipitation, its partitioning into rain or snow, and snowmelt timing; (2) soil characteristics, including soil water holding capacity and rates of drainage; and (3) the total biomass where larger, more abundant vegetation is directly proportional to greater ET. Understanding how these controls influence ET in Mediterranean mountain environments is complicated by shifts between water and energy limitations both within the year and between years. We use a physically based process model to evaluate the strength of climate controls and soil properties in predicting ET in three snow-dominated, mountainous catchments in the western US. As we expect, statistical analysis shows that annual precipitation is a primary control of annual ET across all catchments. However, secondary climate controls vary across catchments. Further, the sensitivity of annual ET to precipitation and other climatic controls varies with soil characteristics. In the drier, more snow-dominated catchments ET is also controlled by spring temperature through its influence on the timing of snowmelt and the synchronicity between seasonal water availability and demand. In wetter catchments that receive a large fraction of winter precipitation as rainfall, the sensitivity to ET is also strongly influenced by soil water holding capacity. We show that in all catchments, soil characteristics affect the sensitivity of annual ET to climatic drivers. Estimates of annual ET become more sensitive to climatic drivers at low soil water holding capacities in the catchments with the stronger decoupling between precipitation and growing season demands.

Garcia, E. S.; Tague, C. L.

2014-02-01

339

Water balance of sandy soils of Niger, West Africa  

E-print Network

WATER BALANCE OF SANDY SOILS OF NIGER, WEST AFRICA A Thesis by WILLIAM ALBERT PAYNE Submitted to the Graduate College of Texas A & M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1987... Major Subject: Soil Science WATER BALANCE OF SANDY SOILS OF NIGER, WEST AFRICA A Thesis by WILLIAM ALBERT PAYNE Approved as to style and content by: L ry Wi ng (Co-Chair of Committe ) Charles Wendt (Co-Chair of Committee) on Newton (Member...

Payne, William Albert

1987-01-01

340

Rethinking soil and water conservation in a changing society : A case study in eastern Burkina Faso  

Microsoft Academic Search

Soil and water conservation is at the top of development agendas in Africa. Virtually every project related to agriculture or the environment has a soil and water conservation component to it and environmental protection plans are being drawn up by African governments in which soil and water conservation figures dominantly. This focus on soil and water conservation is due to

V. M. Mazzucato; D. Niemeijer

2000-01-01

341

UF/IFAS Soil and Water Science 2181 McCarty Hall  

E-print Network

3016 Introduction to Coastal/Oceanographic Engineering 3 sws 4231c Soil, Water, & Land Use 3 sws 4550Contact UF/IFAS Soil and Water Science 2181 McCarty Hall PO Box 110290 Gainesville, FL 32611 Phone: 352.294.3152 E-mail: mjsisk@ufl.edu soils.ifas.ufl.edu soil and water science major WATER SCIENCE u n

Jawitz, James W.

342

Field test of hydrophobic soil clod mulch for soil water conservation in a semiarid area  

E-print Network

of the wasted water, improved maragement should concentrate on its curtailment. The citations of this and the following pages follow the style of the Soil 'Science Socket of America Journal. Before one can attempt to decrease evaporation, the process itself...

Horton, Robert

1977-01-01

343

Soil water dynamics and deep soil recharge in a record wet year in the southern Loess Plateau of China  

Technology Transfer Automated Retrieval System (TEKTRAN)

Analysis of soil water dynamics and recharge is required to understand the regional soil water cycle processes and to guide agricultural production and ecological restoration. It has been reported that soil water reserve in high yield plots had been reduced by 270 mm after 13 years of continuous wh...

344

Water repellency in highly managed soils and turfgrass - How our understanding has changed in the past 20 years.  

NASA Astrophysics Data System (ADS)

Over the past 20 years, a major shift has occurred in how turfgrass managers deal with soil water repellency. Initially, water management strategies focused solely on remediating localized dry spots, the visible effects of hydrophobic soils. Nearly a decade ago at this conference, a group of turfgrass scientists participated in this session on soil water repellency interacting with a broad group of soil physicists setting in motion research, collaborations and discoveries that have resulted in not only a better understanding of the implications of this phenomenon on soil hydraulic properties and plant productivity, but also, development of new strategies, particularly surfactants, to improve water capture, reduce preferential flow, increase irrigation and water use efficiency, improve performance of soil directed pesticides, reduce leaching of nitrogen, increase mineralization of organically bound nitrogen, and enhance plant tolerance to abiotic stress. It also resulted in research utilizing soil moisture measurement tools, specifically, TDR and capacitance probes, which were introduced to and accepted by soil and crop scientists working in amenity turfgrass. Within the past five years, these technologies and strategies for their effective utilization have transitioned from the research community to become accepted by turfgrass managers globally. It is the objective of this presentation to illustrate key discoveries, implications to improved water and resource utilization, and the resulting acceptance of them as new, more sustainable soil management practices.

Kostka, Stan; McMillan, Mica; Oostindie, Klaas; Dekker, Louis; Cisar, John; Leinauer, Bernd; Fidanza, Michael; Bigelow, Cale; Ritsema, Coen

2014-05-01

345

Vertical variations of soil hydraulic properties within two soil profiles and its relevance for soil water simulations  

NASA Astrophysics Data System (ADS)

Numerical simulations of soil water dynamics can be valuable tools for the assessment of different soil and land management practices. For accurate simulations, the soil hydraulic properties (SHP), i.e. the hydraulic conductivity and water retention function have to be properly known. They can be either estimated from physical soil properties by pedotransfer functions (PTF) or measured. In most studies, soil profiles are analyzed and sampled with respect to their pedogenic horizons. While considerable effort has been put on horizontal spatial SHP variations, vertical changes within soil profiles have not been analyzed in detail. Therefore, the objectives of this study were (i) the SHP measurement along vertical transects within two soil profiles, (ii) to evaluate their spatial variation and correlation with physical soil properties, and (iii) to assess the impact of the SHP determination method and its spatial discretization on simulated soil water balance components. Two soils, an agriculturally used silty-loam Chernozem and a forested sandy Cambisol were sampled in 0.05 m increments along vertical transects. The parameters of a dual porosity model were derived using the evaporation method and scaling was applied to derive representative mean SHP parameters and scaling factors as a measure of spatial variability. State-space models described spatial variations of the scaling factors by physical soil properties. Simulations with HYDRUS 1D delivered the soil water balance for different climatic conditions with the SHP being estimated from horizon-wise PTFs, or discretized either sample-wise, according to the pedogenic horizons, or as hydrologically relevant units (hydropedological approach). Considerable SHP variations were found for both soil profiles. In the Chernozem, variations of the hydraulic conductivity were largest within the ploughed Ap-horizon and could be attributed to variations in soil structure (macropores). In the subsoil, soil water retention showed a gradual decrease within each horizon. The observed water retention variations could be described by state-space models that comprised the contents of clay and total carbon, whereas variations of the hydraulic conductivity were described by clay content and total porosity. The hydraulic conductivity in the Cambisol was slightly undulating throughout the profile. Here, water retention was largest in the upper part of the profile and considerably decreased within the lower part of the Bhs-horizon. Simulated soil water balance components differed distinctly between the SHP discretizations. Compared to observed soil water contents, the simulations where the SHP were given by small-scale layers or hydropedological units performed best for both experimental sites. The different SHP discretizations mainly affected the estimated drainage losses and the simulated crop transpiration under medium to dry climatic conditions. The study confirmed the importance of an adequate spatial SHP discretization. The results indicate that SHP estimations by PTFs or the standard horizon-mean sampling strategy might fail to parameterize soil water simulations, especially in structured soils. The presented hydropedological approach showed a way to receive good simulation results by reducing the SHP observation density.

Schwen, Andreas; Zimmermann, Michael; Bodner, Gernot

2014-08-01

346

Impact of interspecific interactions on antimicrobial activity among soil bacteria  

PubMed Central

Certain bacterial species produce antimicrobial compounds only in the presence of a competing species. However, little is known on the frequency of interaction-mediated induction of antibiotic compound production in natural communities of soil bacteria. Here we developed a high-throughput method to screen for the production of antimicrobial activity by monocultures and pair-wise combinations of 146 phylogenetically different bacteria isolated from similar soil habitats. Growth responses of two human pathogenic model organisms, Escherichia coli WA321 and Staphylococcus aureus 533R4, were used to monitor antimicrobial activity. From all isolates, 33% showed antimicrobial activity only in monoculture and 42% showed activity only when tested in interactions. More bacterial isolates were active against S. aureus than against E. coli. The frequency of interaction-mediated induction of antimicrobial activity was 6% (154 interactions out of 2798) indicating that only a limited set of species combinations showed such activity. The screening revealed also interaction-mediated suppression of antimicrobial activity for 22% of all combinations tested. Whereas all patterns of antimicrobial activity (non-induced production, induced production and suppression) were seen for various bacterial classes, interaction-mediated induction of antimicrobial activity was more frequent for combinations of Flavobacteria and alpha- Proteobacteria. The results of our study give a first indication on the frequency of interference competitive interactions in natural soil bacterial communities which may forms a basis for selection of bacterial groups that are promising for the discovery of novel, cryptic antibiotics. PMID:25389421

Tyc, Olaf; van den Berg, Marlies; Gerards, Saskia; van Veen, Johannes A.; Raaijmakers, Jos M.; de Boer, Wietse; Garbeva, Paolina

2014-01-01

347

Soil-structure interaction analysis of jack-up platforms subjected to monochrome and irregular waves  

NASA Astrophysics Data System (ADS)

As jack-up platforms have recently been used in deeper and harsher waters, there has been an increasing demand to understand their behaviour more accurately to develop more sophisticated analysis techniques. One of the areas of significant development has been the modelling of spudcan performance, where the load-displacement behaviour of the foundation is required to be included in any numerical model of the structure. In this study, beam on nonlinear winkler foundation (BNWF) modeling—which is based on using nonlinear springs and dampers instead of a continuum soil media—is employed for this purpose. A regular monochrome design wave and an irregular wave representing a design sea state are applied to the platform as lateral loading. By using the BNWF model and assuming a granular soil under spudcans, properties such as soil nonlinear behaviour near the structure, contact phenomena at the interface of soil and spudcan (such as uplifting and rocking), and geometrical nonlinear behaviour of the structure are studied. Results of this study show that inelastic behaviour of the soil causes an increase in the lateral displacement at the hull elevation and permanent unequal settlement in soil below the spudcans, which are increased by decreasing the friction angle of the sandy soil. In fact, spudcans and the underlying soil cause a relative fixity at the platform support, which changes the dynamic response of the structure compared with the case where the structure is assumed to have a fixed support or pinned support. For simulating this behaviour without explicit modelling of soil-structure interaction (SSI), moment-rotation curves at the end of platform legs, which are dependent on foundation dimensions and soil characteristics, are obtained. These curves can be used in a simplified model of the platform for considering the relative fixity at the soil-foundation interface.

Korzani, Maziar Gholami; Aghakouchak, Ali Akbar

2015-03-01

348

Interaction of water with epoxy  

Microsoft Academic Search

The chemistries of reactants, plasticizers, solvents and additives in an epoxy paint are discussed. Polyamide additives may play an important role in the absorption of molecular iodine by epoxy paints. It is recommended that the unsaturation of the polyamide additive in the epoxy cure be determined. Experimental studies of water absorption by epoxy resins are discussed. These studies show that

Dana Auburn

2009-01-01

349

Soil Water Retention Curves and Their Impact on Evaporation  

NASA Astrophysics Data System (ADS)

An accurate description of soil moisture dynamics in both the liquid and vapor phases is crucial to properly estimate soil evaporation. Soil moisture dynamics are largely dependent on the soil water retention. In the most commonly used models the water retention curve diverges at residual water content, the value below which liquid connectivity is lost and liquid flow stops. Not only this is physically unrealistic but results in incorrect evaporation modeling near dry conditions since the water vapor role is limited. We consider two of the main parametrizations that allow vapor flux below residual water content (modified models): one consists in a re-fit of the standard retention curve with zero residual water content, the other, supported by some laboratory measurements, considers a linear extension (on a semi-log plot) of the standard retention curve in the dry region. For a medium-textured sand and a loam we numerically investigate the effects of both the modified and the standard Van Genuchten models on the liquid and vapor transport during the simulated drying process, with and without surface radiative forcing. In the isothermal case, we show how all the models almost identically describe the capillary-dominated evaporative regime whereas when vapor diffusion is the dominant evaporative mechanism the modified models yield larger and longer sustained vapor fluxes, significantly increasing soil water removal. In the presence of diurnal radiative forcing at the soil surface, we focus on the effects of temperature fluctuations on soil water retention. The impact on liquid and vapor fluxes is analyzed in order to assess whether temperature-dependent and dry-extended retention curves may 'fill the gap' or not between theory and some still debated field experimental evidences (e.g. the midday moisture content rise) without the need of introducing any questionable and ad-hoc empirical terms such as vapor enhancement and/or liquid gain factors.

Ciocca, F.; Lunati, I.; Parlange, M. B.

2013-12-01

350

Interaction of atrazine with soil microorganisms: population changes and accumulation.  

PubMed

A loam soil treated with atrazine at rates of 10, 30, and 100 microgram/g soil resulted in increased populations of actinomycetes, bacteria, and fungi over those in non-treated soil. The increases were in proportion to the amount of atrazine and persisted for at least 2 months. Living actinomycete amd fungal mycelia were incubated for 48 h in distilled water, nutrient broth, or soil containing 5 microgram/ml (g) of the herbicide. Actinomycete and fungal mycelia accumulated atrazine from water to concentrations up to 87-fold and 132-fold, respectively, over that in the ambient medium. The maximum accumulation from soil by actinomycete mycelia was 26-fold and by fungal mycelia 13-fold. Fungi accumulated little or no atrazine from a nutrient medium whereas actinomycetes accumulated up to 13-fold. Dead mycelia usually did not accumulate atrazine in excess of the ambient concentration. Mycelium of Sclerotium rolfsii growing in a nutrient medium containing 20 microgram atrazine/ml accumulated 157 microgram/g wet weight after 8 days. Sclerotia subsequently produced after transfer of similar mats to soil contained 550 microgram/g wet weight. PMID:728848

Percich, J A; Lockwood, J L

1978-10-01

351

Water and Tree-Understory Interactions: A Natural Experiment in a Savanna with Oak Wilt  

Microsoft Academic Search

Savanna trees influence water, light, and nutrient availability under their canopies, but the relative importance of these resources to understory plants is not well understood. In a three-year study in a Texas savanna, trees infected with the disease oak wilt were used in a natural experiment to isolate the effects of light and soil resources, particularly water, in oak-understory interactions.

Laurel J. Anderson; M. Shawn Brumbaugh; Robert B. Jackson

2001-01-01

352

Does pre-dawn water potential reflect conditions of equilibrium in plant and soil water status?  

NASA Astrophysics Data System (ADS)

Variation in base water potential ( ?b, a daily maximum level of plant water potential, which is presumed to correspond to the equilibrium between soil and plant water potentials) was examined in shoots of Picea abies and Vaccinium myrtillus with respect to soil (available water storage, water potential, temperature) and atmospheric (temperature, relative humidity, vapour pressure deficit) conditions. The available soil water storage (W tr) accounted for 77% of the dynamics of ?b, while the influence of atmospheric factors became evident under high evaporative demand. ?b was not always observable immediately before dawn, but on 30% of observation days, the recovery continued up to an hour or two after dawn. Full equilibrium between soil and plant water potentials in P. abies in northern conditions is rather improbable by dawn in summer-time, because of the shortness of the dark period and probable night-time transpiration in the case of high atmospheric vapour pressure deficit.

Sellin, Arne

1999-02-01

353

Soil water retention curve of agrogray soils: Influence of anisotropy and the scaling factor  

NASA Astrophysics Data System (ADS)

The soil water characteristic or soil water retention curve (WRC) of medium-loamy gray forest soil horizons was studied in cylinder-shaped samples of disturbed and undisturbed structure. The sample height varied within 2-4 cm and the diameter within 4.5-10 cm. The soil monoliths were sampled in three profiles: vertically, along the slope, and across the slope in accordance with the intrasoil paleorelief formed by the funnel-shaped surface of the second humus horizon. The experimental WRC were approximated with the van Genuchten equation. The statistical analysis of the WRc approximation parameters proved to differ significantly in filled soil samples and monoliths, and a number of parameters differ for samples of the maximal height and diameter. The reliable differences of the parameters were also noted for the different sampling directions, most often, for those across the paleorelief slope. The noted variation in the WRC approximation parameters may substantially influence the predictive estimation of the spring water reserve for example. This fact suggests the necessity to strictly indicate the sampling procedure, in particular, with respect to the soil profile, the asymmetry in the soil properties, and the sample sizes (scaling factor) used for analyzing the hydrological properties of structured soils.

Umarova, A. B.; Shein, E. V.; Kukharuk, N. S.

2014-12-01

354

The impact of the soil surface properties in water erosion seen through LandSoil model sensitivity analysis  

NASA Astrophysics Data System (ADS)

Quantitative models of soil redistribution at the landscape scale are the current tools for understanding space-time processes in soil and landscape evolution. But models use larger and larger numbers of variables and sometimes it becomes difficult to understand their relative importance and model behaviours in critical conditions. Sensitivity analysis (SA) is widely used to clarify models behaviours, their structure giving fundamental information to ameliorate models their selves. We tested the LandSoil model (LANDscape design for SOIL conservation under soil use and climate change) a model designed for the analysis of agricultural landscape evolution at a fine spatial resolution scale [1-10 meters] and a mid-term temporal scale [10-100 years]. LandSoil is suitable for simulations from parcel to catchment scale. It is spatially distributed, event-based, and considers water and tillage erosion processes that use a dynamic representation of the agricultural landscape through parameters such as a monthly representation of soil surface properties. Our aim was to identify most significant parameters driving the model and to highlight potential particular/singular behaviours of parameter combinations and relationships. The approach was to use local sensitivity analysis, also termed 'one-factor-at-time' (OAT) which consists of a deterministic, derivative method, inquiring the local response O to a particular input factor Pi at a specified point P0 within the full input parameter space of the model expressed as: ?O/?P = (O2-O1) / (P2-P1) The local sensitivity represents the partial derivatives of O with respect to Pi at the point P0. In the SA procedure the topographical entity is represented by a virtual hillslope on which soil loss and sensitivity are calculated. Virtual hillslope is inspired from the virtual catchment framework proposed by Cheviron at al. (2011): a fixed topology consisting of a 3X3 square pixel structure having 150 m length allowing to test different spatial configurations of the properties within the hillslope. To test the model we identified different parameters. A three-category (P,R,p) sensitivity analysis procedure was therefore found possible and appropriate to control the effects of hydrological factors (P,R) and soil-terrain parameters (p). All the analysis were done with the use of the integration of the ArcGis software structure, on which the LandSoil model is based, and the PEST model (Doherty, 2004). PESTR is an iterative, non-linear parameter analysis software platform based on the Gauss-Marquardt-Levenberg algorithm (Marquardt, 1963). The results show the relevance of the rainfall amount in simulation and some interesting interactions between parameters such soil roughness - soil crusting and soil cover.

Ciampalini, Rossano; Follain, Stéphane; Cheviron, Bruno; Le Bissonnais, Yves; Couturier, Alain; Walter, Christian

2014-05-01

355

Numerical Simulation of Soil Water Content in the Unsaturated Zone Using Constraints Provided by Geophysical Measurements  

NASA Astrophysics Data System (ADS)

Soil moisture distribution and variation in the vadose zone is important for agricultural, engineering and contaminant studies. Conventional sampling techniques for estimating soil water moisture content are costly, time consuming, invasive, and typically recover information at a single point in space and time only. Geophysical techniques have the potential to provide dense and accurate information about subsurface soil moisture. However, these data still provide information about water content at the time of measurement only, and geophysical data acquisition is sometimes hindered by cultural or site conditions. For example, although both surface and crosshole GPR techniques have been successfully applied for providing soil moisture information over space and time, the penetration distance of the GPR signal is limited in soils having high electrical conductivity, sometimes inhibiting moisture profiling through the entire vadose zone. In this study, we investigate the potential of coupling geophysical measurements with numerical modeling to provide information about soil moisture variations in space and over time. Such an approach was undertaken to permit estimation of soil moisture throughout the root zone even under difficult GPR data acquisition conditions, and also to yield insight into the dynamics of soil water distribution, including both state variables and fluxes. In this study, surface and crosshole geophysical measurements provide initial and boundary soil moisture conditions to a numerical simulator (TOUGH2-EOS9) based on Richard­_s Equation. Simulations were run using information available from various geophysical techniques collected at a naturally heterogeneous agricultural field site, including surface GPR, crosshole GPR, neutron probe, and TDR measurements. Information about soil heterogeneity was obtained using borehole soil textural information, and meteorological water flux boundary conditions were obtained using rain gauges, sap flow meters and also from a nearby CIMIS weather station. Hydraulic conductivity, one of the most difficult field variables to measure, can be satisfactorily estimated using a stochastic inverse modeling approach. Comparison of soil moisture measurements (collected throughout a year at a field site near Napa, CA) with the various simulations suggested that the approach was able to capture the natural evolution of the vadose zone soil moisture profile at several locations throughout the heterogeneous site. These results illustrate that improvement in the understanding of water cycling and its interaction with ecosystems can be obtained by coupling hydrological theory and measurements available from geophysical and meteorological techniques.

Hou, Z.; Rubin, Y.; Hubbard, S. S.

2002-12-01

356

Influence of soil-structure interaction on floor response spectra  

SciTech Connect

A study was undertaken to investigate the influence of soil-structure interaction on floor response spectra developed in typical nuclear power plant structures. A horizontal earthquake time history, whose spectra envelops the Regulatory Guide 1.60 criteria and is scaled to a log peak acceleration, was used as input to structural models. Two different structural stick models were used, representing typical BWR and PWR facilities. By varying the structural and soil stiffness parameters, a wide range of system behaviors were investigated. Floor response spectra, required to assess equipment qualification, were of primary interest. It was found from a variation of parameter study that the interaction soil parameters, particularly radiation damping, greatly affect the nature of the calculated responses. 2 refs., 2 figs., 2 tabs.

Costantino, C.J.; Miller, C.A.; Curreri, J.R.

1985-01-01

357

Numerical analysis of kinematic soil-pile interaction  

SciTech Connect

In the present study, the response of singles pile to kinematic seismic loading is investigated using the computer program SAP2000. The objectives of the study are: (1) to develop a numerical model that can realistically simulate kinematic soil-structure interaction for piles accounting for discontinuity conditions at the pile-soil interface, energy dissipation and wave propagation; (2) to use the model for evaluating kinematic interaction effects on pile response as function of input ground motion; and (3) to present a case study in which theoretical predictions are compared with results obtained from other formulations. To evaluate the effects of kinematic loading, the responses of both the free-field soil (with no piles) and the pile were compared. Time history and static pushover analyses were conducted to estimate the displacement and kinematic pile bending under seismic loadings.

Castelli, Francesco; Maugeri, Michele [Department of Civil and Environmental Engineering, University of Catania, Viale Andrea Doria no. 6, 95125, Catania (Italy); Mylonakis, George [Department of Civil Engineering, University of Patras, Rio GR-26500, Patras (Greece)

2008-07-08

358

Soil-Earthquake Interactions in Buyukada/ Prinkipo (Istanbul)  

NASA Astrophysics Data System (ADS)

As the largest one of the nine islands comprising the Princes' Islands in the Marmara Sea, close to Istanbul, Buyukada ("Large Isle") consist of with an area of 5.46 km2. The main factor controlling the earthquake hazard for Istanbul is a complex fault system, i.e. the North Anatolian Fault zone, which in the Marmara Sea region. Recent geophysical studies have carried out that this hazard is mainly associated within two active seismogenic areas: the Central Marmara Basin and the Adalar Fault zone, located about 15-30 km south-west and south of Istanbul. Eartquake ground motion affects the structures via the state of the soils. There are several historical buildings on Büyükada, such as the Ayia Yorgi Church and Monastery dating back to the sixth century, the Ayios Dimitrios Church, and the Hamidiye Mosque built by Abdul Hamid II and Greek Orphanage, a huge wooden building etc. The soils and buildings with characteristics of earthquakes could be caused an earthquake damage / loss. One of the most important factors in reducing the earthquake risk in urban areas due to the earthquake ground motion is to estimate gound motion level with interaction of soils. When we look at the geological structure of Buyukada, Paleozoic unites and alluvial deposit are located. Site response of alluvial deposits in Buyukada is also important for the behavior during an earthquake. Geophysical study in the study area in order to estimate the behavior of soils is carried out to obtain the dominant period (microtremor measurements) and shear wave velocity ( MASW - MAM measurements) data. Soil geophysical results is input to earthquake motion for bedrock sites, and is important to the interaction with the ground movement and the soils to estimate Büyükaada's earthquake ground motion. In the earthquake-soil interaction, spectral acceleration is an important criterion. In this study, spectral acceleration are also estiamted for ground motion level in Princes' Islands by using several approaches.

Ozcep, Ferhat; Karabulut, Savas; Caglak, Faruk; Ozel, Oguz

2014-05-01

359

SEISMIC RESPONSE OF DAM WITH SOIL-STRUCTURE INTERACTION.  

USGS Publications Warehouse

An analytical solution to the response of a long trapezoidal-section dam on a foundation consisting of an elastic half-space and subjected to simulated earthquake motion is developed. An optimum seismic design is achieved when the cross section of the dam is triangular. The effect of soil structure interaction is to lower the strain occurring in the dam.

Bycroft, G.N.; Mork, P.N.

1987-01-01

360

Micromechanical Analysis of Geosynthetic-Soil Interaction Under Cyclic Loading  

E-print Network

Micromechanical Analysis of Geosynthetic-Soil Interaction under Cyclic Loading By Anil Bhandari B.E., Tribhuvan University, Nepal, 2003 M.E., Asian Institute of Technology, Thailand, 2006 Submitted to graduate degree program... ____________________ Committee members Dr. Anil Misra ____________________ Dr. Robert L. Parsons ____________________ Dr. Steven D. Schrock ____________________ Dr. W. Lynn Watney Date defended: ________ i The Dissertation Committee for Anil Bhandari certifies...

Bhandari, Anil

2010-05-28

361

Mechanical impedance of soil crusts and water content in loamy soils  

NASA Astrophysics Data System (ADS)

Soil crust development affects soil water dynamics and soil aeration. Soil crusts act as mechanical barriers to fluid flow and, as their mechanical impedance increases with drying, they also become obstacles to seedling emergence. As a consequence, the emergence of seedling cohorts (sensitive seeds) might be reduced. However, this may be of interest to be used as an effective system of weed control. Soil crusting is determined by several factors: soil texture, rain intensity, sedimentation processes, etc. There are different ways to characterize the crusts. One of them is to measure their mechanical impedance (MI), which is linked to their moisture level. In this study, we measured the evolution of the mechanical impedance of crusts formed by three loamy soil types (clay loam, loam and sandy clay loam, USDA) with different soil water contents. The aim of this communication was to establish a mathematical relationship between the crust water content and its MI. A saturated soil paste was prepared and placed in PVC cylinders (50 mm diameter and 10 mm height) arranged on a plastic tray. Previously the plastic tray was sprayed with a hydrophobic liquid to prevent the adherence of samples. The samples on the plastic tray were left to air-dry under laboratory conditions until their IM was measured. To measure IM, a food texture analyzer was used. The equipment incorporates a mobile arm, a load cell to apply force and a probe. The arm moves down vertically at a constant rate and the cylindrical steel probe (4 mm diameter) penetrates the soil sample vertically at a constant rate. The equipment is provided with software to store data (time, vertical distance and force values) at a rate of up to 500 points per second. Water content in crust soil samples was determined as the loss of weight after oven-drying (105°C). From the results, an exponential regression between MI and the water content was obtained (determination coefficient very close to 1). This methodology allows the prediction of the potential mechanical behaviour of soil crusts generated during soil drying, from initial saturated soil conditions (e.g. waterlogging conditions).

Josa March, Ramon; Verdú, Antoni M. C.; Mas, Maria Teresa

2013-04-01

362

Water Intake by Soil, Experiments for High School Students.  

ERIC Educational Resources Information Center

Presented are a variety of surface run-off experiments for high school students. The experiments are analogies to basic concepts about water intake, as related to water delivery, soil properties and management, floods, and conservation measures. The materials needed to perform the experiments are easily obtainable. The experiments are followed by…

1969

363

NEWLY DEVELOPED TECHNOLOGIES FOR SOIL AND WATER CONSERVATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recent discoveries and technological innovations in the field of soil and water conservation can be traced to the works of our predecessors. In this paper, conservation is defined broadly, to include the quality of water lower in watersheds, and is discussed according to contaminants. Within-field s...

364

NEWLY DEVELOPED TECHNOLOGIES FOR SOIL AND WATER CONSERVATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recent discoveries and technological innovations in the field of soil and water conservation have been built on the shoulders of our predecessors’ research. Conservation is defined broadly, to include the quality of water as it moves lower in the watersheds, and is discussed according to contaminant...

365

REDUCTION IN EXCESS SOIL PHOSPHORUS CONCENTRATIONS USING WATER TREATMENT RESIDUALS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Livestock production in the southeastern Coastal Plain region has created environmental concern from the effects of excess soil phosphorus (P) concentrations on water quality. In many Coastal aquatic ecosystems, water quality can be at risk by elevated P transport via runoff, erosion, and leaching f...

366

Earthworm effects on movement of water and solutes in soil  

SciTech Connect

The objectives of this study were to determine and model the effects of earthworms on water and solute movement in soil. Microrelief and rainfall effects on water and solute movement were determined in packed buckets inoculated with earthworms (Aporrectodea tuberculata). A solution of Br[sup [minus

Trojan, M.D.

1993-01-01

367

Human interactions with ground-water  

USGS Publications Warehouse

Ground-Water could be considered as an immense reservoir, from which only a certain amount of water can be withdrawn without affecting the quantity and quality of water. This amount is determined by the characteristics of the environment in which ground-water occurs and by the interactions of ground-water with precipitation, surface water, and people. It should be recognized that quantity and quality of ground-water are intimately related and should be considered accordingly. Quantity refers to usable water and water is usable for any specific purpose only so long as its quality has not deteriorated beyond acceptable limits. Thus an overall quantitative and qualitative management of ground water is inevitable, and its should also involve the uses of ground-water reservoirs for purposes other than water supply. The main objective of ground-water management is to ensure that ground-water resources will be available in appropriate time and in appropriate quantity and quality to meet the most important demands of our society. Traditional, and obvious uses of ground-water are the extraction of water for water supplies (domestic, municipal, agricultural, and industrial) and the natural discharge feeding lakes and maintaining base flow of streams. Not so obvious are the uses of ground-water reservoirs, the very framework within which ground-water occurs and moves, and in which other fluids or materials can be stored. In the last two decades, ground-water reservoirs have been intensively considered for many other purposes than water supplies. Diversified and very often conflicting uses need to be evaluated and dealt with in the most efficient way in order to determine the importance of each possible use, and to assign priorities of these uses. With rising competition for the use of ground-water reservoirs, we will also need to increase the potential for effective planning of ground-water development and protection. Man's development and use of ground-water necessarily modifies the natural conditions and the total natural system must be successfully blended with the unnatural stresses placed upon it. This can be accomplished by introducing new methods (such as ground-water zoning) in and by developing alternative strategies for ground-water management and protection. ?? 1983 D. Reidel Publishing Company.

Zaporozec, A.

1983-01-01

368

Characteristics of soil moisture in permafrost observed in East Siberian taiga with stable isotopes of water  

Microsoft Academic Search

Soil moisture and its isotopic composition were observed at Spasskaya Pad experimental forest near Yakutsk, Russia, during summer in 1998, 1999, and 2000. The amount of soil water (plus ice) was estimated from volumetric soil water content obtained with time domain reflectometry. Soil moisture and its 18O showed large interannual variation depending on the amount of summer rainfall. The soil

A. Sugimoto; D. Naito; N. Yanagisawa; K. Ichiyanagi; N. Kurita; J. Kubota; T. Kotake; T. Ohata; T. C. Maximov; A. N. Fedorov

2003-01-01

369

A case study of energy, water and soil flow chains in an arid ecosystem  

Microsoft Academic Search

Little attention has been directed to the study of soil flow and the complex relationships among energy water and soil flow in terrestrial ecosystems. Soil plays an important role in arid ecosystems. After water soil is the second key factor in the development of an arid ecosystem since soil is the only part of the system capable of absorbing and

A. Yair; M. Shachak

1982-01-01

370

Effects of Water Seal on Reducing 1,3-Dichloropropene Emissions from Different Textured Soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil physical conditions can affect diffusion, environmental fate, and pest-control efficacy of fumigants in soil disinfestation treatments. Water seal (applying water using sprinklers to soil following fumigation) has shown effectiveness to reduce fumigant emissions from sandy loam soils. Soil colu...

371

Groundwater Surface Water Interaction Effects on Pesticide Persistence and Transformation Pathways  

NASA Astrophysics Data System (ADS)

Historical DDT use at Point Pelee National Park (PPNP) has left a legacy of contamination found in the flora, fauna, soils, and groundwater. The transformation pathway and the rate of transformation of DDT to either DDE or DDD, and subsequent metabolites depends on many environmental factors including soil texture, soil moisture, temperature, organic carbon content, flooding, and microbial activity, (Guenzi and Beard 1968, 1976; Spencer et al. 1996; Aigner et al. 1998). Under aerobic conditions the transformation of DDT to DDE is the preferred pathway, whereas under anaerobic conditions, DDT to DDD is the preferred pathway. Also, the transformation of DDT to DDD under anaerobic conditions is faster than that for DDT to DDE under aerobic conditions. Given that one of the primary factors effecting the redox conditions of a soil is soil wetness, and that flooded soils tend to become anaerobic and reducing, it was hypothesized that there may be a relation between the dynamic nature of groundwater-surface water interactions at PPNP and the concentrations and proportions of DDT, DDE, and DDD. The soils are texturally sand and are mostly of the Brunisolic Soil Order (Inceptisols) with the Regosolic Soil Order (Entisols) on the sand dunes and the Organic Soil Order (Histosols) along the margins of the Marsh. The location of the groundwater-surface water interface coinciding with historic water levels within Lake Erie and the marsh has played a significant role.

Smith, J. E.; Crowe, A. S.; Marenco, N.

2004-05-01

372

Solute Export Through Transpiration: A Possible Control of Soil Water Chemistry?  

NASA Astrophysics Data System (ADS)

Recent studies of soil and ground water interactions in western Minnesota have produced seemingly anomalous results. The soil waters beneath highly transpirative plants (Typha sp., Salix sp. and Populus sp.) in a ground water discharge area developed high calcium sulfate concentrations with only minor enrichment of sodium and chloride. It was expected that concentration of solutes by evapo-transpiration would enrich all ions in the originating ground water more equally. Transpired water is generally assumed to be essentially distilled water although there is little analytical data to support this hypothesis. Given the very high evapotranspiration rates of Western Minnesota, greater than 95% of total water movement, even relatively dilute ion concentrations in the transpired water may be significant in the total chemical budget. To investigate the chemistry of transpired water we adapted techniques that have been used to study total transpiration rates as well as isotopic composition of transpired waters. Our initial results from typha sp. have produced waters that while relatively dilute are distinctly not distilled water. Control samples using de-ionized water over dead vegetation produced minor ion enrichment. All results are in ppm. Ion - Ca, Mg, Na, K, P, Mn, Cl , SO4, NO3-N soil water - 18.5, 2.9, 4.8, 3.8, 0.2, 0.2, 5.6, 2.4, 0.5 transpiration - 1.9, 0.6, 1.5, 8.5, 0.3, 0.4, 9.0, 1.6, <0.1 DI control - 0.1, <0.1, 0.1, <0.1, <0.1, <0.1, <0.1, 1.6, <0.1 The observed transpiration chemistries are in rough agreement with reported literature values for plant stem water. While many plants are known to excrete large molecules the expulsion of ions in transpired water would represent a novel chemical plant pathway.

Alexander, S. C.; Boyle, D. B.; Alexander, E. C.

2005-12-01

373

Macrofauna assemblage composition and soil moisture interact to affect soil ecosystem functions  

NASA Astrophysics Data System (ADS)

Changing climatic conditions and habitat fragmentation are predicted to alter the soil moisture conditions of temperate forests. It is not well understood how the soil macrofauna community will respond to changes in soil moisture, and how changes to species diversity and community composition may affect ecosystem functions, such as litter decomposition and soil fluxes. Moreover, few studies have considered the interactions between the abiotic and biotic factors that regulate soil processes. Here we attempt to disentangle the interactive effects of two of the main factors that regulate soil processes at small scales - moisture and macrofauna assemblage composition. The response of assemblages of three common temperate soil invertebrates (Glomeris marginata Villers, Porcellio scaber Latreille and Philoscia muscorum Scopoli) to two contrasting soil moisture levels was examined in a series of laboratory mesocosm experiments. The contribution of the invertebrates to the leaf litter mass loss of two common temperate tree species of contrasting litter quality (easily decomposing Fraxinus excelsior L. and recalcitrant Quercus robur L.) and to soil CO2 fluxes were measured. Both moisture conditions and litter type influenced the functioning of the invertebrate assemblages, which was greater in high moisture conditions compared with low moisture conditions and on good quality vs. recalcitrant litter. In high moisture conditions, all macrofauna assemblages functioned at equal rates, whereas in low moisture conditions there were pronounced differences in litter mass loss among the assemblages. This indicates that species identity and assemblage composition are more important when moisture is limited. We suggest that complementarity between macrofauna species may mitigate the reduced functioning of some species, highlighting the importance of maintaining macrofauna species richness.

Collison, E. J.; Riutta, T.; Slade, E. M.

2013-02-01

374

Water distribution at the root-soil interface: is there more water next to roots?  

NASA Astrophysics Data System (ADS)

Plants are big water movers and have a significant impact on soil water dynamics as well as on the global water cycle. Despite the relevance of root water uptake in terrestrial ecology, the movement of water from soil to roots still presents important open questions, e.g the following two. Which are the properties of the soil near the roots? And what effect do these properties have on soil plant water relations? Most models are based on brute-force spatial averaging of soil properties and assume that the bulk soil has the same properties as the rhizosphere. However, there is evidence in the literature that the rhizosphere has specific properties that may affect water and nutrient uptake (Young 1995, Gregory 2007). In order to investigate the rhizosphere hydraulic properties and their effect on soil plant water relations, we used neutron radiography and neutron tomography to image the water content distribution in soils during plant transpiration. Rectangular (quasi-2D) and cylindrical containers were filled with sandy soil and planted with lupins (Lupinus albus). Three weeks after planting, the samples were equilibrated at water potentials of -10 and 30 hPa and have been imaged for 5 days at intervals of 6 hours. At day 5 the samples were irrigated again via capillary rise and the water distribution was monitored for 4 more days. During the first day of the drying period, regions of water depletion formed around the central part of the tap root where first order laterals were present. As the soil dried up, the picture changed: instead of less water around the roots, as commonly supposed by models, we observed that more water was present around the lateral roots. Interestingly, these regions during drying were retaining high water content, but after irrigation remained markedly drier than the bulk soil. Our hypothesis is that high water content near roots during drying and lower water content during rewetting are explained by the presence of bio-polymers exuded by roots forming a hydrogel that consists of up to 99% water at very negative water potentials (Read et al. 1999). Thanks to its high water holding capacity, this hydrogel maintains a continuous hydraulic pathway across soil and roots for an extended period of time during drying. During rewetting it adversely affects water redistribution, like a storage that needs time to fill up again. These data show for the first time in situ the potential role of mucilage in controlling water dynamics in the rhizosphere and consequences for plant water extraction. Gregory P J, Roots, rhizosphere and soil: the route to a better understanding of soil science? European Journal of Soil Science, 57: 2-12, 2006. Read D P, Gregory P J, and Bell A E. Physical properties of axenic maize root mucilage. Plant and Soil, 211: 87-91, 1999. Young I M. Variation in moisture contents between bulk soil and the rhizosheath of wheat. New Phytologist, 130: 135-139, 1995.

Carminati, A.; Moradi, A.; Oswald, S.; Vetterlein, D.; Weller, U.; Vogel, H.-J.

2009-04-01

375

The effects of groundwater table and flood irrigation strategies on soil water and salt dynamics and reed water use in the Yellow River Delta, China  

Microsoft Academic Search

Vegetation management in shallow groundwater table environments requires an understanding of the interactions between the physical and biological factors that determine root-zone soil salinization and moisture. In this study, the effects of groundwater depth and flood irrigation strategies on water and salt dynamics and reed water use were analyzed in the shallow groundwater region of the Yellow River Delta in

Tao Xie; Xinhui Liu; Tao Sun

2011-01-01

376

The interaction of various polymers with water  

E-print Network

that the methylcellulose is more soluble in water at lower temperatures. This must mean that the partial molar heat 39 (3 a HDi of dissolution of methylcellulose (3 n / in water is negative. Polymer P, T For the polymer to be only partially soluble in water at higher...THE INTERACTION OF VARIOUS POLYMERS WITH WATER A Thesis by BILLY OUOCK Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1976 Major Subject...

Quock, Billy

1976-01-01

377

Spatio-temporal variability of soil water content on the local scale in a Mediterranean mountain area (Vallcebre, North Eastern Spain). How different spatio-temporal scales reflect mean soil water content  

NASA Astrophysics Data System (ADS)

As a result of complex human-land interactions and topographic variability, many Mediterranean mountain catchments are covered by agricultural terraces that have locally modified the soil water content dynamic. Understanding these local-scale dynamics helps us grasp better how hydrology behaves on the catchment scale. Thus, this study examined soil water content variability in the upper 30 cm of the soil on a Mediterranean abandoned terrace in north-east Spain. Using a dataset of high spatial (regular grid of 128 automatic TDR probes at 2.5 m intervals) and temporal (20-min time step) resolution, gathered throughout a 84-day period, the spatio-temporal variability of soil water content at the local scale and the way that different spatio-temporal scales reflect the mean soil water content were investigated. Soil water content spatial variability and its relation to wetness conditions were examined, along with the spatial structuring of the soil water content within the terrace. Then, the ability of single probes and of different combinations of spatial measurements (transects and grids) to provide a good estimate of mean soil water content on the terrace scale was explored by means of temporal stability analyses. Finally, the effect of monitoring frequency on the magnitude of detectable daily soil water content variations was studied. Results showed that soil water content spatial variability followed a bimodal pattern of increasing absolute variability with increasing soil water content. In addition, a linear trend of decreasing soil water content as the distance from the inner part of the terrace increased was identified. Once this trend was subtracted, resulting semi-variograms suggested that the spatial resolution examined was too high to appreciate spatial structuring in the data. Thus, the spatial pattern should be considered as random. Of all the spatial designs tested, the 10 × 10 m mesh grid (9 probes) was considered the most suitable option for a good, time-stable estimate of mean soil water content, as no improvement was obtained with the 5 × 5 m mesh grid (30 probes). Finally, the results of temporal aggregation showed that decreasing the monitoring frequency down to 8 h during wetting-up periods and to 1 day during drying-down ones did not result in a loss of information on daily soil water content variations.

Molina, Antonio J.; Latron, Jérôme; Rubio, Carles M.; Gallart, Francesc; Llorens, Pilar

2014-08-01

378

Soil water sensors:Problems, advances and potential for irrigation scheduling  

Technology Transfer Automated Retrieval System (TEKTRAN)

Irrigation water management has to do with the appropriate application of water to soils, in terms of amounts, rates, and timing to satisfy crop water demands, while protecting the soil and water resources from degradation. In this regard, sensors can be used to monitor the soil water status; and so...

379

Volatile-mediated interactions between phylogenetically different soil bacteria  

PubMed Central

There is increasing evidence that organic volatiles play an important role in interactions between micro-organisms in the porous soil matrix. Here we report that volatile compounds emitted by different soil bacteria can affect the growth, antibiotic production and gene expression of the soil bacterium Pseudomonas fluorescens Pf0–1. We applied a novel cultivation approach that mimics the natural nutritional heterogeneity in soil in which P. fluorescens grown on nutrient-limited agar was exposed to volatiles produced by 4 phylogenetically different bacterial isolates (Collimonas pratensis, Serratia plymuthica, Paenibacillus sp., and Pedobacter sp.) growing in sand containing artificial root exudates. Contrary to our expectation, the produced volatiles stimulated rather than inhibited the growth of P. fluorescens. A genome-wide, microarray-based analysis revealed that volatiles of all four bacterial strains affected gene expression of P. fluorescens, but with a different pattern of gene expression for each strain. Based on the annotation of the differently expressed genes, bacterial volatiles appear to induce a chemotactic motility response in P. fluorescens, but also an oxidative stress response. A more detailed study revealed that volatiles produced by C. pratensis triggered, antimicrobial secondary metabolite production in P. fluorescens. Our results indicate that bacterial volatiles can have an important role in communication, trophic - and antagonistic interactions within the soil bacterial community. PMID:24966854

Garbeva, Paolina; Hordijk, Cornelis; Gerards, Saskia; de Boer, Wietse

2014-01-01

380

Prion Protein Interaction with Soil Humic Substances: Environmental Implications  

PubMed Central

Transmissible spongiform encephalopathies (TSE) are fatal neurodegenerative disorders caused by prions. Animal TSE include scrapie in sheep and goats, and chronic wasting disease (CWD) in cervids. Effective management of scrapie in many parts of the world, and of CWD in North American deer population is complicated by the persistence of prions in the environment. After shedding from diseased animals, prions persist in soil, withstanding biotic and abiotic degradation. As soil is a complex, multi-component system of both mineral and organic components, it is important to understand which soil compounds may interact with prions and thus contribute to disease transmission. Several studies have investigated the role of different soil minerals in prion adsorption and infectivity; we focused our attention on the interaction of soil organic components, the humic substances (HS), with recombinant prion protein (recPrP) material. We evaluated the kinetics of recPrP adsorption, providing a structural and biochemical characterization of chemical adducts using different experimental approaches. Here we show that HS act as potent anti-prion agents in prion infected neuronal cells and in the amyloid seeding assays: HS adsorb both recPrP and prions, thus sequestering them from the prion replication process. We interpreted our findings as highly relevant from an environmental point of view, as the adsorption of prions in HS may affect their availability and consequently hinder the environmental transmission of prion diseases in ruminants. PMID:24937266

Giachin, Gabriele; Narkiewicz, Joanna; Scaini, Denis; Ngoc, Ai Tran; Margon, Alja; Sequi, Paolo; Leita, Liviana; Legname, Giuseppe

2014-01-01

381

Effect of the soil water content on Jatropha seedlings in a tropical climate  

NASA Astrophysics Data System (ADS)

The purpose of this study was to evaluate growth, chlorophyll content, and photosynthesis in Jatropha at different levels of soil moisture. Plants were cultivated in containers and the treatments of the soil water content evaluated were: 0% (without watering), 20, 40, 60, and 80% soil water content. Plant height was statistically similar for all treatments, but the number of leaves differed significantly. Total dry matter and chlorophyll at 40, 60, and 80% soil water content were statistically similar, but different from 0 and 20% soil water content. Leaf area at 40, 60, and 80% soil water content was statistically different from 0 and 20% soil water content. The photosynthetic rate, transpiration and stomatal conductance at 60 and 80% soil water content were statistically similar but different from 0 and 20% soil water content. Water stress affected growth, chlorophyll content, photosynthetic rate, transpiration, and stomatal conductance.

Pérez-Vázquez, A.; Hernández-Salinas, G.; Ávila-Reséndiz, C.; Valdés-Rodríguez, O. A.; Gallardo-López, F.; García-Pérez, E.; Ruiz-Rosado, O.

2013-09-01

382

The Soil Underfoot: Green Water and Global Food Security  

NASA Astrophysics Data System (ADS)

Soils function in agricultural ecosystems as both provisioning and regulatory hydrologic agents through their impacts on evapotranspiration, runoff, and groundwater flow. Two-thirds of the world's food supply is produced through the consumptive use of "green water," the water entering soil by natural precipitation and remaining accessible to plants, while green water accounts for 85 % of all the water consumed globally by croplands. The ability of soils to provide adequate green water depends on their "natural capital" and on their resilience to land-use changes and the flows that link the global atmosphere, biosphere, and hydrosphere, both of which now exhibit a variability that exceeds what has been characteristic of them during the past 10 millennia. Adding to this variability is the growing global food demand, which by mid-century will require a 30 to 50 % increase in the water now consumed annually for food production. Meeting this challenge to global food security will call on hydrologists to provide a much deeper quantitative understanding of how soils perform their provisioning and regulatory functions in the water cycle, how they respond to land-use changes, and how they mediate the global flows of matter and energy.

Sposito, G.

2012-12-01

383

Upscaled soil-water retention using van Genuchten's function  

USGS Publications Warehouse

Soils are often layered at scales smaller than the block size used in numerical and conceptual models of variably saturated flow. Consequently, the small-scale variability in water content within each block must be homogenized (upscaled). Laboratory results have shown that a linear volume average (LVA) of water content at a uniform suction is a good approximation to measured water contents in heterogeneous cores. Here, we upscale water contents using van Genuchten's function for both the local and upscaled soil-water-retention characteristics. The van Genuchten (vG) function compares favorably with LVA results, laboratory experiments under hydrostatic conditions in 3-cm cores, and numerical simulations of large-scale gravity drainage. Our method yields upscaled vG parameter values by fitting the vG curve to the LVA of water contents at various suction values. In practice, it is more efficient to compute direct averages of the local vG parameter values. Nonlinear power averages quantify a feasible range of values for each upscaled vG shape parameter; upscaled values of N are consistently less than the harmonic means, reflecting broad pore-size distributions of the upscaled soils. The vG function is useful for modeling soil-water retention at large scales, and these results provide guidance for its application.

Green, T.R.; Constantz, J.E.; Freyberg, D.L.

1996-01-01

384

Soil and Water Science Department soils.ifas.ufl.edu  

E-print Network

of Florida Institute of Food and Agricultural Sciences Modern Methods for Detection of Water­ and Soilborne and Salmonella outbreaks. Course discussions should inspire you to introduce new, more effective environmental and reduce E. coli and Salmonella contamination of poultry, cattle, pigs, pets, and agricultural produce. 5

Jawitz, James W.

385

Surface interactions of black carbon and soil minerals  

NASA Astrophysics Data System (ADS)

An important mechanism for stabilization of organic matter in soils is its interaction with mineral surfaces. Studies that investigate the nature and strength of such interactions have focused on non-pyrogenic materials, and examination of interactions between minerals and black carbon are scarce. In a chronosequence of black carbon ages, we can show that aluminum and silicon rapidly accumulates on black carbon surfaces after deposition to soil and reaches equilibrium after about 20 years in an Oxisol in Western Kenya. In an attempt to investigate the nature of the interaction between black carbon and mineral surfaces, we utilized near-edge x-ray fine structure (NEXAFS) spectroscopy of black carbon particles in soil aggregates and artificial mixtures of minerals and black carbon. Cluster analyses of the stack images using scanning transmission x-ray microscopy (STXM) revealed greater amounts of carboxyl contents, but also accumulation of aliphatic compounds. The latter may not stem from oxidized surfaces of black carbon particles themselves but adsorbed non-black carbon material. Mixing black carbon and minerals clearly showed changes in peak intensities of the C(1s) NEXAFS spectra indicating a chemical interaction between black carbon and mineral surfaces.

Lehmann, J.; Heymann, K.; Nguyen, B.

2009-04-01

386

Biogenic NO emissions from savanna soils as a function of fire regime, soil type, soil nitrogen, and water status  

NASA Astrophysics Data System (ADS)

A study of NOx emissions from soils representative of nutrient-poor and nutrient-rich savannas and their response to burning and soil water content was carried out in the southern Kruger National Park, South Africa. The study spanned the end of the dry season and the beginning of the wet season (September-December 1992). Nitrogen mineralization rates were measured using an in situ technique simultaneously with measurements of NOx emissions. NOx emissions were almost entirely as NO. The relationship between NO emission rate and soil moisture was parabolic regardless of soil type and management practice, with the lowest NO emission rates being measured at low (<0.087) and high (>0.542) water-filled pore space values. The initial increase in NO emission rates with increasing soil moisture are paralleled by increases in the nitrate concentration in the soil. The highest NO emission rates (20 ng N-NO m-2 s-1—excluding the brief initial peak) were measured on plots from which fire had been excluded for 35 years. The next highest rates (8 ng N-NO m-2 s-1) were measured on the more fertile soils. Infertile soils, burned every second year, had rates of 3.5 ng N-NO m-2 s-1. The NO emission rates show a positive correlation with soil total N content and N nitrification rate. The effect of excluding fire from a savanna is to increase the soil nitrogen content through increased litter inputs, which in turn increases nitrification rates and soil NO emissions.

Parsons, Dirk A. B.; Scholes, Mary C.; Scholes, Robert J.; Levine, Joel S.

1996-10-01

387

Water and heat fluxes in desert soils: 2. Numerical simulations  

NASA Astrophysics Data System (ADS)

Transient one-dimensional fluxes of soil water (liquid and vapor) and heat in response to 1 year of atmospheric forcing were simulated numerically for a site in the Chihuahuan Desert of Texas. The model was initialized and evaluated using the monitoring data presented in a companion paper (Scanlon, this issue). Soil hydraulic and thermal properties were estimated a priori from a combination of laboratory measurements, models, and other published information. In the first simulation, the main drying curves were used to describe soil water retention, and hysteresis was ignored. Remarkable consistency was found between computed and measured water potentials and temperatures. Attenuation and phase shift of the seasonal cycle of water potentials below the shallow subsurface active zone (0.0- to 0.3-m depth) were similar to those of temperatures, suggesting that water potential fluctuations were driven primarily by temperature changes. Water fluxes in the upper 0.3 m of soil were dominated by downward and upward liquid fluxes that resulted from infiltration of rain and subsequent evaporation from the surface. Upward flux was vapor dominated only in the top several millimeters of the soil during periods of evaporation. Below a depth of 0.3 m, water fluxes varied slowly and were dominated by downward thermal vapor flux that decreased with depth, causing a net accumulation of water. In a second simulation, nonhysteretic water retention was instead described by the estimated main wetting curves; the resulting differences in fluxes were attributed to lower initial water contents (given fixed initial water potential) and unsaturated hydraulic conductivities that were lower than they were in the first simulation. Below a depth of 0.3 m, the thermal vapor fluxes dominated and were similar to those in the first simulation. Two other simulations were performed, differing from the first only in the prescription of different (wetter) initial water potentials. These three simulations yielded identical solutions in the upper 0.2 m of soil after infiltration of summer rain; however, the various initial water potentials were preserved throughout the year at depths greater than 0.2 m. Comparison of all four simulations showed that the predominantly upward liquid fluxes below a depth of 0.2 m were very sensitive to the differences in water retention functions and initial water potentials among simulations, because these factors strongly affected hydraulic conductivities. Comparison of numerical modeling results with chemical tracer data showed that values of downward vapor flux below the surface evaporation zone were of the same order of magnitude as those previously estimated by analysis of depth distributions of bomb 3H (volatile) and bomb 36Cl (nonvolatile).

Scanlon, Bridget R.; Milly, P. C. D.

1994-03-01

388

Collimated neutron probe for soil water content measurements  

USGS Publications Warehouse

A collimated neutron probe was designed to enable mesurements in specific directions from the access tube. To determine the size and shape of soil volume affecting the neutron counts, experiments were conducted to evaluate: 1) the vertical distance of soil above and below the probe that influences neutron counts; 2) the horizontal distance away from the probe into the soil that influences neutron counts; 3) the angle of soil viewed by the probe from the collimator; and 4) the three-dimensional thermal-neutron density field. The vertical distance was ~0.5m, the horizontal distance was ~0.2m, and the angle of soil viewed by the probe from the collimator was ~120??. Thermal neutrons detected from distances or angles larger than these values influence the determination of relative water content by 5% or less. -from Authors

Klenke, J.M.; Flint, A.L.

1991-01-01

389

Modeling the effect of antecedent soil water storage on water and heat status in seasonally freezing and thawing agricultural soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Taking Hetao Irrigation District of Inner Mongolia's agricultural production as a background and based on field observation data and field measured meteorological data, the influence of antecedent soil water storage (ASWS) on water and heat conditions was simulated and analyzed using the SHAW model ...

390

Measuring and Modeling Interactions Between Groundwater, Soil Moisture, and Plant Transpiration in Natural and Agricultural Ecosystems  

E-print Network

Measuring and Modeling Interactions Between Groundwater, Soil Moisture, and Plant Transpiration Transpiration in Natural and Agricultural Ecosystems © 2009 by Gretchen Rose Miller #12;1 Abstract Measuring and Modeling Interactions Between Groundwater, Soil Moisture, and Plant Transpiration in Natural

Rubin, Yoram

391

Soil water content dependent wetting front characteristics in sands T.W.J. Bautersa  

E-print Network

that the finger- like pattern in water repellent soil had many similarities with unstable wetting fronts in air dry soil, studies of unstable flow in initially moist coarse or hydrophobic soils (Ritsema et al during water infil- tration at different initial soil water contents between air dry and field capacity

Walter, M.Todd

392

[Research progress on unsaturated and saturated soil water movement in forest catchments].  

PubMed

This paper reviewed the studies on the movement ways, i. e., infiltration, phreatic evaporation, ground water recharge and interflow, of unsaturated and saturated soil water in forest catchments, and introduced the present advances in soil hydraulic parameters, including soil water characteristic curve, and unsaturated and saturated soil hydraulic conductivity. Research directions in the future were also proposed. PMID:16355800

Yang, Hong; Pei, Tiefan

2005-09-01

393

Desert shrub water relations with respect to soil characteristics and plant functional type  

Microsoft Academic Search

Summary 1. Soil characteristics influence plant communities in part through water relations. Hypothetically, finer textured soils in arid climates should be associated with more negative plant and soil water potentials during drought, greater resistance of xylem to cavitation, and shallower root systems than coarse soils. 2. These hypotheses were tested by comparing the water relations of Great Basin shrubs growing

J. S. Sperry; U. G. Hacke

2002-01-01

394

SCALING IN SOIL AGGREGATE DISTRIBUTION AS DEPENDENT ON AGGREGATE WATER CONTENT AND SOIL COMPACTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fractal scaling has been documented in literature for mass of dry soil aggregates. Changes in water content are known to cause shrinking or swelling in aggregates. The objective of this work was to determine (a) whether the fractal scaling will hold for aggregates at various water contents, (b) how ...

395

Impact of reclaimed water irrigation on soil health in urban green areas.  

PubMed

Rapid increase of reclaimed water irrigation in urban green areas requires investigating its impact on soil health conditions. In this research, field study was conducted in 7 parks in Beijing with different histories of reclaimed water irrigation. Twenty soil attributes were analyzed to evaluate the effects of reclaimed water irrigation on the soil health conditions. Results showed that soil nutrient conditions were ameliorated by reclaimed water irrigation, as indicated by the increase of soil organic matter content (SOM), total nitrogen (TN), and available phosphorus (AP). No soil salinization but a slight soil alkalization was observed under reclaimed water irrigation. Accumulation of heavy metals in soil was insignificant. It was also observed that reclaimed water irrigation could significantly improve the soil microorganism activities. Overall, the soil health conditions were improved with reclaimed water irrigation, and the improvement increased when the reclaimed water irrigation period became longer. PMID:25150469

Chen, Weiping; Lu, Sidan; Pan, Neng; Wang, Yanchun; Wu, Laosheng

2015-01-01

396

The effects of water exposure, soil conditions, and fungus exposure on hatching of the larval lone star tick, Amblyomma americanum (Acari: Ixodidae)  

Microsoft Academic Search

We examined whether water functions as a developmental cue for hatching in the lone star tick, Amblyomma americanum. The experiments examined various exposure routes to water: submersion, relative humidity and an ecologically relevant setup of moist soil along with soil fungi to mimic fungus–egg interactions at oviposition sites. We demonstrate that eggs survive for up to a week underwater; increasing

Jay A. Yoder; Benjamin A. Rausch; Brian Z. Hedges; Sarah E. Stueber; Andrew J. Jajack; Joshua B. Benoit

2012-01-01

397

High Resolution Soil Water from Regional Databases and Satellite Images  

NASA Technical Reports Server (NTRS)

This viewgraph presentation provides information on the ways in which plant growth can be inferred from satellite data and can then be used to infer soil water. There are several steps in this process, the first of which is the acquisition of data from satellite observations and relevant information databases such as the State Soil Geographic Database (STATSGO). Then probabilistic analysis and inversion with the Bayes' theorem reveals sources of uncertainty. The Markov chain Monte Carlo method is also used.

Morris, Robin D.; Smelyanskly, Vadim N.; Coughlin, Joseph; Dungan, Jennifer; Clancy, Daniel (Technical Monitor)

2002-01-01

398

Surface reactions of chromium in soils and waters  

Microsoft Academic Search

Chromium is a redox active metal that persists as either Cr(III) or Cr(VI) in the environment. These two oxidation states have opposing toxicities and mobilities: Cr(III) is rather benign and immobile in soils while Cr(VI) is toxic and readily transported. Reactions influencing Cr chemistry in soils and waters must be known in order to predict and understand the fate of

Scott E. Fendorf

1995-01-01

399

Developing joint probability distributions of soil water retention characteristics  

Microsoft Academic Search

A method is presented for developing probability density functions for parameters of soil moisture relationships of capillary head (h(Phi)) and hydraulic conductivity (K(Phi)). These soil moisture parameters are required for the assessment of water flow and solute transport in unsaturated media. The method employs a statistical multiple regression equations proposed in the literature for estimating (h(Phi)) or (K(Phi)) relationships using

Robert F. Carsel; Rudolph S. Parrish

1988-01-01

400

Modeling interactions of Hg(II) and bauxitic soils  

Microsoft Academic Search

The adsorptive interactions of Hg(II) with gibbsite-rich soils (hereafter SOIL-g) were modeled by 1-pK surface complexation theory using charge distribution multi-site ion competition model (CD MUSIC) incorporating basic Stern layer model (BSM) to account for electrostatic effects. The model calibrations were performed for the experimental data of synthetic gibbsite–Hg(II) adsorption. When [NaNO3]?0.01M, the Hg(II) adsorption density values, of gibbsite, ?Hg(II),

Rohan Weerasooriya; Heinz J. Tobschall; Atula Bandara

2007-01-01

401

Soil Moisture: The Hydrologic Interface Between Surface and Ground Waters  

NASA Technical Reports Server (NTRS)

A hypothesis is presented that many hydrologic processes display a unique signature that is detectable with microwave remote sensing. These signatures are in the form of the spatial and temporal distributions of surface soil moisture. The specific hydrologic processes that may be detected include groundwater recharge and discharge zones, storm runoff contributing areas, regions of potential and less than potential evapotranspiration (ET), and information about the hydrologic properties of soils. In basin and hillslope hydrology, soil moisture is the interface between surface and ground waters.

Engman, Edwin T.

1997-01-01

402

Zinc movement in sewage-sludge-treated soils as influenced by soil properties, irrigation water quality, and soil moisture level  

USGS Publications Warehouse

A soil column study was conducted to assess the movement of Zn in sewage-sludge-amended soils. Varables investigated were soil properties, irrigation water quality, and soil moisture level. Bulk samples of the surface layer of six soil series were packed into columns, 10.2 cm in diameter and 110 cm in length. An anaerobically digested municipal sewage sludge was incorporated into the top 20 cm of each column at a rate of 300 mg ha-1. The columns were maintained at moisture levels of saturation and unsaturation and were leached with two waters of different quality. At the termination of leaching, the columns were cut open and the soil was sectioned and analyzed. Zinc movement was evaluated by mass balance accounting and correlation and regression analysis. Zinc movement in the unsaturated columns ranged from 3 to 30 cm, with a mean of 10 cm. The difference in irrigation water quality did not have an effect on Zn movement. Most of the Zn applied to the unsaturated columns remained in the sludge-amended soil layer (96.1 to 99.6%, with a mean of 98.1%). The major portion of Zn leached from the sludge-amended soil layer accumulated in the 0- to 3-cm depth (35.7 to 100%, with a mean of 73.6%). The mean final soil pH values decreased in the order: saturated columns = sludge-amended soil layer > untreated soils > unsaturated columns. Total Zn leached from the sludge-amended soil layer was correlated negatively at P = 0.001 with final pH (r = -0.85). Depth of Zn movement was correlated negatively at P = 0.001 with final pH (r = -0.91). Multiple linear regression analysis showed that the final pH accounted for 72% of the variation in the total amounts of Zn leached from the sludge-amended soil layer of the unsaturated columns and accounted for 82% of the variation in the depth of Zn movement among the unsaturated columns. A significant correlation was not found between Zn and organic carbon in soil solutions, but a negative correlation significant at P = 0.001 was found between pH and Zn (r = -0.61).

Welch, J.E.; Lund, L.J.

1989-01-01

403

Dual-permeability model for water flow and solute transport in shrinking soils  

NASA Astrophysics Data System (ADS)

A dual-permeability approach was extended to describe preferential water flow and solute transport in shrinking soils. In the approach, the soil is treated as a dual-permeability bulk porous medium consisting of dynamic interacting matrix and fractures pore domains. Water flow and solute transport in both the domains are described by the Richards' equation and advection-dispersion equation, respectively. In the model the contributions of the two regions to water flow and solute transport is changed dynamically according to the shrinkage characteristic exhibited under soil drying. Aggregate deformation during wetting/drying cycles is assumed to change only the relative proportions of voids in the fractures and in the aggregates, while the total volume of pores (and thus the layer thickness) remains unchanged. Thus, the partial contributions of the fracture and aggregate domains, are now a function of the water content (or the pressure head h), while their sum, the bulk porosity, is assumed to be constant. Any change in the aggregate contribution to total porosity is directly converted into a proportional change in the fracture porosity. This means that bulk volume change during shrinkage is mainly determined by change in crack volume rather than by change in layer thickness. This simplified approach allows dealing with an expansive soil as with a macroscopically rigid soil. The model was already tested by investigating whether and how well hydraulic characteristics obtained under the assumption of "dynamic" dual-permeability hydraulic parameterizations, or, alternatively, assuming the rigidity of the porous medium, reproduced measured soil water contents in a shrinking soil. Here we will discuss theoretical implications of the model in terms of relative importance of the parameters involved. The relative importance will be evaluated for different flow and transport processes and for different initial and top boundary conditions. Key words: Preferential flow and transport, Double permeability models, Shrinkage characteristics

Coppola, Antonio; Gerke, Horst; Comegna, Alessandro; Basile, Angelo

2014-05-01

404

Complexation of silver and dissolved organic matter in soil water extracts.  

PubMed

An important aspect of the behaviour and fate of silver (Ag) in soils is the interaction with dissolved organic matter (DOM). The complexation and strength of binding of Ag(+) with DOM in soil water extracts was examined and modelled based on a range of chemical and quality DOM measurements. Silver ion binding measured by addition of the (110m)Ag radioisotope in addition to a cation exchange resin technique were used to determine strongly complexed Ag in solutions. Silver was found to be up to 70% strongly complexed. The variability in Ag(+) binding by DOM across different soils was closely related (R(2) = 0.8) to the mid-infrared spectra of these extracts. The affinity of Ag(+) for DOM was stronger in solutions containing a greater content of humic and aromatic structures. The ability of Ag(+) to complex with DOM could result in increased mobilisation of this metal in the soil environment. PMID:25660071

Settimio, Lara; McLaughlin, Mike J; Kirby, Jason K; Langdon, Kate A; Janik, Les; Smith, Scott

2015-04-01

405

Importance of soil organic carbon on surface soil water content variability among agricultural fields  

NASA Astrophysics Data System (ADS)

Improvements to the downscaling estimates of soil water content (SWC) from passive microwave retrievals require detailed knowledge of field scale influences on SWC variability. The Soil Moisture Active Passive Validation Experiment (SMAPVEX-12) field campaign provided SWC and physical properties from 50 cropland fields to assess the influence of soil organic carbon (SOC) on SOC variability in a range of SOC, SWC and soil textural class over a 6 week period. Field average SWC over the duration of the experiment was optimally predicted by combination of soil texture and SOC in all soil wetness conditions, although either %Sand or SOC separately also expressed 82% of variance in SWC over all fields covering three soil textural groups. Soil OC explained greater variance in SWC than texture in dry conditions, while texture predominated in moist conditions. The high correlation between SOC and SWC suggests soil OC may contribute to the initiatives to downscale SWC estimates from satellite to field scale where SWC data are sparse or inaccurate.

Manns, Hida R.; Berg, Aaron A.

2014-08-01

406

Precision and accuracy of three alternative instruments for measuring soil water content in two forest soils of the Pacific Northwest  

Microsoft Academic Search

We compared the accuracy and precision of three devices for measuring soil water content in both natural and repacked soils and evaluated their temperature sensitivity. Calibrations were developed for a capacitance instrument (ECH2O), a time domain reflectometry cable tester (CT), and a water content reflectometer (WCR) in soils collected from the Wind River and H.J. Andrews Experimental Forests. We compared

Nicole M. Czarnomski; Georgianne W. Moore; Tom G. Pypker; Julian Licata; Barbara J. Bond

2005-01-01

407

Pore-Scale Effects of Soil Structure And Microbial EPS Production On Soil Water Retention  

NASA Astrophysics Data System (ADS)

Climate-induced changes to the hydrological cycle will increase the frequency of extreme weather events including powerful storms and prolonged droughts. Moving forward, one of the major factors limiting primary productivity in terrestrial ecosystems will be sub-optimal soil moisture. We focus here on the ability of soils to retain moisture under drying conditions. A soil's ability to retain moisture is influenced by many factors including its texture, its structure, and the activities of soil microbes. In soil microcosms, the addition of small amounts of microbially-produced extracellular polymeric substances (EPS) can dramatically shift moisture retention curves. The objective of this research is to better understand how soil structure and EPS may act together to retain moisture in unsaturated soils. Replicate micromodels with exactly-conserved 2-D physical geometry were initially filled with aqueous suspensions of one of two types of bacteria: one mutant was ultra- muccoid and the other was non-muccoid. Replicate micromodels were held at a fixed, external, relative humidity, and the position of the air-water interface was imaged over time as water evaporates. There was no forced convection of air or water inside the micromodels: drying was achieved by water evaporation and diffusion alone. We used a fully automated, inverted microscope to image replicate drying lanes each with dimensions of 1 mm x 10 mm. A complete set of images was collected every 30 minutes for 30 hours. The results show devices loaded with the highly muccoid strain remained >40% hydrated for 13 h, while devices loaded with the non-muccoid remained >40% hydrated for only 6 h, and were completely dry by 13 h. Current work is comparing interfacial water fluxes in structured and unstructured settings, and is attempting to model the synergistic effects of soil structure and EPS content on moisture retention in real soils. This research may allow more accurate description of naturally-occurring feedbacks between the soil carbon and water cycles, and may enable agriculture biotechnology that enhances natural soil processes for improved resiliency of terrestrial ecosystems.

Orner, E.; Anderson, E.; Rubinstein, R. L.; Chau, J. F.; Shor, L. M.; Gage, D. J.

2013-12-01

408

Evapotranspiration of soil water movement in small area vegetation  

NASA Astrophysics Data System (ADS)

In Greece, crops are frequently cultivated in small isolated areas in close proximity to roads and bare soils and therefore evapotranspiration is affected by local advection. Under these circumstances, oasis effect conditions are present and evapotranspiration is higher than what is expected. In this paper, the evapotranspiration and soil water dynamics of a cotton crop cultivated in small areas under the oasis effect is studied. To this end, two isolated free-drainage lysimeters cultivated with cotton in the year 2007 were used. Soil moisture of the soil profile of both the lysimeters was monitored with two capacitance water content probes. The soil water balance method was used to estimate crop evapotranspiration and corresponding crop coefficients in one of the two lysimeters. These coefficients were 75% larger than the FAO-56 crop coefficients at the mid-season stage. The FAO-56 and the derived crop coefficients were used for the simulation of the water dynamics in the second lysimeter by the SWBACROS model. The derived crop coefficients for these conditions produced much better results than the FAO-56 crop coefficients. The results were improved when crop coefficient value equal to 2.5 was used for the mid-season stage.

Paraskevas, C.; Georgiou, P.; Ilias, A.; Panoras, A.; Babajimopoulos, C.

2013-12-01

409

Reflectance of vegetation, soil, and water  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. Bands 4, 5, and 7 and 5, 6, and 7 were best for distinguishing among crop and soil categories in ERTS-1 SCENES 1182-16322 (1-21-73) and 1308-16323 (5-21-73) respectively. Chlorotic sorghum areas 2.8 acres or larger in size were identified on a computer printout of band 5 data. Reflectance of crop residues was more often different from bare soil in band 4 than in bands 5, 6, and 7. Simultaneously acquired aircraft and spacecraft MSS data indicated that spacecraft surveys are as reliable as aircraft surveys. ERTS-1 data were successfully used to estimate acreage of citrus, cotton, and sorghum as well as idle crop land.

Wiegand, C. L. (principal investigator); Gausman, H. W.; Leamer, R. W.; Richardson, A. J.; Gerbermann, A. H.; Torline, R. J.; Gautreaux, M. R.; Everitt, J. H.; Guellar, J. A.; Rodriguez, R. R.

1974-01-01

410

Natural Processes of Ground-Water and Surface-Water Interaction  

NSDL National Science Digital Library

This site explains the hydrologic cycle and interactions of ground water with surface water, streams, lakes, and wetlands. There are sections about chemical interactions of ground water and surface water; evolution of water chemistry in drainage basins; and interaction of ground water and surface water in different landscapes. Mountainous, riverine, coastal, glacial and dune, and karst terrain are examined.

Thomas Winter

1998-01-01

411

Molecular Indicators of Soil Humification and Interaction with Heavy Metals  

SciTech Connect

For stabilization of heavy metals at contaminated sites, interaction of soil organic matter (SOM) with heavy metal ions is critically important for long-term sustainability, a factor that is poorly understood at the molecular level. Using 13C- and 15N-labeled soil humates (HS), we investigated the turnover of five organic amendments (celluose, wheat straw, pine shavings, chitin and bone meal) in relation to heavy metal ion leaching in soil column experiments. The labeled molecular substructures in HS were examined by multinuclear 2-D NMR and pyrolysis GC-MS while the element profile in the leachates was analyzed by ICP-MS. Preliminary analysis revealed that peptidic and polysaccharidic structures were highly enriched, which suggests their microbial origin. Cd(II) leaching was significantly attenuated with humification of lignocellulosic materials. Correlation of 13C and 15N turnovers of HS substructures to metal leaching is underway.

Fan, Teresa W.-M.; Higashi, Richard M.; Cassel, Teresa; Green, Peter; Lane, Andrew N.

2003-03-26

412

SOIL APPLIED AND WATER APPLIED PHOSPHORUS APPLICATION  

Microsoft Academic Search

Many agricultural workers feel that 10-34-0 is a superior fertilizer for alfalfa since it is thought to move deeper in the soil with irrigation, be more available to the plant, and result in higher yields at equivalent rates compared to 11 -52-0. We found in our study with 24 cuttings over 3 years that alfalfa yields were similar if fertilized

M. J. Ottman; T. L. Thompson; M. T. Rogers; S. A. White

413

Organic compounds in hot-water-soluble fractions from water repellent soils  

NASA Astrophysics Data System (ADS)

Water repellency (WR) is a soil property providing hydrophobic protection and preventing rapid microbial decomposition of organic matter entering the soil with litter or plant residues. Global warming can cause changes in WR, thus influencing water storage and plant productivity. Here we assess two different approaches for analysis of organic compounds composition in hot water extracts from accelerated solvent extraction (ASE) of water repellent soils. Extracts were lyophilized, fractionated on SiO2 (sand) and SPE cartridge, and measured by GC/MS. Dominant compounds were aromatic acids, short chain dicarboxylic acids (C4-C9), sugars, short chain fatty acids (C8-C18), and esters of stearic and palmitic acids. Polar compounds (mainly sugars) were adsorbed on applying SPE clean-up procedure, while esters were highly abundant. In addition to the removal of polar compounds, hydrophobic esters and hydrocarbons (alkanes and alkenes < C20) were extracted through desorption of complex colloids stabilized as micelles in dissolved organic carbon (DOC). Water repellency was completely eliminated by hot water under high pressure. The molecular composition of HWSC can play a critical role in stabilization and destabilization of soil organic matter (SOM), particle wettability and C dynamics in soils. Key words: soil water repellency, hot water soluble carbon (HWSC), GC/MS, hydrophobic compounds

Atanassova, Irena; Doerr, Stefan

2014-05-01

414

Hot water tolerance of soil animals: utility of hot water immersion in preventing invasions of alien soil animals  

Microsoft Academic Search

\\u000a Introduced soil animals have frequently affected native fauna on oceanic islands that have never been connected to a continental\\u000a land mass. Alien soil animals can be unintentionally introduced via transfer in potted plants or by commercial trade among\\u000a islands and continental landmasses. Hot water treatment to destroy pests has recently been used during the quarantine of ornamental\\u000a plants. To examine

Shinji Sugiura

415

Modelling interactions between soil evolution and diffusive surface processes  

NASA Astrophysics Data System (ADS)

Bioturbation, combined with settlement under gravity, generates profiles of bulk density, porosity and hydraulic conductivity (Ksat). Rates of bioturbation are linked to rates of diffusive downslope sediment transport (creep) and rates can be compared via the increase in OSL ages of soil aggregate grains with depth. Some primary porosity is also produced by weathering of rock to saprolite, often with little reduction in bulk density but some dilation of joints. Downward percolation of rain water near the surface is controlled by the diffusion-induced decrease in porosity and Ksat, driving lateral subsurface flow in the zone of fluctuating water table, and leaving progressively less water for downward percolation. As the depth to the weathering front is varied, progressively less water is therefore available for weathering, producing the observed decrease in weathering rate with increasing soil depth. These processes are modelled by repeatedly applying a stochastic realisation of daily rainfalls for an area until the annual hydrological cycle stabilises, providing the average partition of rainfall into its components of evapotranspiration, lateral flow and downward percolation, with depth in the soil. The average hydrology is then applied to drive evolution of the weathering profile over longer time spans.

Kirkby, Mike; Johnson, Michelle; Gloor, Emanual

2014-05-01

416

Soil and water conservation policies: Successes and failures  

SciTech Connect

This book presents an in-depth look at soil and water conservation programs throughout the world. For as far into the future as one can see, governments will probably topple, power will continue to exchange hands, the climate will undergo continuous change, and the global economy will ebb and flow like the oceans. But for the world's many diverse countries--whether they be highly industrialized or third world--one thing will always remain constant: the need to solve the planet's pressing soil and water conservation problems, as well as implement effective policies. This book addresses: Why do some policy initiatives succeed while others fail?

Napier, T.A. [ed.

2000-07-01

417

Modeling interactions of Hg(II) and bauxitic soils.  

PubMed

The adsorptive interactions of Hg(II) with gibbsite-rich soils (hereafter SOIL-g) were modeled by 1-pK surface complexation theory using charge distribution multi-site ion competition model (CD MUSIC) incorporating basic Stern layer model (BSM) to account for electrostatic effects. The model calibrations were performed for the experimental data of synthetic gibbsite-Hg(II) adsorption. When [NaNO(3)] > or = 0.01M, the Hg(II) adsorption density values, of gibbsite, Gamma(Hg(II)), showed a negligible variation with ionic strength. However, Gamma(Hg(II)) values show a marked variation with the [Cl(-)]. When [Cl(-)] > or = 0.01M, the Gamma(Hg(II)) values showed a significant reduction with the pH. The Hg(II) adsorption behavior in NaNO(3) was modeled assuming homogeneous solid surface. The introduction of high affinity sites, i.e., >Al(s)OH at a low concentration (typically about 0.045 sites nm(-2)) is required to model Hg(II) adsorption in NaCl. According to IR spectroscopic data, the bauxitic soil (SOIL-g) is characterized by gibbsite and bayerite. These mineral phases were not treated discretely in modeling of Hg(II) and soil interactions. The CD MUSIC/BSM model combination can be used to model Hg(II) adsorption on bauxitic soil. The role of organic matter seems to play a role on Hg(II) binding when pH>8. The Hg(II) adsorption in the presence of excess Cl(-) ions required the selection of high affinity sites in modeling. PMID:17659321

Weerasooriya, Rohan; Tobschall, Heinz J; Bandara, Atula

2007-11-01

418

Response of rice genotype to straighthead disease as influenced by arsenic level and water management practices in soil.  

PubMed

Arsenic (As) uptake by rice plants and the straighthead disease induced by As-based herbicide are of environmental concerns. Bioavailability or mobility of inorganic As in soil has been reported to be significantly influenced by soil minerals such as iron (hydr) oxide; however, the interactions of organic As such as monosodium methanearsonate (MSMA) with soil minerals are little studied, thus largely unknown. In an effort to minimize the As uptake by rice and determine rice cultivar response to soil MSMA level, a field experiment was conducted on three rice cultivars grown in both MSMA-treated and -untreated soils under continuous or intermittent flood water management practices. Results indicated that the grain yield and the occurrence of straighthead disease were cultivar-dependent and influenced by soil As level and water management practices. Straighthead-resistant cultivars yielded more and had lower grain As than the susceptible ones. Elevated soil As with continuous flood management significantly reduced the grain yield of susceptible cultivars by >89% due to substantially increased straighthead, which were induced by increased As content in grains. Yield reduction by MSMA treatment could be partially mitigated with intermittent flood water practice. The As accumulation was found to be associated with soil iron redox transformation influenced by the water management. This study demonstrates that the selection of less As-susceptible cultivars and intermittent flood water practice could be effective means to lower the As accumulation in grains and minimize the occurrence of the As-induced straighthead symptom and yield reduction. PMID:23183123

Hua, Bin; Yan, Wengui; Yang, John

2013-01-01

419

Improved Instrument for Detecting Water and Ice in Soil  

NASA Technical Reports Server (NTRS)

An instrument measures electrical properties of relatively dry soils to determine their liquid water and/or ice contents. Designed as a prototype of instruments for measuring the liquid-water and ice contents of lunar and planetary soils, the apparatus could also be utilized for similar purposes in research and agriculture involving terrestrial desert soils and sands, and perhaps for measuring ice buildup on aircraft surfaces. This instrument is an improved version of the apparatus described in Measuring Low Concentrations of Liquid Water and Ice in Soil (NPO-41822), NASA Tech Briefs, Vol. 33, No. 2 (February 2009), page 22. The designs of both versions are based on the fact that the electrical behavior of a typical s