WorldWideScience

Sample records for study soil water

  1. Underground waters and soil contamination studies

    International Nuclear Information System (INIS)

    Ferreira, Vinicius V.M.; Camargos, Claudio C.; Santos, Rosana A.M.

    2009-01-01

    Maybe the greatest problem associated to the nuclear energy is what to do with the waste generated. As example, in Portugal, two of the most important of uranium mines produced a significant amount of waste, now deposited in several storage facilities. To evaluate the impacts generated, samples of water, sediments and soils were analyzed. The space distribution of these samples revealed that the contamination is restricted in the vicinity of the mining areas, and the biggest problem happened due to the illegal use of waters for irrigation, originated from the mine effluents treatment stations. In Brazil, the radioactive waste remains a problem for the authorities and population, since there is not until now a final repository to storage them. The objective of this work is to do studies with the software FRAC3DVS, which simulates the contamination of soils and underground waters due to radioactive and no radioactive sources of pollution. The obtained results show that this tool can help in environmental evaluations and decision making processes in the site selection of a radioactive waste repository. (author)

  2. Soil water balance scenario studies using predicted soil hydraulic parameters

    NARCIS (Netherlands)

    Nemes, A.; Wösten, J.H.M.; Bouma, J.; Várallyay, G.

    2006-01-01

    Pedotransfer functions (PTFs) have become a topic drawing increasing interest within the field of soil and environmental research because they can provide important soil physical data at relatively low cost. Few studies, however, explore which contributions PTFs can make to land-use planning, in

  3. A study on water infiltration barriers with compacted layered soils

    International Nuclear Information System (INIS)

    Umeda, Y.; Komori, K.; Fujiwara, A.

    1993-01-01

    In shallow-ground disposal of low-level radioactive wastes, water movements due to natural processes in the soil covering the disposal facility must be properly controlled. A capillary barrier with compacted layered soils can provide an effective means of controlling water movement in the soil covering placed on a low-level radioactive waste disposal facility. An experiment was performed to determine the effectiveness of a full-scale fill as a capillary barrier. The fill used in the experiment was constructed of compacted layers of clay, fine sand, and gravel. Man-made rain was caused to fall on the surfaces of the fill to observe the infiltration of rainwater into the fill and to measure the amount of water drained from within. The experiment established the effectiveness of the capillary barrier

  4. Study on soil water characteristics of tobacco fields based on canonical correlation analysis

    Directory of Open Access Journals (Sweden)

    Xiao-hou Shao

    2009-06-01

    Full Text Available In order to identify the principal factors influencing soil water characteristics (SWC and evaluate SWC effectively, the multivariate-statistical canonical correlation analysis (CCA method was used to study and analyze the correlation between SWC and soil physical and chemical properties. Twenty-two soil samples were taken from 11 main tobacco-growing areas in Guizhou Province in China and the soil water characteristic curves (SWCC and basic physical and chemical properties of the soil samples were determined. The results show that: (1 The soil bulk density, soil total porosity and soil capillary porosity have significant effects on SWC of tobacco fiels. Bulk density and total porosity are positively correlated with soil water retention characteristics (SWRC, and soil capillary porosity is positively correlated with soil water supply characteristics (SWSC. (2 Soil samples from different soil layers at the same soil sampling point show similarity or consistency in SWC. Inadequate soil water supply capability and imbalance between SWRC and SWSC are problems of tobacco soil. (3 The SWC of loamy clay are generally superior to those of silty clay loam.

  5. Electrical resistivity sounding to study water content distribution in heterogeneous soils

    Science.gov (United States)

    Electrical resistivity (ER) sounding is increasingly being used as non-invasive technique to reveal and map soil heterogeneity. The objective of this work was to assess ER sounding applicability to study soil water distribution in spatially heterogeneous soils. The 30x30-m study plot was located at ...

  6. Use of neutron water and gamma density gauges in soil water studies

    International Nuclear Information System (INIS)

    Kirda, C.

    1990-01-01

    Irrigation practices should be improved to increase effective use of water and thereby increasing irrigated areas as well as securing soil productivity under irrigated agriculture. Under dry farming systems of rainfed agriculture, different tillage practices should be tested for improved soil water conservation and rain harvesting. The research work addressing the above mentioned problems requires methods to measure soil water content accurately and conveniently. In the following article, the methods which are currently used to measure field soil water content were discussed. 34 refs, 13 figs, 13 tabs

  7. Studies on soil and water characteristics of Burrow pits for possible ...

    African Journals Online (AJOL)

    Studies on soil and water characteristics of Burrow pits for possible conversion into fish ponds in Niger Delta, Nigeria. ... Soil and water parameters were investigated in 34 burrow pits in Egiland, Rivers State, in the Niger Delta region of Nigeria. The pits surface areas and depths ranged from 30,000 to 40,000 m2 and 1.00 to ...

  8. Study on the subgrade deformation under high-speed train loading and water-soil interaction

    Science.gov (United States)

    Han, Jian; Zhao, Guo-Tang; Sheng, Xiao-Zhen; Jin, Xue-Song

    2016-04-01

    It is important to study the subgrade characteristics of high-speed railways in consideration of the water-soil coupling dynamic problem, especially when high-speed trains operate in rainy regions. This study develops a nonlinear water-soil interaction dynamic model of slab track coupling with subgrade under high-speed train loading based on vehicle-track coupling dynamics. By using this model, the basic dynamic characteristics, including water-soil interaction and without water induced by the high-speed train loading, are studied. The main factors-the permeability coefficient and the porosity-influencing the subgrade deformation are investigated. The developed model can characterize the soil dynamic behaviour more realistically, especially when considering the influence of water-rich soil.

  9. Isotope fractionation of sandy-soil water during evaporation - an experimental study.

    Science.gov (United States)

    Rao, Wen-Bo; Han, Liang-Feng; Tan, Hong-Bing; Wang, Shuai

    2017-06-01

    Soil samples containing water with known stable isotopic compositions were prepared. The soil water was recovered by using vacuum/heat distillation. The experiments were held under different conditions to control rates of water evaporation and water recovery. Recoveries, δ 18 O and δ 2 H values of the soil water were determined. Analyses of the data using a Rayleigh distillation model indicate that under the experimental conditions only loosely bound water is extractable in cases where the recovery is smaller than 100 %. Due to isotopic exchange between vapour and remaining water in the micro channels or capillaries of the soil matrix, isotopic fractionation may take place under near-equilibrium conditions. This causes the observed relationship between δ 2 H and δ 18 O of the extracted water samples to have a slope close to 8. The results of this study may indicate that, in arid zones when soil that initially contains water dries out, the slope of the relationship between δ 2 H and δ 18 O values should be close to 8. Thus, a smaller slope, as observed by some groundwater and soil water samples in arid zones, may be caused by evaporation of water before the water has entered the unsaturated zone.

  10. A vegetation-focused soil-plant-atmospheric continuum model to study hydrodynamic soil-plant water relations

    Science.gov (United States)

    Deng, Zijuan; Guan, Huade; Hutson, John; Forster, Michael A.; Wang, Yunquan; Simmons, Craig T.

    2017-06-01

    A novel simple soil-plant-atmospheric continuum model that emphasizes the vegetation's role in controlling water transfer (v-SPAC) has been developed in this study. The v-SPAC model aims to incorporate both plant and soil hydrological measurements into plant water transfer modeling. The model is different from previous SPAC models in which v-SPAC uses (1) a dynamic plant resistance system in the form of a vulnerability curve that can be easily obtained from sap flow and stem xylem water potential time series and (2) a plant capacitance parameter to buffer the effects of transpiration on root water uptake. The unique representation of root resistance and capacitance allows the model to embrace SPAC hydraulic pathway from bulk soil, to soil-root interface, to root xylem, and finally to stem xylem where the xylem water potential is measured. The v-SPAC model was tested on a native tree species in Australia, Eucalyptus crenulata saplings, with controlled drought treatment. To further validate the robustness of the v-SPAC model, it was compared against a soil-focused SPAC model, LEACHM. The v-SPAC model simulation results closely matched the observed sap flow and stem water potential time series, as well as the soil moisture variation of the experiment. The v-SPAC model was found to be more accurate in predicting measured data than the LEACHM model, underscoring the importance of incorporating root resistance into SPAC models and the benefit of integrating plant measurements to constrain SPAC modeling.

  11. Soil Water Retention Curve

    Science.gov (United States)

    Johnson, L. E.; Kim, J.; Cifelli, R.; Chandra, C. V.

    2016-12-01

    Potential water retention, S, is one of parameters commonly used in hydrologic modeling for soil moisture accounting. Physically, S indicates total amount of water which can be stored in soil and is expressed in units of depth. S can be represented as a change of soil moisture content and in this context is commonly used to estimate direct runoff, especially in the Soil Conservation Service (SCS) curve number (CN) method. Generally, the lumped and the distributed hydrologic models can easily use the SCS-CN method to estimate direct runoff. Changes in potential water retention have been used in previous SCS-CN studies; however, these studies have focused on long-term hydrologic simulations where S is allowed to vary at the daily time scale. While useful for hydrologic events that span multiple days, the resolution is too coarse for short-term applications such as flash flood events where S may not recover its full potential. In this study, a new method for estimating a time-variable potential water retention at hourly time-scales is presented. The methodology is applied for the Napa River basin, California. The streamflow gage at St Helena, located in the upper reaches of the basin, is used as the control gage site to evaluate the model performance as it is has minimal influences by reservoirs and diversions. Rainfall events from 2011 to 2012 are used for estimating the event-based SCS CN to transfer to S. As a result, we have derived the potential water retention curve and it is classified into three sections depending on the relative change in S. The first is a negative slope section arising from the difference in the rate of moving water through the soil column, the second is a zero change section representing the initial recovery the potential water retention, and the third is a positive change section representing the full recovery of the potential water retention. Also, we found that the soil water moving has traffic jam within 24 hours after finished first

  12. The study heavy metals in water,soil and Vegatable in Shahroud

    OpenAIRE

    saied Nazemi; ahmad khosravi

    2011-01-01

    Introduction: The arrival of toxic metals by human activities has lead to the contamination of soil. Heavy metals are among the most important pollutants in the environment. This study aimed at determining the concentration of heavy metals in soils, water and vegetables of Shhnama region in Shahroud. Methods: Vegetables studied included parsley, leek, leaf beet, fenugreek, cress, basil, radish and the coriander. The sampling was performed during 3 months, from September to October, 2008. The ...

  13. Tightly bound soil water introduces isotopic memory effects on mobile and extractable soil water pools.

    Science.gov (United States)

    Newberry, Sarah L; Prechsl, Ulrich E; Pace, Matthew; Kahmen, Ansgar

    2017-08-01

    Cryogenic vacuum extraction is the well-established method of extracting water from soil for isotopic analyses of waters moving through the soil-plant-atmosphere continuum. We investigate if soils can alter the isotopic composition of water through isotope memory effects, and determined which mechanisms are responsible for it. Soils with differing physicochemical properties were re-wetted with reference water and subsequently extracted by cryogenic water distillation. Results suggest some reference waters bind tightly to the soil and not all of this tightly bound water is removed during cryogenic vacuum extraction. Kinetic isotopic fractionation occurring when reference water binds to the soil is likely responsible for the 18 O-depletion of re-extracted reference water, suggesting an enrichment of the tightly bound soil water pool. Further re-wetting of cryogenically extracted soils indicates an isotopic memory effect of tightly bound soil water on water added to the soil. The data suggest tightly bound soil water can influence the isotopic composition of mobile soil water. Findings show that soils influence the isotope composition of soil water by (i) kinetic fractionation when water is bound to the soil and (ii) equilibrium fractionation between different soil water pools. These findings could be relevant for plant water uptake investigations and complicate ecohydrological and paleohydrological studies.

  14. Geochemical and isotopic study of soils and waters from an Italian contaminated site: Agro Aversano (Campania)

    Science.gov (United States)

    Bove, M.A.; Ayuso, R.A.; de Vivo, B.; Lima, A.; Albanese, S.

    2011-01-01

    Lead isotope applications have been widely used in recent years in environmental studies conducted on different kinds of sampled media. In the present paper, Pb isotope ratios have been used to determine the sources of metal pollution in soils and waters in the Agro Aversano area. During three different sampling phases, a total of 113 surface soils (5-20. cm), 20 samples from 2 soil profiles (0-1. m), 11 stream waters and 4 groundwaters were collected. Major element concentrations in sampled media have been analyzed by the ICP-MS technique. Surface soils (20 samples), all soil profiles and all waters have been also analyzed for Pb isotope compositions by thermal ionization (TIMS). The geochemical data were assessed using statistic methods and cartographically elaborated in order to have a clear picture of the level of disturbance of the area. Pb isotopic data were studied to discriminate between anthropogenic and geologic sources. Our results show that As (5.6-25.6. mg/kg), Cu (9-677. mg/kg), Pb (22-193. mg/kg), Tl (0.53-3.62. mg/kg), V (26-142. mg/kg) and Zn (34-215. mg//kg) contents in analyzed soils, exceed the intervention limits fixed by the Italian Environmental Law for residential areas in some of the sampled sites, while intervention limit for industrial areas is exceeded only for Cu concentrations. Lead isotopic data, show that there is a high similarity between the ratios measured in the leached soil samples and those deriving from anthropic activities. This similarity with anthropogenic Pb is also evident in the ratios measured in both groundwater and stream water samples. ?? 2010 Elsevier B.V.

  15. Soil tension mediates isotope fractionation during soil water evaporation

    Science.gov (United States)

    Gaj, Marcel; McDonnell, Jeffrey

    2017-04-01

    Isotope tracing of the water cycle is increasing in its use and usefulness. Many new studies are extracting soil waters and relating these to streamflow, groundwater recharge and plant transpiration. Nevertheless, unlike isotope fractionation factors from open water bodies, soil water fractionation factors are poorly understood and until now, only empirically derived. In contrast to open water evaporation where temperature, humidity and vapor pressure gradient define fractionation (as codified in the well-known Craig and Gordon model), soil water evaporation includes additionally, fractionation by matrix effects. There is yet no physical explanation of kinetic and equilibrium fraction from soil water within the soil profile. Here we present a simple laboratory experiment with four admixtures of soil grain size (from sand to silt to clay). Oven-dried samples were spiked with water of known isotopic composition at different soil water contents. Soils were then stored in sealed bags and the headspace filled with dry air and allowed to equilibrate for 24hours. Isotopic analysis of the headspace vapor was done with a Los Gatos Inc. water vapor isotope analyzer. Soil water potential of subsamples were measured with a water potential meter. We show for the first time that soil tension controls isotope fractionation in the resident soil water. Below a Pf 3.5 the δ-values of 18O and 2H of the headspace vapor is more positive and increases with increasing soil water potential. Surprisingly, we find that the relationship between soil tension and equilibrium fractionation is independent of soil type. However, δ-values of each soil type plot along a distinct evaporation line. These results indicate that equilibrium fractionation is affected by soil tension in addition to temperature. Therefore, at high soil water tension (under dry conditions) equilibrium fractionation is not consistent with current empirical formulations that ignore these effects. These findings may have

  16. Impact of saline water on soil properties and crop yield: a simulation study

    NARCIS (Netherlands)

    Tedeschi, A.; Barbieri, G.; Menenti, M.

    1996-01-01

    A field experiment on vegetable crops was carried out between 1988 and 1993 near Naples (Italy). The effect of saline water on soil properties was assessed by means of laboratory experiments on undisturbed soil cores. Significant differences in the soil water retention curves and unsaturated

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

    NARCIS (Netherlands)

    Mazzucato, V.; Niemeijer, D.

    2000-01-01

    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

  18. FAO/IAEA interregional training course on the use of isotope and radiation techniques in studies on soil/plant relationships with emphasis on soil water management

    International Nuclear Information System (INIS)

    1993-01-01

    The document presents an outline and programme schedule for the FAO/IAEA Inter-regional Training Workshop on the Use of Isotope and Radiation Techniques in Studies on Soil-Plant Relationships held in Vienna, 1 June - 9 July 1993. The major topics include instrumentation and radiometric assay, liquid scintillation counting, isotope techniques in fertilizer use efficiency and nitrogen fixation, crop-soil-water-atmosphere relations. General topics such as plant growth, water requirement and soil erosion processes are also covered

  19. Water repellent soils: the case for unsaturated soil mechanics

    Directory of Open Access Journals (Sweden)

    Beckett Christopher

    2016-01-01

    Full Text Available Water repellent (or “hydrophobic” or “non-wetting” soils have been studied by soil scientists for well over a century. These soils are typified by poor water infiltration, which leads to increased soil erosion and poor crop growth. However, the importance of water repellence on determining soil properties is now becoming recognised by geotechnical engineers. Water repellent soils may, for example, offer novel solutions for the design of cover systems overlying municipal or mine waste storage facilities. However, investigations into factors affecting their mechanical properties have only recently been initiated. This purpose of this paper is to introduce geotechnical engineers to the concept of water repellent soils and to discuss how their properties can be evaluated under an unsaturated soils framework. Scenarios in which water repellent properties might be relevant in geotechnical applications are presented and methods to quantify these properties in the laboratory and in the field examined.

  20. Simulation study of soil water and heat dynamics at two sites with significant preferential flow

    Science.gov (United States)

    Votrubova, J.; Vogel, T.; Dohnal, M.; Tesar, M.

    2012-04-01

    Numerical models based on two hydraulically contrasting flow domains coupled through a simple transfer formula have become a useful tool for modeling both water flow and associated substance transport in structured soils. A comparative numerical study focused on the preferential flow effects on the soil heat transport is presented. Sites located in two different headwater catchments were included. Experimental catchment Liz is situated in a forested mountain area of Sumava Mts. in the southern part of the Czech Republic (altitude: 830 m, mean annual temperature: 6.3°C, mean annual precipitation: 861 mm). Uhlirska catchment is located in the north-west of the Czech Republic in Jizera Mts. and is currently undergoing reforestation (altitude: 820 m, mean annual temperature: 4.6°C, mean annual precipitation: 1400 mm). Both sites are instrumented for monitoring of the relevant meteorological and hydrological variables, as well as the soil moisture and temperature distribution. Changes of the soil water content and temperature during vegetation season were simulated. Model performance was qualitatively evaluated and shown to replicate the field measurements. The soils' heat budgets and the preferential flow effect thereon was compared and analyzed.

  1. Study of lead pollution in air, soil and water samples of Quetta city

    International Nuclear Information System (INIS)

    Khan, M.; Khan, G.M.; Akbar, S.; Panezai, M.A.; Haq, Z.U.

    2011-01-01

    This study briefly presents the collected data of lead pollution in the environment of Quetta City in Balochistan, Pakistan. The samples were collected from different sites. The analysis of lead was carried out in underground water samples, the exhaust of different vehicles, roadside and sewage soils from selected points of Quetta City. The average discharge resulted in deposition by motorcycles (29.12 g/h), cars (44.47 g/h), wagons (176.54 g/h) and buses (141.52 g/h). The maximum deposition was 222.96 g/h from auto-rickshaws. The value for lead in smoke of different vehicles seems quite high when extrapolated to the large number of such vehicles for a longer time. The concentration of lead in roadside soil varied from 73.3 mg/kg (T and T closed colony) to 731.9 mg/kg (Sirki road bus-stop). The average content of lead in sewage soil of City Nala is 1250.6 mg/kg. The level of lead was more than WHO standards for such soils. The lead quantity in all 24 tube- well water samples, was slightly above the WHO standards (10 macro g/L).The results of this study were comparable to similar study in twin cities of Rawalpindi and islamabad. (author)

  2. Water balance at an arid site: a model validation study of bare soil evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Jones, T.L.; Campbell, G.S.; Gee, G.W.

    1984-03-01

    This report contains results of model validation studies conducted by Pacific Northwest Laboratory (PNL) for the Department of Energy's (DOE) National Low Level Waste Management Program (NLLWMP). The model validation tests consisted of using unsaturated water flow models to simulate water balance experiments conducted at the Buried Waste Test Facility (BWTF) located at the Department of Energy's Hanford site, near Richland, Washington. The BWTF is a lysimeter facility designed to collect field data on long-term water balance and radionuclide tracer movement. It has been operated by PNL for the NLLWMP since 1978. An experimental test case, developed from data collected at the BWTF, was used to evaluate predictions from different water flow models. The major focus of the validation study was to evaluate how the use of different evaporation models affected the accuracy of predictions of evaporation, storage, and drainage made by the whole model. Four evaporation models were tested including two empirical models and two mechanistic models. The empirical models estimate actual evaporation from potential evaporation; the mechanistic models describe water vapor diffusion within the soil profile and between the soil and the atmosphere in terms of fundamental soil properties, and transport processes. The water flow models that included the diffusion-type evaporation submodels performed best overall. The empirical models performed poorly in their description of evaporation and profile water storage during summer months. The predictions of drainage were supported quite well by the experimental data. This indicates that the method used to estimate hydraulic conductivity needed for the Darcian submodel was adequate. This important result supports recommendations for these procedures that were made previously based on laboratory results.

  3. Soil water sensing for climate change studies; Applicability of COSMOS and local sensor networks

    Science.gov (United States)

    Soil water sensors are used to characterize water content in the near-surface, the root zone and below for agricultural and ecosystem management, but only a few are capable of sensing soil volumes larger than a few hundred liters. Scientists with the USDA-ARS Conservation & Production Research Labor...

  4. Isotopic fractionation of soil water during evaporation

    International Nuclear Information System (INIS)

    Leopoldo, P.R.; Salati, E.; Matsui, E.

    1974-01-01

    The study of the variation of D/H relation in soil water during evaporation is studied. The isotopic fractionation of soil water has been observed in two soils of light and heavy texture. Soil columns were utilized. Soil water has been extracted in a system operated under low pressure and the gaseous hydrogen was obtained by the decomposition of water through the use of metalic uranium and was analysed in a GD-150 mass spectrometer for its deuterium content. The variation of the delta sub(eta) 0 / 00 value during the evaporation showed that for water held at potentials below 15 atm, the deuterium content of soil water stays practically constant. For water held at potentials higher than 15 atm, corresponding to the third stage of evaporation, there is a strong tendency of a constant increase of delta sub(eta) 0 / 00 of the remaining water [pt

  5. Molecular modelling studies of clay-exopolysaccharide complexes: Soil aggregation and water retention phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Henao, Lina J. [Centre de Recherches sur les Macromolecules Vegetales (CERMAV-CNRS), BP53, 38041 Grenoble cedex 9 (France); Mazeau, Karim, E-mail: karim.mazeau@cermav.cnrs.fr [Centre de Recherches sur les Macromolecules Vegetales (CERMAV-CNRS), BP53, 38041 Grenoble cedex 9 (France)

    2009-10-15

    In soils, the bacterial exopolysaccharides (EPS) aggregate mineral particles, enhancing their cohesion and their ability to retain water. These phenomena have been studied at the atomic scale by molecular modelling; we have considered seven rhizospheric polysaccharides interacting with the basal surfaces of montmorillonite. Models accounted for the aggregation phenomena induced by EPS: some segments of the polysaccharide were adsorbed on the mineral surfaces while others formed loops and bridges linking two surfaces. Adsorption energies were favourable and depended mostly on the interacting area. Cohesion of aggregates was estimated by the adhesion work, predicted values differed from one EPS to the other, suggesting that the chemical structure influences interaction strength with the mineral surface. Mechanisms of water uptake and release have also been investigated: hydration energies revealed that EPS strongly retain water at low water concentrations.

  6. Phosphorus dynamics in soils irrigated with reclaimed waste water or fresh water - A study using oxygen isotopic composition of phosphate

    Science.gov (United States)

    Zohar, I.; Shaviv, A.; Young, M.; Kendall, C.; Silva, S.; Paytan, A.

    2010-01-01

    Transformations of phosphate (Pi) in different soil fractions were tracked using the stable isotopic composition of oxygen in phosphate (??18Op) and Pi concentrations. Clay soil from Israel was treated with either reclaimed waste water (secondary, low grade) or with fresh water amended with a chemical fertilizer of a known isotopic signature. Changes of ??18Op and Pi within different soil fractions, during a month of incubation, elucidate biogeochemical processes in the soil, revealing the biological and the chemical transformation impacting the various P pools. P in the soil solution is affected primarily by enzymatic activity that yields isotopic equilibrium with the water molecules in the soil solution. The dissolved P interacts rapidly with the loosely bound P (extracted by bicarbonate). The oxides and mineral P fractions (extracted by NaOH and HCl, respectively), which are considered as relatively stable pools of P, also exhibited isotopic alterations in the first two weeks after P application, likely related to the activity of microbial populations associated with soil surfaces. Specifically, isotopic depletion which could result from organic P mineralization was followed by isotopic enrichment which could result from preferential biological uptake of depleted P from the mineralized pool. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with reclaimed waste water compared to the fertilizer treated soil. ?? 2010 Elsevier B.V.

  7. Spatial analysis of water infiltration in urban soils. Case study of Iasi municipality (Romania)

    Science.gov (United States)

    Cristian Vasilica, Secu; Ionut, Minea

    2013-04-01

    The post-communist period (after 1989) caused important changes in the functional structure of Iasi municipality. The partly dismantling of the industrial area, the urban sprawl against the periurban and agricultural space, the new infrastructure works, all these determined important changes of soils' physical and morphological properties (e.g. porosity, density, compaction, infiltration rate etc., in the first case, and changes in soil horizons, in the second case etc.). This study aims to prove the variability of physical properties through the combination of statistical and geostatistical methods intended for a correct spatial representation. Water infiltration in urban soils was analyzed in relation to land use and the age of parental materials. Field investigations consisted in measurements of the water infiltration (by the means of Turf Tech infiltrometer), resistance to penetration (penetrologger), moisture deficit (Theta Probe) and resistivity (EC) for 70 equally distanced points (750 m x 750 m) placed in a grid covering more than 33 km2. In the laboratory, there were determined several parameters as density, porosity (air pycnometer), gravimetric moisture and other hydrophysical indicators. Filed investigations results are very heterogeneous, because of the human intervention on soils. The curves of variation for the rate water infiltration in soils indicate a downward trend, from high values in first time interval (one minute), between 5000 and 60 mm/h-1, gradually decreasing to the interval of 5-10 minutes (between 30 and 1000 mm/ h-1 to a general trend of flattening after a large time interval (in the timeframe of 50-60 minutes, the infiltration rate ranges between 4 and 142 mm•h-1). The highest frequency (≥65%) caracterizes the infiltration rates between 20 and 65 mm•h-1. For each analyzed sector (residential areas, industrial areas, degraded lands, recreational areas - parks and botanical gardens, forests heterogeneous agricultural lands), the

  8. Tracer-aided studies of the movement of toxic elements in soil-plant-water systems under controlled conditions

    International Nuclear Information System (INIS)

    Stewart, J.W.B.; Bettany, J.R.; Rennie, D.A.; Huang, P.M.; McKercher, R.B.

    1975-01-01

    Techniques were developed and applied in a comparative study of the behaviour of arsenic and mercury in soil-plant-water systems in the context of soil contaminating toxic elements. The arsenic content of Saskatchewan soils ranged from 2 to 5 ppm. The results obtained suggested that arsenic adsorption by soil mica minerals would severely restrict the movement of arsenic in soils (e.g., into groundwater) under conditions of relatively low precipitation and near neutral pH. The mercury content of Canadian prairie soils ranged from 0.01 to 0.04 ppm. The results showed that relatively large amounts of mercury can be added to soils as HgCl 2 , HgSO 4 , or phenyl mercuric acetate (fungicide) and that subsequent accumulation by such representative crops as alfalfa, rape, wheat and rutabegas will be small, apparently as a result of a root barrier. (author)

  9. Modeling soil conservation, water conservation and their tradeoffs: a case study in Beijing.

    Science.gov (United States)

    Bai, Yang; Ouyang, Zhiyun; Zheng, Hua; Li, Xiaoma; Zhuang, Changwei; Jiang, Bo

    2012-01-01

    Natural ecosystems provide society with important goods and services. With the rapid increase in human populations and excessive utilization of natural resources, humans frequently enhance the production of some services at the expense of the others. Although the need for tradeoffs between conservation and development is urgent, the lack of efficient methods to assess such tradeoffs has impeded progress. Three land use strategy scenarios (development scenario, plan trend scenario and conservation scenario) were created to forecast potential changes in ecosystem services from 2007 to 2050 in Beijing, China. GIS-based techniques were used to map spatial and temporal distribution and changes in ecosystem services for each scenario. The provision of ecosystem services differed spatially, with significant changes being associated with different scenarios. Scenario analysis of water yield (as average annual yield) and soil retention (as retention rate per unit area) for the period 2007 to 2050 indicated that the highest values for these parameters were predicted for the forest habitat under all three scenarios. Annual yield/retention of forest, shrub, and grassland ranked the highest in the conservation scenario. Total water yield and soil retention increased in the conservation scenario and declined dramatically in the other two scenarios, especially the development scenario. The conservation scenario was the optimal land use strategy, resulting in the highest soil retention and water yield. Our study suggests that the evaluation and visualization of ecosystem services can effectively assist in understanding the tradeoffs between conservation and development. Results of this study have implications for planning and monitoring future management of natural capital and ecosystem services, which can be integrated into land use decision-making.

  10. Study on the Effects of Irrigation with Reclaimed Water on the Content and Distribution of Heavy Metals in Soil

    Directory of Open Access Journals (Sweden)

    Shibao Lu

    2016-03-01

    Full Text Available Reclaimed water is an important resource for irrigation, and exploration in making full use of it is an important way to alleviate water shortage. This paper analyzes the effects of irrigation with reclaimed water through field trials on the content and distribution of heavy metals in both tomatoes and the soil. By exploring the effects of reclaimed water after secondary treatment on the content and distribution characteristics of heavy metals in tomatoes and the heavy metal balance in the soil-crop system under different conditions, the study shows that there are no significant differences in the heavy metal content when the quantity of reclaimed water for irrigation varies. Reclaimed water for short-term irrigation does not cause pollution to either the soil environment or the crops. Nor will it cause the accumulation of heavy metals, and the index for the heavy metal content is far below the critical value of the national standard, which indicates that the vegetables irrigated with reclaimed water during their growth turn out to be free of pollutants. The heavy metals brought into the soil by reclaimed water are less than that taken away by the crops. The input and output quantities have only small effects on the heavy metal balance in the soil. This paper provides a reference for the evaluation and safety control of irrigation with reclaimed water.

  11. Study on Relationship between Dielectric Constant and Water Content of Rock-Soil Mixture by Time Domain Reflectometry

    Directory of Open Access Journals (Sweden)

    Daosheng Ling

    2016-01-01

    Full Text Available It is important to test water content of rock-soil mixtures efficiently and accurately to ensure both the quality control of compaction and assessment of the geotechnical engineering properties. To overcome time and energy wastage and probe insertion problems when using the traditional calibration method, a TDR coaxial test tube calibration arrangement using an upward infiltration method was designed. This arrangement was then used to study the influence of dry density, pore fluid conductivity, and soil/rock ratio on the relationship between water content and the dielectric constant of rock-soil mixtures. The results show that the empirical calibration equation forms for rock-soil mixtures can be the same as for soil materials. The effect of dry density on the calibration equation has the most significance and the influence of pore fluid conductivity can be ignored. The impact of variation of the soil/rock ratio can be neutralized by considering the effect of dry density in the calibration equation for the same kind of soil and rock. The empirical equations proposed by Zhao et al. show a good accuracy for rock-soil mixtures, indicating that the TDR method can be used to test gravimetric water content conveniently and efficiently without calibration in the field.

  12. A Time Series Analysis of Global Soil Moisture Data Products for Water Cycle Studies

    Science.gov (United States)

    Zhan, X.; Yin, J.; Liu, J.; Fang, L.; Hain, C.; Ferraro, R. R.; Weng, F.

    2017-12-01

    Water is essential for sustaining life on our planet Earth and water cycle is one of the most important processes of out weather and climate system. As one of the major components of the water cycle, soil moisture impacts significantly the other water cycle components (e.g. evapotranspiration, runoff, etc) and the carbon cycle (e.g. plant/crop photosynthesis and respiration). Understanding of soil moisture status and dynamics is crucial for monitoring and predicting the weather, climate, hydrology and ecological processes. Satellite remote sensing has been used for soil moisture observation since the launch of the Scanning Multi-channel Microwave Radiometer (SMMR) on NASA's Nimbus-7 satellite in 1978. Many satellite soil moisture data products have been made available to the science communities and general public. The soil moisture operational product system (SMOPS) of NOAA NESDIS has been operationally providing global soil moisture data products from each of the currently available microwave satellite sensors and their blends. This presentation will provide an update of SMOPS products. The time series of each of these soil moisture data products are analyzed against other data products, such as precipitation and evapotranspiration from other independent data sources such as the North America Land Data Assimilation System (NLDAS). Temporal characteristics of these water cycle components are explored against some historical events, such as the 2010 Russian, 2010 China and 2012 United States droughts, 2015 South Carolina floods, etc. Finally whether a merged global soil moisture data product can be used as a climate data record is evaluated based on the above analyses.

  13. Contribution to the study of pollution of soil and water in Oued El Maleh area (Mohammedia, Morocco)

    Science.gov (United States)

    El hajjaji, Souad; Dahchour, Abdelmalek; Belhsaien, Kamal; Zouahri, Abdelmjid; Moussadek, Rachid; Douaik, Ahmed

    2016-04-01

    In Morocco, diffuse ground and surface water pollution in irrigated areas has caused an increase in the risk of water and soil quality deterioration. This has generated a health and environmental risks. The present study was carried out in the Oued El Maleh region located 65 Km to the south of Rabat on the Moroccan Atlantic coast. It covers a surface area of 310 km2 where agriculture constitutes the main activity of the population. This region is considered as a very important agricultural area, known nationally for its high potential for market gardening. This intensification has been accompanied by an excessive use of agrochemical inputs and poor control of irrigation and drainage. Consequently, salinization phenomena and deterioration of soil structure as well as water are about to create an alarming situation. In order to assess the state of pollution of waters and soil in the region, our study focuses on the determination of physicochemical parameters for the quality of water and soil. The obtained results from sampled wells and surface water show relatively higher values of nitrate and conductivity exceeding Moroccan national standards and revealing net degradation of water quality; therefore the water can be considered not suitable for human consumption and can induce a degradation of soil. The results of the studied soil show that the pH of these soils is weakly to moderately basic; they are usually non-saline with organic matter content moderately filled. Moreover, very high concentrations of nutrients (potassium, phosphorus and nitrogen) were recorded, highlighting poor management fertilizing vegetable crops in the region of Oued El Maleh.

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

    Science.gov (United States)

    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...

  15. Soil-plant water status and wine quality: the case study of Aglianico wine (the ZOViSA project)

    Science.gov (United States)

    Bonfante, Antonello; Manna, Piero; Albrizio, Rossella; Basile, Angelo; Agrillo, Antonietta; De Mascellis, Roberto; Caputo, Pellegrina; Delle Cave, Aniello; Gambuti, Angelita; Giorio, Pasquale; Guida, Gianpiero; Minieri, Luciana; Moio, Luigi; Orefice, Nadia; Terribile, Fabio

    2014-05-01

    The terroir analysis, aiming to achieve a better use of environmental features with respect to plant requirement and wine production, needs to be strongly rooted on hydropedology. In fact, the relations between wine quality and soil moisture regime during the cropping season is well established. The ZOViSA Project (Viticultural zoning at farm scale) tests a new physically oriented approach to terroir analysis based on the relations between the soil-plant water status and wine quality. The project is conducted in southern Italy in the farm Quintodecimo of Mirabella Eclano (AV) located in the Campania region, devoted to quality Aglianico red wine production (DOC). The soil spatial distribution of study area (about 3 ha) was recognized by classical soil survey and geophysics scan by EM38DD; then the soil-plant water status was monitored for three years in two experimental plots from two different soils (Cambisol and Calcisol). Daily climate variables (temperature, solar radiation, rainfall, wind), daily soil water variables (through TDR probes and tensiometers), crop development (biometric and physiological parameters), and grape must and wine quality were monitored. The agro-hydrological model SWAP was calibrated and applied in the two experimental plots to estimate soil-plant water status in different crop phenological stages. The effects of crop water status on crop response and wine quality was evaluated in two different pedo-systems, comparing the crop water stress index with both: crop physiological measurements (leaf gas exchange, leaf water potential, chlorophyll content, LAI measurement), grape bunches measurements (berry weight, sugar content, titratable acidity, etc.) and wine quality (aromatic response). Finally a "spatial application" of the model was carried out and different terroirs defined.

  16. Soil and Water Conservation Prioritization Using Geospatial Technology – a Case Study of Part of Subarnarekha Basin, Jharkhand, India

    Directory of Open Access Journals (Sweden)

    Firoz Ahmad

    2017-08-01

    Full Text Available Changing patterns of land use and land cover have exploited the natural resources. Soil, water and forests are degraded, both quantitatively and qualitatively. Deforestation in recent years has led to changes in the environment and more of soil erosion and loss of potable water. In order to conserve and sustainably use soil and water, a watershed management approach is necessary. It helps in restoring water by increasing the infiltration and reducing the erosion of soil. Such measures should be propagated in rainfall deficit areas. The present study has attempted to study the upper watershed part of Subarnarekha basin in Jharkhand state of India. Remote sensing satellite data (Landsat 8 OLI/TIRS 2013 was used for delineation of the land use/land cover and vegetation index maps. Several thematic layers like slope, drainage and rainfall were integrated to achieve a priority area map using spatial multicriteria decision making. It delineated high medium and low priority areas within the watershed for soil and water conservation. The high priority area was 16.63% of the total study area. Further, the causes were analysed and conservation measures proposed.

  17. Soils and water [Chapter 18

    Science.gov (United States)

    Goran Berndes; Heather Youngs; Maria Victoria Ramos Ballester; Heitor Cantarella; Annette L. Cowie; Graham Jewitt; Luiz Antonio Martinelli; Dan Neary

    2015-01-01

    Bioenergy production can have positive or negative impacts on soil and water. To best understand these impacts, the effects of bioenergy systems on water and soil resources should be assessed as part of an integrated analysis considering environmental, social and economic dimensions. Bioenergy production systems that are strategically integrated in the landscape to...

  18. Bioconcentration of some macrominerals in soil, forage and buffalo hair continuum: A case study on pasture irrigated with sewage water.

    Science.gov (United States)

    Khan, Zafar Iqbal; Ahmad, Kafeel; Ashraf, Iqra; Gondal, Sumaira; Sher, Muhammad; Hayat, Zafar; Laudadio, Vito; Tufarelli, Vincenzo

    2015-05-01

    The present study aimed to evaluate the bioaccumulation of some macrominerals in grazing buffaloes fed forage irrigated with sewage water or canal water. In particular, the transfer of sodium (Na), magnesium (Mg), potassium (K) and calcium (Ca) from soil to plant and in turn to animals was evaluated under sub-tropical environmental conditions. Samples of soil, forage and buffalo hair were collected and digested by wet method. Sodium and K concentrations were significantly higher in the soil but lower in the forages; however, Mg and Ca concentrations in both soil and forages were higher. The correlation between soil, forage and hair showed an imbalanced flow of Na, Mg and K and a balanced flow of Ca from soil to forage and then to animals. Based on the findings, the highest rates of transfer of minerals were found for sewage water treatment, whereas lowest rates were found for canal water treatment, except for Na. As the transfer of minerals depends on their bioavailability, the highest values may be due to the high rates of mineral uptake by plants. Thus, the high transfer rate of some elements by plants could become toxic in future causing detrimental effect to grazing livestock.

  19. Simulation models: a current indispensable tool in studies of the continuous water-soil-plant - atmosphere

    International Nuclear Information System (INIS)

    Lopez Seijas, Teresa; Gonzalez, Felicita; Cid, G.; Osorio, Maria de los A.; Ruiz, Maria Elena

    2008-01-01

    Full text: This work assesses the current use of simulation models as a tool useful and indispensable for the advancement in the research and study of the processes related to the continuous water-soil - plant-atmosphere. In recent years they have reported in the literature many jobs where these modeling tools are used as a support to the decision-making process of companies or organizations in the agricultural sphere and in Special for the design of optimal management of irrigation and fertilization strategies of the crops. Summarizes some of the latest applications reported with respect to the use of water transfers and solutes, such simulation models mainly to nitrate leaching and groundwater contamination problems. On the other hand also summarizes important applications of simulation models of growth of cultivation for the prediction of effects on the performance of different conditions of water stress, and finally some other applications on the management of the different irrigation technologies as kingpins, superfiail irrigation and drip irrigation. Refer also the main work carried out in Cuba. (author)

  20. Effects of soil and water conservation practices on selected soil ...

    African Journals Online (AJOL)

    Although different types of soil and water conservation practices (SWCPs) were introduced, the sustainable use of these practices is far below expectations, and soil erosion continues to be a severe problem in Ethiopia. Therefore, this study was conducted at Debre Yakobe Micro-Watershed (DYMW), Northwest Ethiopia ...

  1. Water movement in stony soils: The influence of stoniness on soil water content profiles

    Science.gov (United States)

    Novak, Viliam; Knava, Karol

    2010-05-01

    WATER MOVEMENT IN STONY SOILS: THE INFLUENCE OF STONINESS ON SOIL WATER CONTENT PROFILES Viliam Novák, Karol Kňava Institute of Hydrology, Slovak Academy of Sciences, Racianska 75, 831 02 Bratislava 3, Slovakia, e-mail: novak@uh.savba.sk Soils containing rock fragments are widespread over the world, on Europe such soil account for 30%, 60% in Mediterranean region. In comparison to fine earth soils (soil particles are less then 2 mm) stony soils contain rock fragments characterized by the low retention capacity and hydraulic conductivity. So, for stony soils -in comparison to the fine-earth soils - is typical lower hydraulic conductivity and retention capacity, which lead to the decrease decrease of infiltration rate and low water retention. So, water movement and its modeling in stony soil would differ from fine earth (usually agricultural) soil. The aim of this contribution is to demonstrate the differences in water movement in homogeneous soil (fine earth) and stony soil. The influence of different stoniness on soil water content and soil water dynamics was studied too. Windthrow at High Tatra mountains in Slovakia (November 2004) cleared nearly 12 000 ha of 80 year conifers and this event initiated complex research of windthrow impact on the ecosystem. The important part of this study was water movement in impacted area. Specific feature of the soil in this area was moraine soil consisting of fine earth, characterized as silty sand, with the relative stone content up to 0.49, increasing with depth. Associated phenomenon to the forest clearing is the decrease of rain interception and higher undercanopy precipitation. Conifers interception capacity can be three times higher than low canopy interception, and can reach up to 40% of annual precipitation in Central Europe. Stones in the soil are decreasing infiltration rate, but paradoxically increased understorey precipitation and followingly the increased cumulative infiltration led to the increase of the soil

  2. The impact of water vapor diodes on soil water redistribution

    Science.gov (United States)

    Wang, Zhuangji; Ankeny, Mark; Horton, Robert

    2017-09-01

    Diurnal soil temperature fluctuations are the prime cause for subsurface water vapor fluxes. In arid and semi-arid areas, water vapor flux is the dominant means of soil water redistribution. The directions of water vapor flux shift from upward to downward diurnally following the variations of the soil thermal gradient. A water vapor diode (WVD), acting as a check valve, allows water vapor flux in one direction but heat flux in both directions. By installing a subsurface WVD, it is possible to impose direction-controlled vapor fluxes, and WVDs can be used to accumulate or remove water in particular soil layers. The egg carton shape, with pores situated at selected peaks and valleys, is a possible design for WVDs. In this study, we provide the concept and the properties of the ideal WVDs, and we discuss four WVD configurations to control soil water redistribution. Numerical simulation is used to evaluate the impacts of the ideal WVDs. The results indicate that WVDs can increase local water contents by at least 0.1 m3m-3 in a silt loam. For a fixed initial water and thermal condition, the effect of WVDs is related to the deployment depth and distance between two consecutive WVDs. WVDs can be used to manipulate soil water redistribution and accumulate water at specific depths to support plant growth. The numerical simulation results indicate the potential effectiveness of the ideal WVDs, and field tests should be performed to determine their function under specific soil conditions.

  3. A method to study response of large trees to different amounts of available soil water

    Science.gov (United States)

    D.H. Marx; Shi-Jean S. Sung; J.S. Cunningham; M.D. Thompson; L.M. White

    1995-01-01

    A method was developed to manipulate available soil water on large trees by intercepting thrufall with gutters placed under tree canopies and irrigating the intercepted thrufall onto other trees. With this design, trees were exposed for 2 years to either 25% less thrufall, normal thrufall, or 25% additional thrufall.Undercanopy construction in these plots moderately...

  4. Studying water in the soil-plant-atmosphere continuum: a bibliographic guide to techniques

    CSIR Research Space (South Africa)

    Scholes, RJ

    1989-01-01

    Full Text Available The parameters used to describe the flow of water, and energy to a lesser extent, through the soil-plant-atmosphere continuum are reviewed and the techniques used for estimating their values contrasted. The measurements which are necessary...

  5. Effects of middle-term land reclamation on nickel soil-water interaction: a case study from reclaimed salt marshes of Po River Delta, Italy.

    Science.gov (United States)

    Di Giuseppe, Dario; Melchiorre, Massimiliano; Faccini, Barbara; Ferretti, Giacomo; Coltorti, Massimo

    2017-09-26

    Reclaimed salt marshes are fragile environments where water salinization and accumulation of heavy metals can easily occur. This type of environment constitutes a large part of the Po River Delta (Italy), where intensive agricultural activities take place. Given the higher Ni background of Po River Delta soils and its water-soluble nature, the main aim of this contribution is to understand if reclamation can influence the Ni behavior over time. In this study, we investigated the geochemical features of 40 soils sampled in two different localities from the Po River Delta with different reclamation ages. Samples of salt marsh soils reclaimed in 1964 were taken from Valle del Mezzano while soils reclaimed in 1872 were taken nearby Codigoro town. Batch solubility tests and consecutive determination of Ni in pore-water were compared to bulk physicochemical compositions of soils. Bulk Ni content of the studied soils is naturally high, since these soils originated from Po River sediments derived from the erosion of ultramafic rocks. Moreover, it seems that Ni concentration increases during soil evolution, being probably related to the degradation of serpentine. Instead, the water-soluble Ni measured in the leaching tests is greater in soils recently reclaimed compared to the oldest soils. Soil properties of two soil profiles from a reclaimed wetland area were examined to determine soil evolution over one century. Following reclamation, pedogenic processes of the superficial horizons resulted in organic matter mineralization, pH buffer, and a decrease of Ni water solubility from recently to evolved reclaimed soil.

  6. Study on the water retention effect of compound soil of arsenic sandstone and sand under the condition of typical crop planting

    Science.gov (United States)

    Liu, S. Y.; Wang, N.; Xie, J. C.; Jiang, R. G.; Zhao, M. L.

    2017-08-01

    Arsenic sandstone is the main reason of soil erosion in the Mu Us Sandy Land, simultaneously was proved to be a kind of good water retaining agent. In order to provide references for the utilization of water and soil resources and the prevention and control of desertification and soil erosion of the southern margin of Mu Us Sandy Land, on the basis of earlier studies the farmland experiments of compound soil with three ratios of 1:1, 1:2 and 1:5 between arsenic sandstone and sand under maize planting patterns were designed, whose experimental process was divided into six stages according to the crop growth status. The results showed that the soil moisture content was highest in the layer of 0˜40cm where the compound soil mainly concentrated in, which was related to the potent water retention of arsenic sandstone and strong water permeability of undisturbed sandy soil. The variation coefficients in the soil of 1:1 and 1:2 were more stable and evenly distributed. The compound soil can effectively improve the soil water retention capacity, and prolong the storage time of soil water. Among them, water loss rate in soil of 1:1 and 1:2 were lower. The coefficient of variation also confirms that the water distributions of the two types of soil were more uniform and stable. Besides illustrating the effects of the soil amelioration measures on spatial and temporal variation of soil moisture content and the improvement of soil water regime, the study provides some references for the development and utilization of agriculture in Mu Us Sandy Land.

  7. Model validation studies of water flow and radionuclide transport in vegetated soils using lysimeter data

    Energy Technology Data Exchange (ETDEWEB)

    Butler, A.; Jining Chen [Imperial College of Science, Technology and Medicine, London (United Kingdom)] [and others

    1996-09-01

    involved in tritium assessment, with the opportunity to test this component of their codes. In total six groups participated in the study, three groups undertaking solely hydrological simulations, the other three also including radionuclide transport. One factor which was soon identified was, owing to previous applications and development objectives, some of the models had structural forms which were inappropriate for the lysimeter scenario. In many cases participants found that they had difficulty applying the fixed water table and specified concentration boundary conditions to their models. This immediately introduced a degree of uncertainty into the model simulations. In other instances the onset of free drainage once the soil moisture reached a specified 'field capacity' led to marked discrepancies between simulated and observed hydrological data. In addition, the manner in which this free drainage mobilised radionuclides also had an important bearing on soil radioactivity profiles. The manner in which modelers selected parameter values was an important aspect of the user interpretation component of the study. Where appropriate, modelers sought to derive parameter values from the supplied data. However, in one instance a more generic approach to the identification of hydrological parameters resulted in model behaviour which was markedly different from the experimental data. This identified a discrepancy in the soil physical textural analysis and the measured hydraulic parameters compared with standard classification schemes. The effect of user interpretation on parameter selection was also clearly seen in the choice of the soil sorption K{sub d} values. One group tended to take a rather conservative view in order to provide a 'worst case' scenario, whereas in the other erred towards significantly higher values. The degree of discretization used by the various models played an important role in the dispersive transport of radionuclides up the soil

  8. Model validation studies of water flow and radionuclide transport in vegetated soils using lysimeter data

    International Nuclear Information System (INIS)

    Butler, A.; Jining Chen

    1996-09-01

    assessment, with the opportunity to test this component of their codes. In total six groups participated in the study, three groups undertaking solely hydrological simulations, the other three also including radionuclide transport. One factor which was soon identified was, owing to previous applications and development objectives, some of the models had structural forms which were inappropriate for the lysimeter scenario. In many cases participants found that they had difficulty applying the fixed water table and specified concentration boundary conditions to their models. This immediately introduced a degree of uncertainty into the model simulations. In other instances the onset of free drainage once the soil moisture reached a specified 'field capacity' led to marked discrepancies between simulated and observed hydrological data. In addition, the manner in which this free drainage mobilised radionuclides also had an important bearing on soil radioactivity profiles. The manner in which modelers selected parameter values was an important aspect of the user interpretation component of the study. Where appropriate, modelers sought to derive parameter values from the supplied data. However, in one instance a more generic approach to the identification of hydrological parameters resulted in model behaviour which was markedly different from the experimental data. This identified a discrepancy in the soil physical textural analysis and the measured hydraulic parameters compared with standard classification schemes. The effect of user interpretation on parameter selection was also clearly seen in the choice of the soil sorption K d values. One group tended to take a rather conservative view in order to provide a 'worst case' scenario, whereas in the other erred towards significantly higher values. The degree of discretization used by the various models played an important role in the dispersive transport of radionuclides up the soil profile. This, in turn, revealed a strong

  9. Problem - oriented studies on plant - soil - water relations : sowing strategies for maize in rainfed agriculture in Southern Mozambique : water management in bog relicts in the Netherlands

    NARCIS (Netherlands)

    Schouwenaars, J.M.

    1990-01-01

    Plant-soil-water models are applied in two case studies. Attention is given to the desired level of accuracy in (agro-)hydrological. research when applied in problem-oriented studies. In the case studies it is shown that when decision criteria are only roughly known and when only

  10. Prediction of soil water erosion risk within GIS-case study of Beni Amrane Dam catchment (North of Algeria)

    Science.gov (United States)

    Touahir, S.; Khenter, K.; Remini, B.; Saad, H.

    2017-08-01

    Isser River is one of North Algeria’s major resources. It is vulnerable to water soil erosion because of favourable conjunctions of different geomorphological, hydro-climatic and lithologic factors. This case study has been carried out on the Beni Amrane dam Catchment, which is located in the bottom of Isser River, in North Algeria. The study involves a mapping of main factors of water erosion: rainfall erosivity, soil erodibility, slope and land use. Essentially a data mapping specification analysis shows, on each factor, how to identify the areas that are prone to water erosion. 04 classes of multifactorial vulnerability to water erosion have been identified: areas with low vulnerability (10 per cent); area with middle vulnerability (49 per cent); areas with high and very high vulnerability (38 per cent and 3 per cent). This could be a first guidance document for a rational use of land in the region and better secure the Beni Amrane dam against reservoir siltation.

  11. Three Principles of Water Flow in Soils

    Science.gov (United States)

    Guo, L.; Lin, H.

    2016-12-01

    Knowledge of water flow in soils is crucial to understanding terrestrial hydrological cycle, surface energy balance, biogeochemical dynamics, ecosystem services, contaminant transport, and many other Critical Zone processes. However, due to the complex and dynamic nature of non-uniform flow, reconstruction and prediction of water flow in natural soils remain challenging. This study synthesizes three principles of water flow in soils that can improve modeling water flow in soils of various complexity. The first principle, known as the Darcy's law, came to light in the 19th century and suggested a linear relationship between water flux density and hydraulic gradient, which was modified by Buckingham for unsaturated soils. Combining mass balance and the Buckingham-Darcy's law, L.A. Richards quantitatively described soil water change with space and time, i.e., Richards equation. The second principle was proposed by L.A. Richards in the 20th century, which described the minimum pressure potential needed to overcome surface tension of fluid and initiate water flow through soil-air interface. This study extends this principle to encompass soil hydrologic phenomena related to varied interfaces and microscopic features and provides a more cohesive explanation of hysteresis, hydrophobicity, and threshold behavior when water moves through layered soils. The third principle is emerging in the 21st century, which highlights the complex and evolving flow networks embedded in heterogeneous soils. This principle is summarized as: Water moves non-uniformly in natural soils with a dual-flow regime, i.e., it follows the least-resistant or preferred paths when "pushed" (e.g., by storms) or "attracted" (e.g., by plants) or "restricted" (e.g., by bedrock), but moves diffusively into the matrix when "relaxed" (e.g., at rest) or "touched" (e.g., adsorption). The first principle is a macroscopic view of steady-state water flow, the second principle is a microscopic view of interface

  12. Compost improves urban soil and water quality

    Science.gov (United States)

    Construction in urban zones compacts the soil, which hinders root growth and infiltration and may increase erosion, which may degrade water quality. The purpose of our study was to determine the whether planting prairie grasses and adding compost to urban soils can mitigate these concerns. We simula...

  13. Stable isotope study of soil water, WIPP site New Mexico: estimation of recharge to Rustler aquifers

    International Nuclear Information System (INIS)

    Campbell, A.R.; Phillips, F.M.; Vanlandingham, R.J.

    1996-01-01

    Defining the hydrologic setting of the Waste Isolation Pilot Plant (WIPP) is an important step for site characterization and performance assessment. From past research there is a controversy about the timing of recharge to the aquifers in the Rustler Formation which overlies the repository. The stable isotopic composition (δD and δD 18 O) of the water has been used in this argument but with ambiguous conclusions. Soil cores from WIPP have been sampled for δD, δD 18 O, Cl - and water content. The data indicate that there is a small amount of infiltration (.2 to 2 mm/yr) through the desert soil. The δD and δD 18 O analyses suggest that meteoric water in the area can have a stable isotope composition similar to that in the Rustler Fm. Further supporting evidence come from the isotopic composition of drip and pool waters in nearby Carlsbad Caverns. This indicates that the water in the Rustler Fm. need not have been recharged in the past (>10,000 yrs.) under different climatic conditions. (author) 8 figs., 2 tabs., 16 refs

  14. Soil - water relationships in the Weatherley catchment, South Africa ...

    African Journals Online (AJOL)

    Soil water content is influenced by soil and terrain factors, but studies on the predictive value of diagnostic horizon type for the degree and duration of wetness seem to be lacking. The aim of this paper is therefore to describe selected hydropedological soil-water relationships for important soils and diagnostic horizons in the ...

  15. Estimates of Soil Moisture Using the Land Information System for Land Surface Water Storage: Case Study for the Western States Water Mission

    Science.gov (United States)

    Liu, P. W.; Famiglietti, J. S.; Levoe, S.; Reager, J. T., II; David, C. H.; Kumar, S.; Li, B.; Peters-Lidard, C. D.

    2017-12-01

    Soil moisture is one of the critical factors in terrestrial hydrology. Accurate soil moisture information improves estimation of terrestrial water storage and fluxes, that is essential for water resource management including sustainable groundwater pumping and agricultural irrigation practices. It is particularly important during dry periods when water stress is high. The Western States Water Mission (WSWM), a multiyear mission project of NASA's Jet Propulsion Laboratory, is operated to understand and estimate quantities of the water availability in the western United States by integrating observations and measurements from in-situ and remote sensing sensors, and hydrological models. WSWM data products have been used to assess and explore the adverse impacts of the California drought (2011-2016) and provide decision-makers information for water use planning. Although the observations are often more accurate, simulations using land surface models can provide water availability estimates at desired spatio-temporal scales. The Land Information System (LIS), developed by NASA's Goddard Space Flight Center, integrates developed land surface models and data processing and management tools, that enables to utilize the measurements and observations from various platforms as forcings in the high performance computing environment to forecast the hydrologic conditions. The goal of this study is to implement the LIS in the western United States for estimates of soil moisture. We will implement the NOAH-MP model at the 12km North America Land Data Assimilation System grid and compare to other land surface models included in the LIS. Findings will provide insight into the differences between model estimates and model physics. Outputs from a multi-model ensemble from LIS can also be used to enhance estimated reliability and provide quantification of uncertainty. We will compare the LIS-based soil moisture estimates to the SMAP enhanced 9 km soil moisture product to understand the

  16. Complex linkage between soil, soil water, atmosphere and Eucalyptus Plantations

    Science.gov (United States)

    Shukla, C.; Tiwari, K. N.

    2017-12-01

    Eucalyptus is most widely planted genus grown in waste land of eastern region of India to meet the pulp industry requirements. Sustainability of these plantations is of concern because in spite of higher demand water and nutrients of plantations, they are mostly planted on low-fertility soils. This study has been conducted to quantify effect of 25 years old, a fully established eucalyptus plantations on i.) Alteration in physico-chemical and hydrological properties of soil of eucalyptus plantation in comparison to soil of natural grassland and ii.) Spatio-temporal variation in soil moisture under eucalyptus plantations. Soil physico-chemical properties of two adjacent plots covered with eucatuptus and natural grasses were analyzed for three consecutive depths (i.e. 0-30 cm, 30-60 cm and 60-90 cm) with five replications in each plot. Soil infiltration rate and saturated hydraulic conductivity (Ks) were measured in-situ to incorporate the influence of macro porosity caused due to roots of plantations. Daily soil moisture at an interval of 10 cm upto 160 cm depth with 3 replications and Leaf Area Index (LAI) at an interval of 15 days with 5 replications were recorded over the year. Significant variations found at level of 0.05 between soil properties of eucalyptus and natural grass land confirm the effect of plantations on soil properties. Comparative results of soil properties show significant alteration in soil texture such as percent of sand, organic matter and Ks found more by 20%, 9% and 22% respectively in eucalyptus plot as compare to natural grass land. Available soil moisture (ASM) was found constantly minimum in top soil excluding rainy season indicate upward movement of water and nutrients during dry season. Seasonal variation in temperature (T), relative humidity (RH) and leaf area index (LAI) influenced the soil moisture extraction phenomenon. This study clearly stated the impact of long term establishment of eucalyptus plantations make considerable

  17. A study of the utilization of ERTS-1 data from the Wabash River Basin. [soil mapping, crop identification, water resources

    Science.gov (United States)

    Landgrebe, D. A. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. In soil association mapping, computerized analysis of ERTS-1 MSS data has yielded images which will prove useful in the ongoing Cooperative Soil Survey program, involving the Soil Conservation Service of USDA and other state and local agencies. In the present mode of operation, a soil survey for a county may take up to 5 years to be completed. Results indicate that a great deal of soils information can be extracted from ERTS-1 data by computer analysis. This information is expected to be very valuable in the premapping conference phase of a soil survey, resulting in more efficient field operations during the actual mapping. In the earth surface features mapping effort it was found that temporal data improved the classification accuracy of forest classification in Tippecanoe County, Indiana. In water resources study a severe scanner look angle effect was observed in the aircraft scanner data of a test lake which was not present in ERTS-1 data of the same site. This effect was greatly accentuated by surface roughness caused by strong winds. Quantitative evaluation of urban features classification in ERTS-1 data was obtained. An 87.1% test accuracy was obtained for eight categories in Marion County, Indiana.

  18. Soil physics and the water management of spatially variable soils

    International Nuclear Information System (INIS)

    Youngs, E.G.

    1983-01-01

    The physics of macroscopic soil-water behaviour in inert porous materials has been developed by considering water flow to take place in a continuum. This requires the flow region to consist of an assembly of representative elementary volumes, repeated throughout space and small compared with the scale of observations. Soil-water behaviour in swelling soils may also be considered as a continuum phenomenon so long as the soil is saturated and swells and shrinks in the normal range. Macroscale heterogeneity superimposed on the inherent microscale heterogeneity can take many forms and may pose difficulties in the definition and measurement of soil physical properties and also in the development and use of predictive theories of soil-water behaviour. Thus, measurement techniques appropriate for uniform soils are often inappropriate, and criteria for soil-water management, obtained from theoretical considerations of behaviour in equivalent uniform soils, are not applicable without modification when there is soil heterogeneity. The spatial variability of soil-water properties is shown in results from field experiments concerned with water flow measurements; these illustrate both stochastic and deterministic heterogeneity in soil-water properties. Problems of water management of spatially variable soils when there is stochastic heterogeneity appear to present an insuperable problem in the application of theory. However, for soils showing deterministic heterogeneity, soil-water theory has been used in the solution of soil-water management problems. Thus, scaling using similar media theory has been applied to the infiltration of water into soils that vary over a catchment area. Also, the drain spacing to control the water-table height in soils in which the hydraulic conductivity varies with depth has been calculated using groundwater seepage theory. (author)

  19. WATER AS A REAGENT FOR SOIL REMEDIATION

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-11-12

    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.

  20. Characterization of soil water content variability and soil texture using GPR groundwave techniques

    Energy Technology Data Exchange (ETDEWEB)

    Grote, K.; Anger, C.; Kelly, B.; Hubbard, S.; Rubin, Y.

    2010-08-15

    Accurate characterization of near-surface soil water content is vital for guiding agricultural management decisions and for reducing the potential negative environmental impacts of agriculture. Characterizing the near-surface soil water content can be difficult, as this parameter is often both spatially and temporally variable, and obtaining sufficient measurements to describe the heterogeneity can be prohibitively expensive. Understanding the spatial correlation of near-surface soil water content can help optimize data acquisition and improve understanding of the processes controlling soil water content at the field scale. 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 data were acquired with 450 MHz and 900 MHz antennas, and measurements of the GPR groundwave were used to estimate soil water content at four different times. Additional water content estimates were obtained using time domain reflectometry measurements, and soil texture measurements were also acquired. Variograms were calculated for each set of measurements, and comparison of these variograms showed that the horizontal spatial correlation was greater for deeper water content measurements than for shallower measurements. Precipitation and irrigation were both shown to increase the spatial variability of water content, while shallowly-rooted vegetation decreased the variability. Comparison of the variograms of water content and soil texture showed that soil texture generally had greater small-scale spatial correlation than water content, and that the variability of water content in deeper soil layers was more closely correlated to soil texture than were shallower water content measurements. Lastly, cross-variograms of soil texture and water content were calculated, and co-kriging of water content estimates and soil texture

  1. Application of time-lapse ERT to Characterize Soil-Water-Disease Interactions of Citrus Orchard - Case Study

    Science.gov (United States)

    Peddinti, S. R.; Kbvn, D. P.; Ranjan, S.; Suradhaniwar, S.; J, P. A.; R M, G.

    2015-12-01

    Vidarbha region in Maharashtra, India (home for mandarin Orange) experience severe climatic uncertainties resulting in crop failure. Phytopthora are the soil-borne fungal species that accumulate in the presence of moisture, and attack the root / trunk system of Orange trees at any stage. A scientific understanding of soil-moisture-disease relations within the active root zone under different climatic, irrigation, and crop cycle conditions can help in practicing management activities for improved crop yield. In this study, we developed a protocol for performing 3-D time-lapse electrical resistivity tomography (ERT) at micro scale resolution to monitor the changes in resistivity distribution within the root zone of Orange trees. A total of 40 electrodes, forming a grid of 3.5 m x 2 m around each Orange tree were used in ERT survey with gradient and Wenner configurations. A laboratory test on un-disturbed soil samples of the region was performed to plot the variation of electrical conductivity with saturation. Curve fitting techniques were applied to get the modified Archie's model parameters. The calibrated model was further applied to generate the 3-D soil moisture profiles of the study area. The point estimates of soil moisture were validated using TDR probe measurements at 3 different depths (10, 20, and 40 cm) near to the root zone. In order to understand the effect of soil-water relations on plant-disease relations, we performed ERT analysis at two locations, one at healthy and other at Phytopthora affected Orange tree during the crop cycle, under dry and irrigated conditions. The degree to which an Orange tree is affected by Phytopthora under each condition is evaluated using 'grading scale' approach following visual inspection of the canopy features. Spatial-temporal distribution of moisture profiles is co-related with grading scales to comment on the effect of climatic and irrigation scenarios on the degree and intensity of crop disease caused by Phytopthora.

  2. Relation of some Soil Water-transmission Characteristics to some ...

    African Journals Online (AJOL)

    A study was conducted to determine soil physical properties of an Alfisol constituting the soil of a proposed tillage and irrigation water management field laboratory and to relate the physical properties to the water transmission characteristics. The soil was found to be mainly sandy loam on the surface with high infiltration ...

  3. Determination of radionuclide levels in soil and water around ...

    African Journals Online (AJOL)

    The study of the radionuclide concentration levels in soil and water samples in Eagle, Atlas and rock cement companies in Port Harcourt was carried out. Soil and water samples collected from the respective premises were analyzed using the gamma -ray spectrometry. The average absorbed dose rates of the soil samples ...

  4. Effectiveness of submerged drains in reducing subsidence of peat soils in agricultural use, and their effects on water management and nutrient loading of surface water: modelling of a case study in the western peat soil area of The Netherlands

    Science.gov (United States)

    Hendriks, Rob F. A.; van den Akker, Jan J. A.

    2017-04-01

    Effectiveness of submerged drains in reducing subsidence of peat soils in agricultural use, and their effects on water management and nutrient loading of surface water: modelling of a case study in the western peat soil area of The Netherlands In the Netherlands, about 8% of the area is covered by peat soils. Most of these soils are in use for dairy farming and, consequently, are drained. Drainage causes decomposition of peat by oxidation and accordingly leads to surface subsidence and greenhouse gas emission. Submerged drains that enhance submerged infiltration of water from ditches during the dry and warm summer half year were, and are still, studied in The Netherlands as a promising tool for reducing peat decomposition by raising groundwater levels. For this purpose, several pilot field studies in the Western part of the Dutch peat area were conducted. Besides the effectiveness of submerged drains in reducing peat decomposition and subsidence by raising groundwater tables, some other relevant or expected effects of these drains were studied. Most important of these are water management and loading of surface water with nutrients nitrogen, phosphorus and sulphate. Because most of these parameters are not easy to assess and all of them are strongly depending on the meteorological conditions during the field studies some of these studies were modelled. The SWAP model was used for evaluating the hydrological results on groundwater table and water discharge and recharge. Effects of submerged drains were assessed by comparing the results of fields with and without drains. An empirical relation between deepest groundwater table and subsidence was used to convert effects on groundwater table to effects on subsidence. With the SWAP-ANIMO model nutrient loading of surface water was modelled on the basis of field results on nutrient concentrations . Calibrated models were used to assess effects in the present situation, as thirty-year averages, under extreme weather

  5. Soil-water content characterisation in a modified Jarvis-Stewart model: A case study of a conifer forest on a shallow unconfined aquifer

    Science.gov (United States)

    Guyot, Adrien; Fan, Junliang; Oestergaard, Kasper T.; Whitley, Rhys; Gibbes, Badin; Arsac, Margaux; Lockington, David A.

    2017-01-01

    Groundwater-vegetation-atmosphere fluxes were monitored for a subtropical coastal conifer forest in South-East Queensland, Australia. Observations were used to quantify seasonal changes in transpiration rates with respect to temporal fluctuations of the local water table depth. The applicability of a Modified Jarvis-Stewart transpiration model (MJS), which requires soil-water content data, was assessed for this system. The influence of single depth values compared to use of vertically averaged soil-water content data on MJS-modelled transpiration was assessed over both a wet and a dry season, where the water table depth varied from the surface to a depth of 1.4 m below the surface. Data for tree transpiration rates relative to water table depth showed that trees transpire when the water table was above a threshold depth of 0.8 m below the ground surface (water availability is non-limiting). When the water table reached the ground surface (i.e., surface flooding) transpiration was found to be limited. When the water table is below this threshold depth, a linear relationship between water table depth and the transpiration rate was observed. MJS modelling results show that the influence of different choices for soil-water content on transpiration predictions was insignificant in the wet season. However, during the dry season, inclusion of deeper soil-water content data improved the model performance (except for days after isolated rainfall events, here a shallower soil-water representation was better). This study demonstrated that, to improve MJS simulation results, appropriate selection of soil water measurement depths based on the dynamic behaviour of soil water profiles through the root zone was required in a shallow unconfined aquifer system.

  6. Study of downward movement of soil water in unsaturated zones using isotopic techniques. Part of a coordinated programme on studying physical and isotopic behaviour of soil moisture in the zones of aeration

    International Nuclear Information System (INIS)

    Sajjad, M.I.

    1984-08-01

    Experiments carried out to study the relative contribution from canal system, precipitation and irrigated fields to water table are described. The normal delta of irrigation water does not seem to have any appreciable effect on the water table through heavy textured soil. The contribution from irrigated fields and rains through sandy soils is significant. However, the groundwater rise (water logging) is mainly due to the infiltration from the canal system. Flow velocities at 1 m depth and 20 vol. % moisture are of the order of 16 m/a and 1.6 m/a for sandy and loamy soils respectively. The contribution from irrigated fields and rains to groundwater recharge is considered to be less than 30%

  7. Effects of progressive soil water deficit on growth, and physiological and biochemical responses of populus euphratica in arid area: a case study in China

    International Nuclear Information System (INIS)

    Yang, Y.; Chen, Y.; Li, W.; Zhu, C.

    2015-01-01

    The aim of this study was to investigate the responses of Populus euphratica seedlings under a short-term soil water deficit. To mimic natural conditions in which drought stress develops gradually, stress was imposed by subjecting plants to a gradual decrease of soil water content for a period of 21 d. We studied growth, physiological and biochemical responses to progressive soil water deficit of potted Populus euphratica seedlings at outdoors. Results showed that, in 6 d of water withholding, the soil moisture content decreased to a slight drought stress level, and it reached a severe drought stress level after 15 d of water withholding in July. In the process of soil water declining from saturated to severe drought levels, the increasing soil water deficit resulted in decreases in the height, stem base diameter, number of lateral branches. Leaf predawn water potential decreased after 15 d of withholding irrigation. After 21 d of withholding irrigation, actual photochemical efficiency of photosystem II (PSII) in light-adapted leaves and photochemical quenching coefficient decreased, respectively; the peroxidase activity, the content of chlorophyll a and chlorophyll b decreased. There were no significant changes in proline, malondialdehyde content, chlorophyll a/b value and superoxide dismutase activity. (author)

  8. Use of Clay Dispersed in Water for Decreasing Soil Water Repellency

    NARCIS (Netherlands)

    Diamantis, Vasileios; Pagorogon, Lorvi; Gazani, Eleutheria; Gkiougkis, Ioannis; Pechtelidis, Alexandros; Pliakas, Fotios; Elsen, van den Erik; Doerr, Stefan H.; Ritsema, Coen

    2017-01-01

    In this study, we examined the efficiency of a kaolinite clayey soil to mitigate water repellency of a sandy soil with olive trees. The treatment was applied to the soil zone below the tree canopy, which displayed the highest degree of water repellency [average water drop penetration time (WDPT)

  9. Acid-base properties of water-soluble organic matter of forest soils, studied by the pK-spectroscopy method.

    Science.gov (United States)

    Shamrikova, E V; Ryazanov, M A; Vanchikova, E V

    2006-11-01

    Using the potentiometric titration and pK spectroscopy method, acid-base properties of water-soluble organic matter of forest soils have been studied. Five acidic classes composed of different substances with pK(a) values around 3.6; 4.8; 6.7; 8.7 and 9.7 have been identified. Testing the properties of soluble soil fraction, it is to be taken into account that when it is isolated from non-soluble soil matter, some water-soluble substances remain in soil and do not pass into the solution. Most firmly adsorbed in soil are water-soluble components with pK(a) 9.6-9.8.

  10. The "GEOMODEL" at Kiel University: A Hydrogeophysical full scale model to study pore water, contamination and structure of vadose soils

    Science.gov (United States)

    Hagrey, S. A.; Rabbel, W.; Working Group Of Wateruse

    2003-04-01

    Erecting new improved GeoModel at Kiel University is based on our experiences with the pilot model for studying preferential flow processes and takes into account objectives of the EU - project "wateruse" for developing new high resolving techniques for hydro- and bio-geophysical studies. The GeoModel consists of a soil model (3x5x2m), computer room and monitoring chamber. A special irrigation device is installed above the model to simulate irrigations of different rates, intensities and contaminations (tracers). At the base a filter pebble layer divided into different segments for monitoring lateral distribution of discharge indicating for flowpaths and processes. A self developed vacuum aperture is installed to overcome effects of the hydraulic capillary barrier which is related to the abrupt jump in grain size at the soil sand-filter pebble interface. The concept of the GeoModel is to carry out controlled experiment with predefined boundary conditions (as in laboratory) on a full scale soil model (as in the field, i.e., no scale problems). The GeoModel, currently filled with silty sand is equipped with diverse fine electrode grids, radar hardware, TDR-, Tensiometer probes for measuring electrical resistivity, electromagnetic wave velocity and amplitude, water content and potential, respectively. The (infiltration) experiments aim at developing high resolution integrative spatiotemporal 3D techniques for monitoring flow processes of fluids and contaminants, mapping fine structure as preferential flow paths, root networks and trunk rings (which opens new applications in biogeophysics and geobiology), quantification of soil water content. The GeoModel serve for calibration of new instruments and techniques and is applied for special geotechnical and environmental experiments (e.g. anti-person mines, tracer experiments) as well as for technical courses for specialists. Also laboratory study of petrophysical parameters of soil material is carried out to establish

  11. Soil water regime under homogeneous eucalyptus and pine forests

    International Nuclear Information System (INIS)

    Lima, W.P.; Reichardt, K.

    1977-01-01

    Measurement of precipitation and monthly soil water content during two consecutive years, in 6-year old plantations of eucalypt and pine, and also in an open plot containing natural herbaceous vegetation, were used to compare the soil water regime of these vegetation covers. Precipitation was measured in the open plot with a recording and a non-recording rain gage. Soil water was assessed by the neutron scattering technique to a depth of 1,80 meters. Results indicate that there was, in general, water available in the soil over the entire period of study in all three vegetation conditions. The annual range of soil water in eucalypt, pine, and in natural herbaceous vegetation was essentially similar. The analysis of the average soil water regime showed that the soil under herbaceous vegetation was, generally, more umid than the soil under eucalypt and pine during the period of soil water recharge (September through February); during the period of soil water depletion, the opposite was true. Collectively, the results permit the conclusion that there were no adverse effects on the soil water regime which could be ascribed to reflorestation with eucalypt or pine, as compared with that observed for the natural herbaceous vegetation [pt

  12. Importance of soil-water relation in assessment endpoint in bioremediated soils: Plant growth and soil physical properties

    International Nuclear Information System (INIS)

    Li, X.; Sawatsky, N.

    1995-01-01

    Much effort has been focused on defining the end-point of bioremediated soils by chemical analysis (Alberta Tier 1 or CCME Guideline for Contaminated Soils) or toxicity tests. However, these tests do not completely assess the soil quality, or the capability of soil to support plant growth after bioremediation. This study compared barley (Hordeum vulgare) growth on: (i) non-contaminated, agricultural topsoil, (2) oil-contaminated soil (4% total extractable hydrocarbons, or TEH), and (3) oil-contaminated soil treated by bioremediation (< 2% TEH). Soil physical properties including water retention, water uptake, and water repellence were measured. The results indicated that the growth of barley was significantly reduced by oil-contamination of agricultural topsoil. Furthermore, bioremediation did not improve the barley yield. The lack of effects from bioremediation was attributed to development of water repellence in hydrocarbon contaminated soils. There seemed to be a critical water content around 18% to 20% in contaminated soils. Above this value the water uptake by contaminated soil was near that of the agricultural topsoil. For lower water contents, there was a strong divergence in sorptivity between contaminated and agricultural topsoil. For these soils, water availability was likely the single most important parameter controlling plant growth. This parameter should be considered in assessing endpoint of bioremediation for hydrocarbon contaminated soils

  13. Controlled release of diuron from an alginate-bentonite formulation: water release kinetics and soil mobility study.

    Science.gov (United States)

    Fernández-Pérez, M; Villafranca-Sánchez, M; González-Pradas, E; Flores-Céspedes, F

    1999-02-01

    The herbicide diuron was incorporated in alginate-based granules to obtain controlled release (CR) properties. The standard formulation (alginate-herbicide-water) was modified by the addition of different sorbents. The effect on diuron release rate caused by incorporation of natural and acid-treated bentonites in alginate formulation was studied by immersion of the granules in water under static conditions. The release of diuron was diffusion-controlled. The time taken for 50% release of active ingredient to be released into water, T(50), was calculated for the comparison of formulations. The addition of bentonite to the alginate-based formulation produced the higher T(50) values, indicating slower release of the diuron. The mobility of technical and formulated diuron was compared by using soil columns. The use of alginate-based CR formulations containing bentonite produced a less vertical distribution of the active ingredient as compared to the technical product and commercial formulation. Sorption capacities of the various soil constituents for diuron were also determined using batch experiments.

  14. Experimental Study on the Feasibility of Using Water Glass and Aluminum Sulfate to Treat Complications in High Liquid Limit Soil Subgrade

    Directory of Open Access Journals (Sweden)

    Wen-hui Zhang

    2015-01-01

    Full Text Available The feasibility of using water glass and aluminum sulfate to treat high liquid limit soil subgrade diseases is studied through laboratory experiments, and the following results were observed. After improving the high liquid limit clay with water glass and aluminum sulfate, the liquid limit decreases, the plastic limit increases, and the plasticity index decreases. Compared with untreated soil, the clay content of the improved soil decreases, while the silt and coarse contents increase. The absolute and relative expansion rates of the improved soil are both lower than those of the untreated soil. With the same number of dry and wet cycles, the decreased degrees of cohesion and internal friction angle of the improved soil are, respectively, one-half and one-third of those of the untreated soil. After three dry and wet cycles, the California bearing ratio (CBR of the untreated soil does not meet the requirements of specifications. However, after being cured for seven days and being subjected to three dry and wet cycles, the CBR of the improved soil, with 4% water glass solution and 0.4% aluminum sulfate, meets the requirements of specifications.

  15. Estimating respiration of roots in soil: interactions with soil CO2, soil temperature and soil water content

    NARCIS (Netherlands)

    Bouma, T.J.; Nielsen, K.F.; Eissenstat, D.M.; Lynch, J.P.

    1997-01-01

    Little information is available on the variability of the dynamics of the actual and observed root respiration rate in relation to abiotic factors. In this study, we describe I) interactions between soil CO2 concentration, temperature, soil water content and root respiration, and II) the effect of

  16. Sugarbeet leaf growth and yield response to soil water deficit ...

    African Journals Online (AJOL)

    18 oct. 1999 ... This study evaluated the responses of sugarbeet leaf growth, sugar yield and yield components to soil water deficit imposed at various periods during growth in a glasshouse. Leaf growth showed high sensitivity to soil water deficit and responses varied with periods at which the deficit occurred. Water deficit ...

  17. Mitigation of water repellency in burned soils applying hydrophillic polymers

    Science.gov (United States)

    Neris, Jonay; de la Torre, Sara; Vidal-Vazquez, Eva; Lado, Marcos

    2017-04-01

    In this study, the effect of fire on water repellency was analyzed in soils from different parent materials, as well as the suitability of anionic polyacrylamide (PAM) to reduce water repellency in these soils. Samples were collected in four different sites where wildfires took place: two in the Canary Islands, with soils developed on volcanic materials, and two in Galicia (NW Spain), with soils developed on plutonic rocks. In Galicia, two soil samples were collected in each site, one in the burnt area and one in an adjacent unburnt area. In the Canary Islands, four samples were collected from each site, three inside the burnt area where the soils were affected by different fire intensities, and one in an unburnt adjacent area. Samples were air-dried and sieved by a 2-mm mesh sieve. Water repellency was measured using the Water Drop Penetration Time test. An amount of 10 g of soil was placed in a tray. Five drops of deionized water were place on the soil surface with a pipette, and the time for each drop to fully penetrate into the soil was recorded. PAM solution was applied to the burnt soils simulating a field application rate of 1gm-2. The polymer used was Superfloc A-110 (Kemira Water Solutions BV, Holland) with 1x107 Da molecular weigth and 15% hydrolysis. PAM was sprayed on the soil surface as solution with a concentration 0.2 g/L. After the application, the samples were dried and the WDPT test was performed. Three replicates for each treatment and soil were used, and the treatments included: dry soil, dry soil after a wetting treatment, dry PAM-treated soil. The results showed that water repellency was modified by fire differently in the various soils. In hydrophilic soils and soils with low water repellency, water repellency was increased after the action of fire. In soils with noticeable initial water repellency, this was reduced or eliminated after the fire. Wetting repellent soils caused a decrease in water repellency most probably because of the spatial

  18. Soil Water and Temperature System (SWATS) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Bond, D

    2005-01-01

    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.

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

    Science.gov (United States)

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

    2013-01-01

    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

  20. Modeling Water Pollution of Soil

    Directory of Open Access Journals (Sweden)

    V. Doležel

    2008-01-01

    Full Text Available The government of the Czech Republic decided that in the location to the west of Prague, capital city of the Czech Republic, some deep mines should be closed because of their low efficiency of coal mined i.e. small amounts and low quality of the coal extracted in the final stage of mining. The locations near Prague influenced the decision to do maintenance on the abandoned mines, as the thread of soil pollution was unacceptably high in the neighborhood of the capital city. Before the mines were closed it was necessary to separate existed extensive horizontal location of salt water below a clay layer in order not to deteriorate the upper fresh water. The salt water could not be allowed to pollute the upper layer with the fresh water, as many wells in villages in the neighborhood of the former mines would be contaminated. Two horizontal clay layers (an insulator and a semi-insulator separated the two horizons containing salt water and fresh water. Before starting deep mining, vertical shafts had to be constructed with concrete linings to enable the miners to access the depths. The salt water was draining away throughout the existence of the mine. The drainage was designed very carefully to avoid possible infiltration of salt water into the upper horizon. Before the mines were abandoned it was necessary to prevent contact between the two kinds of waters in the shafts. Several options were put forward, the most efficient of which appeared to be one that proposed filling the shafts with spoil soil and creating a joint seal made of disparate material at the interface between the salt water and fresh water to create a reliable stopper. The material for the spoil soil was delivered from deposits located not far from the shafts. This material consisted of a variety of grains of sand, big boulders of slate, slaty clay, sandstone, etc.. Chemical admixtures were considered to improve the flocculation of the filling material. The stopper was positioned at a

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

    Science.gov (United States)

    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...

  2. Estimation of soil water retention curve using fractal dimension ...

    African Journals Online (AJOL)

    The soil water retention curve (SWRC) is a fundamental hydraulic property majorly used to study flow transport in soils and calculate plant-available water. Since, direct measurement of SWRC is time-consuming and expensive, different models have been developed to estimate SWRC. In this study, a fractal-based model ...

  3. Coupling of soil water and dissolved carbon measurements to estimate the carbon flux in forest ecosystems a case study

    Science.gov (United States)

    Fink, M.; Krause, P.; Gleixner, G.

    2003-04-01

    We used the 250 year old forest of the national park Hainich, Germany, to estimate carbon storage and export to the ground water in old grown forests. The Hainich is one of the largest deciduous forest ecosystems in middle Europe and the protected area is unmanaged for at least 50 years. It is one of the flux sites of the Carboeurop cluster (www.carboeurop.de) equipped with an eddy covariance system to measure net ecosystem exchange (NEE). Surprisingly NEE of this old grown forest is about 5 t carbon/ha*a. This high amount of carbon uptake can not be explained only by biomass or litter increase. Therefore we quantified the amount of carbon lost as dissolved carbon from the upper soil layer. To determine if carbon is washed out and transported by water fluxes in form of dissolved carbon, the measurement campaign was extended by sophisticated hydrometrical instruments, like frequency domain reflectrometry (FDR) probes, high frequency rain measurement equipment and ceramic plates to take soil water samples. The FDR probes characterize the soil hydrology and quantify the amount of water percolating horizontal and vertical through the soil. In the water samples dissolved organic carbon and dissolved inorganic carbon were determined. Both the quantification of the soil hydrology and the chemical characterization of the soil water enable the calculation of the carbon export from the system. The measurement equipment and layout will be presented and results of dissolved carbon contents in the subsurface water fluxes will be presented. Preliminary estimations of the carbon loss by seepages will be presented also.

  4. Analytical solution for soil water redistribution during evaporation process.

    Science.gov (United States)

    Teng, Jidong; Yasufuku, Noriyuki; Liu, Qiang; Liu, Shiyu

    2013-01-01

    Simulating the dynamics of soil water content and modeling soil water evaporation are critical for many environmental and agricultural strategies. The present study aims to develop an analytical solution to simulate soil water redistribution during the evaporation process. This analytical solution was derived utilizing an exponential function to describe the relation of hydraulic conductivity and water content on pressure head. The solution was obtained based on the initial condition of saturation and an exponential function to model the change of surface water content. Also, the evaporation experiments were conducted under a climate control apparatus to validate the theoretical development. Comparisons between the proposed analytical solution and experimental result are presented from the aspects of soil water redistribution, evaporative rate and cumulative evaporation. Their good agreement indicates that this analytical solution provides a reliable way to investigate the interaction of evaporation and soil water profile.

  5. Using Cesium-137 technique to study the characteristics of different aspect of soil erosion in the Wind-water Erosion Crisscross Region on Loess Plateau of China

    Energy Technology Data Exchange (ETDEWEB)

    Li Mian E-mail: hnli-mian@163.com; Li Zhanbin; Liu Puling; Yao Wenyi

    2005-01-01

    The most serious soil erosion on Loess Plateau exists in the Wind-water Erosion Crisscross Region. In the past 20 years, the types and intensity of soil erosion and its temporal and spatial distribution were studied, but studies on the difference of soil erosion between slope aspects and slope positions in this area have no report. However, it is very important to analyze and evaluate quantitatively the characteristics of different aspects and positions of soil loss for the prevention and treatment of soil erosion in this area. The spatial pattern of net soil loss on 4 downslope transects in four aspects (east, west, south and north) on a typical Mao (round loess mound) in Liudaogou catchment in Wind-water Erosion Crisscross Region was measured in 2000 using the resident cesium-137 deficit technique. The purposes of this investigation were undertaken to determine whether or not {sup 137}Cs measurement would give a useful indication of the extent of soil loss and their characteristics from cultivated hillsides in different slope aspect and slope position in the study area. The results showed that the difference of soil erosion in different aspect was significant and the erosion rate was in this order: north>east>south>west. Compared with other areas, the difference of erosion rate between north hillside and south hillside was on the contrary, and the possible explanations could be the effect of wind erosion. Also, the percentage of wind erosion was estimated to be at least larger than 18% of total soil loss by comparing the difference of erosion amount in south hillside and north hillside. The erosion rates on different slope positions in all aspects were also different, the highest net soil loss occurred in the lower slope position, and the upper and middle slope positions were slight. The general trend of net soil loss on sloping surface was to increase in fluctuation with increasing downslope distance.

  6. Citrus orchards management and soil water repellency in Eastern Spain

    Science.gov (United States)

    Cerdà, A.; González Peñaloza, F. A.; Jordán, A.; Zavala, L. M.

    2012-04-01

    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 (Cerdà 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 (Cerdà et al., 2009). This research aims to show the water repellency on citrus orchards located on the sloping terrain (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

  7. Effects of soil management techniques on soil water erosion in apricot orchards.

    Science.gov (United States)

    Keesstra, Saskia; Pereira, Paulo; Novara, Agata; Brevik, Eric C; Azorin-Molina, Cesar; Parras-Alcántara, Luis; Jordán, Antonio; Cerdà, Artemi

    2016-05-01

    Soil erosion is extreme in Mediterranean orchards due to management impact, high rainfall intensities, steep slopes and erodible parent material. Vall d'Albaida is a traditional fruit production area which, due to the Mediterranean climate and marly soils, produces sweet fruits. However, these highly productive soils are left bare under the prevailing land management and marly soils are vulnerable to soil water erosion when left bare. In this paper we study the impact of different agricultural land management strategies on soil properties (bulk density, soil organic matter, soil moisture), soil water erosion and runoff, by means of simulated rainfall experiments and soil analyses. Three representative land managements (tillage/herbicide/covered with vegetation) were selected, where 20 paired plots (60 plots) were established to determine soil losses and runoff. The simulated rainfall was carried out at 55mmh(-1) in the summer of 2013 (soil moisture) for one hour on 0.25m(2) circular plots. The results showed that vegetation cover, soil moisture and organic matter were significantly higher in covered plots than in tilled and herbicide treated plots. However, runoff coefficient, total runoff, sediment yield and soil erosion were significantly higher in herbicide treated plots compared to the others. Runoff sediment concentration was significantly higher in tilled plots. The lowest values were identified in covered plots. Overall, tillage, but especially herbicide treatment, decreased vegetation cover, soil moisture, soil organic matter, and increased bulk density, runoff coefficient, total runoff, sediment yield and soil erosion. Soil erosion was extremely high in herbicide plots with 0.91Mgha(-1)h(-1) of soil lost; in the tilled fields erosion rates were lower with 0.51Mgha(-1)h(-1). Covered soil showed an erosion rate of 0.02Mgha(-1)h(-1). These results showed that agricultural management influenced water and sediment dynamics and that tillage and herbicide

  8. Digital soil mapping of available water capacity for metropolitan France

    OpenAIRE

    Roman Dobarco, Mercedes; Martin, Manuel; Saby, Nicolas; Bourennane, Hocine; Arrouays, Dominique; Cousin, Isabelle; Le Bas, Christine

    2017-01-01

    Soil hydraulic characteristics are often required for modeling hydrological processes, crop pro- ductivity, biogeochemical cycles, and movement of pollutants. The objective of this study was producing a digital soil map of available water capacity (AWC) for metropolitan France following GlobalSoilMap (GSM) specifications. The digital soil mapping approach consisted in predicting sand and clay for the six GSM depth intervals and then applying pedotransfer functions (PTF) for es...

  9. Field, laboratory and estimated soil-water content limits

    African Journals Online (AJOL)

    2005-01-21

    Jan 21, 2005 ... For the purpose of irrigation scheduling, estimates of soil-water content limits are determined using field or laboratory meas- urements or empirically-based regression equations. In this study the field method involved measuring simultaneously the soil-water content (using a frequency domain reflectometer ...

  10. Soil water potential requirement for germination of winter wheat

    Science.gov (United States)

    In semi-arid climates seed is often sown into soil with inadequate water for rapid germination. This study was designed to measure the soil water potential limits for rapid, adequate, and marginal germination of winter wheat (Triticum aestivum L.). We also tested for differences between cultivars an...

  11. Field, laboratory and estimated soil-water content limits ...

    African Journals Online (AJOL)

    For the purpose of irrigation scheduling, estimates of soil-water content limits are determined using field or laboratory measurements or empirically-based regression equations. In this study the field method involved measuring simultaneously the soil-water content (using a frequency domain reflectometer with the PR1 ...

  12. Study of soil water-erosion intensity and vegetation cover of an oak-spruce forest in the Pokutsko-Bukovina Carpathians, Ukraine

    Directory of Open Access Journals (Sweden)

    Blinkova Olena

    2017-01-01

    Full Text Available The effect of soil erosion on dynamic changes in vegetation cover is an important subject of regional ecological research of the Ukrainian Carpathians. Studies on soil erosion on the Pokutsko-Bukovina Carpathians have focused on the impact of soil water erosion on tree, shrub and herbaceous layers in intensive, moderate, slight and light erosion zones. Results have shown that the intensity of water erosion and runoff, which depend on slope steepness, have a great impact on changes in the vegetation cover. This paper compares the main morphometric parameters of formed ravines, the health and composition of trees, and the composition of the herbaceous layer. The floristic list of the all experimental plots comprised 61 grass species. The stands formed Quercus robur L. and Abies alba L. Assessment of the functional types of plant species showed that the balance between competition, stress and disturbance is disrupted along a gradient of water-erosion soil transformation. Soil erosion is likely to have caused a change in the edaphic matrix. The distribution of life forms is also disturbed. Analysis of species richness of the vegetation cover under water erosion and the prevailing soil conditions showed that the values of indices depend on erosion intensity.

  13. Scenario Analysis of Soil and Water Conservation in Xiejia Watershed Based on Improved CSLE Model

    Science.gov (United States)

    Liu, Jieying; Yu, Ming; Wu, Yong; Huang, Yao; Nie, Yawen

    2018-01-01

    According to the existing research results and related data, use the scenario analysis method, to evaluate the effects of different soil and water conservation measures on soil erosion in a small watershed. Based on the analysis of soil erosion scenarios and model simulation budgets in the study area, it is found that all scenarios simulated soil erosion rates are lower than the present situation of soil erosion in 2013. Soil and water conservation measures are more effective in reducing soil erosion than soil and water conservation biological measures and soil and water conservation tillage measures.

  14. Study on the Strategies for the Soil and Water Resource Con-servation of Slopeland in Taiwan in Response to the Extreme Climate

    Science.gov (United States)

    Huang, Wen-Cheng

    2014-05-01

    Global climate change results in extreme weather, especially ex-treme precipitation in Taiwan. Though the total amount of precipi-tation remains unchanged, the frequency of rainfall return period increases which affects slopeland and causes sediment disaster. In Taiwan, slopeland occupies about 73% of national territory. Under harsh environmental stress, soil and water conservation of slope-land becomes more important. In response to the trends of global-ization impacts of climate change, long term strategic planning be-comes more necessary. This study reviewed international practices and decision making process about soil and water conservation of slopeland; and conducted the compilation and analysis of water and soil conservation related research projects in Taiwan within the past five years. It is necessary for Taiwan to design timely adaptive strategies about conducting the all-inclusive conservation of na-tional territory, management and business operation of watershed based on the existing regulation with the effects of extreme weather induced by climate change and the changes of social-economic en-vironments. In order to realize the policy vision of "Under the premise of multiple uses, operating the sustainable business and management of the water and soil resources in the watershed through territorial planning in response to the climate and so-cial-economic environment change". This study concluded the future tasks for soil and water con-servation: 1.Design and timely amend strategies for soil and wand water conservation in response to extreme weather. 2. Strengthen the planning and operating of the land management and integrated conservation of the water and soil resources of key watershed. 3. Manage and operate the prevention of debris flow disaster and large-scale landslide. 4. Formulate polices, related regulations and assessment indicators of soil and water conservation. 5. Maintain the biodiversity of the slopeland and reduce the ecological footprint

  15. Water vapour fluxes trends on different time scales and their relationship with weather and soil drivers: a case study from a dehesa site in South Spain

    Science.gov (United States)

    Polo, María José; Egüen, Marta; Andreu, Ana; Carpintero, Elisabet; Gómez-Giráldez, Pedro; Patrocinio González-Dugo, María

    2017-04-01

    Water vapour fluxes between the soil surface and the atmosphere constitute one of the most important components of the water cycle in the continental areas. Their regime directly affect the availability of water to plants, water storage in surface bodies, air humidity in the boundary layer, snow persistence… among others, and the list of indirectly affected processes comprises a large number of components. Water potential or wetness gradients are some of the main drivers of water vapour fluxes to the atmosphere; soil humidity is usually monitored as key variable in many hydrological and environmental studies, and its estimated series are used to calibrate and validate the modelling of certain hydrological processes. However, such results may differ when water fluxes are used instead of water state variables, such as humidity. This work shows the analysis of high resolution water vapour fluxes series from a dehesa area in South Spain where a complete energy and water fluxes/variables monitoring site has been operating for the last four years. The results include pasture and tree vegetated control points. The daily water budget calculation on both types of sites has been performed from weather and energy fluxes measurements, and soil moisture measurements, and the results have been aggregated on a weekly, monthly and seasonal basis. Comparison between observed trends of soil moisture and calculated trends of water vapour fluxes is included to show the differences arising in terms of the regime of the dominant weather variables in this type of ecosystems. The results identify significant thresholds for each weather variable driver and highlight the importance of the wind regime, which is the somehow forgotten variable in future climate impacts on hydrology. Further work is being carried out to assess water cycle potential trends under future climate conditions and their impacts on the vegetation in dehesa ecosystems.

  16. Effects of soil water content and grass recycling on N2O emission in an urban lawn under laboratory incubation study

    Science.gov (United States)

    Nataningtyas, Dilin Rahayu; Morita, Shunsuke; Hatano, Ryusuke

    2017-12-01

    In the context of global warming, the increase of N2O gas production from the agricultural area has gained enhancing concern due to N2O is a potent greenhouse gas and an ozone depleted substance. While adding clipping grass has been accepted to replace N-fertilizer input in urban law management its effect on soil gas emission still questionable. A laboratory incubation study had been conducted to evaluate the effect of soil water content and grass recycling on greenhouse gas emission from an urban lawn. The soil samples were taken from Yurigahara Park, Sapporo, Hokkaido Japan. The 17 days at 25°C incubation study was started after adjusting soil water content to 35% and 50% with and without adding the clipping grass on soil surfaces. Greenhouse gas emissions were higher with the addition of grass, however, for NO and N2O considerably higher in 35% than 50% water content. The denitrification process was responsible for the N2O increase in this action. Soil chemical and microbial properties, pH, WEOC, NO3--N, NH4+-N and microbial biomass nitrogen (MBN) as well as N-grass content were also measured to know their correlation with N2O emission. The fine-scale heterogeneity occurred in the soil has impact on the variability of soil chemical properties that influenced the N2O emission. In the other hand, the effect of grass recycling appeared to increased soil N-inorganic contents and stimulated the N-gaseous concentration.

  17. DESIRE FOR LEVELS. Background study for the policy document "Setting Environmental Quality Standards for Water and Soil"

    NARCIS (Netherlands)

    van de Meent D; Aldenberg T; Canton JH; van Gestel CAM; Slooff W

    1990-01-01

    The report provides scientific support for setting environmental quality objectives for water, sediment and soil. Quality criteria are not set in this report. Only options for decisions are given. The report is restricted to the derivation of the 'maximally acceptable risk' levels (MAR)

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

    Science.gov (United States)

    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...

  19. Water erosion and soil water infiltration in different stages of corn development and tillage systems

    Directory of Open Access Journals (Sweden)

    Daniel F. de Carvalho

    2015-11-01

    Full Text Available ABSTRACTThis study evaluated soil and water losses, soil water infiltration and infiltration rate models in soil tillage systems and corn (Zea mays, L. development stages under simulated rainfall. The treatments were: cultivation along contour lines, cultivation down the slope and exposed soil. Soil losses and infiltration in each treatment were quantified for rains applied using a portable simulator, at 0, 30, 60 and 75 days after planting. Infiltration rates were estimated using the models of Kostiakov-Lewis, Horton and Philip. Based on the obtained results, the combination of effects between soil tillage system and corn development stages reduces soil and water losses. The contour tillage system promoted improvements in soil physical properties, favoring the reduction of erosion in 59.7% (water loss and 86.6% (soil loss at 75 days after planting, and the increase in the stable infiltration rate in 223.3%, compared with the exposed soil. Associated to soil cover, contour cultivation reduces soil and water losses, and the former is more influenced by management. Horton model is the most adequate to represent soil water infiltration rate under the evaluated conditions.

  20. Estimating soil water evaporation using radar measurements

    Science.gov (United States)

    Sadeghi, Ali M.; Scott, H. D.; Waite, W. P.; Asrar, G.

    1988-01-01

    Field studies were conducted to evaluate the application of radar reflectivity as compared with the shortwave reflectivity (albedo) used in the Idso-Jackson equation for the estimation of daily evaporation under overcast sky and subhumid climatic conditions. Soil water content, water potential, shortwave and radar reflectivity, and soil and air temperatures were monitored during three soil drying cycles. The data from each cycle were used to calculate daily evaporation from the Idso-Jackson equation and from two other standard methods, the modified Penman and plane of zero-flux. All three methods resulted in similar estimates of evaporation under clear sky conditions; however, under overcast sky conditions, evaporation fluxes computed from the Idso-Jackson equation were consistently lower than the other two methods. The shortwave albedo values in the Idso-Jackson equation were then replaced with radar reflectivities and a new set of total daily evaporation fluxes were calculated. This resulted in a significant improvement in computed soil evaporation fluxes from the Idso-Jackson equation, and a better agreement between the three methods under overcast sky conditions.

  1. Water as a Reagent for Soil Remediation

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-03-06

    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.

  2. Soil water availability as controlling factor for actual evapotranspiration in urban soil-vegetation-systems

    Science.gov (United States)

    Thomsen, Simon; Reisdorff, Christoph; Gröngröft, Alexander; Jensen, Kai; Eschenbach, Annette

    2015-04-01

    The City of Hamburg is characterized by a large number of greens, parks and roadside trees: 600.000 trees cover about 14% of the city area, and moreover, 245.000 roadside trees can be found here. Urban vegetation is generally known to positively contribute to the urban micro-climate via cooling by evapotranspiration (ET). The water for ET is predominantly stored in the urban soils. Hence, the actual evapotranspiration (ETa) is - beside atmospheric drivers - determined by soil water availability at the soil surface and in the rooting zones of the respective vegetation. The overall aim of this study is to characterize soil water availability as a regulative factor for ETa in urban soil-vegetation systems. The specific questions addressed are: i) What is the spatio-temporal variation in soil water availability at the study sites? ii) Which soil depths are predominantly used for water uptake by the vegetation forms investigated? and iii) Which are the threshold values of soil water tension and soil water content (Θ), respectively, that limit ETa under dry conditions on both grass-dominated and tree-dominated sites? Three study areas were established in the urban region of Hamburg, Germany. We selected areas featuring both single tree stands and grass-dominated sites, both representing typical vegetation forms in Hamburg. The areas are characterized by relatively dry soil conditions. However, they differ in regard to soil water availability. At each area we selected one site dominated by Common Oak (Quercus ruber L.) with ages from 40 to 120 years, and paired each oak tree site with a neighboring grass-dominated site. All field measurements were performed during the years 2013 and 2014. At each site, we continuously measured soil water tension and Θ up to 160 cm depth, and xylem sap flux of each of three oak trees per site in a 15 min-resolution. Furthermore, we measured soil hydraulic properties as pF-curve, saturated and unsaturated conductivity at all sites

  3. Effects of soil water availability on water fluxes in winter wheat

    Science.gov (United States)

    Cai, G.; Vanderborght, J.; Langensiepen, M.; Vereecken, H.

    2014-12-01

    Quantifying soil water availability in water-limited ecosystems on plant water use continues to be a practical problem in agronomy. Transpiration which represents plant water demand is closely in relation to root water uptake in the root zone and sap flow in plant stems. However, few studies have been concentrated on influences of soil moisture on root water uptake and sap flow in crops. This study was undertaken to investigate (i) whether root water uptake and sap flow correlate with the transpiration estimated by the Penman-Monteith model for winter wheat(Triticum aestivum), and (ii) for which soil water potentials in the root zone, the root water uptake and sap flow rates in crop stems would be reduced. Therefore, we measured sap flow velocities by an improved heat-balance approach (Langensiepen et al., 2014), calculated crop transpiration by Penman-Monteith model, and simulated root water uptake by HYDRUS-1D on an hourly scale for different soil water status in winter wheat. In order to assess the effects of soil water potential on root water uptake and sap flow, an average soil water potential was calculated by weighting the soil water potential at a certain depth with the root length density. The temporal evolution of root length density was measured using horizontal rhizotubes that were installed at different depths.The results showed that root water uptake and sap flow matched well with the computed transpiration by Penman-Monteith model in winter wheat when the soil water potential was not limiting root water uptake. However, low soil water content restrained root water uptake, especially when soil water potential was lower than -90 kPa in the top soil. Sap flow in wheat was not affected by the observed soil water conditions, suggesting that stomatal conductance was not sensitive to soil water potentials. The effect of drought stress on root water uptake and sap flow in winter wheat was only investigated in a short time (after anthesis). Further research

  4. Water storage change estimation from in situ shrinkage measurements of clay soils

    NARCIS (Netherlands)

    Brake, te B.; Ploeg, van der M.J.; Rooij, de G.H.

    2012-01-01

    Water storage in the unsaturated zone is a major determinant of the hydrological behaviour of the soil, but methods to quantify soil water storage are limited. The objective of this study is to assess the applicability of clay soil surface elevation change measurements to estimate soil water storage

  5. Large zero-tension plate lysimeters for soil water and solute collection in undisturbed soils

    Directory of Open Access Journals (Sweden)

    A. Peters

    2009-09-01

    Full Text Available Water collection from undisturbed unsaturated soils to estimate in situ water and solute fluxes in the field is a challenge, in particular if soils are heterogeneous. Large sampling devices are required if preferential flow paths are present. We present a modular plate system that allows installation of large zero-tension lysimeter plates under undisturbed soils in the field. To investigate the influence of the lysimeter on the water flow field in the soil, a numerical 2-D simulation study was conducted for homogeneous soils with uni- and bimodal pore-size distributions and stochastic Miller-Miller heterogeneity. The collection efficiency was found to be highly dependent on the hydraulic functions, infiltration rate, and lysimeter size, and was furthermore affected by the degree of heterogeneity. In homogeneous soils with high saturated conductivities the devices perform poorly and even large lysimeters (width 250 cm can be bypassed by the soil water. Heterogeneities of soil hydraulic properties result into a network of flow channels that enhance the sampling efficiency of the lysimeter plates. Solute breakthrough into zero-tension lysimeter occurs slightly retarded as compared to the free soil, but concentrations in the collected water are similar to the mean flux concentration in the undisturbed soil. To validate the results from the numerical study, a dual tracer study with seven lysimeters of 1.25×1.25 m area was conducted in the field. Three lysimeters were installed underneath a 1.2 m filling of contaminated silty sand, the others deeper in the undisturbed soil. The lysimeters directly underneath the filled soil material collected water with a collection efficiency of 45%. The deeper lysimeters did not collect any water. The arrival of the tracers showed that almost all collected water came from preferential flow paths.

  6. Soil washing treatability study

    International Nuclear Information System (INIS)

    Krstich, M.

    1995-12-01

    Soil washing was identified as a viable treatment process option for remediating soil at the FEMP Environmental Management Project (FEMP). Little information relative to the specific application and potential effectiveness of the soil washing process exists that applies to the types of soil at the FEMP. To properly evaluate this process option in conjunction with the ongoing FEMP Remedial Investigation/Feasibility Study (RI/FS), a treatability testing program was necessary to provide a foundation for a detailed technical evaluation of the viability of the process. In August 1991, efforts were initiated to develop a work plan and experimental design for investigating the effectiveness of soil washing on FEMP soil. In August 1992, the final Treatability Study Work Plan for Operable Unit 5: Soil Washing (DOE 1992) was issued. This document shall be referenced throughout the remainder of this report as the Treatability Study Work Plan (TSWP). The purpose of this treatability study was to generate data to support initial screening and the detailed analysis of alternatives for the Operable Unit 5 FS

  7. Soil - the critical switch of water pathways

    Science.gov (United States)

    Vogel, Hans-Joerg; Weller, Ulrich; Wollschläger, Ute

    2017-04-01

    Generally, the port of entry for water into terrestrial systems is the soil surface. The subsequent flow path of any water molecule towards productive transpiration, nonproductive evaporation, seepage to groundwater or surface runoff is decided within the upper decimeters of soil. Moreover, a substantial fraction of 70% of the Earth's freshwater resources is used by agriculture. Thus, let's say soil is relevant. The dynamics of water within the unsaturated soil is mostly vertical, since the gradients in the gravitational field of the Earth are typically pointing either upwards or downwards. Thus a relevant scale for modeling soil water dynamics is the vertical profile across different soil layers having different hydraulic properties. Based on these considerations and having in mind the management of water resources some crucial questions pop up: i) To what detail do we need to know the basic soil hydraulic properties (i.e. water retention characteristic and unsaturated hydraulic conductivity function)? ii) How useful are sophisticated lab measurement to predict what is happening in the field? How to handle the highly non-linear change in flow paths as a function of the hydraulic state and its history? These questions are addressed based on the evidence of field measurements. Then, another crucial question is how to connect soil hydrology to the larger scales which, depending on the context, might be relevant as well.

  8. Studies on the behaviour of some radioactive pollutants into soil-fresh water environment

    International Nuclear Information System (INIS)

    Sayed, M.S.

    1989-01-01

    The overwhelming increase in the use of nuclear power plants comes to cover many purposes, such as generating of electricity, desalination of sea water, and producing radioactive isotopes in large quantities. There is no doubt that the continuous increase in the production of radioisotope, presents an outstanding potential health hazard to man and its environment. Many radio-nuclide wastes, may be released to the environment from nuclear research reactors, hospitals, universities etc in large quantities and low radioactive level which can contaminate drinking and underground water, plants, animals and air. The present work includes introduction which is a literature survey of uses of natural minerals and clays in the treatment of low level radioactive wastes and the different chemical methods used for their treatment e.g. co-participation, adsorption chromatography, ion exchange , solvent extraction, coagulation and flocculation etc

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

    Science.gov (United States)

    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

    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.

  10. Transformation between Phreatic Water and Soil Water during Freeze–Thaw Periods

    Directory of Open Access Journals (Sweden)

    Junfeng Chen

    2018-03-01

    Full Text Available During freeze–thaw periods, the exchange between shallow groundwater and soil water is unusually strong and bidirectional, which causes soil salinization and affects the accuracy of water resources assessment. The objectives of this study were to explore the laws of transformation between phreatic water and soil water through nine different groundwater table depths (GTDs and three kinds of lithologies during three successive freeze–thaw periods using field lysimeters. The results showed that phreatic evaporation increased with smaller average soil particle sizes. The differences between phreatic evaporation and recharge to groundwater (DPR and GTDs were well fitted by the semi-logarithmic model, and the regression coefficients A and B of the model were well fitted by the linear relationship with the average soil particle size. With the increase of soil particle size, the change of DPR decreased with the change rate of soil particle size. The extent of transformation between phreatic water and soil water decreased with the increase of soil particle size. During the whole freeze–thaw period, the negative value of DPR increased with an decrease in GTD. The groundwater depths of zero DPR (D-zero of sandy loam, fine sand and sandy soil during the freeze–thaw periods were 2.79 m, 2.21 m and 2.12 m, respectively. This research is significant for the prevention of soil salinization disasters and the accurate assessment of water resources.

  11. The influence of stony soil properties on water dynamics modeled by the HYDRUS model

    Directory of Open Access Journals (Sweden)

    Hlaváčiková Hana

    2018-06-01

    Full Text Available Stony soils are composed of two fractions (rock fragments and fine soil with different hydrophysical characteristics. Although stony soils are abundant in many catchments, their properties are still not well understood. This manuscript presents an application of the simple methodology for deriving water retention properties of stony soils, taking into account a correction for the soil stoniness. Variations in the water retention of the fine soil fraction and its impact on both the soil water storage and the bottom boundary fluxes are studied as well. The deterministic water flow model HYDRUS-1D is used in the study. The results indicate that the presence of rock fragments in a moderate-to-high stony soil can decrease the soil water storage by 23% or more and affect the soil water dynamics. Simulated bottom fluxes increased or decreased faster, and their maxima during the wet period were larger in the stony soil compared to the non-stony one.

  12. Effects of rainfall partitioning by Mediterranean vegetation on soil water content dynamics. Results from field studies along a climatic gradient in Spain.

    Science.gov (United States)

    Llorens, Pilar; Latron, Jérôme; Muzylo, Aleksandra; Schnabel, Susanne; Domingo, Francisco; Cantón, Yolanda; Gallart, Francesc

    2010-05-01

    The role played by rainfall partitioning by vegetation is of paramount importance for the water balance both at local and catchment scales. Rainfall partitioning fluxes (throughfall and stemflow) have a large degree of temporal and spatial variability and may consequently lead to significant changes in the volume and composition of water that reach the understory vegetation and the soil. Throughfall affects the surface soils horizons and stemflow, channelled by branches and stems, can reach deeper soil layers and remain available for the roots. This work investigates the effect of rainfall partitioning on soil water content in three Mediterranean study areas covering a strong climatic gradient and different vegetation species. From Northern to Southern Spain the study areas are: The Vallcebre research catchments (42° 12'N, 1° 49'E) with forest patches of Pinus sylvestris and of Quercus pubescens, The Parapuños research catchment (39° 35'N, 6° 5'W ), a wooded rangeland with Quercus rotundifolia and annual grasses in open areas, and the Tabernas experimental area (37° 0'N, 2° 26'W) with disperse shrubs and a mixture of annual plants and biological soil crusts in open areas. Mean annual rainfall ranges between 862 and 235 mm (in Vallcebre and Tabernas respectively). For the studied tree species throughfall was the dominant flux and have a similar rate, being stemflow only a small part of the bulk rainfall. For the studied shrubs, measured throughfall as well as stemflow were highly variable between species. Superficial soil water content was on average lower under forest (Vallcebre) or individual trees (Parapuños) that in the open areas. Contrarily, in Tabernas soil was wetter under shrubs than in open areas, although with higher variability. Driest soils below continous forest covers, as in Vallcebre, or even in sparse covered areas as in the Parapuños catchment, may be explained by the dominant role of rainfall interception and transpiration. In Tabernas

  13. Engineering assessment and feasibility study of Chattanooga Shale as a future source of uranium. [Preliminary mining; data on soils, meteorology, water resources, and biological resources

    Energy Technology Data Exchange (ETDEWEB)

    1978-06-01

    This volume contains five appendixes: Chattanooga Shale preliminary mining study, soils data, meteorologic data, water resources data, and biological resource data. The area around DeKalb County in Tennessee is the most likely site for commercial development for recovery of uranium. (DLC)

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

    Science.gov (United States)

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

    2015-01-01

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Soil management and green water in sloping rainfed vineyards

    Science.gov (United States)

    José Marqués Pérez, María; Ruíz-Colmenero, Marta; García-Díaz, Andrés; Bienes Allas, Ramón

    2017-04-01

    Improved crop production in areas with restricted water availability is of particular interest. Farmers need to maximize the water use efficiency when the possibilities of further extension of irrigation are limited and water is becoming scarce and expensive. Water in rainfed crops depends on rainfall depth and soil characteristics such as texture and structure, water holding capacity, previous moisture, infiltration, soil surface conditions, steepness and slope length. Land management practices can be used to maximise water availability. In previous studies the unwillingness of farmers to change their practices towards more sustainable use was mainly due to the worry about water competition. This work is aimed at understanding the influence of management practices in the water partitioning of this land use. This study was conducted in a sloping vineyard in the centre of Spain. A rain gauge recorded rainfall depth and intensity in the area. Three different soil management practices were considered: 1) traditional tillage, 2) permanent cover and 3) mowed cover of cereals, both sown in the strips between vines. Two moisture sensors were buried at 10 and 35 cm depths. Three replicates per management practice were performed. It is expected that the lack of tillage increase the potential for litter to protect the soil surface against raindrop impact and to contribute to increasing soil organic carbon, and the corresponding increase in infiltration and water holding capacity. The analysis of two years of daily records of rainfall, runoff and soil moisture are intended to establish any influence of management practices on the partitioning of water. Particularly, the so-called "green water" was estimated, i.e. the fraction of rainfall that infiltrates into the soil and will be further available to plants. Soil characteristics such as texture, structure, moisture, infiltration were established. In addition simulated rainfalls carried out in summer and winter over bounded

  16. Soil water repellency under stones, forest residue mulch and bare soil following wildfire.

    Science.gov (United States)

    Martins, Martinho A. S.; Prats, Sérgio A.; van Keulen, Daan; Vieira, Diana C. S.; Silva, Flávio C.; Keizer, Jan J.; Verheijen, Frank G. A.

    2017-04-01

    Soil water repellency (SWR) is a physical property that is commonly defined as the aptitude of soil to resist wetting. It has been documented for a wide range of soil and vegetation types, and can vary with soil organic matter (SOM) content and type, soil texture, soil moisture content (SMC) and soil temperature. Fire can induce, enhance or destroy SWR and, therefore, lead to considerable changes in soil water infiltration and storage and increase soil erosion by water, thereby weakening soil quality. In Portugal, wildfires occur frequently and affect large areas, on average some 100000 ha per year, but over 300000 ha in extreme years such as 2003 and 2005. This can have important implications in geomorphological and hydrological processes, as evidenced by the strong and sometimes extreme responses in post-fire runoff and erosion reported from various parts of the world, including Portugal. Thereby, the application of mulches from various materials to cover burned areas has been found to be an efficient stabilization treatment. However, little is known about possible side effects on SWR, especially long term effects. Forest SWR is very heterogeneous, as a result of variation in proximity to trees/shrubs, litter type and thickness, cracks, roots, and stones. This study targeted the spatial heterogeneity of soil water repellency under eucalypt plantation, five years after a wildfire and forest residue mulching application. The main objectives of this work were: 1) to assess the long-term effect of mulching application on the strength and spatial heterogeneity of topsoil SWR, by comparing SWR on bare soil, under stones, and under mulching remains; 2) to assess SWR at 1 cm depth between O and Ah horizons. The soil surface results showed that untreated bare soil areas were slightly more water repellent than mulched areas. However, under stones there were no SWR differences between mulched and control areas. At 1 cm depth, there was a marked mulching effect on SWR, even

  17. Prediction of the soil water retention curve for structured soil from saturation to oven-dryness

    DEFF Research Database (Denmark)

    Karup, Dan; Møldrup, Per; Tuller, Markus

    2017-01-01

    . In this research we evaluated a new two-stage approach developed recently to predict the SWRC based onmeasurements for disturbed repacked soil samples. Our study involved undisturbed structured soil and took into account the effects of bulk density, organic matter content and particle-size distribution......The soil water retention curve (SWRC) is the most fundamental soil hydraulic function required for modelling soil–plant–atmospheric water flow and transport processes. The SWRC is intimately linked to the distribution of the size of pores, the composition of the solid phase and the soil specific...... surface area. Detailed measurement of the SWRC is impractical in many cases because of the excessively long equilibration times inherent to most standard methods, especially for fine textured soil. Consequently, it is more efficient to predict the SWRCbased on easy-to-measure basic soil properties...

  18. Performance Evaluation of FAO Model for Prediction of Yield Production, Soil Water and Solute Balance under Environmental Stresses (Case Study Winter Wheat

    Directory of Open Access Journals (Sweden)

    V. Rezaverdinejad

    2014-11-01

    Full Text Available In this study, the FAO agro-hydrological model was investigated and evaluated to predict of yield production, soil water and solute balance by winter wheat field data under water and salt stresses. For this purpose, a field experimental was conducted with three salinity levels of irrigation water include: S1, S2 and S3 corresponding to 1.4, 4.5 and 9.6 dS/m, respectively, and four irrigation depth levels include: I1, I2, I3 and I4 corresponding to 50, 75, 100 and 125% of crop water requirement, respectively, for two varieties of winter wheat: Roshan and Ghods, with three replications in an experimental farm of Birjand University for 1384-85 period. Based on results, the mean relative error of the model in yield prediction for Roshan and Ghods were obtained 9.2 and 26.1%, respectively. The maximum error of yield prediction in both of the Roshan and Ghods varieties, were obtained for S1I1, S2I1 and S3I1 treatments. The relative error of Roshan yield prediction for S1I1, S2I1 and S3I1 were calculated 20.0, 28.1 and 26.6%, respectively and for Ghods variety were calculated 61, 94.5 and 99.9%, respectively, that indicated a significant over estimate error under higher water stress. The mean relative error of model for all treatments, in prediction of soil water depletion and electrical conductivity of soil saturation extract, were calculated 7.1 and 5.8%, respectively, that indicated proper accuracy of model in prediction of soil water content and soil salinity.

  19. Contribution to the study of water stress on olive growing under the effect of climate change behind the soil and water conservation techniques in South East of Tunisia

    Science.gov (United States)

    Hachani, Amal; Ouessar, Mohamed; Zerrim, Ammar

    2015-04-01

    Climate change (CC) is a main issue of interest at the international as well as the national levels. It is important at this stage to guide the research to the analysis of impacts and adaptation strategies. The objective of this study is to evaluate the water stress of the olive within the context of CC behind the soil and water conservation techniques in the South East of Tunisia (watershed of Oum Zessar, Medenine) using hydrological modeling (HidroMORE model). Data on rainfall and temperature were collected from available stations, while those for future scenarios (Horizons 2030 and 2090) were obtained using the Coupled Model Intercomparison Project Phase 5 CMIP5 (GFDL HIRAM C360). Model parameterization was based from already conducted studies in the region while estimations have been made for the other case. In comparison with the reference period (1996-2005) and following the increase in temperature (1°C) and (5°C) and rainfall decrease of (5.4%) and (20%), ET0 recorded an increase of (3%) (9%) and ETCadj was reduced by (13%) and (30%), respectively for the 2030 and 2090 horizons. Thus, it is expected that the land suitable for olive cultivation will experience shrinkage and this cropping system would become increasingly problematic.

  20. [Ecological effect of hygroscopic and condensate water on biological soil crusts in Shapotou region of China].

    Science.gov (United States)

    Pan, Yan-Xia; Wang, Xin-Ping; Zhang, Ya-Feng; Hu, Rui

    2013-03-01

    By the method of field experiment combined with laboratory analysis, this paper studied the ecological significance of hygroscopic and condensate water on the biological soil crusts in the vegetation sand-fixing area in Shapotou region of China. In the study area, 90% of hygroscopic and condensate water was within the 3 cm soil depth, which didn' t affect the surface soil water content. The hygroscopic and condensate water generated at night involved in the exchange process of soil surface water and atmosphere water vapor, made up the loss of soil water due to the evaporation during the day, and made the surface soil water not reduced rapidly. The amount of the generated hygroscopic and condensate water had a positive correlation with the chlorophyll content of biological soil crusts, indicating that the hygroscopic and condensate water could improve the growth activity of the biological soil crusts, and thus, benefit the biomass accumulation of the crusts.

  1. Dual-frequency surface-based Ground-Penetrating Radar (GPR) for the quantitative study of soil-water infiltration

    Science.gov (United States)

    Klenk, Patrick; Jaumann, Stefan; Keicher, Viktoria; Roth, Kurt

    2015-04-01

    High-resolution surface-based GPR measurements allow studying the evolution of the capillary fringe in very dynamic hydraulic regimes. We use a dual-frequency surface-based multichannel GPR system to investigate imbibition, drainage, and infiltration in a complicated but known subsurface structure. These hydraulic dynamics are induced by varying the ground water table through pumping water into and out of an observation well or by infiltration with a sprinkler system. The precision of our GPR measurements permits to place close scrutiny on the underlying hydraulic processes. Here, we specifically focus on an experiment featuring high-resolution monitoring of two artificially induced infiltration events into two different kinds of sands at our test site by an eight channel, dual-frequency GPR system measuring at center frequencies of 200 and 600 MHz. During these infiltration events, which lasted for several hours each, 2D-common offset data were acquired along the 20 m center axis of our test site at a time resolution of approximately one radargram per minute. The subsequent relaxation of the system has been monitored by repeated status measurements for about three months. In this presentation, we (i) show the efficacy of our dual-frequency multichannel setup for quantitative studies of both the highly dynamic infiltration phase and the increasingly small variations during subsequent months of relaxation, (ii) assess the currently attainable precision with our commercial GPR instruments, and (iii) discuss the use of observed differences in the GPR response of the different materials for estimating soil hydraulic properties from these datasets.

  2. Stochastic soil water balance under seasonal climates.

    Science.gov (United States)

    Feng, Xue; Porporato, Amilcare; Rodriguez-Iturbe, Ignacio

    2015-02-08

    The analysis of soil water partitioning in seasonally dry climates necessarily requires careful consideration of the periodic climatic forcing at the intra-annual timescale in addition to daily scale variabilities. Here, we introduce three new extensions to a stochastic soil moisture model which yields seasonal evolution of soil moisture and relevant hydrological fluxes. These approximations allow seasonal climatic forcings (e.g. rainfall and potential evapotranspiration) to be fully resolved, extending the analysis of soil water partitioning to account explicitly for the seasonal amplitude and the phase difference between the climatic forcings. The results provide accurate descriptions of probabilistic soil moisture dynamics under seasonal climates without requiring extensive numerical simulations. We also find that the transfer of soil moisture between the wet to the dry season is responsible for hysteresis in the hydrological response, showing asymmetrical trajectories in the mean soil moisture and in the transient Budyko's curves during the 'dry-down' versus the 'rewetting' phases of the year. Furthermore, in some dry climates where rainfall and potential evapotranspiration are in-phase, annual evapotranspiration can be shown to increase because of inter-seasonal soil moisture transfer, highlighting the importance of soil water storage in the seasonal context.

  3. CO2 efflux from soils with seasonal water repellency

    Science.gov (United States)

    Urbanek, Emilia; Doerr, Stefan H.

    2017-10-01

    Soil carbon dioxide (CO2) emissions are strongly dependent on pore water distribution, which in turn can be modified by reduced wettability. Many soils around the world are affected by soil water repellency (SWR), which reduces infiltration and results in diverse moisture distribution. SWR is temporally variable and soils can change from wettable to water-repellent and vice versa throughout the year. Effects of SWR on soil carbon (C) dynamics, and specifically on CO2 efflux, have only been studied in a few laboratory experiments and hence remain poorly understood. Existing studies suggest soil respiration is reduced with increasing severity of SWR, but the responses of soil CO2 efflux to varying water distribution created by SWR are not yet known.Here we report on the first field-based study that tests whether SWR indeed reduces soil CO2 efflux, based on in situ measurements carried out over three consecutive years at a grassland and pine forest sites under the humid temperate climate of the UK.Soil CO2 efflux was indeed very low on occasions when soil exhibited consistently high SWR and low soil moisture following long dry spells. Low CO2 efflux was also observed when SWR was absent, in spring and late autumn when soil temperatures were low, but also in summer when SWR was reduced by frequent rainfall events. The highest CO2 efflux occurred not when soil was wettable, but when SWR, and thus soil moisture, was spatially patchy, a pattern observed for the majority of the measurement period. Patchiness of SWR is likely to have created zones with two different characteristics related to CO2 production and transport. Zones with wettable soil or low persistence of SWR with higher proportion of water-filled pores are expected to provide water with high nutrient concentration resulting in higher microbial activity and CO2 production. Soil zones with high SWR persistence, on the other hand, are dominated by air-filled pores with low microbial activity, but facilitating O2

  4. CO2 efflux from soils with seasonal water repellency

    Directory of Open Access Journals (Sweden)

    E. Urbanek

    2017-10-01

    Full Text Available Soil carbon dioxide (CO2 emissions are strongly dependent on pore water distribution, which in turn can be modified by reduced wettability. Many soils around the world are affected by soil water repellency (SWR, which reduces infiltration and results in diverse moisture distribution. SWR is temporally variable and soils can change from wettable to water-repellent and vice versa throughout the year. Effects of SWR on soil carbon (C dynamics, and specifically on CO2 efflux, have only been studied in a few laboratory experiments and hence remain poorly understood. Existing studies suggest soil respiration is reduced with increasing severity of SWR, but the responses of soil CO2 efflux to varying water distribution created by SWR are not yet known.Here we report on the first field-based study that tests whether SWR indeed reduces soil CO2 efflux, based on in situ measurements carried out over three consecutive years at a grassland and pine forest sites under the humid temperate climate of the UK.Soil CO2 efflux was indeed very low on occasions when soil exhibited consistently high SWR and low soil moisture following long dry spells. Low CO2 efflux was also observed when SWR was absent, in spring and late autumn when soil temperatures were low, but also in summer when SWR was reduced by frequent rainfall events. The highest CO2 efflux occurred not when soil was wettable, but when SWR, and thus soil moisture, was spatially patchy, a pattern observed for the majority of the measurement period. Patchiness of SWR is likely to have created zones with two different characteristics related to CO2 production and transport. Zones with wettable soil or low persistence of SWR with higher proportion of water-filled pores are expected to provide water with high nutrient concentration resulting in higher microbial activity and CO2 production. Soil zones with high SWR persistence, on the other hand, are dominated by air-filled pores with low microbial activity

  5. Soil water evaporation and crop residues

    Science.gov (United States)

    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...

  6. Characteristics of soil under variations in clay, water saturation, and water flow rates, and the implications upon soil remediation

    International Nuclear Information System (INIS)

    Aikman, M.; Mirotchnik, K.; Kantzas, A.

    1997-01-01

    A potential remediation method for hydrocarbon contaminated soils was discussed. The new method was based on the use of proven and economic petroleum reservoir engineering methods for soil remediation. The methods that were applied included water and gas displacement methods together with horizontal boreholes as the flow inlet and outlets. This system could be used in the case of spills that seep beneath a plant or other immovable infrastructure which requires in-situ treatment schemes to decontaminate the soil. A study was conducted to characterize native soils and water samples from industrial plants in central Alberta and Sarnia, Ontario and to determine the variables that impact upon the flow conditions of synthetic test materials. The methods used to characterize the soils included X-Ray computed tomographic analysis, grain size and density measurements, and X-Ray diffraction. Clay content, initial water saturation, and water and gas flow rate were the variables that impacted on the flow conditions

  7. Prediction of the Soil Water Characteristic from Soil Particle Volume Fractions

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Møldrup, Per; Tuller, Markus

    2012-01-01

    (w)-model) for the SWC, derived from readily available soil properties such as texture and bulk density. A total of 46 undisturbed soils from different horizons at 15 locations across Denmark were used for model evaluation. The F-w-model predicts the volumetric water content as a function of volumetric fines content......Modeling water distribution and flow in partially saturated soils requires knowledge of the soil water characteristic (SWC). However, measurement of the SWC is challenging and time-consuming and, in some cases, not feasible. This study introduces two predictive models (F-w-model and A...... as a function of volumetric content of different particle size fractions (organic matter, clay, silt, and fine and coarse sands). The volumetric content of a particular soil particle size fraction was considered if it contributed to the pore size fraction still occupied with water at the given pF value. Hereby...

  8. Mini Tensiometer-Time Domain Reflectometry Coil Probe for Measuring Soil Water Retention Properties

    DEFF Research Database (Denmark)

    Subedi, Shaphal; Kawamoto, Ken; Karunarathna, Anurudda Kumara

    2013-01-01

    Time domain reflectometry (TDR) is used widely for measuring soil-water content. New TDR coil probe technology facilitates the development of small, nondestructive probes for simultaneous measurement of soil-water content (θ) and soil-water potential (ψ). In this study we developed mini tensiomet...... between measured soil-water retention curves (ψ > –100 cm H2O) by the new T-TDR coil probes and independent measurements by the hanging water column method....

  9. Isotopic studies in soil and plant nutrition

    International Nuclear Information System (INIS)

    Pasricha, N.S.

    2001-01-01

    One of the most important peaceful applications of isotopes is in research for the enhancement of our understanding for increased crop production and better management of resources with higher economic efficiency and environmental safety. Nuclear techniques helped in generating useful information on such aspects as use-efficiency of fertilizer nutrients, quantifying their losses from soil and their biological transformations. Such information was, hitherto, obtained indirectly by conventional methods. Radio and stable isotopes have also been successfully employed for getting information in such diverse fields as soil erosion, turnover of soil organic matter, pesticide retention in soil ground water recharge etc. The property of 137 Cs adhering tightly to certain exchange surface in soil and its chemically inert nature has made it a useful tool for soil erosion studies. In this paper, applications of isotopes in the research and other such studies as degradation, movement and retention of pesticides, movement of nitrate in soil, biological and ammoniacal nitrogen fixation in soil is discussed

  10. Impacts of mining on water and soil.

    Science.gov (United States)

    Warhate, S R; Yenkie, M K N; Pokale, W K

    2007-04-01

    Out of seven coal mines situated in Wardha River Valley located at Wani (Dist. Yavatmal), five open caste coal mines are run by Western Coal Field Ltd, India. The results of 25 water and 19 soil samples (including one over burden) from Nilapur, Bramhani, Kolera, Gowari, Pimpari and Aheri for their pH, TDS, hardness, alkalinity, fluoride, chloride, nitrite, nitrate, phosphate, sulfate, cadmium, lead, zinc, copper, nickel, arsenic, manganese, sodium and potassium are studied in the present work. Statistical analysis and graphical presentation of the results are discussed in this paper.

  11. Soil water and mineral nitrogen content as influenced by crop ...

    African Journals Online (AJOL)

    ) and wheat–medic rotation (McWMcW) and tillage, conventional-till (CT), minimum-till (MT), no-till (NT) and zero-till (ZT) were studied. Crop rotation did not influence soil moisture content. Soil water content in CT tended to be lower compared ...

  12. Exponential increase of publications related to soil water repellency

    NARCIS (Netherlands)

    Dekker, L.W.; Oostindie, K.; Ritsema, C.J.

    2005-01-01

    Soil water repellency is much more wide-spread than formerly thought. During the last decades, it has been a topic of study for soil scientists and hydrologists in at least 21 States of the USA, in Canada, Australia, New Zealand, Mexico, Colombia, Chile, Congo, Nepal, India, Hong Kong, Taiwan,

  13. Water magnetization and phosphorus transport parameters in the soil

    OpenAIRE

    Generoso, Tarcila N.; Martinez, Mauro A.; Rocha, Genelício C.; Hamakawa, Paulo J.

    2017-01-01

    ABSTRACT There are scientific studies describing changes in properties of the water when subjected to the action of a magnetic field, which may favor the availability of some nutrients in the soil solution. Some nutrients, although they are essential to the process of crop development, can be sources of pollution for watercourses and soil. The aim of this study was to evaluate the effect of water magnetization on transport parameters of the phosphate ion in a Red Latosol (RL) and in a Quartza...

  14. Modelling soil-water dynamics in the rootzone of structured and water-repellent soils

    Science.gov (United States)

    Brown, Hamish; Carrick, Sam; Müller, Karin; Thomas, Steve; Sharp, Joanna; Cichota, Rogerio; Holzworth, Dean; Clothier, Brent

    2018-04-01

    In modelling the hydrology of Earth's critical zone, there are two major challenges. The first is to understand and model the processes of infiltration, runoff, redistribution and root-water uptake in structured soils that exhibit preferential flows through macropore networks. The other challenge is to parametrise and model the impact of ephemeral hydrophobicity of water-repellent soils. Here we have developed a soil-water model, which is based on physical principles, yet possesses simple functionality to enable easier parameterisation, so as to predict soil-water dynamics in structured soils displaying time-varying degrees of hydrophobicity. Our model, WEIRDO (Water Evapotranspiration Infiltration Redistribution Drainage runOff), has been developed in the APSIM Next Generation platform (Agricultural Production Systems sIMulation). The model operates on an hourly time-step. The repository for this open-source code is https://github.com/APSIMInitiative/ApsimX. We have carried out sensitivity tests to show how WEIRDO predicts infiltration, drainage, redistribution, transpiration and soil-water evaporation for three distinctly different soil textures displaying differing hydraulic properties. These three soils were drawn from the UNSODA (Unsaturated SOil hydraulic Database) soils database of the United States Department of Agriculture (USDA). We show how preferential flow process and hydrophobicity determine the spatio-temporal pattern of soil-water dynamics. Finally, we have validated WEIRDO by comparing its predictions against three years of soil-water content measurements made under an irrigated alfalfa (Medicago sativa L.) trial. The results provide validation of the model's ability to simulate soil-water dynamics in structured soils.

  15. Measuring and understanding soil water repellency through novel interdisciplinary approaches

    Science.gov (United States)

    Balshaw, Helen; Douglas, Peter; Doerr, Stefan; Davies, Matthew

    2017-04-01

    Food security and production is one of the key global issues faced by society. It has become evermore essential to work the land efficiently, through better soil management and agronomy whilst protecting the environment from air and water pollution. The failure of soil to absorb water - soil water repellency - can lead to major environmental problems such as increased overland flow and soil erosion, poor uptake of agricultural chemicals and increased risk of groundwater pollution due to the rapid transfer of contaminants and nutrient leaching through uneven wetting and preferential flow pathways. Understanding the causes of soil hydrophobicity is essential for the development of effective methods for its amelioration, supporting environmental stability and food security. Organic compounds deposited on soil mineral or aggregate surfaces have long been recognised as a major factor in causing soil water repellency. It is widely accepted that the main groups of compounds responsible are long-chain acids, alkanes and other organic compounds with hydrophobic properties. However, when reapplied to sands and soils, the degree of water repellency induced by these compounds and mixtures varied widely with compound type, amount and mixture, in a seemingly unpredictable way. Our research to date involves two new approaches for studying soil wetting. 1) We challenge the theoretical basis of current ideas on the measured water/soil contact angle measurements. Much past and current discussion involves Wenzel and Cassie-Baxter models to explain anomalously high contact angles for organics on soils, however here we propose that these anomalously high measured contact angles are a consequence of the measurement of a water drop on an irregular non-planar surface rather than the thermodynamic factors of the Cassie-Baxter and Wenzel models. In our analysis we have successfully used a much simpler geometric approach for non-flat surfaces such as soil. 2) Fluorescent and phosphorescent

  16. Hydrologic behavior of model slopes with synthetic water repellent soils

    Science.gov (United States)

    Zheng, Shuang; Lourenço, Sérgio D. N.; Cleall, Peter J.; Chui, Ting Fong May; Ng, Angel K. Y.; Millis, Stuart W.

    2017-11-01

    In the natural environment, soil water repellency decreases infiltration, increases runoff, and increases erosion in slopes. In the built environment, soil water repellency offers the opportunity to develop granular materials with controllable wettability for slope stabilization. In this paper, the influence of soil water repellency on the hydrological response of slopes is investigated. Twenty-four flume tests were carried out in model slopes under artificial rainfall; soils with various wettability levels were tested, including wettable (Contact Angle, CA 90°). Various rainfall intensities (30 mm/h and 70 mm/h), slope angles (20° and 40°) and relative compactions (70% and 90%) were applied to model the response of natural and man-made slopes to rainfall. To quantitatively assess the hydrological response, a number of measurements were made: runoff rate, effective rainfall rate, time to ponding, time to steady state, runoff acceleration, total water storage and wetting front rate. Overall, an increase in soil water repellency reduces infiltration and shortens the time for runoff generation, with the effects amplified for high rainfall intensity. Comparatively, the slope angle and relative compaction had only a minor contribution to the slope hydrology. The subcritical water repellent soils sustained infiltration for longer than both the wettable and water repellent soils, which presents an added advantage if they are to be used in the built environment as barriers. This study revealed substantial impacts of man-made or synthetically induced soil water repellency on the hydrological behavior of model slopes in controlled conditions. The results shed light on our understanding of hydrological processes in environments where the occurrence of natural soil water repellency is likely, such as slopes subjected to wildfires and in agricultural and forested slopes.

  17. [Stable Isotopes Characters of Soil Water Movement in Shijiazhuang City].

    Science.gov (United States)

    Chen, Tong-tong; Chen, Hui; Han, Lu; Xing, Xing; Fu, Yang-yang

    2015-10-01

    In this study, we analyzed the stable hydrogen and oxygen isotope values of precipitation, soil water, irrigation water that collected in Shijiazhuang City from April 2013 to May 2014 to investigate the changing rule of the stable isotopes in different soil profiles and the process of soil water movement according to using the isotope tracer technique. The results showed that the mean excess deuterium of the local precipitation was -6.188 5 per thousand. Those reflected that the precipitation in Shijiazhuang City mainly brought by the monsoon from the ocean surface moisture, and also to some extent by the local evaporation. Precipitation was the main source of the soil water and the irrigation water played the supplementary role. In the rainy season, precipitation was enough to supply the soil water. The stable oxygen isotopes at 10-100 cm depth decreased with the increase of depth, the maximum depth of evaporation in the rainy season reached 40 cm. The peak of stable oxygen isotopes of soil water pushed down along the profile, which was infected by the interaction of the precipitation infiltration, evaporation and the mixing water.

  18. Kinetic and Equilibrium Studies of Sorption of Ammonium in the Soil-Water Environment in Agricultural Areas of Central Poland

    Directory of Open Access Journals (Sweden)

    Anna Sieczka

    2016-09-01

    Full Text Available Sorption characteristics of nitrogen compounds is necessary in ascertaining their fate in the soil-water environment. This paper presents a laboratory “batch” experiment for determining the sorption parameters of ammonium in the soil-water environment. Three agricultural soils (silt loam, loam, and sand with different contents of the clay fraction, significantly affecting the range of the adsorption of contaminants on the surface of solid particles, were chosen as research material. Considering the composition of ammonium nitrate (a commonly used fertilizer in Poland, ammonium solutions with a concentration of 0–52 mg NH4+/L were used as markers. Pseudo-first order, pseudo-second order, and intra-particle diffusion kinetic models were used to describe the mechanisms of ammonium adsorption. Experimental data obtained from the equilibrium tests have been analysed using two-parameter (Freundlich, Langmuir, Temkin and three-parameter (Redlich-Peterson, Hill, Sips models. In order to adjust the parameters of the considered isotherms to the experimental data, the method of minimization of the sum of squared errors was used. Additionally, the maximum sorption capacities and reduction ratios of ammonium versus time were assessed. It was observed that the presence of silt loam and loam in the soil profile can increase the possibility of ammonium adsorption up to almost 20%. Taking into consideration the results of the batch tests, it was concluded that ammonium adsorption attains equilibrium within 48 h. Experimental data was best followed by the pseudo-second order equation and the adsorption isotherm conformed to the Redlich-Peterson model for loam and sand.

  19. Water management in sandy soil using neutron scattering method

    International Nuclear Information System (INIS)

    Mohamed, K.M.

    2011-01-01

    This study was carried out during 2008/2009 at the Experimental Field of Soil and Water Research Department, Nuclear Research Center, Atomic Energy Authority, Inshas in a newly reclaimed sandy soil. The aims of this work are,- determine soil moisture tension within the active root zone and - detecting the behavior of soil moisture within the active root zoon by defines the total hydraulic potential within the soil profile to predict both of actual evapotranspiration and rate of moisture depletion This work also is aimed to study soil water distribution under drip irrigation system.- reducing water deep percolation under the active root depth.This study included two factors, the first one is the irrigation intervals, and the second one is the application rate of organic manure. Irrigation intervals were 5, 10 and 15 days, besides three application rates of organic manure (0 m 3 /fed, 20 m 3 /fed. and 30 m 3 /fed.) in -three replicates under drip irrigation system, Onion was used as an indicator plant. Obtained data show, generally, that neutron scattering technique and soil moisture retention curve model helps more to study the water behavior in the soil profile.Application of organic manure and irrigation to field capacity is a good way to minimize evapotranspiration and deep percolation, which was zero mm/day in the treated treatments.The best irrigation interval for onion plant, in the studied soil, was 5 days with 30m 3 /fad. an application rate of organic manure.Parameter α of van Genuchent's 1980 model was affected by the additions of organic manure, which was decreased by addition of organic manure decreased it. Data also showed that n parameter was decreased by addition of organic manure Using surfer program is a good tool to describe the water distribution in two directions (vertical and horizontal) through soil profile.

  20. Monitoring and predicting the soil water content in the deeper soil profile of Loess Plateau, China

    Directory of Open Access Journals (Sweden)

    Aijuan Wang

    2016-03-01

    Full Text Available Estimation of soil water content (SWC in deep soil profiles is of crucial importance for strategic management of water resource for sustainable land use in arid and semi-arid zones, as well as for soil and water conservation. Soil properties have a very important effect on SWC. This study aimed to analyze the influence of soil particle size on SWC, for the first time using soil particle size to estimate SWC in deep soil profiles. SWC was measured mainly in farmland, natural grasslands and plantations of Caragana from the surface to more than 20 m depth. The same soil samples were also tested for particle size. The results show that the soil desiccation is formed in the caragana forest in 3–18 m soil layers, but almost no formation in 18–24 m layers; water content of farmland and grassland is different in all soil profiles although they are both shallow rooted plants. Correlation analysis indicated that SWC could be well predicted by clay content and the close correlation between SWC and clay content yielded a coefficient of determination (R2 of 0.82 and 0.72, respectively, for farmland and grassland. After multiple regression analysis, a regression model was built using SWC, clay content and sand content data, giving R2=0.66. The model provided reliable estimates of SWC profile based on textural class. This can assist in estimating water depletion by vegetation, by comparing moisture of farmland and grassland soils with that of plantation forests, and in selecting sustainable land use of arid land.

  1. The hydrology of water repellent soils

    Science.gov (United States)

    Shillito, R.; Berli, M.; Ghezzehei, T. A.; Moore, H. K.

    2016-12-01

    The occurrence of wildfire throughout the western U.S. is expected to increase. So, too, will flooding and erosion associated with the aftereffects of the fires. Soil water repellency (hydrophobicity) has frequently been observed after fires and is believed to increase the post-fire runoff potential, although current runoff models cannot directly account for this effect. Many physically-based runoff models incorporate an infiltration reduction factor or manipulate the soil hydraulic conductivity parameter to account for water-repellent soils in runoff generation. Beginning with fundamental principles, we developed a methodology to physically account for soil water repellency and directly account for it in the Kineros2 runoff and erosion model.

  2. What is the role played by organic matter fractions from different sieve-size particles in the development of soil water repellency? A case study using analytical pyrolysis.

    Science.gov (United States)

    Jiménez-Morillo, Nicasio T.; González-Pérez, José A.; González-Vila, Francisco J.; Zavala, Lorena M.; Jordán, Antonio; Jiménez-González, Marco A.

    2014-05-01

    1. INTRODUCTION It is known that soil water repellency (WR) is induced by organic substances covering the surface of minerals particles and aggregates or present as interstitial substances in the soil matrix. It has also been suggested that the persistence of WR is largely conditioned by specific chemical characteristics of soil organic matter (SOM). Most of these substances are abundant in ecosystems and are released into soils as exudates of roots, organic residues in decomposition, or secretions by fungi and other microorganisms. Soil free lipids correspond to a diverse collection of hydrophobic substances including complex substances as sterols, terpenes, polynuclear hydrocarbons, chlorophylls, fatty acids, waxes, and resins. Some of these organic substances, responsible of soil water repellency may be studied using analytical pyrolisis (de la Rosa et al., 2011; González-Pérez et al., 2011). This research aims to study the relation between soil WR and SOM quantity and quality, assessing the impact of organic fractions and its distribution in soil particles of different size on soil WR from sandy soils. 2. METHODS Soil samples were collected under selected species growing in sandy soils from the Doñana National Park (SW Spain), cork oak (Quercus suber, QS), eagle fern (Pteridium aquilinum, PA), pine (Pinus pinea, PP) and rockrose (Halimium halimifolium, HH). Soil WR and physical chemical characteristics including SOM content were assessed in fine earth soil samples (PA>PP>HH. A positive correlation was observed between WR from each sieve size fraction and SOM content. The most severe WR was detected in QS for all sieve size fractions, followed by the finer fractions form PA, PP and HH samples, which that also shows the highest SOM content, ranging between 20.9% (PP) and 46.9% (QS). Coarser soil fractions (1-2 mm) under PA, PP and HH showed the highest long-chain-even C numbered fatty acids (LCE-FA) in the order PP>PA>HH. No fatty acids were detected neither

  3. Sorption study of system soil/water solution of CsCl using 137Cs as a radio-indicator

    International Nuclear Information System (INIS)

    Varga, R.; Krajnakova, M.; Lesny, J.; Matusek, I.

    2003-01-01

    Mobility of the radiocesium in natural environment is a function of all scale of variables, including the time. The important factor that influences on the mobility is quality and quantity of loamy minerals in soils. This paper represents a study of sorption characteristics of soils of the object No. 41, which is in the area of the Jaslovske Bohunice NPP, for radiocesium, examined experimentally appointed adsorption isotherms according to Langmuir and Freundlich. The identical experiments with the montmorillonite K-10 were realized simultaneously for a comparison of the results. (authors)

  4. Variations in annual water-energy balance and their correlations with vegetation and soil moisture dynamics: A case study in the Wei River Basin, China

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shengzhi; Huang, Qiang; Leng, Guoyong; Zhao, Menglong; Meng, Erhao

    2017-03-01

    It is of importance to investigate watershed water-energy balance variations and to explore their correlations with vegetation and soil moisture dynamics, which helps better understand the interplays between underlying surface dynamics and the terrestrial water cycle. The heuristic segmentation method was adopted to identify change points in the parameter to series in Fu's equation belonging to the Budyko framework in the Wei River Basin (WRB) and its sub-basins aiming to examine the validity of stationary assumptions. Additionally, the cross wavelet analysis was applied to explore the correlations between vegetation and soil moisture dynamics and to variations. Results indicated that (1) the omega variations in the WRB are significant, with some change points identified except for the sub-basin above Zhangjiashan, implying that the stationarity of omega series in the WRB is invalid except for the sub-basin above Zhangjiashan; (2) the correlations between soil moisture series and to series are weaker than those between Normalized Difference Vegetation Index (NDVI) series and omega series; (3) vegetation dynamics show significantly negative correlations with omega variations in 1983-2003 with a 4-8 year signal in the whole WRB, and both vegetation and soil moisture dynamics exert strong impacts on the parameter omega changes. This study helps understanding the interactions between underlying land surface dynamics and watershed water-energy balance. (C) 2017 Elsevier B.V. All rights reserved.

  5. Measured and simulated soil water evaporation from four Great Plains soils

    Science.gov (United States)

    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...

  6. Studies on the mobility and adsorption of metalaxyl in soils

    International Nuclear Information System (INIS)

    Peng Genyuan; Qi Mengwen; Wang Huaguo

    1995-01-01

    Distribution of 14 C-metalaxyl alcohol in water and n-octyl and its mobility and adsorption in soils were studied. The results showed that distribution coefficient of metalaxyl between n-octyl alcohol and water was 12.01, and it was easy for metalaxyl to accumulate in biobody. The TLC of soil showed that metalaxyl was hardly mobile in black soil, but the mobilities in sandy soil and brown soil were at middle level. The results of adsorption showed that the adsorbed amount in soil proportionally increased with the concentration of metalaxyl and adsorption percentages were similar for the same soil and different for different soils

  7. Heavy water tracing of soil-water transfers under irrigation

    International Nuclear Information System (INIS)

    Moutonnet, P.; Couchat, P.

    1982-01-01

    In soil columns, a horizon was labeled with heavy (deuterated) water (D 2 O), and the evolution of D 2 O during the experiment was monitored in situ by gamma-neutron counting. An automatic irrigation device was used for crop watering. Based on the results of two consecutive experiments (H 2 O and D 2 O balance and water transfer analysis), the system was found to provide fully satisfactory irrigation. Deuterated water labeling, moreover, proved to be an effective technique for evaluating root uptake in a soil horizon

  8. Soil remediation time to achieve clean-up goals I: Influence of soil water content.

    Science.gov (United States)

    Alvim-Ferraz, Maria da Conceição M; Albergaria, José Tomás; Delerue-Matos, Cristina

    2006-02-01

    The current models are not simple enough to allow a quick estimation of the remediation time. This work reports the development of an easy and relatively rapid procedure for the forecasting of the remediation time using vapour extraction. Sandy soils contaminated with cyclohexane and prepared with different water contents were studied. The remediation times estimated through the mathematical fitting of experimental results were compared with those of real soils. The main objectives were: (i) to predict, through a simple mathematical fitting, the remediation time of soils with water contents different from those used in the experiments; (ii) to analyse the influence of soil water content on the: (ii(1)) remediation time; (ii(2)) remediation efficiency; and (ii(3)) distribution of contaminants in the different phases present into the soil matrix after the remediation process. For sandy soils with negligible contents of clay and natural organic matter, artificially contaminated with cyclohexane before vapour extraction, it was concluded that (i) if the soil water content belonged to the range considered in the experiments with the prepared soils, then the remediation time of real soils of similar characteristics could be successfully predicted, with relative differences not higher than 10%, through a simple mathematical fitting of experimental results; (ii) increasing soil water content from 0% to 6% had the following consequences: (ii(1)) increased remediation time (1.8-4.9h, respectively); (ii(2)) decreased remediation efficiency (99-97%, respectively); and (ii(3)) decreased the amount of contaminant adsorbed onto the soil and in the non-aqueous liquid phase, thus increasing the amount of contaminant in the aqueous and gaseous phases.

  9. Water Repellency, Infiltration and Water Retention Properties of Forest Soils Under Different Management Practices

    Science.gov (United States)

    Wahl, N. A.; Bens, O.; Schäfer, B.; Hüttl, R. F.

    For soils under both agricultural and forest use, management and tillage practice can have significant influence on the hydraulic properties. It is therefore supposed, that management practices are capable of altering surface runoff, water retention and flood- ing risk for river catchments. Soil water repellency (hydrophobicity) can adversely affect soil hydrological properties, e.g. reduce infiltration capacity and induce pref- erential flow, thus enhancing the overall risk of flooding in river catchment areas. Hydrophobic effects are especially pronounced in coniferous forest soils. Investigations were carried out on several study plots in the German Northeastern Lowlands, located app. 50 km NE of Berlin in Brandenburg. Soils found in the area are mainly of glacifluvial origin with a pronounced sandy texture (with medium sized sand dominating). The four stands investigated represent different stages of forest transfor- mation, in a sense of a SfalseT chronosequence and are made up of populations of & cedil;Pinus sylvestris and Fagus sylvatica of different ages. Infiltration was measured with hood infiltrometers, and single infiltration rings at soil surface. Water retention capacity and the influence of soil organic matter on water storage were evaluated with laboratory methods. Water repellency was quantified with the water drop penetration time (WDPT) test, for determining the persistence of water repellency, and the ethanol percentage (EP) test, for measuring the severity/degree of water repellency. Soil samples from the four forest plots and different soil depths (0U160 cm) were used for the measurements. SPotentialT water repellencies were & cedil;determined after 3-day oven-drying at 45 C. The results indicate that for sandy forest soils, the overall infiltration capacity of the plots is low due to the effects of water repellency. The inter-variability of the plots is mainly caused by changes in the textural composition of the soils. For all plots a

  10. Soil water repellency in long term drought and warming experiments

    Science.gov (United States)

    Urbanek, Emilia; Emmett, Bridget; Tietema, Albert; Robinson, David

    2017-04-01

    Increased global temperatures, altered rainfall patterns and frequently occurring extreme climatic events are already observed globally as a result of the climatic changes and further increases are predicted by the climatic models. Extreme weather events such as prolonged dry spells and heat waves can significantly affect soil ecosystem functions mainly due to decrease in soil moisture. Several studies suggested an increase in soil water repellency severity and spread as a consequence of the warming and drought, however, such understanding is based on the laboratory experimentations with soil treated as a 'black box'. In this study we tested the hypothesis of increased severity of soil water repellency subjected to drought and warming under field conditions. Occurrence and severity of soil water repellency was tested in soils subjected to a long-term (10 years) climatic simulation at two upland heathland sites in Oldebroek (Netherlands) and in Clocaenog (UK)[1]. Soil plots with similar vegetation were subjected to repeated drought and warming, compared with the control plots. Drought effect was created by a rainfall exclusion using an automatic self-retracting waterproof curtains while the warming effect was made by using a self-retracting curtains reflecting infrared radiation overnight. The results available to date provide a strong indication that climatic conditions do affect the development of SWR.

  11. Soil, water, nutrients and soil organic matter losses by water erosion as a function of soil management in the Posses sub-watershed, Extrema, Minas Gerais, Brazil

    Directory of Open Access Journals (Sweden)

    Diêgo Faustolo Alves Bispo

    2017-08-01

    Full Text Available Knowledge of the quantity and quality of the material lost by soil erosion due to soil management is a basic need to identify land management zones in catchments. The aim of this study was to investigate the influence of soil management on the quantity and quality of soil material lost by erosion in the Posses sub-watershed, Municipality of Extrema, State of Minas Gerais, Brazil. Water and sediments lost by natural rainfall erosion were sampled from erosion plots located on a Red-Yellow Argisol (PVA under the following systems: bare soil, subsistence farming (maize/beans/pumpkin/jack-beans/fallow, degraded pasture, well-managed pasture, and reforestation set up in 2013; and in a Litholic Neosol (RL: reforestation set up in 2008, bare soil, and native forest. Ca, Mg, K, P, N and soil organic matter (SOM contents were determined in sediment and soil samples (at 0-5 cm depth for the determination of the runoff enrichment ratios. Management influences soil losses more so than water losses. Minor losses were found in reforestation set up in 2013 (soil; in well-managed pasture (water; and in reforestations (nutrients and SOM. These losses tend to stability with time. The general sequence of nutrient losses was N > Ca > Mg > K > P in PVA; and N > Ca > K > Mg > P in RL. Loss rates of SOM and N followed the order: bare soil > subsistence farming > degraded pasture > well-managed pasture > reforestation, in PVA; and bare soil > native forest > reforestation, in RL. Reforestation and well-management pasture are effective conservation strategies in order to lower the erosion process in the Posses sub-watershed. Soil losses, as well as nutrients and organic matter losses were more influenced by soil management than water losses. The safeguarding native forest under Litholic Neosol is essential to the conservation of this pedoenvironment, especially in steep slopes.

  12. Modelling Soil Water Retention for Weed Seed Germination Sensitivity to Water Potential

    Directory of Open Access Journals (Sweden)

    W. John Bullied

    2012-01-01

    Full Text Available Soil water retention is important for the study of water availability to germinating weed seeds. Six soil water retention models (Campbell, Brooks-Corey, four- and five-parameter van Genuchten, Tani, and Russo with residual soil water parameter derivations were evaluated to describe water retention for weed seed germination at minimum threshold soil water potential for three hillslope positions. The Campbell, Brooks-Corey, and four-parameter van Genuchten model with modified or estimated forms of the residual parameter had superior but similar data fit. The Campbell model underestimated water retention at a potential less than −0.5 MPa for the upper hillslope that could result in underestimating seed germination. The Tani and Russo models overestimated water retention at a potential less than −0.1 MPa for all hillslope positions. Model selection and residual parameter specification are important for weed seed germination by representing water retention at the level of minimum threshold water potential for germination. Weed seed germination models driven by the hydrothermal soil environment rely on the best-fitting soil water retention model to produce dynamic predictions of seed germination.

  13. Environmental assessment of water and soil contamination in Rajakhali Canal of Karnaphuli River (Bangladesh) impacted by anthropogenic influences: a preliminary case study

    Science.gov (United States)

    Islam, M. Rafiqul; Das, N. G.; Barua, Prabal; Hossain, M. Belal; Venkatramanan, S.; Chung, S. Y.

    2017-05-01

    Soil and water quality determines the health of an aquatic ecosystem. Rajakhali Canal, a tributary of Karnaphuli River estuary, flowing through Chittagong City (the commercial capital of Bangladesh) receives a huge amount of domestic and industrial wastes and sewages. Monitoring the environmental status of Karnaphuli River and its tributaries is very important for their ecological and economical services provided to city areas. This study evaluated some environmental characteristics of water and soil in the Rajakhali Canal as it affected the environment, and ultimately the life and human beings of Chittagong City. The mean concentrations of physico-chemical parameters were pH (8.5), DO (0.1 mg/L), TA (47.6 mg/L), TDS (631.8 mg/L), TSS (280 mg/L), SO4-S (2.3 mg/L), NH3 (1.1 mg/L), NO3-N (0.2 mg/L) and PO4-P (0.1 mg/L) in the dry season. During the rainy season, the mean concentrations of physico-chemical parameters were pH (7.01), DO (0.55 mg/L), TA (65.9 mg/L), TDS (653.6 mg/L), TSS (300.3 mg/L), SO4-S (1 mg/L), NH3 - (0.6 mg/L), (NO3-N (0.3 mg/L) and PO4-P (0.5 mg/L) in water. In case of soil, the mean concentration of physico-chemical parameters in dry and rainy seasons was represented respectively as follows: pH (6.8), OM (4.5 %), sand (71.7 %), silt (3.1 %), clay (25.2 %), organic nitrogen (45.4 ppm) and phosphorus (9.6 ppm); and pH (6.7), OM (4.5 %), sand (74.4 %), silt (2.4 %), clay (23.2 %), organic nitrogen (35.3 ppm) and phosphorus (7.6 ppm). The result revealed that water and soil quality of this canal became deteriorated and that the total environment of the water body became polluted due to the anthropogenic activities such as industrial, domestic and irrigation effluents. Statistical analyses also supported that water and soil parameters were strongly correlated (1-tailed 0.05 level and 0.01 level significant) with each other at all stations during all seasons. The result of this study will be useful for management and planning for water quality

  14. Soil water retention and structure stability as affected by water quality

    Directory of Open Access Journals (Sweden)

    Amrakh I. Mamedov

    2014-04-01

    Full Text Available In arid and semi-arid zones with a short water resources studying the effects of water quality on soil water retention and structure is important for the development of effective soil and water conservation and management practices. Three water qualities (electrical conductivity, EC ~ 2, 100 and 500 μS cm-1 with a low SAR representing rain, canal-runoff and irrigation water respectively and semi-arid loam and clay soils were tested to evaluate an effect of soil texture and water quality on water retention, and aggregate and structure stability using the high energy moisture characteristic (HEMC method. The water retention curves obtained by the HEMC method were characterized by the modified van Genuchten (1980 model that provides (i model parameters α and n, which represent the location (of the inflection point and the steepness of the S-shaped water retention curve respectively, and (ii a volume of drainable pores (VDP, which is an indicator for the quantity of water released by the tested sample over the range of suction studied, and modal suction (MS, which corresponds to the most frequent pore sizes, and soil structure index, SI =VDP/MS. Generally (i treatments significantly affected the shape of the water retention curves (α and n and (ii contribution of soil type, water EC, and wetting rate and their interaction had considerable effect on the stability induces and model parameters. Most of changes due to the water quality and wetting condition were in the range of matric potential (ψ, 1.2-2.4; and 2.4-5.0 J kg-1 (pore size 125-250 μm and 60-125 μm. The VDP, SI and α increased, and MS and n decreased with the increase in clay content, water EC and the decrease in rate of aggregate wetting. The SI increased exponentially with the increase in VDP, and with the decrease in MS. Contribution of water EC on stability indices and model parameters was not linear and was soil dependent, and could be more valuable at medium water EC. Effect of

  15. Soil and ground-water remediation techniques

    International Nuclear Information System (INIS)

    Beck, P.

    1996-01-01

    Urban areas typically contain numerous sites underlain by soils or ground waters which are contaminated to levels that exceed clean-up guidelines and are hazardous to public health. Contamination most commonly results from the disposal, careless use and spillage of chemicals, or the historic importation of contaminated fill onto properties undergoing redevelopment. Contaminants of concern in soil and ground water include: inorganic chemicals such as heavy metals; radioactive metals; salt and inorganic pesticides, and a range of organic chemicals included within petroleum fuels, coal tar products, PCB oils, chlorinated solvents, and pesticides. Dealing with contaminated sites is a major problem affecting all urban areas and a wide range of different remedial technologies are available. This chapter reviews the more commonly used methods for ground-water and soil remediation, paying particular regard to efficiency and applicability of specific treatments to different site conditions. (author). 43 refs., 1 tab., 27 figs

  16. [Characteristics of soil water movement using stable isotopes in red soil hilly region of northwest Hunan].

    Science.gov (United States)

    Tian, Ri-Chang; Chen, Hong-Song; Song, Xian-Fang; Wang, Ke-Lin; Yang, Qing-Qing; Meng, Wei

    2009-09-15

    Stable isotope techniques provide a new approach to study soil water movement. The process of water movement in soils under two kinds of plant types (oil tea and corn) were studied based on the observed values of hydrogen and oxygen isotopes of precipitation and soil water at different depths in red-soil sloping land. The results showed that stable isotopes of precipitation in this area had obvious seasonal effect and rainfall effect. The stable isotopes at 0-50 cm depth in oil tea forestland and at 0-40 cm depth in corn cropland increased with the increase in depth, respectively, but they had the opposite tendency after rainfall in arid time. The stable isotopes decreased with the increase in depth below 50 cm depth in oil tea forestland and below 40 cm depth in corn cropland where evaporation influence was weak. The infiltrate rate of soil in oil tea land was affected by precipitation obviously, and it was about 50-100 mm/d after 2-3 days in heavy rain, slowed sharply later, and soil water at 50 cm depth often became a barrier layer. The permeability of soil in corn land was poor and the infiltration rate was lower. The change of stable isotopes in soil water in red soil hilly region was mainly affected by the mixing water which was formed by the antecedent precipitation, and evaporation effect took the second place. The evaporation intensity in oil tea land was lower than that in corn land, but the evaporation depth was higher.

  17. Dynamics of pedogenic carbonate accumulation in soils under different land use as an impulse to simulation study of water flows in their profiles

    Science.gov (United States)

    Khokhlova, Olga; Arkhangelskaya, Tatiana

    2016-04-01

    carbonate depths and status is due to repeating upward water fluxes, which are much greater in soils under fallow than under vegetation. Mathematical modeling has shown that under the bare fallow the hydrological regime of Chernozems changed dramatically. In the absence of transpiring vegetation, soil moisture increased as compared to the areas under corn in almost the whole profile of the soil under bare fallow. Under corn a significant part of moisture moves up along the plant roots. As a result, under the same weather conditions the plot under bare fallow provides much more favorable hydrological conditions for the rise of carbonates and their accumulation in the upper part of the profile as compared with the plot under corn. The reported study was funded by RFBR according to the research projects №№14-04-01761-a, 16-05-00669-a

  18. WATER INFILTRATION IN TWO CULTIVATED SOILS IN SOUTHERN BRAZIL

    Directory of Open Access Journals (Sweden)

    Ildegardis Bertol

    2015-04-01

    Full Text Available Infiltration is the passage of water through the soil surface, influenced by the soil type and cultivation and by the soil roughness, surface cover and water content. Infiltration absorbs most of the rainwater and is therefore crucial for planning mechanical conservation practices to manage runoff. This study determined water infiltration in two soil types under different types of management and cultivation, with simulated rainfall of varying intensity and duration applied at different times, and to adjust the empirical model of Horton to the infiltration data. The study was conducted in southern Brazil, on Dystric Nitisol (Nitossolo Bruno aluminoférrico húmico and Humic Cambisol (Cambissolo Húmico alumínico léptico soils to assess the following situations: simulated rains on the Nitisol from 2001 to 2012 in 31 treatments, differing in crop type, sowing direction, type of soil opener on the seeder, amount and type of crop residue and amount of liquid swine manure applied; on the Cambisol, rains were simlated from 2006 to 2012 and 18 treatments were evaluated, differing in crop, seeding direction and crop residue type. The constant of the water infiltration rate into the soil varies significantly with the soil type (30.2 mm h-1 in the Nitisol and 6.6 mm h-1 in the Cambisol, regardless of the management system, application time and rain intensity and duration. At the end of rainfalls, soil-water infiltration varies significantly with the management system, with the timing of application and rain intensity and duration, with values ranging from 13 to 59 mm h-1, in the two studied soils. The characteristics of the sowing operation in terms of relief, crop type and amount and type of crop residue influenced soil water infiltration: in the Nitisol, the values of contour and downhill seeding vary between 27 and 43 mm h-1, respectively, with crop residues of corn, wheat and soybean while in the Cambisol, the variation is between 2 and 36 mm h-1

  19. Case studies: Soil mapping using multiple methods

    Science.gov (United States)

    Petersen, Hauke; Wunderlich, Tina; Hagrey, Said A. Al; Rabbel, Wolfgang; Stümpel, Harald

    2010-05-01

    Soil is a non-renewable resource with fundamental functions like filtering (e.g. water), storing (e.g. carbon), transforming (e.g. nutrients) and buffering (e.g. contamination). Degradation of soils is meanwhile not only to scientists a well known fact, also decision makers in politics have accepted this as a serious problem for several environmental aspects. National and international authorities have already worked out preservation and restoration strategies for soil degradation, though it is still work of active research how to put these strategies into real practice. But common to all strategies the description of soil state and dynamics is required as a base step. This includes collecting information from soils with methods ranging from direct soil sampling to remote applications. In an intermediate scale mobile geophysical methods are applied with the advantage of fast working progress but disadvantage of site specific calibration and interpretation issues. In the framework of the iSOIL project we present here some case studies for soil mapping performed using multiple geophysical methods. We will present examples of combined field measurements with EMI-, GPR-, magnetic and gammaspectrometric techniques carried out with the mobile multi-sensor-system of Kiel University (GER). Depending on soil type and actual environmental conditions, different methods show a different quality of information. With application of diverse methods we want to figure out, which methods or combination of methods will give the most reliable information concerning soil state and properties. To investigate the influence of varying material we performed mapping campaigns on field sites with sandy, loamy and loessy soils. Classification of measured or derived attributes show not only the lateral variability but also gives hints to a variation in the vertical distribution of soil material. For all soils of course soil water content can be a critical factor concerning a succesful

  20. Difficulties in the evaluation and measuring of soil water infiltration

    Science.gov (United States)

    Pla-Sentís, Ildefonso

    2013-04-01

    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

  1. Zinc in soils, water and food crops.

    Science.gov (United States)

    Noulas, Christos; Tziouvalekas, Miltiadis; Karyotis, Theodore

    2018-02-14

    A basic knowledge of the dynamics of zinc (Zn) in soils, water and plants are important steps in achieving sustainable solutions to the problem of Zn deficiency in crops and humans. This paper aims at reviewing and discussing the relevant aspects of the role of Zn in the soil-water-plant agro biological system: from the origins of Zn in soils and water to soil Zn deficiency distribution and the factors affecting soil Zn availability to plants, therefore to elucidate the strategies potentially help combating Zn deficiency problems in soil-plant-human continuum. This necessitates identifying the main areas of Zn-deficient soils and food crops and treating them with Zn amendments, mainly fertilizers in order to increase Zn uptake and Zn use efficiency to crops. In surface and groundwater, Zn enters the environment from various sources but predominately from the erosion of soil particles containing Zn. In plants is involved in several key physiological functions (membrane structure, photosynthesis, protein synthesis, and drought and disease tolerance) and is required in small but nevertheless critical contents. Several high revenue food crops such as beans, citrus, corn, rice etc are highly susceptible to Zn deficiency and biofortification is considered as a promising method to accumulate high content of Zn especially in grains. With the world population continuing to rise and the problems of producing extra food rich in Zn to provide an adequate standard of nutrition to increase, it is very important that any losses in production easily corrected so as Zn deficiencies are prevented. Copyright © 2018 Elsevier GmbH. All rights reserved.

  2. Soil water status under perennial and annual pastures on an acid duplex soil

    International Nuclear Information System (INIS)

    Heng, L.K.; White, R.E.; Chen, D.

    2000-01-01

    A comprehensive field study of soil water balance, nitrogen (N) cycling, pasture management and animal production was carried out on an acid duplex soil at Book Book near Wagga Wagga in southern New South Wales. The experiment, carried out over a 3-year period, tested the hypothesis that sown perennial grass pastures improve the sustainability of a grazing system through better use of water and N. The treatments were: annual pastures without lime (AP-), annual pastures with lime (AP+), perennial pastures without lime (PP-) and perennial pastures with lime (PP+). Soil water measurement was made using a neutron probe on one set of the treatments comprising four adjacent paddocks. Over three winter and spring periods, the results showed that perennial grass pastures, especially PP+, consistently extracted about 40 mm more soil water each year than did the annual grass pastures. As a result, surface runoff, sub-surface flow and deep drainage (percolation below 180 cm depth) were about 40 mm less from the perennial pastures. The soil water status of the four pasture treatments was simulated reasonably well using a simple soil water model. Together with the long-term simulation of deep drainage, using past meteorological records, it is shown that proper management of perennial pastures can reduce recharge to groundwater and make pastoral systems more sustainable in the high rainfall zone. However, to completely reduce recharge, more-deeply rooted plants or trees are needed. (author)

  3. Modeling Water Pollution of Soil

    OpenAIRE

    V. Doležel; P. Procházka; V. Křístek

    2008-01-01

    The government of the Czech Republic decided that in the location to the west of Prague, capital city of the Czech Republic, some deep mines should be closed because of their low efficiency of coal mined i.e. small amounts and low quality of the coal extracted in the final stage of mining. The locations near Prague influenced the decision to do maintenance on the abandoned mines, as the thread of soil pollution was unacceptably high in the neighborhood of the capital city. Before the mines we...

  4. Study of the rheological properties of water and Martian soil simulant mixtures for engineering applications on the red planet

    Science.gov (United States)

    Taylor, Lewis; Alberini, Federico; Sullo, Antonio; Meyer, Marit E.; Alexiadis, Alessio

    2018-03-01

    The rheological properties of mixtures of water and the Martian soil simulant JSC-Mars-1A are investigated by preparing and testing samples at various solids concentrations. The results indicate that the dispersion is viscoelastic and, at small timescales (∼0.1 s), reacts to sudden strain as an elastic solid. At longer timescales the dispersion behaves like a Bingham fluid and exhibits a yield stress. Hysteresis loops show that rapid step-changes (2 s duration) of shear-rate result in thixotropic behaviour, but slower changes (>10 s duration) can result in rheopexy. These observations are explained with the breakdown and recovery of the packing structure under stress. The rheological information is used to generate practical tools, such as the system curve and the Moody chart that can be used for designing piping systems, and calculating pump sizes and pressure requirements.

  5. Association of water spectral indices with plant and soil water relations in contrasting wheat genotypes.

    Science.gov (United States)

    Gutierrez, Mario; Reynolds, Matthew P; Klatt, Arthur R

    2010-07-01

    Spectral reflectance indices can be used to estimate the water status of plants in a rapid, non-destructive manner. Water spectral indices were measured on wheat under a range of water-deficit conditions in field-based yield trials to establish their relationship with water relations parameters as well as available volumetric soil water (AVSW) to indicate soil water extraction patterns. Three types of wheat germplasm were studied which showed a range of drought adaptation; near-isomorphic sister lines from an elite/elite cross, advanced breeding lines, and lines derived from interspecific hybridization with wild relatives (synthetic derivative lines). Five water spectral indices (one water index and four normalized water indices) based on near infrared wavelengths were determined under field conditions between the booting and grain-filling stages of crop development. Among all water spectral indices, one in particular, which was denominated as NWI-3, showed the most consistent associations with water relations parameters and demonstrated the strongest associations in all three germplasm sets. NWI-3 showed a strong linear relationship (r(2) >0.6-0.8) with leaf water potential (psi(leaf)) across a broad range of values (-2.0 to -4.0 MPa) that were determined by natural variation in the environment associated with intra- and inter-seasonal affects. Association observed between NWI-3 and canopy temperature (CT) was consistent with the idea that genotypes with a better hydration status have a larger water flux (increased stomatal conductance) during the day. NWI-3 was also related to soil water potential (psi(soil)) and AVSW, indicating that drought-adapted lines could extract more water from deeper soil profiles to maintain favourable water relations. NWI-3 was sufficiently sensitive to detect genotypic differences (indicated by phenotypic and genetic correlations) in water status at the canopy and soil levels indicating its potential application in precision

  6. Modelling soil water content variations under drought stress on soil column cropped with winter wheat

    Directory of Open Access Journals (Sweden)

    Csorba Szilveszter

    2014-12-01

    Full Text Available Mathematical models are effective tools for evaluating the impact of predicted climate change on agricultural production, but it is difficult to test their applicability to future weather conditions. We applied the SWAP model to assess its applicability to climate conditions, differing from those, for which the model was developed. We used a database obtained from a winter wheat drought stress experiment. Winter wheat was grown in six soil columns, three having optimal water supply (NS, while three were kept under drought-stressed conditions (S. The SWAP model was successfully calibrated against measured values of potential evapotranspiration (PET, potential evaporation (PE and total amount of water (TSW in the soil columns. The Nash-Sutcliffe model efficiency coefficient (N-S for TWS for the stressed columns was 0.92. For the NS treatment, we applied temporally variable soil hydraulic properties because of soil consolidation caused by regular irrigation. This approach improved the N-S values for the wetting-drying cycle from -1.77 to 0.54. We concluded that the model could be used for assessing the effects of climate change on soil water regime. Our results indicate that soil water balance studies should put more focus on the time variability of structuredependent soil properties.

  7. Modeling plant competition for soil water balance in Water-limited Mediterranean Ecosystems

    Science.gov (United States)

    Cortis, C.; Montaldo, N.

    2009-12-01

    In heterogeneous ecosystems, such Mediterranean ecosystems, contrasting plant functional types (PFTs, e.g., grass and woody vegetation) compete for the water use. In these complex ecosystems current modeling approaches need to be improved due to a general lack of knowledge about the relationship between ET and the plant survival strategies for the different PFTs under water stress. Indeed, still unsolved questions are: how the PFTs (in particular the root systems) compete for the water use, the impact of this competition on the water balance terms, and the role of the soil type and soil depth in this competition. For this reasons an elaborated coupled Vegetation dynamic model (VDM) - land surface model (LSM) model able to also predict root distribution of competing plant systems is developed. The transport of vertical water flow in the unsaturated soil is modelled through a Richards’ equation based model. The water extraction (sink) term is considered as the root water uptake. Two VDMs predict vegetation dynamics, including spatial and temporal distribution/evolution of the root systems in the soil of two competing species (grass and woody vegetation). An innovative method for solving the unlinear system of predicting equations is proposed. The coupled model is able to predict soil and root water potential of the two competing plant species. The model is tested for the Orroli case study, situated in the mid-west of Sardinia within the Flumendosa river watershed. The site landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and coark oaks, different shrubs and herbaceous species. In particular two contrasting plant functional types (grass and woody vegetation) have been included. The model well predict the soil moisture and vegetation dynamics for the case study, and significantly different root potentials are predicted for the two PFTs, highlighting the root competition for the water use. The soil depth is low in the case

  8. Soil water dynamics during precipitation in genetic horizons of Retisol

    Science.gov (United States)

    Zaleski, Tomasz; Klimek, Mariusz; Kajdas, Bartłomiej

    2017-04-01

    Retisols derived from silty deposits dominate in the soil cover of the Carpathian Foothills. The hydrophysical properties of these are determined by the grain-size distribution of the parent material and the soil's "primary" properties shaped in the deposition process. The other contributing factors are the soil-forming processes, such as lessivage (leaching of clay particles), and the morphogenetic processes that presently shape the relief. These factors are responsible for the "secondary" differentiation of hydrophysical properties across the soil profile. Both the primary and secondary hydrophysical properties of soils (the rates of water retention, filtration and infiltration, and the moisture distribution over the soil profile) determine their ability to take in rainfall, the amount of rainwater taken in, and the ways of its redistribution. The aims of the study, carried out during 2015, were to investigate the dynamics of soil moisture in genetic horizons of Retisol derived from silty deposits and to recognize how fast and how deep water from precipitation gets into soil horizons. Data of soil moisture were measured using 5TM moisture and temperature sensor and collected by logger Em50 (Decagon Devices USA). Data were captured every 10 minutes from 6 sensors at depths: - 10 cm, 20 cm, 40 cm, 60 cm and 80 cm. Precipitation data come from meteorological station situated 50 m away from the soil profile. Two zones differing in the type of water regime were distinguished in Retisol: an upper zone comprising humic and eluvial horizons, and a lower zone consisting of illuvial and parent material horizons. The upper zone shows smaller retention of water available for plants, and relatively wide fluctuations in moisture content, compared to the lower zone. The lower zone has stable moisture content during the vegetation season, with values around the water field capacity. Large changes in soil moisture were observed while rainfall. These changes depend on the volume

  9. Spatial and temporal patterns of soil water storage and vegetation water use in humid northern catchments.

    Science.gov (United States)

    Geris, Josie; Tetzlaff, Doerthe; McDonnell, Jeffrey J; Soulsby, Chris

    2017-10-01

    Using stable isotope data from soil and vegetation xylem samples across a range of landscape positions, this study provides preliminary insights into spatial patterns and temporal dynamics of soil-plant water interactions in a humid, low-energy northern environment. Our analysis showed that evaporative fractionation affected the isotopic signatures in soil water at shallow depths but was less marked than previously observed in other environments. By comparing the temporal dynamics of stable isotopes in soil water mainly held at suctions around and below field capacity, we found that these waters are not clearly separated. The study inferred that vegetation water sources at all sites were relatively constant, and most likely to be in the upper profile close to the soil/atmosphere interface. The data analyses also suggested that both vegetation type and landscape position, including soil type, may have a strong influence on local water uptake patterns, although more work is needed to explicitly identify water sources and understand the effect of plant physiological processes on xylem isotopic water signatures. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. The soil-water system as basis for a climate proof and healthy urban environment: opportunities identified in a Dutch case-study.

    Science.gov (United States)

    Claessens, Jacqueline; Schram-Bijkerk, Dieneke; Dirven-van Breemen, Liesbet; Otte, Piet; van Wijnen, Harm

    2014-07-01

    One of the effects of climate change expected to take place in urban areas in the Netherlands is an increase in periods of extreme heat and drought. How the soil can contribute to making cities more climate proof is often neglected. Unsealed soil and green spaces increase water storage capacity and can consequently prevent flooding. The planning of public or private green spaces can have a cooling effect and, in general, have a positive effect on how people perceive their health. This paper reviews existing guidelines from Dutch policy documents regarding unsealed soil and green spaces in the Netherlands; do they support climate adaptation policies? Scientific literature was used to quantify the positive effects of green spaces on water storage capacity, cooling and public health. Finally we present a case study of a model town where different policy areas are linked together. Maps were made to provide insight into the ratio of unsealed soil and the number of green spaces in relation to existing guidelines using Geographical Information Systems (GIS). Maps marking the age and social-economic status of the population were also made. The benefits of green spaces are difficult to express in averages because they depend on many different factors such as soil properties, type of green spaces, population characteristics and spatial planning. Moreover, it is not possible to provide quantifications of the benefits of green spaces because of a lack of scientific evidence at the moment. Based on the maps, however, policy assessments can be made, for example, in which site a neighborhood will most benefit from investment in parks and public gardens. Neighborhoods where people have a low social-economic status have for example fewer green spaces than others. This offers opportunities for efficient adaptation policies linking goals of several policy fields. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Environmental Evaluation of Soil Salinity with Various Watering Technologies Assessment.

    Science.gov (United States)

    Seitkaziev, Adeubay; Shilibek, Kenzhegali; Fakhrudenova, Idiya; Salybayev, Satybaldy; Zhaparova, Sayagul; Duisenbayeva, Saule; Bayazitova, Zulfia; Aliya, Maimakova; Seitkazieva, Karlygash; Aubakirov, Hamit

    2018-01-01

      The purpose of this study is to develop mathematical tools for evaluating the level of environmental safety of various watering technologies. A set of indicators, was developed with regard to the natural factors, the nature of the man-induced load, degradation type, and characteristics of the disruption of humification conditions. Thermal and physical characteristics of the soil, the state of its surface, and meteorological factors, including air temperature, relative humidity, precipitation, wind speed, solar radiation, etc. were studied with a view to determining the heat and air exchange in the soil. An environmental evaluation of the methods for saline land development was conducted with regard to the heat and moisture supply. This tool can be used to determine the level of environmental safety of soil salinization during the environmental evaluation of the investigation of soil salinity with various watering technologies.

  12. SOIL AND WATER CONSERVATION MANAGEMENT THROUGH ...

    African Journals Online (AJOL)

    Osondu

    excess water for the field. However, according to farmers' opinion, through time most of these structures are accelerating soil erosion. During a transect walk with DAs gullies associated with the construction of these structure especially, between the boundaries of plots, were commonly observed. Leaving crop residues on ...

  13. Parameterizing the soil - water - plant root system

    NARCIS (Netherlands)

    Feddes, R.A.; Raats, P.A.C.

    2004-01-01

    Root water uptake is described from the local scale, to the field scale and to the regional and global scales. The local macroscopic model can be incorporated in Soil-Plant-Atmosphere Continuum (SPAC) numerical models, like the SWAP, HYSWASOR, HYDRUS, ENVIRO-GRO and FUSSIM models. These SPAC models

  14. Effect of Soil Water Content on the Distribution of Diuron into Organomineral Aggregates of Highly Weathered Tropical Soils.

    Science.gov (United States)

    Regitano, Jussara B; Rocha, Wadson S D; Bonfleur, Eloana J; Milori, Debora; Alleoni, Luís R F

    2016-05-25

    We evaluated the effects of soil water content on the retention of diuron and its residual distribution into organomineral aggregates in four Brazilian oxisols. (14)C-Diuron was incubated for days at 25, 50, and 75% of maximum water-holding capacity for each soil. After 42 days, the physical fractionation method was used to obtain >150, 53-150, 20-53, 2-20, and Diuron retention increased with increasing soil water content for all soils. At lower soil water content, diuron's retention was higher in the sandier soil. It was mostly retained in the fine (53 μm). The sorption coefficients (Kd and Koc) generated by batch studies should be carefully used because they do not provide information about aggregation and diffusion effects on pesticides soil sorption.

  15. Theory of evapotranspiration. 2. Soil and intercepted water evaporation

    OpenAIRE

    Budagovskyi, Anatolij Ivanovič; Novák, Viliam

    2011-01-01

    Evaporation of water from the soil is described and quantified. Formation of the soil dry surface layer is quantitatively described, as a process resulting from the difference between the evaporation and upward soil water flux to the soil evaporating level. The results of evaporation analysis are generalized even for the case of water evaporation from the soil under canopy and interaction between evaporation rate and canopy transpiration is accounted for. Relationships describing evapotranspi...

  16. Experimental Study of Factors Affecting Soil Erodibility

    Science.gov (United States)

    Larionov, G. A.; Bushueva, O. G.; Gorobets, A. V.; Dobrovolskaya, N. G.; Kiryukhina, Z. P.; Krasnov, S. F.; Litvin, L. F.; Maksimova, I. A.; Sudnitsyn, I. I.

    2018-03-01

    The effect of different factors and preparation conditions of monofraction samples from the arable horizon of leached chernozem on soil erodibility and its relationship with soil tensile strength (STS) has been studied. The exposure of samples at 38°C reduces their erodibility by two orders of magnitude. The drying of samples, on the contrary, increases their erodibility. It has been shown that erodibility decreases during the experiment. It has been found that the inoculation of soil with yeast cultures ( Naganishia albida, Lipomyces tetrasporus) reliably increases the STS value in 1.5-1.9 times. The sterile soil is eroded more intensively than the unsterile soil: at 4.9 and 0.3 g/(m2 s), respectively. The drying of soil followed by wetting to the initial water content (30%) has no significant effect on the STS value in almost all experimental treatments.

  17. Measuring Soil Water Potential for Water Management in Agriculture: A Review

    OpenAIRE

    Marco Bittelli

    2010-01-01

    Soil water potential is a soil property affecting a large variety of bio-physical processes, such as seed germination, plant growth and plant nutrition. Gradients in soil water potential are the driving forces of water movement, affecting water infiltration, redistribution, percolation, evaporation and plants’ transpiration. The total soil water potential is given by the sum of gravity, matric, osmotic and hydrostatic potential. The quantification of the soil water potential is necessary for ...

  18. Soil Water Dynamics In Central Europe and Brazil

    DEFF Research Database (Denmark)

    Klein, Markus; Mahler, Claudio F.; Trapp, Stefan

    2000-01-01

    The comprehension of the soil water dynamics is important for the study of environmental processes. Precipitation, temperature, and water balance of Rio de Janeiro, Southeast Brazil and locations in Germany, Central Europe, are significantly different. Experience from one region could not be used...... on both approaches are applied to an actual case with the conditions in Germany. This case is also analyzed under the conditions of Rio de Janeiro. The effects of tropical environmental conditions on water transport in unsaturated soils are also discussed.......The comprehension of the soil water dynamics is important for the study of environmental processes. Precipitation, temperature, and water balance of Rio de Janeiro, Southeast Brazil and locations in Germany, Central Europe, are significantly different. Experience from one region could not be used...... directly in the other region. This means that models of the water balance need to be tested again and the coefficients at least must be adapted to the new environmental conditions. Two methods for the calculation of water movement in the unsaturated soil zone are described. Simulation programs based...

  19. Cumulative soil water evaporation as a function of depth and time

    Science.gov (United States)

    Soil water evaporation is an important component of the surface water balance and the surface energy balance. Accurate and dynamic measurements of soil water evaporation enhance the understanding of water and energy partitioning at the land-atmosphere interface. The objective of this study is to mea...

  20. Soil water availability and rooting depth as determinants of hydraulic architecture of Patagonian woody species

    Science.gov (United States)

    Sandra J. Bucci; Fabian G. Scholz; Guillermo Goldstein; Frederick C. Meinzer; Maria E. Arce

    2009-01-01

    We studied the water economy of nine woody species differing in rooting depth in a Patagonian shrub steppe from southern Argentina to understand how soil water availability and rooting depth determine their hydraulic architecture. Soil water content and potentials, leaf water potentials (Leaf) hydraulic conductivity, wood density (Pw), rooting depth, and specific leaf...

  1. Water and nitrogen distribution in uncropped ridge- tilled soil under ...

    African Journals Online (AJOL)

    Administrator

    2011-09-21

    Sep 21, 2011 ... tional complexity by affecting infiltration and evaporation and soil water extraction by roots directly affects soil water content (Kemper et al., 1975). MATERIALS AND METHODS. Soil properties and experimental equipment description. Three horizons were identified for the clay-loam soil used in this.

  2. Soil organic matter studies

    International Nuclear Information System (INIS)

    1977-01-01

    A total of 77 papers were presented and discussed during this symposium, 40 are included in Volume I. A number of papers deal with the behaviour and functions of organic matter and make a contribution to increasing agricultural production by proposing improved management practices. Other papers discuss turnover of plant residues, release of plant nutrients through biodegradation of organic compounds, and nitrogen economy and the dynamics of transformation of organic forms of nitrogen. Separate entries have been prepared for those 8 papers which discuss the use of tracer techniques in soil studies

  3. Model development for prediction of soil water dynamics in plant production.

    Science.gov (United States)

    Hu, Zhengfeng; Jin, Huixia; Zhang, Kefeng

    2015-09-01

    Optimizing water use in agriculture and medicinal plants is crucially important worldwide. Soil sensor-controlled irrigation systems are increasingly becoming available. However it is questionable whether irrigation scheduling based on soil measurements in the top soil could make best use of water for deep-rooted crops. In this study a mechanistic model was employed to investigate water extraction by a deep-rooted cabbage crop from the soil profile throughout crop growth. The model accounts all key processes governing water dynamics in the soil-plant-atmosphere system. Results show that the subsoil provides a significant proportion of the seasonal transpiration, about a third of water transpired over the whole growing season. This suggests that soil water in the entire root zone should be taken into consideration in irrigation scheduling, and for sensor-controlled irrigation systems sensors in the subsoil are essential for detecting soil water status for deep-rooted crops.

  4. WATER AS A REAGENT FOR SOIL REMEDIATION

    Energy Technology Data Exchange (ETDEWEB)

    Indira S. Jayaweera; Jordi Diaz-Ferraro

    2000-02-28

    SRI International is conducting experiments to develop and evaluate hydrothermal extraction technology for remediating petroleum-contaminated soils. Most current remediation practices generally fail (or are cost prohibitive) to remove the polycyclic aromatic hydrocarbons (PAHs) found in petroleum-contaminated sites or they require the use of organic solvents to achieve removal, 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. Initial work is being conducted at SRI to measure the solubility and rate of solubilization of selected PAHs (anthracene, fluoranthene, pyrene, and chrysene) 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. Preliminary results with pyrene and fluoranthene in water clearly indicate a significant enhancement of solubility with increase in temperature. During this quarter, we conducted experiments with pyrene in the temperature range 200 to 300 C and observed a great enhancement in solubility with an increase in temperature. We also started experiments with real-world soil samples purchased from the subcontractor.

  5. Predicting and mapping soil available water capacity in Korea

    OpenAIRE

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

    2013-01-01

    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...

  6. Spatial Irrigation Management Using Remote Sensing Water Balance Modeling and Soil Water Content Monitoring

    Science.gov (United States)

    Barker, J. Burdette

    Spatially informed irrigation management may improve the optimal use of water resources. Sub-field scale water balance modeling and measurement were studied in the context of irrigation management. A spatial remote-sensing-based evapotranspiration and soil water balance model was modified and validated for use in real-time irrigation management. The modeled ET compared well with eddy covariance data from eastern Nebraska. Placement and quantity of sub-field scale soil water content measurement locations was also studied. Variance reduction factor and temporal stability were used to analyze soil water content data from an eastern Nebraska field. No consistent predictor of soil water temporal stability patterns was identified. At least three monitoring locations were needed per irrigation management zone to adequately quantify the mean soil water content. The remote-sensing-based water balance model was used to manage irrigation in a field experiment. The research included an eastern Nebraska field in 2015 and 2016 and a western Nebraska field in 2016 for a total of 210 plot-years. The response of maize and soybean to irrigation using variations of the model were compared with responses from treatments using soil water content measurement and a rainfed treatment. The remote-sensing-based treatment prescribed more irrigation than the other treatments in all cases. Excessive modeled soil evaporation and insufficient drainage times were suspected causes of the model drift. Modifying evaporation and drainage reduced modeled soil water depletion error. None of the included response variables were significantly different between treatments in western Nebraska. In eastern Nebraska, treatment differences for maize and soybean included evapotranspiration and a combined variable including evapotranspiration and deep percolation. Both variables were greatest for the remote-sensing model when differences were found to be statistically significant. Differences in maize yield in

  7. Effects of soil water saturation on sampling equilibrium and kinetics of selected polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Kim, Pil-Gon; Roh, Ji-Yeon; Hong, Yongseok; Kwon, Jung-Hwan

    2017-10-01

    Passive sampling can be applied for measuring the freely dissolved concentration of hydrophobic organic chemicals (HOCs) in soil pore water. When using passive samplers under field conditions, however, there are factors that might affect passive sampling equilibrium and kinetics, such as soil water saturation. To determine the effects of soil water saturation on passive sampling, the equilibrium and kinetics of passive sampling were evaluated by observing changes in the distribution coefficient between sampler and soil (K sampler/soil ) and the uptake rate constant (k u ) at various soil water saturations. Polydimethylsiloxane (PDMS) passive samplers were deployed into artificial soils spiked with seven selected polycyclic aromatic hydrocarbons (PAHs). In dry soil (0% water saturation), both K sampler/soil and k u values were much lower than those in wet soils likely due to the contribution of adsorption of PAHs onto soil mineral surfaces and the conformational changes in soil organic matter. For high molecular weight PAHs (chrysene, benzo[a]pyrene, and dibenzo[a,h]anthracene), both K sampler/soil and k u values increased with increasing soil water saturation, whereas they decreased with increasing soil water saturation for low molecular weight PAHs (phenanthrene, anthracene, fluoranthene, and pyrene). Changes in the sorption capacity of soil organic matter with soil water content would be the main cause of the changes in passive sampling equilibrium. Henry's law constant could explain the different behaviors in uptake kinetics of the selected PAHs. The results of this study would be helpful when passive samplers are deployed under various soil water saturations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Behavior of Copper Oxide Nanoparticles in Soil Pore Waters as Influenced by Soil Characteristics, Bacteria, and Wheat Roots

    OpenAIRE

    Hortin, Joshua

    2017-01-01

    The goal of this project was to study the behavior of copper oxide nanoparticles in soil environments. Copper oxide nanoparticles have antimicrobial properties and may also be used in agricultural settings to provide a source of copper for plant health, but accidental or misapplication of these nanoparticles to soil may be damaging to the plant and its associated bacteria. Dissolved soil organic matter that is present in soil pore waters dissolved nanoparticles, but did not dissolve the ex...

  9. Conservation and maintenance of soil and water resources

    Science.gov (United States)

    Brian G. Tavernia; Mark D. Nelson; Titus S. Seilheimer; Dale D. Gormanson; Charles H. (Hobie) Perry; Peter V. Caldwell; Ge. Sun

    2016-01-01

    Forest ecosystem productivity and functioning depend on soil and water resources. But the reverse is also true—forest and land-use management activities can significantly alter forest soils, water quality, and associated aquatic habitats (Ice and Stednick 2004, Reid 1993, Wigmosta and Burges 2001). Soil and water resources are protected through the allocation of land...

  10. Soil and Water Indicators of the Sustainable Rangelands Roundtable

    Science.gov (United States)

    M.G. Sherm Karl; D.A. Pyke; P.T. Tueller; G.E. Schuman; R.W. Shafer; S.J. Borchard; D.T. Booth; W.G. Ypsilantis; R.H. Jr. Barrett

    2006-01-01

    The Sustainable Rangelands Roundtable (SRR) has explicitly included conservation and maintenance of soil and water resources as a criterion, a category of conditions or processes that can be assessed nationally to determine if the current level of rangeland management will ensure sustainability. Within the soil/water criterion, 10 indicators, 5 soil-based and 5 water-...

  11. Observing plants dealing with soil water stress: Daily soil moisture fluctuations derived from polymer tensiometers

    Science.gov (United States)

    van der Ploeg, Martine; de Rooij, Gerrit

    2014-05-01

    Periods of soil water deficit often occur within a plant's life cycle, even in temperate deciduous and rain forests (Wilson et al. 2001, Grace 1999). Various experiments have shown that roots are able to sense the distribution of water in the soil, and produce signals that trigger changes in leaf expansion rate and stomatal conductance (Blackman and Davies 1985, Gollan et al. 1986, Gowing et al. 1990 Davies and Zhang 1991, Mansfield and De Silva 1994, Sadras and Milroy 1996). Partitioning of water and air in the soil, solute distribution in soil water, water flow through the soil, and water availability for plants can be determined according to the distribution of the soil water potential (e.g. Schröder et al. 2013, Kool et al. 2014). Understanding plant water uptake under dry conditions has been compromised by hydrological instrumentation with low accuracy in dry soils due to signal attenuation, or a compromised measurement range (Whalley et al. 2013). Development of polymer tensiometers makes it possible to study the soil water potential over a range meaningful for studying plant responses to water stress (Bakker et al. 2007, Van der Ploeg et al. 2008, 2010). Polymer tensiometer data obtained from a lysimeter experiment (Van der Ploeg et al. 2008) were used to analyse day-night fluctuations of soil moisture in the vicinity of maize roots. To do so, three polymer tensiometers placed in the middle of the lysimeter from a control, dry and very dry treatment (one lysimeter per treatment) were used to calculate water content changes over 12 hours. These 12 hours corresponded with the operation of the growing light. Soil water potential measurements in the hour before the growing light was turned on or off were averaged. The averaged value was used as input for the van Genuchten (1980) model. Parameters for the model were obtained from laboratory determination of water retention, with a separate model parameterization for each lysimeter setup. Results show daily

  12. Relating soil microbial activity to water content and tillage-induced differences in soil structure

    DEFF Research Database (Denmark)

    Schjønning, Per; Thomsen, Ingrid Kaag; Petersen, Søren O

    2011-01-01

    Several studies have identified optima in soil water content for aerobic microbial activity, and this has been ascribed to a balance between gas and solute diffusivity as limiting processes. We investigated the role of soil structure, as created by different tillage practices (moldboard ploughing......, MP, or shallow tillage, ST), in regulating net nitrification, applied here as an index of aerobic microbial activity. Intact soil cores were collected at 0–4 and 14–18 cm depth from a fine sandy (SAND) and a loamy (LOAM) soil. The cores were drained to one of seven matric potentials ranging from − 15...... to − 1500 hPa and subjected to measurements of gas diffusivity prior to incubation at 20 °C for 31 days. Net nitrification was calculated from nitrate accumulation during incubation. The upper layer of ST and MP soil had similar physical properties in terms of bulk density, pore size distribution...

  13. Principles of water capture, evaporation, and soil water retention

    Science.gov (United States)

    Successful dryland crop production in semiarid environments is dependent upon efficient storage of precipitation and use of stored soil water supplies. The objectives of this presentation are to: 1. Summarize information regarding the effects of time of year; environmental parameters; residue orient...

  14. Soil water retention measurements using a combined tensiometer-coiled time domain reflectometry probe

    DEFF Research Database (Denmark)

    Vaz, C.M.P.; Hopmans, J.W.; Macedo, A.

    2002-01-01

    in situ soil water retention data from simultaneous soil water matric potential and water content measurements within approximately the same small soil volume around the combined probe, but requires soil specific calibration because of slight desaturation of the porous cup of the tensiometer.......The objective of the presented study was to develop a single probe that can be used to determine soil water retention curves in both laboratory and field conditions, by including a coiled time domain reflectometry (TDR) probe around the porous cup of a standard tensiometer. The combined tensiometer...

  15. Water consumption and soil moisture distribution in melon crop with mulching and in a protected environment

    Directory of Open Access Journals (Sweden)

    Rodrigo Otávio Câmara Monteiro

    2013-06-01

    Full Text Available Mulching has become an important technique for land cover, but there are some technical procedures which should be adjusted for these new modified conditions to establish optimum total water depth. It is also important to observe the soil-water relations as soil water distribution and wetted volume dimensions. The objective of the present study was to estimate melon evapotranspiration under mulching in a protected environment and to verify the water spatial distribution around the melon root system in two soil classes. Mulching provided 27 mm water saving by reducing water evaporation. In terms of volume each plant received, on average, the amount of 175.2 L of water in 84 days of cultivation without mulching, while when was used mulching the water requirement was 160.2 L per plant. The use of mulching reduced the soil moisture variability throughout the crop cycle and allowed a greater distribution of soil water that was more intense in the clay soil. The clayey soil provided on average 43 mm more water depth retention in 0.50 m soil deep relative to the sandy loam soil, and reduced 5.6 mm the crop cycle soil moisture variation compared to sandy loam soil.

  16. Impact of regression methods on improved effects of soil structure on soil water retention estimates

    Science.gov (United States)

    Nguyen, Phuong Minh; De Pue, Jan; Le, Khoa Van; Cornelis, Wim

    2015-06-01

    Increasing the accuracy of pedotransfer functions (PTFs), an indirect method for predicting non-readily available soil features such as soil water retention characteristics (SWRC), is of crucial importance for large scale agro-hydrological modeling. Adding significant predictors (i.e., soil structure), and implementing more flexible regression algorithms are among the main strategies of PTFs improvement. The aim of this study was to investigate whether the improved effect of categorical soil structure information on estimating soil-water content at various matric potentials, which has been reported in literature, could be enduringly captured by regression techniques other than the usually applied linear regression. Two data mining techniques, i.e., Support Vector Machines (SVM), and k-Nearest Neighbors (kNN), which have been recently introduced as promising tools for PTF development, were utilized to test if the incorporation of soil structure will improve PTF's accuracy under a context of rather limited training data. The results show that incorporating descriptive soil structure information, i.e., massive, structured and structureless, as grouping criterion can improve the accuracy of PTFs derived by SVM approach in the range of matric potential of -6 to -33 kPa (average RMSE decreased up to 0.005 m3 m-3 after grouping, depending on matric potentials). The improvement was primarily attributed to the outperformance of SVM-PTFs calibrated on structureless soils. No improvement was obtained with kNN technique, at least not in our study in which the data set became limited in size after grouping. Since there is an impact of regression techniques on the improved effect of incorporating qualitative soil structure information, selecting a proper technique will help to maximize the combined influence of flexible regression algorithms and soil structure information on PTF accuracy.

  17. Soil-structure interaction Vol.3. Influence of ground water

    International Nuclear Information System (INIS)

    Costantino, C.J.

    1986-04-01

    This study has been performed for the Nuclear Regulatory Commission (NRC) by the Structural Analysis Division of Brookhaven National Laboratory (BNL). The study was conducted during the fiscal year 1965 on the program entitled 'Benchmarking of Structural Engineering Problems' sponsored by NRC. The program considered three separate but complementary problems, each associated with the soil-structure interaction (551) phase of the seismic response analysis of nuclear plant facilities. The reports, all entitled Soil-Structure Interaction, are presented in three separate volumes, namely: Vol. 1 Influence of Layering by AJ Philippacopoulos, Vol. 2 Influence of Lift-Off by C.A. Miller, Vol. 3 Influence of Ground Water by C.J. Costantino. The two problems presented in Volumes 2 and 3 were conducted at the City University of New York (CUNY) under subcontract to BNL. This report, Volume 3 of the report, presents a summary of the first year's effort on the subject of the influence of foundation ground water on the SSI phenomenon. A finite element computer program was developed for the two-phased formulation of the combined soil-water problem. This formulation is based on the Biot dynamic equations of motion for both the solid and fluid phases of a typical soil. Frequency dependent interaction coefficients were generated for the two-dimensional plane problem of a rigid surface footing moving against a saturated linear soil. The results indicate that interaction coefficients are significantly modified as compared to the comparable values for a dry soil, particularly for the rocking mode of response. Calculations were made to study the impact of the modified interaction coefficients on the response of a typical nuclear reactor building. The amplification factors for a stick model placed atop a dry and saturated soil were computed. It was found that pore water caused the rocking response to decrease and translational response to increase over the frequency range of interest, as

  18. Soil salinity study in Northern Great Plains sodium affected soil

    Science.gov (United States)

    Kharel, Tulsi P.

    Climate and land-use changes when combined with the marine sediments that underlay portions of the Northern Great Plains have increased the salinization and sodification risks. The objectives of this dissertation were to compare three chemical amendments (calcium chloride, sulfuric acid and gypsum) remediation strategies on water permeability and sodium (Na) transport in undisturbed soil columns and to develop a remote sensing technique to characterize salinization in South Dakota soils. Forty-eight undisturbed soil columns (30 cm x 15 cm) collected from White Lake, Redfield, and Pierpont were used to assess the chemical remediation strategies. In this study the experimental design was a completely randomized design and each treatment was replicated four times. Following the application of chemical remediation strategies, 45.2 cm of water was leached through these columns. The leachate was separated into 120- ml increments and analyzed for Na and electrical conductivity (EC). Sulfuric acid increased Na leaching, whereas gypsum and CaCl2 increased water permeability. Our results further indicate that to maintain effective water permeability, ratio between soil EC and sodium absorption ratio (SAR) should be considered. In the second study, soil samples from 0-15 cm depth in 62 x 62 m grid spacing were taken from the South Dakota Pierpont (65 ha) and Redfield (17 ha) sites. Saturated paste EC was measured on each soil sample. At each sampling points reflectance and derived indices (Landsat 5, 7, 8 images), elevation, slope and aspect (LiDAR) were extracted. Regression models based on multiple linear regression, classification and regression tree, cubist, and random forest techniques were developed and their ability to predict soil EC were compared. Results showed that: 1) Random forest method was found to be the most effective method because of its ability to capture spatially correlated variation, 2) the short wave infrared (1.5 -2.29 mum) and near infrared (0

  19. Multifractal Model of Soil Water Erosion

    Science.gov (United States)

    Oleshko, Klaudia

    2017-04-01

    Breaking of solid surface symmetry during the interaction between the rainfall of high erosivity index and internally unstable volcanic soil/vegetation systems, results in roughness increasing as well as fertile horizon loosing. In these areas, the sustainability of management practices depends on the ability to select and implement the precise indicators of soil erodibility and vegetation capacity to protect the system against the extreme damaging precipitation events. Notwithstanding, the complex, non-linear and scaling nature of the phenomena involved in the interaction among the soil, vegetation and precipitation is still not taken into account by the numerous commonly used empirical, mathematical and computer simulation models: for instance, by the universal soil loss equation (USLE). The soil erodibility factor (K-factor) is still measuring by a set of empirical, dimensionless parameters and indexes, without taking into account the scaling (frequently multifractal) origin of a broad range of heterogeneous, anisotropic and dynamical phenomena involved in hydric erosion. Their mapping is not representative of this complex system spatial variability. In our research, we propose to use the toolbox of fractals and multifractals techniques in vista of its ability to measure the scale invariance and type/degree of soil, vegetation and precipitation symmetry breaking. The hydraulic units are chosen as the precise measure of soil/vegetation stability. These units are measured and modeled for soils with contrasting architecture, based on their porosity/permeability (Poroperm) as well as retention capacity relations. The simple Catalog of the most common Poroperm relations is proposed and the main power law relations among the elements of studied system are established and compared for some representative agricultural and natural Biogeosystems of Mexico. All resulted are related with the Mandelbrot' Baby Theorem in order to construct the universal Phase Diagram which

  20. Radioecology of tritiated water in subarctic soils and vegetation

    International Nuclear Information System (INIS)

    Salonen, L.; Miettinen, J.K.

    1982-01-01

    The residence times of tritium in various types of soils and plants have been determined in southern and northern Finland. The experiments were conducted in forest and agricultural environments where tritiated water was applied to the soil surface in the form of a single fall of rain. After that the movement and loss of tritiated water from the unsaturated zone was followed over a 2-4-year period in some forest areas. Uptake and loss of tritium in the tissue-free water and organic compounds of some native plants was studied in each area. The results indicated that in the subarctic area the half-residence times of tritium in soils and plants were greatly dependent on the climatic conditions at the time of the labelling and during the short growing seasons and also on the rate of water movement in the soil. In the experiments started during the best growing season the half-residence times in soil and plants do not differ from those determined in more temperate latitudes. (author)

  1. Estimation of soil clay content from hygroscopic water content measurements

    OpenAIRE

    Wuddivira, Mark N.; Robinson, David A.; Lebron, Inma; Brechet, Laëtitia; Atwell, Melissa; De Caires, Sunshine; Oatham, Michael; Jones, Scott B.; Abdu, Hiruy; Verma, Aditya K.; Tuller, Markus

    2012-01-01

    Soil texture and the soil water characteristic are key properties used to estimate flow and transport parameters. Determination of clay content is therefore critical for understanding of plot-scale soil heterogeneity. With increasing interest in proximal soil sensing, there is the need to relate obtained signals to soil properties of interest. Inference of soil texture, especially clay mineral content, from instrument response from electromagnetic induction and radiometric methods is of subst...

  2. Effect of some surface and subsurface attributes on soil water erosion

    Science.gov (United States)

    Bertol, Ildegardis; César Ramos, Júlio; Vidal Vázquez, Eva; Mirás Avalos, José Manuel

    2013-04-01

    Soil erosion is a complex phenomenon depending on climate, topography, soil intrinsic characteristics, crop and residue cover, and management and conservation practices that may be accelerated by man activities. Within the above mentioned factors, soil cover and soil management most influence soil erosion. Soil management includes mechanical mobilization and in soil conservationist systems soil residues are mobilized for increasing soil surface roughness. Even if soil roughness is ephemeral, it increases soil water storage and sediment retention in surface microdepressions, which contributes to decrease water erosion. Conservationist soil management systems also maintain the soil surface covered by crop residues, which are more persistent than roughness and contribute to dissipate kinetic energy from raindrops and partly also from runoff. Crop residues are more efficient than soil roughness in controlling water erosion because of its ability to retain detached soil particles. The objective of this study was to assess the efficiency of both soil cover by crop residues and soil surface roughness in controlling water erosion. A field experiments was performed on an Inceptisol in South Brazil under simulated rainfall conditions during 2012. The following treatments were evaluated: 1) residues of Italian ryegrass (Lolium multiflorum), 2) residues of common vetch (Vicia sativa), 3) scarification after cultivation of Italian ryegrass, 4) scarification after cultivation of common vetch, 5) scarified bare soil with high roughness as a control. Treatments #1 and 2 involved no-tilled soil with a rather smooth soil surface, where roots and crop residues of the previous crop were maintained. Treatments # 3 and 4 involved a rather high roughness, absence of previous crop residues and maintenance of antecedent roots. Experimental plots were 11 m long and 3.5 m wide with an area of 38.5 m2. Six successive simulated rainfall tests were applied using a rotating-boom rain simulator

  3. Soil Specific Surface Area and Non-Singularity of Soil-Water Retention at Low Saturations

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Møldrup, Per

    2013-01-01

    The dry end of the soil water characteristic (SWC) is important for modeling vapor flow dynamics and predicting soil properties such as specific surface area (SSA) and clay content (CL). Verification of new instrumentation for rapid measurement of the dry end of the SWC is relevant to avoid long...... equilibration times and potential for hydraulic decoupling. The objectives of this study were to measure both adsorption and desorption branches of the dry end of the SWC for 21 variably-textured Arizona soils using new, fully automated instrumentation (AquaSorp); apply the data to parameterize the Tuller...... and Or (TO) and new single-parameter non-singularity (SPN) models; and evaluate estimates of SSA from water sorption, ethylene glycol monoethyl ether (EGME), and N2–BET methods. The AquaSorp successfully measured water sorption isotherms (∼140 data points) within a reasonably short time (1–3 d). The SPN...

  4. Selenium status in soil, water and essential crops of Iran

    Directory of Open Access Journals (Sweden)

    Nazemi Lyly

    2012-11-01

    Full Text Available Abstracts As a contributing factor to health, the trace element selenium (Se is an essential nutrient of special interest for humans and all animals. It is estimated that 0.5 to 1 billion people worldwide suffer from Se deficiency. In spite of the important role of Se, its concentrations in soil, water and essential crops have not been studied in Iran. Therefore, the main aim of the current study was to determine the Se content of soil, water, and essential crops (rice in North, wheat in Center, date, and pistachio in South of different regions of Iran. Sampling was performed in the North, South, and Central regions of Iran. In each selected area in the three regions, 17 samples of surface soil were collected; samples of water and essential crops were also collected at the same sampling points. Upon preliminary preparation of all samples, the Se concentrations were measured by ICP-OES Model Varian Vista-MPX. The amount of soil-Se was found to be in the range between 0.04 and 0.45 ppm in the studied areas; the Se content of soil in the central region of Iran was the highest compared to other regions (p

  5. Hillslope scale temporal stability of soil water storage in diverse soil layers

    Science.gov (United States)

    Jia, Xiaoxu; Shao, Ming'an; Wei, Xiaorong; Wang, Yunqiang

    2013-08-01

    Knowledge of the soil water storage (SWS) of soil profiles on the scale of a hillslope is important for the optimal management of soil water and revegetation on sloping land in semi-arid areas. This study aimed to investigate the temporal stability of SWS profiles (0-1.0, 1.0-2.0, and 2.0-3.0 m) and to identify representative sites for reliably estimating the mean SWS on two adjacent hillslopes of the Loess Plateau in China. We used two indices: the standard deviation of relative difference (SDRD) and the mean absolute bias error (MABE). We also endeavored to identify any correlations between temporal stability and soil, topography, or properties of the vegetation. The SWS of the soil layers was measured using neutron probes on 15 occasions at 59 locations arranged on two hillslopes (31 and 28 locations for hillslope A (HA) and hillslope B (HB), respectively) from 2009 to 2011. The time-averaged mean SWS for the three layers differed significantly (P management of soil water on sloping land on the Loess Plateau.

  6. Influence of the initial soil water content on Beerkan water infiltration experiments

    Science.gov (United States)

    Lassabatere, L.; Loizeau, S.; Angulo-Jaramillo, R.; Winiarski, T.; Rossier, Y.; Delolme, C.; Gaudet, J. P.

    2012-04-01

    Understanding and modeling of water flow in the vadose zone are important with regards water management and infiltration devices design. Water infiltration process clearly depends on initial soil water content, in particular for sandy soils with high organic matter content. This study investigates the influence of initial water content on water infiltration in a hydrophobic sandy soil and on the related derivation of hydraulic parameters using the BEST algorithm (Lassabatere et al., 2006). The studied sandy soil has a high total organic content decreasing from 3.5% (w/w) at the surface to 0.5% (w/w) below 1cm depth. The highest TOC at surface was due to the presence of a dense biofilm and resulted in a high surface hydrophobicity under dry conditions (low initial water contents). The water infiltration experiments consisted in infiltrating known volumes of water through a simple ring at null pressure head (Beerkan method). The infiltrations were performed during three successive days after a dry period with a storm event between the first and the second day (5 mm) and another between the second and the third day (35 mm). These events resulted in an increase in initial water contents, from less than 5% for the first day to around 10% for the last day. Experiments were performed for appropriate conditions for Beerkan experiments: initial water contents below 1/4 of the saturated water content and uniform water profile resulting from water redistribution after each rainfall event. The analysis of the infiltration data clearly highlights the strong effect of hydrophobicity. For the driest initial conditions (first day), infiltration rates increased with time, whereas they decreased with time for wetter conditions. Such a decrease agreed with the principles of water infiltration without hydrophobicity. In addition, total cumulative infiltrations were far higher for the wettest conditions. Regarding hydraulic characterization, only the data obtained during the last

  7. Implications of market access on soil and water conservation ...

    African Journals Online (AJOL)

    Market access is one of the motivating mechanisms for farmers to invest in soil and water conservation (SWC). Areas of relatively high agricultural potential but remote from major markets face numerous challenges in marketing their outputs. The objective of this study was to explore the market access determinants of farmer ...

  8. Difficulties in assessing outcomes of soil and water conservation ...

    African Journals Online (AJOL)

    Mo

    techniques, mulching, compost manure and contour bunds, are to be more widely applied. The study also revealed difficulties in using specifications for soil and water techniques as an objective way of assessing effectiveness and outcomes of extension, firstly because of lack of clarity of the specifications and, secondly ...

  9. The exchangeable cations in soils flooded with sea water

    NARCIS (Netherlands)

    Molen, van der W.H.

    1958-01-01

    The changes in the exchangeable cations of soils flooded with sea-water were extensively studied in the Netherlands after the inundations of 1940, 1945 and 1953. A synopsis of the results was given, both from a theoretical and a practical viewpoint.

    Current formulae for ion-exchange tested in the

  10. [Simulation of effects of soil properties and plants on soil water-salt movement with reclaimed water irrigation by ENVIRO-GRO model].

    Science.gov (United States)

    Lü, Si-Dan; Chen, Wei-Ping; Wang, Mei-E

    2012-12-01

    In order to promote safe irrigation with reclaimed water and prevent soil salinisation, the dynamic transport of salts in urban soils of Beijing under irrigation of reclaimed water was simulated by ENVIRO-GRO model in this study. The accumulation trends and profile distribution of soil salinity were predicted. Simultaneously, the effects of different soil properties and plants on soil water-salt movement and salt accumulation were investigated. Results indicated that soil salinity in the profiles reached uniform equilibrium conditions by repeated simulation, with different initial soil salinity. Under the conditions of loam and clay loam soil, salinity in the profiles increased over time until reaching equilibrium conditions, while under the condition of sandy loam soil, salinity in the profiles decreased over time until reaching equilibrium conditions. The saturated soil salinity (EC(e)) under equilibrium conditions followed an order of sandy loam soil salinity were also different in these three types of plants. In addition, the growth of the plants was not influenced by soil salinity (except clay loam), but mild soil salinization occurred under all conditions (except sandy loam).

  11. Effect of Initial Water Content on the Properties of Compacted Expansive Unsaturated Soil

    Directory of Open Access Journals (Sweden)

    Mohammed Yousif Fattah

    2015-03-01

    Full Text Available Unsaturated soil can raise many geotechnical problems upon wetting and drying resulting in swelling upon wetting and collapsing (shrinkage in drying and changing in the soil shear strength. The classical principles of saturated soil are often not suitable in explaining these phenomena. In this study, expansive soil (bentonite and sand were tested in different water contents and dry unit weight chosen from the compaction curve to examine the effect of water content change on soil properties (swelling pressure, expansion index, shear strength (soil cohesion and soil suction by the filter paper method. The physical properties of these soils were studied by conducting series of tests in laboratory. Fitting methods were applied to obtain the whole curve of the SWRC measured by the filter paper method with the aid of the (Soil Vision program. The study reveals that the initial soil conditions (water content and dry unit weight affect the soil cohesion, soil suction and soil swelling, where all these parameters marginally decrease with the increase in soil water content especially on the wet side of optimum.

  12. Effect of biochar on soil structural characteristics: water retention and gas transport

    DEFF Research Database (Denmark)

    Sun, Zhencai; Møldrup, Per; Vendelboe, Anders Lindblad

    Biochar addition to agricultural soil has been reported to reduce climate gas emission, as well as improve soil fertility and crop productivity. Little, however, is known about biochar effects on soil structural characteristics. This study investigates if biochar-application changes soil structural...... characteristics, as indicated from water retention and gas transport measurements on intact soil samples. Soil was sampled from a field experiment on a sandy loam with four control plots (C) without biochar and four plots (B) with incorporated biochar at a rate of 20 tons per hectare (plot size, 6 x 8 m). The C......-gas diffusivity on intact 100cm3 soil samples (5 replicates in each plot). We found that biochar application significantly decreased soil bulk density, hereby creating higher porosity. At the same soil-water matric potential, all the soil-gas phase parameters (air-filled porosity, air permeability and gas...

  13. Relating climatic attributes and water resources allocation: A study using surface water supply and soil moisture indices in the Snake River basin, Idaho

    Science.gov (United States)

    Hoekema, David J.; Sridhar, Venkataramana

    2011-07-01

    Climate change forced by anthropogenic activities has been ongoing since at least the beginning of the industrial revolution. Part of the recent warming in the western United States has been attributed to anthropogenic climate change. This research seeks to answer the basic question of how declining streamflow, increasing temperatures, and fluctuation in precipitation have impacted water resource allocation in the Snake River Plain over the past 35 years (1971-2005). Understanding how changes in climatic attributes have historically impacted water allocation should help water managers better understand how projected climate change may influence allocation. Annual and monthly diversion trends from 62 locations in the Snake River Plain were compared to temperature and precipitation trends at 10 climate stations across the basin. We found a strong trend of declining annual surface water diversions across the study area. Of the 62 diversion points examined, 45 have highly significant decreasing annual diversion trends, while an additional 8 have significant decreasing trends. Despite the annual decline in surface water diversions, April diversions have increased at more than half of the diversion points, with 15 locations showing highly significant trends and an additional 17 showing significant increasing diversion trends. A comparison of diversions to the Surface Water Supply Index indicates that the decline in midseason and late season diversions is mostly caused by decreasing supply in the study period, while a comparison of diversions to Palmer's Z index and the Standardized Precipitation Index indicates that early season diversions are highly correlated to early season moisture anomalies.

  14. The cultural economy of soil and water conservation: Market principles and social networks in Eastern Burkina Faso

    OpenAIRE

    Mazzucato, V.; Niemeijer, D.

    2000-01-01

    Metadata only record Soil and water conservation interventions in Africa have had a checkered history, calling into question the way in which soil and water conservation technologies have been studied in the past. This article draws on a case study from eastern Burkina Faso to explore an area usually ignored by soil and water conservation studies-the role of social institutions in guiding decisions regarding the use of technologies. It looks at soil and water conservation through the histo...

  15. Soil and terrestrial biology studies

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    Soil and terrestrial biology studies focused on developing an understanding of the uptake of gaseous substances from the atmosphere by plants, biodegradation of oil, and the movement of Pu in the terrestrial ecosystems of the southeastern United States. Mathematical models were developed for SO 2 and tritium uptake from the atmosphere by plants; the uptake of tritium by soil microorganisms was measured; and the relationships among the Pu content of soil, plants, and animals of the Savannah River Plant area were studied. Preliminary results are reported for studies on the biodegradation of waste oil on soil surfaces

  16. Water Stress Assessment in Jharkhand State Using Soil Data and GIS

    African Journals Online (AJOL)

    In this paper an attempt has been made to study the interrelationship of water resources available with that of soil class and its properties including soil drainage and erosional characteristics which has been used to generate drainage stress map and water stress map inferring the basic reason for water scarcity in the district ...

  17. Evaluation of soil and water salinity for irrigation in North-eastern ...

    African Journals Online (AJOL)

    For sound land use and water management in irrigated area, knowledge of the chemical composition of soils, water, climate, drainage condition and irrigation methods before action are crucial for sustainability of irrigation projects. The study aimed to evaluate the physicochemical properties of soils and water for intended ...

  18. Structural Soil and Water Conservation Practices in Farta District ...

    African Journals Online (AJOL)

    Soil degradation is one of the most serious environmental problems in Ethiopia. The Ethiopian highlands have been experiencing declining soil fertility and severe soil erosion due to intensive farming on steep and fragile lands and other factors attributed to population pressure. Although different soil and water conservation ...

  19. Effects of burning intensity on soil water storage and transmission ...

    African Journals Online (AJOL)

    ... slight burn and heavy burn over no burn. Burning appeared beneficial to both soil water movement and crop yield although with temporary effects. To maintain soil productivity, leguminous species were suggested to protect the soil from leaching and erosion and to improve both soil physical and chemical conditions.

  20. Quantification of soil water storage available to plants in the Nitra River basin

    OpenAIRE

    Andrej Tárník; Dušan Igaz

    2015-01-01

    Soil water storage is systematically studied by expert from various scientific disciplines. This increased interest is mainly due to anthropogenic activities of human beings, but also due to activities of natural processes influencing the dynamics and amount of water in this water resource. The aim of this study is determination of amount of plants available soil water in the Nitra river basin for year 2013. Water storage was calculated in periods from January to March, from April to August a...

  1. A simulation study of the effect of soil water balance andwater stress on winter wheat production under different climate change scenarios

    Czech Academy of Sciences Publication Activity Database

    Eitzinger, J.; Šťastná, M.; Žalud, Z.; Dubrovský, Martin

    2003-01-01

    Roč. 61, - (2003), s. 195-217 ISSN 0378-3774 R&D Projects: GA ČR GA521/99/D040 Institutional research plan: CEZ:AV0Z3042911 Keywords : water stress effect * soil water balance * DSSAT crop model Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.865, year: 2003

  2. Bench Scale Treatability Studies of Contaminated Soil Using Soil Washing Technique

    OpenAIRE

    Gupta, M. K.; Srivastava, R. K.; Singh, A. K.

    2010-01-01

    Soil contamination is one of the most widespread and serious environmental problems confronting both the industrialized as well as developing nations like India. Different contaminants have different physicochemical properties, which influence the geochemical reactions induced in the soils and may bring about changes in their engineering and environmental behaviour. Several technologies exist for the remediation of contaminated soil and water. In the present study soil washing technique using...

  3. Bench Scale Treatability Studies of Contaminated Soil Using Soil Washing Technique

    Directory of Open Access Journals (Sweden)

    M. K. Gupta

    2010-01-01

    Full Text Available Soil contamination is one of the most widespread and serious environmental problems confronting both the industrialized as well as developing nations like India. Different contaminants have different physicochemical properties, which influence the geochemical reactions induced in the soils and may bring about changes in their engineering and environmental behaviour. Several technologies exist for the remediation of contaminated soil and water. In the present study soil washing technique using plain water with surfactants as an enhancer was used to study the remediation of soil contaminated with (i an organic contaminant (engine lubricant oil and (ii an inorganic contaminant (heavy metal. The lubricant engine oil was used at different percentages (by dry weight of the soil to artificially contaminate the soil. It was found that geotechnical properties of the soil underwent large modifications on account of mixing with the lubricant oil. The sorption experiments were conducted with cadmium metal in aqueous medium at different initial concentration of the metal and at varying pH values of the sorbing medium. For the remediation of contaminated soil matrices, a nonionic surfactant was used for the restoration of geotechnical properties of lubricant oil contaminated soil samples, whereas an anionic surfactant was employed to desorb cadmium from the contaminated soil matrix. The surfactant in case of soil contaminated with the lubricant oil was able to restore properties to an extent of 98% vis-à-vis the virgin soil, while up to 54% cadmium was desorbed from the contaminated soil matrix in surfactant aided desorption experiments.

  4. Effect of soil and cover conditions on soil-water relationships

    Science.gov (United States)

    George R., Jr. Trimble; Charles E. Hale; H. Spencer Potter

    1951-01-01

    People who make flood-control surveys for the U.S. Department of Agriculture are concerned with the physical condition of the soils in the watersheds. The condition of the soil determines how fast water moves into and through the soil, and how much water is held in storage. The condition of the soil has a great influence on stream flow, erosion, floods and water supply...

  5. Precision agriculture and soil and water management in cranberry production

    Science.gov (United States)

    Recent research on soil and water management of cranberry farms is presented in a special issue in Canadian Journal of Soil Science. The special issue (“Precision Agriculture and Soil Water Management in Cranberry Production”) consists of ten articles that include field, laboratory, and modeling stu...

  6. Pedotransfer functions to estimate soil water content at field capacity ...

    Indian Academy of Sciences (India)

    20

    available scarce water resources in dry land agriculture, but direct measurement thereof for multiple locations in the field is not always feasible. Therefore, pedotransfer functions (PTFs) were developed to estimate soil water retention at FC and PWP for dryland soils of India. A soil database available for Arid Western India ...

  7. Effects of fire ash on soil water retention

    NARCIS (Netherlands)

    Stoof, C.R.; Wesseling, J.G.; Ritsema, C.J.

    2010-01-01

    Despite the pronounced effect of fire on soil hydrological systems, information on the direct effect of fire on soil water retention characteristics is limited and contradictory. To increase understanding in this area, the effect of fire on soil water retention was evaluated using laboratory burning

  8. A one-dimensional model for simulating soil water movement ...

    African Journals Online (AJOL)

    ... regression analysis revealed the relati-onship to be exponential. The values of calculated and measured soil water content and total evapotranspiration decreased with number of days after rain or irrigation. The nodal soil water content also decreased with the soil depth. (Journal of Applied Science and Technology: 2001 ...

  9. Response of Eucalyptus grandis trees to soil water deficits

    CSIR Research Space (South Africa)

    Dye, PJ

    1996-01-01

    Full Text Available site, plastic sheeting was laid over the ground to prevent soil water recharge and thereby allow the roots in the soil to induce a continuous progressive depletion of soil water. Measurements of predawn xylem pressure potential, leaf area index, growth...

  10. Saturate hydraulic conductivity, water stable aggregates and soil ...

    African Journals Online (AJOL)

    Saturate hydraulic conductivity, water stable aggregates and soil organic matter in a sandy-loam soil in Ikwuano lga of Abia state. ... carbon content of the soil. . Keywords: Toposequence, Water stable aggregates, Saturated hydraulic conductivity, Organic carbon, Slope position. Agro-Science Vol. 4 (1) 2005: pp. 34-37.

  11. Modeling Soil Water Retention Curves in the Dry Range Using the Hygroscopic Water Content

    DEFF Research Database (Denmark)

    Chen, Chong; Hu, Kelin; Arthur, Emmanuel

    2014-01-01

    Accurate information on the dry end (matric potential less than −1500 kPa) of soil water retention curves (SWRCs) is crucial for studying water vapor transport and evaporation in soils. The objectives of this study were to assess the potential of the Oswin model for describing the water adsorption...... curves of soils and to predict SWRCs at the dry end using the hygroscopic water content at a relative humidity of 50% (θRH50). The Oswin model yielded satisfactory fits to dry-end SWRCs for soils dominated by both 2:1 and 1:1 clay minerals. Compared with the Oswin model, the Campbell and Shiozawa model...... for soils dominated by 2:1 and 1:1 clays, respectively. Comparison of the Oswin model combined with the Kelvin equation, with water potential estimated from θRH50 (Oswin-KRH50), CS model combined with the Arthur equation (CS-A), and CS-K model, with water potential obtained from θRH50 (CS-KRH50) indicated...

  12. The influence of vegetation on soil water repellency-markers and soil hydrophobicity.

    Science.gov (United States)

    Mao, Jiefei; Nierop, Klaas G J; Rietkerk, Max; Sinninghe Damsté, Jaap S; Dekker, Stefan C

    2016-10-01

    Soil water repellency (SWR) markers are defined as hydrophobic compounds in soil causing SWR and are mainly derived from plants. Previous studies have shown the types and abundance of SWR-markers in soils. However, how these SWR-markers are exactly related to SWR and their origin is poorly understood. This study aims to understand the relationship between SWR-markers, vegetation type and cover and SWR for a simple sandy soil ecosystem, consisting of oaks with sedge and six grass species. All the soil (at different depth) and vegetation samples were collected in the field along a 6m transect, starting from an oak tree. Further along the transect grasses and sedges became more abundant. Free and ester-bound lipids from soils and plant leaves/roots were obtained using a sequential extraction method and identified by gas chromatography-mass spectrometry. Significant linear correlations were found between the main soil characteristics, such as total organic carbon content, and SWR. Single long-chain (>C20) SWR-markers derived from both plant leaf waxes and roots positively related to SWR. Both ester-bound ω-hydroxy fatty acids and C22 and C24 α,ω-dicarboxylic acids were predominantly present in the grass roots, but to a lesser extent in the roots of oak and sedge. These suberin-derived ω-hydroxy fatty acids and α,ω-dicarboxylic acids characteristic of roots could well predict the SWR. Additionally, the SWR predictors abundantly present in the soils matched well with high concentrations of the corresponding biomarkers in the dominant vegetation species that covered the soils. Our analyses demonstrated that grass roots influenced SWR more due to their more substantial contribution of organic matter to the topsoils than oak roots. This led to a stronger SWR of the soils covered with grass than those covered with oak vegetation. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Measuring Soil Water Potential for Water Management in Agriculture: A Review

    Directory of Open Access Journals (Sweden)

    Marco Bittelli

    2010-05-01

    Full Text Available Soil water potential is a soil property affecting a large variety of bio-physical processes, such as seed germination, plant growth and plant nutrition. Gradients in soil water potential are the driving forces of water movement, affecting water infiltration, redistribution, percolation, evaporation and plants’ transpiration. The total soil water potential is given by the sum of gravity, matric, osmotic and hydrostatic potential. The quantification of the soil water potential is necessary for a variety of applications both in agricultural and horticultural systems such as optimization of irrigation volumes and fertilization. In recent decades, a large number of experimental methods have been developed to measure the soil water potential, and a large body of knowledge is now available on theory and applications. In this review, the main techniques used to measure the soil water potential are discussed. Subsequently, some examples are provided where the measurement of soil water potential is utilized for a sustainable use of water resources in agriculture.

  14. Water Use Efficiency in Saline Soils under Cotton Cultivation in the Tarim River Basin

    Directory of Open Access Journals (Sweden)

    Xiaoning Zhao

    2015-06-01

    Full Text Available The Tarim River Basin, the largest area of Chinese cotton production, is receiving increased attention because of serious environmental problems. At two experimental stations (Korla and Aksu, we studied the influence of salinity on cotton yield. Soil chemical and physical properties, soil water content, soil total suction and matric suction, cotton yield and water use efficiency under plastic mulched drip irrigation in different saline soils was measured during cotton growth season. The salinity (mS·cm−1 were 17–25 (low at Aksu and Korla, 29–50 (middle at Aksu and 52–62 (high at Aksu for ECe (Electrical conductivity measured in saturation-paste extract of soil over the 100 cm soil profile. The soil water characteristic curves in different saline soils showed that the soil water content (15%–23% at top 40 cm soil, lower total suction power (below 3500 kPa and lower matric suction (below 30 kPa in low saline soil at Korla had the highest water use efficiency (10 kg·ha−1·mm−1 and highest irrigation water use efficiency (12 kg·ha−1·mm−1 and highest yield (6.64 t·ha−1. Higher water content below 30 cm in high saline soil increased the salinity risk and led to lower yield (2.39 t·ha−1. Compared to low saline soils at Aksu, the low saline soil at Korla saved 110 mm irrigation and 103 mm total water to reach 1 t·ha−1 yield and increased water use efficiency by 5 kg·ha−1·mm−1 and 7 kg·ha−1·mm−1 for water use efficiency (WUE and irrigation water use efficiency (IWUE respectively.

  15. Soil properties evolution after irrigation with reclaimed water

    Science.gov (United States)

    Leal, M.; González-Naranjo, V.; de Miguel, A.; Martínez-Hernández, V.; Lillo, J.

    2012-04-01

    Many arid and semi-arid countries are forced to look for new and alternative water sources. The availability of suitable quality water for agriculture in these regions often is threatened. In this context of water scarcity, the reuse of treated wastewater for crop irrigation could represent a feasible solution. Through rigorous planning and management, irrigation with reclaimed water presents some advantages such as saving freshwater, reducing wastewater discharges into freshwater bodies and decreasing the amount of added fertilizers due to the extra supply of nutrients by reclaimed water. The current study, which involves wastewater reuse in agriculture, has been carried out in the Experimental Plant of Carrión de los Céspedes (Sevile, Spain). Here, two survey parcels equally designed have been cultivated with Jatropha curcas L, a bioenergetic plant and a non-interfering food security crop. The only difference between the two parcels lies on the irrigation water quality: one is irrigated with groundwater and another one with reclaimed water. The main aim of this study focuses on analysing the outstanding differences in soil properties derived from irrigation with two water qualities, due to their implications for plant growth. To control and monitor the soil variables, soil samples were collected before and after irrigation in the two parcels. pH, electrical conductivity, cation exchange capacity, exchangeable cations (Ca2+, Mg2+, Na+ and K+), kjeldahl nitrogen, organic matter content and nutrients (boron, phosphorus, nitrogen, potassium) were measured. Data were statistically analyzed using the R package. To evaluate the variance ANOVA test was used and to obtain the relations between water quality and soil parameters, Pearson correlation coefficient was computed. According to other authors, a decrease in the organic matter content and an increase of parameters such as pH, electrical conductivity and some exchangeable cations were expected. To date and after

  16. A Survey of Heavy Metals content of Soil and plants As Affected by Long-Term Application of Sewage Water. A Case Study

    Directory of Open Access Journals (Sweden)

    Abd El Lateef E. M.

    2014-07-01

    Full Text Available As part of a four year study evaluating the practicability and value of sewage sludge use in Egypt, soil and plant surveys were carried out on a citrus plantation, irrigated with Cairo sewage since the 1920s, in order to evaluate the long-term accumulation of trace elements and heavy metals and their bioavailability. While total and DTPA soil concentrations correlated well, no relationship could be found between soil and plant tissue concentrations, despite elevated levels of heavy metals in the soil. Study of long-term contamination of soil with potentially toxic elements (PTEs has not demonstrated a potential risk to crop quality and yield or human health from the slow accumulation of PTEs in sludge-treated agricultural soil. PTE concentrations in plant tissues remained low and within normal ranges despite significant increases in soil content after long-term irrigation with sewage effluent. Concentrations of PTEs in plant tissues were not related to total or DTPA extractable metals in contaminated soil. DTPA may not be a sufficiently reliable indicator of actual phytoavailability of trace elements in sludge-treated soil, although it is accepted that DTPA is widely used in nutrient diagnosis assessment. These data provide assurance about the minimal risk to the environment from trace elements and PTEs in sludge-treated agricultural soil, but a more detailed dietary analysis of Cd intakes under Egyptian conditions is recommended, following the approaches adopted in the UK and US for setting Cd soil limits or loading rates for this element.

  17. Effects of Soil Management Practices on Water Erosion under Natural Rainfall Conditions on a Humic Dystrudept

    Directory of Open Access Journals (Sweden)

    Vinicius Ferreira Chaves de Souza

    Full Text Available ABSTRACT Water erosion is the main cause of soil degradation and is influenced by rainfall, soil, topography, land use, soil cover and management, and conservation practices. The objective of this study was to quantify water erosion in a Humic Dystrudept in two experiments. In experiment I, treatments consisted of different rates of fertilizer applied to the soil surface under no-tillage conditions. In experiment II, treatments consisted of a no-tillage in natural rangeland, burned natural rangeland and natural rangeland. Forage turnip, black beans, common vetch, and corn were used in rotation in the treatments with crops in the no-tillage during study period. The treatments with crops and the burned rangeland and natural rangeland were compared to a bare soil control, without cultivation and without fertilization. Increasing fertilization rates increased organic carbon content, soil resistance to disintegration, and the macropore volume of the soil, due to the increase in the dry mass of the crops, resulting in an important reduction in water erosion. The exponential model of the ŷ = ae-bx type satisfactorily described the reduction in water and soil losses in accordance with the increase in fertilization rate and also described the decrease in soil losses in accordance with the increase in dry mass of the crops. Water erosion occurred in the following increasing intensity: in natural rangeland, in cultivated natural rangeland, and in burned natural rangeland. Water erosion had less effect on water losses than on soil losses, regardless of the soil management practices.

  18. Seasonal variations in soil water in two woodland savannas of central Brazil with different fire history.

    Science.gov (United States)

    Quesada, Carlos Alberto; Hodnett, Martin G; Breyer, Lacê M; Santos, Alexandre J B; Andrade, Sérgio; Miranda, Heloisa S; Miranda, Antonio Carlos; Lloyd, Jon

    2008-03-01

    Changes in soil water content were determined in two cerrado (sensu stricto) areas with contrasting fire history and woody vegetation density. The study was undertaken near Brasília, Brazil, from 1999 to 2001. Soil water content was measured with a neutron probe in three access tubes per site to a depth of 4.7 m. One site has been protected from fire for more than 30 years and, as a consequence, has a high density of woody plants. The other site had been frequently burned, and has a high herbaceous vegetation density and less woody vegetation. Soil water uptake patterns were strongly seasonal, and despite similarities in hydrological processes, the protected area systematically used more water than the burned area. Three temporarily contiguous patterns of water absorption were differentiated, characterized by variation in the soil depth from which water was extracted. In the early dry season, vegetation used water from throughout the soil profile but with a slight preference for water in the upper soil layers. Toward the peak of the dry season, vegetation had used most or all available water from the surface to a depth of 1.7 m, but continued to extract water from greater depths. Following the first rains, all water used was from the recently wetted upper soil layers only. Evaporation rates were a linear function of soil water availability, indicating a strong coupling of atmospheric water demand and the physiological response of the vegetation.

  19. Analyzing ecological restoration strategies for water and soil conservation

    Science.gov (United States)

    Mota da Silva, Jonathan; Silva, Marx Leandro Naves; Guimarães, João Luis Bittencourt; Sousa Júnior, Wilson Cabral; Figueiredo, Ricardo de Oliveira; da Rocha, Humberto Ribeiro

    2018-01-01

    The choice of areas for nature conservation involves the attempt to maximize the benefits, whether by carrying out an economic activity or by the provision of Ecosystem Services. Studies are needed to improve the understanding of the effect of the extent and position along the watershed of restored areas on soil and water conservation. This study aimed to understand how different restoration strategies might reflect in soil conservation and sediment retention. Using InVEST tool, sediment transport was simulated in a small 12 km2 watershed (Posses River, in Southeast Brazil), where one of first Brazilian Payment for Ecosystem Services (PES) projects is being carried out, comparing different hypothetical restoration strategies. With 25% of restoration, sediment export decreased by 78% for riparian restoration, and 27% for the steepest slopes restoration. On the other hand, the decrease in soil loss was lower for riparian restoration, with a 16% decrease, while the steepest slopes restoration reduced it by 21%. This mismatch between the reduction of sediment export and soil loss was explained by the fact that forest not only reduces soil loss locally but also traps sediment arriving from the upper parts of the watershed. While the first mechanism is important to provide soil stability, decreasing the risk of landslip, and to maintain agricultural productivity, the second can improve water quality and decrease the risk of silting, with positive effects on the water reservoirs at the outlet of the watershed. This suggests that Riparian and the Steepest Slopes restoration strategies are complementary in the sense of preventing sediments from reaching the water bodies as well as protecting them at their origin (with the reduction of erosion), so it will be advisable to consider the two types of restoration. PMID:29425214

  20. Analyzing ecological restoration strategies for water and soil conservation.

    Directory of Open Access Journals (Sweden)

    Sandra Isay Saad

    Full Text Available The choice of areas for nature conservation involves the attempt to maximize the benefits, whether by carrying out an economic activity or by the provision of Ecosystem Services. Studies are needed to improve the understanding of the effect of the extent and position along the watershed of restored areas on soil and water conservation. This study aimed to understand how different restoration strategies might reflect in soil conservation and sediment retention. Using InVEST tool, sediment transport was simulated in a small 12 km2 watershed (Posses River, in Southeast Brazil, where one of first Brazilian Payment for Ecosystem Services (PES projects is being carried out, comparing different hypothetical restoration strategies. With 25% of restoration, sediment export decreased by 78% for riparian restoration, and 27% for the steepest slopes restoration. On the other hand, the decrease in soil loss was lower for riparian restoration, with a 16% decrease, while the steepest slopes restoration reduced it by 21%. This mismatch between the reduction of sediment export and soil loss was explained by the fact that forest not only reduces soil loss locally but also traps sediment arriving from the upper parts of the watershed. While the first mechanism is important to provide soil stability, decreasing the risk of landslip, and to maintain agricultural productivity, the second can improve water quality and decrease the risk of silting, with positive effects on the water reservoirs at the outlet of the watershed. This suggests that Riparian and the Steepest Slopes restoration strategies are complementary in the sense of preventing sediments from reaching the water bodies as well as protecting them at their origin (with the reduction of erosion, so it will be advisable to consider the two types of restoration.

  1. Mapping soil resistance under different soil water content conditions using indicator kriging

    Science.gov (United States)

    Miras-Avalos, J. M.; Bonnin-Acosta, J.; Sande-Fouz, P.; Pereira-Lanças, K.; Paz-Gonzalez, A.

    2009-04-01

    In many agricultural problems, it is of interest to map the zones where the variable under study shows the probability of being greater than a threshold value. Soil resistances higher than 2 MPa might difficult the establishment of cultures; therefore, further management or tillage techniques should be undertaken. The aim of this work was to map soil resistance using geostatistical techniques, therefore, an analysis of the spatial distribution of soil compaction and the influence of soil water content on the resistance to penetration was carried out. The studied clay-textured soil was managed under no-tillage practices. Soil resistance was described by the cone index which was obtained using a penetrometer. This attribute was assessed at 5 different depths, i.e. 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm and deeper than 40 cm, whereas soil water content was described at 0-20 cm and 20-40 cm. In the end, 73 data points were surveyed. Soil water conditions varied during the five different samplings. Statistical analysis showed that datasets followed a normal distribution, therefore, no transformation was required. Studied attributes showed low and non-significant correlation coefficients which impeded the application of cross-variogram and cokriging techniques. Because of the limited number of measured data, only the omnidirectional semivariogram was computed, and hence the spatial variability is assumed to be identical in all directions. Spatial dependence was observed in 33 out of 35 data series, both for cone index and soil water content. Fitted theoretical structures corresponded to exponential models in 20 cases, 10 Gaussian models and 3 spherical models. Nugget effect varied from 0 to 44.4 depending on the dataset and spatial dependence maximum range was 90 m. A strong spatial dependence was observed in 18 of the data sets whereas only 2 showed a weak autocorrelation. Taking into account the 2 MPa threshold, indicator kriging was used to map the soil resistance

  2. A study of the utilization of ERTS-1 data from the Wabash River Basin. [crop identification, water resources, urban land use, soil mapping, and atmospheric modeling

    Science.gov (United States)

    Landgrebe, D. A. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. The most significant results were obtained in the water resources research, urban land use mapping, and soil association mapping projects. ERTS-1 data was used to classify water bodies to determine acreages and high agreement was obtained with USGS figures. Quantitative evaluation was achieved of urban land use classifications from ERTS-1 data and an overall test accuracy of 90.3% was observed. ERTS-1 data classifications of soil test sites were compared with soil association maps scaled to match the computer produced map and good agreement was observed. In some cases the ERTS-1 results proved to be more accurate than the soil association map.

  3. Effect of grass cover on water and pesticide transport through undisturbed soil columns, comparison with field study (Morcille watershed, Beaujolais)

    International Nuclear Information System (INIS)

    Dousset, S.; Thevenot, M.; Schrack, D.; Gouy, V.; Carluer, N.

    2010-01-01

    The purpose of this work is to assess the effectiveness of two grass covers (buffer zone and grass-covered inter-row), to reduce pesticide leaching, and subsequently to preserve groundwater quality. Lower amounts of pesticides leached through grass-cover soil columns (2.7-24.3% of the initial amount) than the bare soil columns (8.0-55.1%), in correspondence with their sorption coefficients. Diuron was recovered in higher amounts in leachates (8.9-32.2%) than tebuconazole (2.7-12.9%), in agreement with their sorption coefficients. However, despite having a sorption coefficient similar to that of diuron, more procymidone was recovered in the leachates (10.2-55.1%), probably due to its facilitated transport by dissolved organic matter. Thus even in this very permeable soil, higher organic matter contents associated with grass-cover reduce the amount of pesticide leaching and limit the risk of groundwater contamination by the pesticides. The results of diuron and tebuconazole transfer through undisturbed buffer zone soil columns are in agreement with field observations on the buffer zone. - Grass-covered soils reduce the amount of pesticide leaching, due mainly to their higher organic matter contents, thereby reducing the risk of groundwater contamination.

  4. Effect of grass cover on water and pesticide transport through undisturbed soil columns, comparison with field study (Morcille watershed, Beaujolais)

    Energy Technology Data Exchange (ETDEWEB)

    Dousset, S., E-mail: sylvie.dousset@limos.uhp-nancy.f [Nancy-Universite, CNRS, LIMOS, BP 70239, 54506 Vandoeuvre-les-Nancy (France); Thevenot, M. [Universite de Lille 1, CNRS, Geosystemes, 59655 Villeneuve d' Ascq (France); Schrack, D. [INRA-SAD ASTER, 88500 Mirecourt (France); AFSSA, Laboratoire d' Etudes et de Recherches en Hydrologie, 54000 Nancy (France); Gouy, V.; Carluer, N. [UR Milieux Aquatiques, Ecologie et Pollution, Cemagref, 69336 Lyon Cedex (France)

    2010-07-15

    The purpose of this work is to assess the effectiveness of two grass covers (buffer zone and grass-covered inter-row), to reduce pesticide leaching, and subsequently to preserve groundwater quality. Lower amounts of pesticides leached through grass-cover soil columns (2.7-24.3% of the initial amount) than the bare soil columns (8.0-55.1%), in correspondence with their sorption coefficients. Diuron was recovered in higher amounts in leachates (8.9-32.2%) than tebuconazole (2.7-12.9%), in agreement with their sorption coefficients. However, despite having a sorption coefficient similar to that of diuron, more procymidone was recovered in the leachates (10.2-55.1%), probably due to its facilitated transport by dissolved organic matter. Thus even in this very permeable soil, higher organic matter contents associated with grass-cover reduce the amount of pesticide leaching and limit the risk of groundwater contamination by the pesticides. The results of diuron and tebuconazole transfer through undisturbed buffer zone soil columns are in agreement with field observations on the buffer zone. - Grass-covered soils reduce the amount of pesticide leaching, due mainly to their higher organic matter contents, thereby reducing the risk of groundwater contamination.

  5. Differential effects of fine root morphology on water dynamics in the root-soil interface

    Science.gov (United States)

    DeCarlo, K. F.; Bilheux, H.; Warren, J.

    2017-12-01

    Soil water uptake form plants, particularly in the rhizosphere, is a poorly understood question in the plant and soil sciences. Our study analyzed the role of belowground plant morphology on soil structural and water dynamics of 5 different plant species (juniper, grape, maize, poplar, maple), grown in sandy soils. Of these, the poplar system was extended to capture drying dynamics. Neutron radiography was used to characterize in-situ dynamics of the soil-water-plant system. A joint map of root morphology and soil moisture was created for the plant systems using digital image processing, where soil pixels were connected to associated root structures via minimum distance transforms. Results show interspecies emergent behavior - a sigmoidal relationship was observed between root diameter and bulk/rhizosphere soil water content difference. Extending this as a proxy for extent of rhizosphere development with root age, we observed a logistic growth pattern for the rhizosphere: minimal development in the early stages is superceded by rapid onset of rhizosphere formation, which then stabilizes/decays with the likely root suberization. Dynamics analysis of water content differences between the root/rhizosphere, and rhizosphere/bulk soil interface highlight the persistently higher water content in the root at all water content and root size ranges. At the rhizosphere/bulk soil interface, we observe a shift in soil water dynamics by root size: in super fine roots, we observe that water content is primarily lower in the rhizosphere under wetter conditions, which then gradually increases to a relatively higher water content under drier conditions. This shifts to a persistently higher rhizosphere water content relative to bulk soil in both wet/dry conditions with increased root size, suggesting that, by size, the finest root structures may contribute the most to total soil water uptake in plants.

  6. Soil Water and Temperature System (SWATS) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Cook, David R. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-04-01

    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 U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Southern Great Plains (SGP) 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.

  7. Air sparging and soil vapor extraction to remediate ground water

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, T.P.; Finkbeiner, J.A.; Warmus, P.J. [ATEC Associates, Inc., Raleigh, NC (United States)

    1994-12-31

    An Air Sparging and Soil Vapor Extraction System was chosen to remediate petroleum impacted ground water over traditional remedial alternatives, such as ``pump and treat``, to expedite site closure. Field pilot testing, computer modeling and cost benefit analyses performed for several alternatives. Air Sparging and Soil Vapor Extraction pilot studies proved this technology to be the most effective with respect to remedial and economic concerns. Underground Storage Tanks (USTs) were closed at the facility located in North Eastern North Carolina in August of 1992. During UST closure, petroleum impacted ground water and soils were encountered. ATEC performed a Comprehensive Site assessment to delineate the impacted soil and ground water plume. Following completion of the site assessment, a Corrective Action Plan was prepared. As part of the Corrective Action Plan preparation, field pilot testing was performed to evaluate remedial alternatives and provide information for full scale design. The full scale treatment system was installed and started in January 1994. This effective Remedial System was selected over other options due to successful pilot testing results with site closure petitioning scheduled within 12 to 14 months after start up. The Air Sparging System, properly applied, is an effective and ``quick`` remedial option with no generation of ground water for disposal and permitting. This paper concentrates on the Air Sparging application applied at this North Carolina site. Although Vapor extraction was also implemented, this presentation does not elaborate on vapor extraction design or implementation and only discusses vapor extraction where it is directly related to the Air Sparging System.

  8. Preliminary study of soil permeability properties using principal component analysis

    Science.gov (United States)

    Yulianti, M.; Sudriani, Y.; Rustini, H. A.

    2018-02-01

    Soil permeability measurement is undoubtedly important in carrying out soil-water research such as rainfall-runoff modelling, irrigation water distribution systems, etc. It is also known that acquiring reliable soil permeability data is rather laborious, time-consuming, and costly. Therefore, it is desirable to develop the prediction model. Several studies of empirical equations for predicting permeability have been undertaken by many researchers. These studies derived the models from areas which soil characteristics are different from Indonesian soil, which suggest a possibility that these permeability models are site-specific. The purpose of this study is to identify which soil parameters correspond strongly to soil permeability and propose a preliminary model for permeability prediction. Principal component analysis (PCA) was applied to 16 parameters analysed from 37 sites consist of 91 samples obtained from Batanghari Watershed. Findings indicated five variables that have strong correlation with soil permeability, and we recommend a preliminary permeability model, which is potential for further development.

  9. Horizontal soil water potential heterogeneity: simplifying approaches for crop water dynamics models

    Science.gov (United States)

    Couvreur, V.; Vanderborght, J.; Beff, L.; Javaux, M.

    2014-05-01

    Soil water potential (SWP) is known to affect plant water status, and even though observations demonstrate that SWP distribution around roots may limit plant water availability, its horizontal heterogeneity within the root zone is often neglected in hydrological models. As motive, using a horizontal discretisation significantly larger than one centimetre is often essential for computing time considerations, especially for large-scale hydrodynamics models. In this paper, we simulate soil and root system hydrodynamics at the centimetre scale and evaluate approaches to upscale variables and parameters related to root water uptake (RWU) for two crop systems: a densely seeded crop with an average uniform distribution of roots in the horizontal direction (winter wheat) and a wide-row crop with lateral variations in root density (maize). In a first approach, the upscaled water potential at soil-root interfaces was assumed to equal the bulk SWP of the upscaled soil element. Using this assumption, the 3-D high-resolution model could be accurately upscaled to a 2-D model for maize and a 1-D model for wheat. The accuracy of the upscaled models generally increased with soil hydraulic conductivity, lateral homogeneity of root distribution, and low transpiration rate. The link between horizontal upscaling and an implicit assumption on soil water redistribution was demonstrated in quantitative terms, and explained upscaling accuracy. In a second approach, the soil-root interface water potential was estimated by using a constant rate analytical solution of the axisymmetric soil water flow towards individual roots. In addition to the theoretical model properties, effective properties were tested in order to account for unfulfilled assumptions of the analytical solution: non-uniform lateral root distributions and transient RWU rates. Significant improvements were however only noticed for winter wheat, for which the first approach was already satisfying. This study confirms that the

  10. Uranium in soils and water; Uran in Boden und Wasser

    Energy Technology Data Exchange (ETDEWEB)

    Dienemann, Claudia; Utermann, Jens

    2012-07-15

    The report of the Umweltbundesamt (Federal Environmental Agency) on uranium in soils and water covers the following chapters: (1) Introduction. (2) Deposits and properties: Use of uranium; toxic effects on human beings, uranium in ground water and drinking water, uranium in surface waters, uranium in soils, uranium in the air. (3) Legal regulations. (4) Uranium deposits, uranium mining, polluted area recultivation. (5) Diffuse uranium entry in soils and water: uranium insertion due to fertilizers, uranium insertion due to atmospheric precipitation, uranium insertion from the air. (6) Diffuse uranium release from soils and transfer in to the food chain. (7) Conclusions and recommendations.

  11. Impact of Sewage Sludge on Water Movement in Calcareous Sandy Soils

    Directory of Open Access Journals (Sweden)

    A.M. AI-Omran

    1997-01-01

    Full Text Available The present study was undertaken to investigate the changes in soil physical properties and their effect on water movement under ponded irrigation. Sewage sludge was applied to 10 cm soil depth at rates of 0.25. 75  and 100 Mg-ha-1 to two disturbed soils differing in CaCO3 content. The results showed that cumulative infiltration (1 decreased with an increase in sewage sludge rates. Basic infiltration for slightly calcareous sandy soil was higher than that of moderately calcareous sandy soil, laboratory measurements showed an exponential decrease in saturated hydraulic conductivity and an increase in available water capacity with an increase in sewage sludge rates. For both soils, water diffusivity (D(Q decreased with an increase in sewage sludge rates. The (oral values of slightly calcareous sandy soils were higher than those of moderately calcareous sandy soils.

  12. Project Increase of infrastructure: 'Establishment of a laboratory for studies of pollutants in air, water and soil through atomic and nuclear techniques

    International Nuclear Information System (INIS)

    Aldape U, F.

    1993-10-01

    In this report there are the guidelines of this project as well as the goals, activities and costs. The general objectives were: 1. A laboratory that allows to analyze with efficiency samples of air, water and soil pollutants using atomic and nuclear origin techniques as PIXE (Proton Induced X-ray Emission, NRA (Nuclear Reaction Analysis) and RBS (Rutherford Backscattering) as well as auxiliary and/or complementary techniques. 2. To obtain indicators of the influence of the pollution of the Valley of Mexico about the ecology and the health of the inhabitants of Mexico City with perspectives of carrying out studies in other cities. 3. To develop an appropriate technology for the realization of those studies and to generate human resources in this area. (Author)

  13. Effect of grass cover on water and pesticide transport through undisturbed soil columns, comparison with field study (Morcille watershed, Beaujolais).

    Science.gov (United States)

    Dousset, S; Thévenot, M; Schrack, D; Gouy, V; Carluer, N

    2010-07-01

    The purpose of this work is to assess the effectiveness of two grass covers (buffer zone and grass-covered inter-row), to reduce pesticide leaching, and subsequently to preserve groundwater quality. Lower amounts of pesticides leached through grass-cover soil columns (2.7-24.3% of the initial amount) than the bare soil columns (8.0-55.1%), in correspondence with their sorption coefficients. Diuron was recovered in higher amounts in leachates (8.9-32.2%) than tebuconazole (2.7-12.9%), in agreement with their sorption coefficients. However, despite having a sorption coefficient similar to that of diuron, more procymidone was recovered in the leachates (10.2-55.1%), probably due to its facilitated transport by dissolved organic matter. Thus even in this very permeable soil, higher organic matter contents associated with grass-cover reduce the amount of pesticide leaching and limit the risk of groundwater contamination by the pesticides. The results of diuron and tebuconazole transfer through undisturbed buffer zone soil columns are in agreement with field observations on the buffer zone. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  14. Relations between soil surface roughness, tortuosity, tillage treatments, rainfall intensity and soil and water losses from a red yellow latosol

    Directory of Open Access Journals (Sweden)

    Julieta Bramorski

    2012-08-01

    Full Text Available The soil surface roughness increases water retention and infiltration, reduces the runoff volume and speed and influences soil losses by water erosion. Similarly to other parameters, soil roughness is affected by the tillage system and rainfall volume. Based on these assumptions, the main purpose of this study was to evaluate the effect of tillage treatments on soil surface roughness (RR and tortuosity (T and to investigate the relationship with soil and water losses in a series of simulated rainfall events. The field study was carried out at the experimental station of EMBRAPA Southeastern Cattle Research Center in São Carlos (Fazenda Canchim, in São Paulo State, Brazil. Experimental plots of 33 m² were treated with two tillage practices in three replications, consisting of: untilled (no-tillage soil (NTS and conventionally tilled (plowing plus double disking soil (CTS. Three successive simulated rain tests were applied in 24 h intervals. The three tests consisted of a first rain of 30 mm/h, a second of 30 mm/h and a third rain of 70 mm/h. Immediately after tilling and each rain simulation test, the surface roughness was measured, using a laser profile meter. The tillage treatments induced significant changes in soil surface roughness and tortuosity, demonstrating the importance of the tillage system for the physical surface conditions, favoring water retention and infiltration in the soil. The increase in surface roughness by the tillage treatments was considerably greater than its reduction by rain action. The surface roughness and tortuosity had more influence on the soil volume lost by surface runoff than in the conventional treatment. Possibly, other variables influenced soil and water losses from the no-tillage treatments, e.g., soil type, declivity, slope length, among others not analyzed in this study.

  15. Agent-based model of soil water dynamics

    Science.gov (United States)

    Mewes, Benjamin; Schumann, Andreas

    2017-04-01

    In the last decade, agent based modelling became more and more popular in social science, biology and environmental modelling. The concept is designed to simulate systems that are highly dynamic and sensitive to small variations in their composition and their state. As hydrological systems often show dynamic and nonlinear behaviour, agent based modelling can be an adequate way to model aquatic systems. Nevertheless, up to now only a few results on agent based modelling are known in hydrology. Processes like the percolation of water through the soil are highly responsive to the state of the pedological system. To simulate these water fluxes correctly by known approaches like the Green-Ampt model or approximations to the Richards equation, small time steps and a high spatial discretisation are needed. In this study a new approach for modelling water fluxes in a soil column is presented: autonomous water agents that transport water through the soil while interacting with their environment as well as with other agents under physical laws. Setting up an agent-based model requires a predefined rule set for the behaviour of the autonomous agents. Moreover, we present some principle assumptions of the interaction not only between agents, but as well between agents and their environment. Our study shows that agent-based modelling in hydrology leads to very promising results but we also have to face new challenges.

  16. An efficient soil water balance model based on hybrid numerical and statistical methods

    Science.gov (United States)

    Mao, Wei; Yang, Jinzhong; Zhu, Yan; Ye, Ming; Liu, Zhao; Wu, Jingwei

    2018-04-01

    Most soil water balance models only consider downward soil water movement driven by gravitational potential, and thus cannot simulate upward soil water movement driven by evapotranspiration especially in agricultural areas. In addition, the models cannot be used for simulating soil water movement in heterogeneous soils, and usually require many empirical parameters. To resolve these problems, this study derives a new one-dimensional water balance model for simulating both downward and upward soil water movement in heterogeneous unsaturated zones. The new model is based on a hybrid of numerical and statistical methods, and only requires four physical parameters. The model uses three governing equations to consider three terms that impact soil water movement, including the advective term driven by gravitational potential, the source/sink term driven by external forces (e.g., evapotranspiration), and the diffusive term driven by matric potential. The three governing equations are solved separately by using the hybrid numerical and statistical methods (e.g., linear regression method) that consider soil heterogeneity. The four soil hydraulic parameters required by the new models are as follows: saturated hydraulic conductivity, saturated water content, field capacity, and residual water content. The strength and weakness of the new model are evaluated by using two published studies, three hypothetical examples and a real-world application. The evaluation is performed by comparing the simulation results of the new model with corresponding results presented in the published studies, obtained using HYDRUS-1D and observation data. The evaluation indicates that the new model is accurate and efficient for simulating upward soil water flow in heterogeneous soils with complex boundary conditions. The new model is used for evaluating different drainage functions, and the square drainage function and the power drainage function are recommended. Computational efficiency of the new

  17. Mesquite root distribution and water use efficiency in response to long-term soil moisture manipulations

    Science.gov (United States)

    R. J. Ansley; T. W. Boutton; P. W. Jacoby

    2007-01-01

    This study quantified honey mesquite (Prosopis glandulosa) root growth and water use efficiency following chronic soil drought or wetness on a clay loam site in north Texas. Root systems of mature trees were containerized with barriers inserted into the soil. Soil moisture within containers was manipulated with irrigation (Irrigated) or rain...

  18. Quantitative imaging of water flow in soil and roots using neutron radiography and deuterated water

    International Nuclear Information System (INIS)

    Zarebanadkouki, Mohsen

    2013-01-01

    Where and how fast do roots take up water? Despite its importance in plant and soil sciences, there is limited experimental information on the location of water uptake along the roots of transpiring plants growing in soil. The answer to this question requires direct and in-situ measurement of the local flow of water into the roots. The aim of this study was to develop and apply a new method to quantify the local fluxes of water into different segments of the roots of intact plants. To this end, neutron radiography was used to trace the transport of deuterated water (D 2 O) into the roots of lupines. Lupines were grown in aluminum containers filled with sandy soil. The soil was partitioned into different compartments using 1 cm-thick layers of coarse sand as capillary barriers. These barriers limited the diffusion of D 2 O within the soil compartments. D 2 O was locally injected into the selected soil compartments during the day (transpiring plants) and night (non-transpiring plants). Transport of D 2 O into roots was then monitored by neutron radiography with spatial resolution of 100 μm and time intervals of 10 seconds. Neutron radiographs showed that: i) transport of D 2 O into roots was faster during the day than during the night; 2) D 2 O quickly moved along the roots towards the shoots during the day, while at night this axial transport was negligible. The differences between day and night measurements were explained by convective transport of D 2 O into the roots. To quantify the net flow of water into roots, a simple convection-diffusion model was developed, where the increase rate of D 2 O concentration in roots depended on the convective transport (net root water uptake) and the diffusion of D 2 O into roots. The results showed that water uptake was not uniform along the roots. Water uptake was higher in the upper soil layers than in the deeper ones. Along an individual roots, the water uptake rate was higher in the proximal segments than in the distal

  19. The geographic distribution of Sr isotopes from surface waters and soil extracts over the island of Bornholm (Denmark) – A base for provenance studies in archaeology and agriculture

    DEFF Research Database (Denmark)

    Frei, Robert; Frei, Karin Margarita

    2013-01-01

    In this paper we report the Sr isotope signatures, and Sr, Al and Na concentrations of 30 surface waters (lakes/ponds and rivers/creeks) and 19 soil sample extracts from the island of Bornholm (Denmark) and present a categorized 87Sr/86Sr value distribution map that may serve as a base for proven...... and low 87Sr/86Sr values, and a source with lower [Sr] delivering radiogenic Sr to the surface waters, which we equate with Sr leached from the products of mineral weathering (soils)....

  20. A lysimeter study of nitrate leaching, optimum fertilisation rate and growth responses of corn (Zea mays L.) following soil amendment with water-saving super-absorbent polymer.

    Science.gov (United States)

    Islam, M Robiul; Mao, Sishuai; Xue, Xuzhang; Eneji, A Egrinya; Zhao, Xingbao; Hu, Yuegao

    2011-08-30

    Nitrate leaching and the resulting groundwater contamination from intensive cereal production has become a major concern for long-term farmland efficiency and environmental sustainability in northern China. The aim of this study was to evaluate a water-saving super-absorbent polymer (SAP) for minimising NO(3)(-) leaching from soil and optimising corn growth and yield. Thirty-six undisturbed soil lysimeters were installed in a field lysimeter facility in drought-affected northern China to study the growth and yield characteristics of summer corn (Zea mays L.) as well as the amount of NO(3)-leaching losses under different fertiliser (standard, medium or 75% and low, or 50% of conventional fertilisation rate) and SAP (control, 0; level-1, 15 kg ha(-1) and level-2, 30 kg ha(-1)) treatments. Corn yield fell by 19.7% under medium and 37.7% under low fertilisation; the application of SAP increased yield significantly by 44.4% on level-1 and 80.3% on level-2. Similarly, plant height, leaf area, number of grains as well as protein, soluble sugar and starch contents in the grain also increased with SAP treatment. Application of SAP at 30 kg ha(-1) plus half of conventional fertilisation can reduce maximum (64.1%) nitrate leaching losses from soil. Application of SAP at 30 kg ha(-1) plus only half the amount of conventional fertiliser rate (150 kg urea, and 50 kg each of superphosphate and potassium sulfate) would be a more appropriate practice both for minimising nitrate leaching and sustainable corn production under the arid and semiarid conditions of northern China. Copyright © 2011 Society of Chemical Industry.

  1. Relationships between soil erosion risk, soil use and soil properties in Mediterranean areas. A comparative study of three typical sceneries

    Science.gov (United States)

    Gil, Juan; Priego-Navas, Mercedes; Zavala, Lorena M.; Jordán, Antonio

    2013-04-01

    Generally, literature shows that the high variability of rainfall-induced soil erosion is related to climatic differences, relief, soil properties and land use. Very different runoff rates and soil loss values have been reported in Mediterranean cropped soils depending on soil management practices, but also in soils under natural vegetation types. OBJECTIVES The aim of this research is to study the relationships between soil erosion risk, soil use and soil properties in three typical Mediterranean areas from southern Spain: olive groves under conventional tillage, minimum tillage and no-till practices, and soils under natural vegetation. METHODS Rainfall simulation experiments have been carried out in order to assess the relationship between soil erosion risk, land use, soil management and soil properties in olive-cropped soils under different types of management and soils under natural vegetation type from Mediterranean areas in southern Spain RESULTS Results show that mean runoff rates decrease from 35% in olive grove soils under conventional tillage to 25% in olive (Olea europaea) grove soils with minimum tillage or no-till practices, and slightly over 22% in soils under natural vegetation. Moreover, considering the different vegetation types, runoff rates vary in a wide range, although runoff rates from soils under holm oak (Quercus rotundifolia), 25.70%, and marginal olive groves , 25.31%, are not significantly different. Results from soils under natural vegetation show that the properties and nature of the organic residues play a role in runoff characteristics, as runoff rates above 50% were observed in less than 10% of the rainfall simulations performed on soils with a organic layer. In contrast, more than half of runoff rates from bare soils reached or surpassed 50%. Quantitatively, average values for runoff water losses increase up to 2.5 times in unprotected soils. This is a key issue in the study area, where mean annual rainfall is above 600 mm

  2. Soil water characteristics of Middle Pleistocene paleosol layers on ...

    African Journals Online (AJOL)

    Soil water plays an important role in water quality monitoring, irrigation scheduling, solute migration, and plant growth. ... Information about the soil hydraulic properties of Middle Pleistocene paleosol layers within the Yingpan section on the Loess Plateau of China is necessary since it may affect water cycle processes both ...

  3. Pedotransfer functions to estimate soil water content at field capacity ...

    Indian Academy of Sciences (India)

    20

    Soil water retention, Dry lands, Western India, Pedotransfer functions, Soil moisture calculator. 1. 2. 3. 4 ..... samples although it is known that structure and macro-porosity of the sample affect water retention (Unger ..... and OC content has positive influence on water retention whereas interaction of clay and OC has negative ...

  4. Reflectance of vegetation, soil, and water

    Science.gov (United States)

    Wiegand, C. L. (Principal Investigator)

    1973-01-01

    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.

  5. Post-fire interactions between soil water repellency, soil fertility and plant growth in soil collected from a burned piñon-juniper woodland

    Science.gov (United States)

    Fernelius, Kaitlynn J.; Madsen, Matthew D.; Hopkins, Bryan G.; Bansal, Sheel; Anderson, Val J.; Eggett, Dennis L.; Roundy, Bruce A.

    2017-01-01

    Woody plant encroachment can increase nutrient resources in the plant-mound zone. After a fire, this zone is often found to be water repellent. This study aimed to understand the effects of post-fire water repellency on soil water and inorganic nitrogen and their effects on plant growth of the introduced annual Bromus tectorum and native bunchgrass Pseudoroegneria spicata. Plots centered on burned Juniperus osteosperma trees were either left untreated or treated with surfactant to ameliorate water repellency. After two years, we excavated soil from the untreated and treated plots and placed it in zerotension lysimeter pots. In the greenhouse, half of the pots received an additional surfactant treatment. Pots were seeded separately with B. tectorum or P. spicata. Untreated soils had high runoff, decreased soilwater content, and elevated NO3eN in comparison to surfactant treated soils. The two plant species typically responded similar to the treatments. Above-ground biomass and microbial activity (estimated through soil CO2 gas emissions) was 16.8-fold and 9.5-fold higher in the surfactant-treated soils than repellent soils, respectably. This study demonstrates that water repellency can influence site recovery by decreasing soil water content, promoting inorganic N retention, and impairing plant growth and microbial activity.

  6. Archaeol: An Indicator of Methanogenesis in Water-Saturated Soils

    Directory of Open Access Journals (Sweden)

    Katie L. H. Lim

    2012-01-01

    Full Text Available Oxic soils typically are a sink for methane due to the presence of high-affinity methanotrophic Bacteria capable of oxidising methane. However, soils experiencing water saturation are able to host significant methanogenic archaeal communities, potentially affecting the capacity of the soil to act as a methane sink. In order to provide insight into methanogenic populations in such soils, the distribution of archaeol in free and conjugated forms was investigated as an indicator of fossilised and living methanogenic biomass using gas chromatography-mass spectrometry with selected ion monitoring. Of three soils studied, only one organic matter-rich site contained archaeol in quantifiable amounts. Assessment of the subsurface profile revealed a dominance of archaeol bound by glycosidic headgroups over phospholipids implying derivation from fossilised biomass. Moisture content, through control of organic carbon and anoxia, seemed to govern trends in methanogen biomass. Archaeol and crenarchaeol profiles differed, implying the former was not of thaumarcheotal origin. Based on these results, we propose the use of intact archaeol as a useful biomarker for methanogen biomass in soil and to track changes in moisture status and aeration related to climate change.

  7. Soil water repellency of the artificial soil and natural soil in rocky slopes as affected by the drought stress and polyacrylamide.

    Science.gov (United States)

    Chen, Zhang; Wang, Ruixin; Han, Pengyuan; Sun, Hailong; Sun, Haifeng; Li, Chengjun; Yang, Lixia

    2018-04-01

    Soil water repellency (SWR) causes reduced soil water storage, enhanced runoff and reduced ecosystem productivity. Therefore, characterization of SWR is a prerequisite for effective environmental management. SWR has been reported under different soils, land uses and regions of the world, particularly in forest land and after wildfires; however, the understanding of this variable in the artificial soil of rocky slope eco-engineering is still rather limited. This study presented the characterization of SWR in the artificial soil affected by the polyacrylamide (PAM) and drought stress. There were two molecular weights of PAM, and the CK was without PAM application. Three types of soil were studied: natural soil and two types of artificial soil which have been sprayed for 1y and 5y, respectively. The drought stress experiments had three drought gradients, lasted for three weeks. Water repellency index (WRI) and soil-water contact angle (β) were determined using intrinsic sorptivity method by measuring the water sorptivity (S W ) and ethanol sorptivity (S E ) in all soil samples. The results showed that (1) Polyacrylamide treatments significantly increased S W by 3% to 38%, and reduced S E by 1% to 15%, WRI by 6% to 38%, β by 3% to 23% compared to the control group. Polyacrylamide treatments also increased water-stable aggregates content and total porosity by 22% to 33%, 11% to 20% relative to the control, while PAM with a higher molecular weight performed best. (2) The interaction between PAM and drought stress had a significant effect on WRI and β for all soil types (Pnatural soil. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Influence of salinity and water content on soil microorganisms

    Directory of Open Access Journals (Sweden)

    Nan Yan

    2015-12-01

    Full Text Available Salinization is one of the most serious land degradation problems facing world. Salinity results in poor plant growth and low soil microbial activity due to osmotic stress and toxic ions. Soil microorganisms play a pivotal role in soils through mineralization of organic matter into plant available nutrients. Therefore it is important to maintain high microbial activity in soils. Salinity tolerant soil microbes counteract osmotic stress by synthesizing osmolytes which allows them to maintain their cell turgor and metabolism. Osmotic potential is a function of the salt concentration in the soil solution and therefore affected by both salinity (measured as electrical conductivity at a certain water content and soil water content. Soil salinity and water content vary in time and space. Understanding the effect of changes in salinity and water content on soil microorganisms is important for crop production, sustainable land use and rehabilitation of saline soils. In this review, the effects of soil salinity and water content on microbes are discussed to guide future research into management of saline soils.

  9. Field soil-water properties measured through radiation techniques

    International Nuclear Information System (INIS)

    1984-07-01

    This report shows a major effort to make soil physics applicable to the behaviour of the field soils and presents a rich and diverse set of data which are essential for the development of effective soil-water management practices that improve and conserve the quality and quantity of agricultural lands. This piece of research has shown that the neutron moisture meter together with some complementary instruments like tensiometers, can be used not only to measure soil water contents but also be extremely handy to measure soil hydraulic characteristics and soil water flow. It is, however, recognized that hydraulic conductivity is highly sensitive to small changes in soil water content and texture, being extremely variable spatially and temporally

  10. Effects of Revolution on soil wetting, turf performance and nitrogen efficiency of a fairway prone to soil water repellency

    NARCIS (Netherlands)

    Oostindie, K.; Dekker, L.W.; Geissen, V.; Ritsema, C.J.

    2013-01-01

    This study reports on the effects of applications of the surfactant Revolution on soil wetting and turf performance of fairway 10 of the Rosendaelsche Golfclub, located near Arnhem, The Netherlands. In addition, the influence of Revolution on soil water repellency and the nitrogen contents in grass

  11. New Comparative Experiments of Different Soil Types for Farmland Water Conservation in Arid Regions

    Directory of Open Access Journals (Sweden)

    Yiben Cheng

    2018-03-01

    Full Text Available Irrigated farmland is the main food source of desert areas, and moisture is the main limiting factor of desert farmland crop productivity. Study on the influence of irrigation on desert farmland soil moisture can guide the agricultural water resource utilization and agricultural production in those regions. At present, the efficiency of irrigation water usage in Northwest China is as low as approximately 40% of the irrigated water. To understand the response of farmland soil moisture in different soil types on irrigation in the Ulan Buh Desert of Inner Mongolia of China, this experimental study takes advantage of different infiltration characteristics and hydraulic conductivities of sand, clay, and loam to determine an optimized soil combination scheme with the purpose of establishing a hydraulic barrier that reduces infiltration. This study includes three comparative experiments with each consisting of a 100 cm thick of filled sand, or clay, or loam soil underneath a 50 cm plough soil, with a total thickness of 150 cm soil profile. A new type of lysimeter is installed below the above-mentioned 150 cm soil profile to continuously measure deep soil recharge (DSR, and the ECH2O-5 soil moisture sensors are installed at different depths over the 150 cm soil profile to simultaneously monitor the soil moisture above the lysimeter. The study analyzes the characteristics of soil moisture dynamics, the irrigation-related recharge on soil moisture, and the DSR characteristics before and after irrigation, during the early sowing period from 2 April to 2 May 2017. Research results show that: (1 Irrigation significantly influences the soil moisture of 0–150 cm depths. The soil moisture increase after the irrigation follows the order from high to low when it is in the order of loam, sand, and clay. (2 Irrigation-induced soil moisture recharge occurs on all three soil combinations at 0–150 cm layers, and the order of soil moisture recharge from high to low

  12. Ecohydrology of dry regions: storage versus pulse soil water dynamics

    Science.gov (United States)

    Lauenroth, William K.; Schlaepfer, Daniel R.; Bradford, John B.

    2014-01-01

    Although arid and semiarid regions are defined by low precipitation, the seasonal timing of temperature and precipitation can influence net primary production and plant functional type composition. The importance of precipitation seasonality is evident in semiarid areas of the western U.S., which comprise the Intermountain (IM) zone, a region that receives important winter precipitation and is dominated by woody plants and the Great Plains (GP), a region that receives primarily summer precipitation and is dominated by perennial grasses. Although these general relationships are well recognized, specific differences in water cycling between these regions have not been well characterized. We used a daily time step soil water simulation model and twenty sites from each region to analyze differences in soil water dynamics and ecosystem water balance. IM soil water patterns are characterized by storage of water during fall, winter, and spring resulting in relatively reliable available water during spring and early summer, particularly in deep soil layers. By contrast, GP soil water patterns are driven by pulse precipitation events during the warm season, resulting in fluctuating water availability in all soil layers. These contrasting patterns of soil water—storage versus pulse dynamics—explain important differences between the two regions. Notably, the storage dynamics of the IN sites increases water availability in deep soil layers, favoring the deeper rooted woody plants in that region, whereas the pulse dynamics of the Great Plains sites provide water primarily in surface layers, favoring the shallow-rooted grasses in that region. In addition, because water received when plants are either not active or only partially so is more vulnerable to evaporation and sublimation than water delivered during the growing season, IM ecosystems use a smaller fraction of precipitation for transpiration (47%) than GP ecosystems (49%). Recognizing the pulse-storage dichotomy in

  13. Integrated double mulching practices optimizes soil temperature and improves soil water utilization in arid environments

    Science.gov (United States)

    Yin, Wen; Feng, Fuxue; Zhao, Cai; Yu, Aizhong; Hu, Falong; Chai, Qiang; Gan, Yantai; Guo, Yao

    2016-09-01

    Water shortage threatens agricultural sustainability in many arid and semiarid areas of the world. It is unknown whether improved water conservation practices can be developed to alleviate this issue while increasing crop productivity. In this study, we developed a "double mulching" system, i.e., plastic film coupled with straw mulch, integrated together with intensified strip intercropping. We determined (i) the responses of soil evaporation and moisture conservation to the integrated double mulching system and (ii) the change of soil temperature during key plant growth stages under the integrated systems. Experiments were carried out in northwest China in 2009 to 2011. Results show that wheat-maize strip intercropping in combination with plastic film and straw covering on the soil surface increased soil moisture (mm) by an average of 3.8 % before sowing, 5.3 % during the wheat and maize co-growth period, 4.4 % after wheat harvest, and 4.9 % after maize harvest, compared to conventional practice (control). The double mulching decreased total evapotranspiration of the two intercrops by an average of 4.6 % ( P < 0.05), compared to control. An added feature was that the double mulching system decreased soil temperature in the top 10-cm depth by 1.26 to 1.31 °C in the strips of the cool-season wheat, and by 1.31 to 1.51 °C in the strips of the warm-season maize through the 2 years. Soil temperature of maize strips higher as 1.25 to 1.94 °C than that of wheat strips in the top 10-cm soil depth under intercropping with the double mulching system; especially higher as 1.58 to 2.11 °C under intercropping with the conventional tillage; this allows the two intercrops to grow in a well "collaborative" status under the double mulching system during their co-growth period. The improvement of soil moisture and the optimization of soil temperature for the two intercrops allow us to conclude that wheat-maize intensification with the double mulching system can be used as an

  14. Integrated double mulching practices optimizes soil temperature and improves soil water utilization in arid environments.

    Science.gov (United States)

    Yin, Wen; Feng, Fuxue; Zhao, Cai; Yu, Aizhong; Hu, Falong; Chai, Qiang; Gan, Yantai; Guo, Yao

    2016-09-01

    Water shortage threatens agricultural sustainability in many arid and semiarid areas of the world. It is unknown whether improved water conservation practices can be developed to alleviate this issue while increasing crop productivity. In this study, we developed a "double mulching" system, i.e., plastic film coupled with straw mulch, integrated together with intensified strip intercropping. We determined (i) the responses of soil evaporation and moisture conservation to the integrated double mulching system and (ii) the change of soil temperature during key plant growth stages under the integrated systems. Experiments were carried out in northwest China in 2009 to 2011. Results show that wheat-maize strip intercropping in combination with plastic film and straw covering on the soil surface increased soil moisture (mm) by an average of 3.8 % before sowing, 5.3 % during the wheat and maize co-growth period, 4.4 % after wheat harvest, and 4.9 % after maize harvest, compared to conventional practice (control). The double mulching decreased total evapotranspiration of the two intercrops by an average of 4.6 % (P soil temperature in the top 10-cm depth by 1.26 to 1.31 °C in the strips of the cool-season wheat, and by 1.31 to 1.51 °C in the strips of the warm-season maize through the 2 years. Soil temperature of maize strips higher as 1.25 to 1.94 °C than that of wheat strips in the top 10-cm soil depth under intercropping with the double mulching system; especially higher as 1.58 to 2.11 °C under intercropping with the conventional tillage; this allows the two intercrops to grow in a well "collaborative" status under the double mulching system during their co-growth period. The improvement of soil moisture and the optimization of soil temperature for the two intercrops allow us to conclude that wheat-maize intensification with the double mulching system can be used as an effective farming model in alleviating water shortage issues experiencing in water

  15. Impact of agricultural extensification on the relation between soil biodiversity and ecosystem services (soil structure maintenance, water regulation)

    DEFF Research Database (Denmark)

    Faber, J.; Pérès, G.; Groot, A. de

    Introduction – There are increasing pressures on soil biodiversity and soil degradation remains a pertinent issue. In this context, one aim of the EcoFINDERS European project was to assess the impact of agricultural extensification, across a broad range of European land-use systems, on the relati...... biodiversity, providing better soil structure and water infiltration. These results provide more quantitative insights that allow for ecohydrological modelling (forecasting) and economic valuation......., on the relationships between soil biodiversity and ecosystem services. Special attention was given to the relation between i) soil biodiversity and aggregate stability, and ii) earthworms and soil macroporosity and water infiltration.  Method - Data from seven long-term field studies (France, Germany, United......-Kingdom, Slovenia, Denmark) on replicated plots of different land management scenarios (grassland, arable cropping, mixed crop-grassland, reduced or conventional tillage) were analysed. Earthworms were sampled using hand sorting and chemical extraction. Aggregate stability was measured using wet sieving method...

  16. Predicting and mapping soil available water capacity in Korea.

    Science.gov (United States)

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

    2013-01-01

    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.

  17. Predicting and mapping soil available water capacity in Korea

    Directory of Open Access Journals (Sweden)

    Suk Young Hong

    2013-04-01

    Full Text Available 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.

  18. Implementing a physical soil water flow model with minimal soil characteristics and added value offered by surface soil moisture measurements assimilation.

    Science.gov (United States)

    Chanzy, André

    2010-05-01

    Soil moisture is a key variable for many soil physical and biogeochemical processes. Its dynamic results from water fluxes in soil and at its boundaries, as well as soil water storage properties. If the water flows are dominated by diffusive processes, modelling approaches based on the Richard's equation or the Philip and de Vries coupled heat and water flow equations lead to a satisfactory representation of the soil moisture dynamic. However, It requires the characterization of soil hydraulic functions, the initialisation and the boundary conditions, which are expensive to obtain. The major problem to assess soil moisture for decision making or for representing its spatiotemporal evolution over complex landscape is therefore the lack of information to run the models. The aim of the presentation is to analyse how a soil moisture model can be implemented when only climatic data and basic soil information are available (soil texture, organic matter) and what would be the added of making a few soil moisture measurements. We considered the field scale, which is the key scale for decision making application (the field being the management unit for farming system) and landscape modelling (field size being comparable to the computation unit of distributed hydrological models). The presentation is limited to the bare soil case in order to limit the complexity of the system and the TEC model based on Philip and De Vries equations is used in this study. The following points are addressed: o the within field spatial variability. This spatial variability can be induced by the soil hydraulic properties and/or by the amount of infiltrated water induced by water rooting towards infiltration areas. We analyse how an effective parameterization of soil properties and boundary conditions can be used to simulate the field average moisture. o The model implementation with limited information. We propose strategies that can be implemented when information are limited to soil texture and

  19. Increases in the annual range of soil water storage at northern middle and high latitudes under global warming

    Science.gov (United States)

    Wu, Wen-Ying; Lan, Chia-Wei; Lo, Min-Hui; Reager, John T.; Famiglietti, James S.

    2015-05-01

    Soil water storage is a fundamental signal in the land hydrological cycle and changes in soil moisture can affect regional climate. In this study, we used simulations from Coupled Model Intercomparison Project Phase 5 archives to investigate changes in the annual range of soil water storage under global warming at northern middle and high latitudes. Results show that future warming could lead to significant declines in snowfall, and a corresponding lack of snowmelt water recharge to the soil, which makes soil water less available during spring and summer. Conversely, more precipitation as rainfall results in higher recharge to soil water during its accumulating season. Thus, the wettest month of soil water gets wetter, and the driest month gets drier, resulting in an increase of the annual range and suggesting that stronger heterogeneity in global water distribution (changing extremes) could occur under global warming; this has implications for water management and water security under a changing climate.

  20. Seasonal change in precipitation, snowpack, snowmelt, soil water and streamwater chemistry, northern Michigan

    Science.gov (United States)

    Stottlemyer, R.; Toczydlowski, D.

    1999-01-01

    We have studied weekly precipitation, snowpack, snowmelt, soil water and streamwater chemistry throughout winter for over a decade in a small (176 ha) northern Michigan watershed with high snowfall and vegetated by 60 to 80 year-old northern hardwoods. In this paper, we examine physical, chemical, and biological processes responsible for observed seasonal change in streamwater chemistry based upon intensive study during winter 1996-1997. The objective was to define the contributions made to winter and spring streamwater chemical concentration and flux by processes as snowmelt, over-winter forest floor and surface soil mineralization, immobilization, and exchange, and subsurface flowpath. The forest floor and soil were unfrozen beneath the snowpack which permitted most snowmelt to enter. Over-winter soil mineralization and other biological processes maintain shallow subsurface ion and dissolved organic carbon (DOC) reservoirs. Small, but steady, snowmelt throughout winter removed readily mobilized soil NO3- which resulted in high over-winter streamwater concentrations but little flux. Winter soil water levels and flowpaths were generally deep which increased soil water and streamwater base cation (C(B)), HCO3-, and Si concentrations. Spring snowmelt increased soil water levels and removal of ions and DOC from the biologically active forest floor and shallow soils. The snowpack solute content was a minor component in determining streamwater ion concentration or flux during and following peak snowmelt. Exchangeable ions, weakly adsorbed anions, and DOC in the forest floor and surface soils dominated the chemical concentration and flux in soil water and streamwater. Following peak snowmelt, soil microbial immobilization and rapidly increased plant uptake of limiting nutrients removed nearly all available nitrogen from soil water and streamwater. During the growing season high evapotranspiration increased subsurface flowpath depth which in turn removed weathering

  1. Effects on Soil Water and Soil Air Caused by the Dry Summer 2003

    Energy Technology Data Exchange (ETDEWEB)

    Theis, D.; Aeschlimann, D.; Blum, H. [Eth Zurich (Switzerland); Frossard, E. [ETH Zuerich (Switzerland); Siegwolf, R.T.W.

    2004-03-01

    Efflux of CO{sub 2} and water vapor from soils influence the isotopic composition of above ground air. Prolonged hot and dry weather conditions can cause significant changes in soil air and soil water {sup 13}C and {sup 18}O isotope ratios. After a period of hot and dry weather in summer 2003 soil samples showed an increase of up to 0.5% on{delta}{sup 18}O of soil water in all sampled depths (0-12cm), and at the same time {delta}{sup 13}C of soil air CO{sub 2} rose by 0.4% with an up to four-fold decrease of soil CO{sub 2} concentration. These effects are thought to be caused by alteration of the soil structure and changes in microbial activity due to dryness. (author)

  2. Water-stable aggregates of Niger floodplain soils and their organic ...

    African Journals Online (AJOL)

    Five soil profiles were studied along a soil sequence in the Niger river floodplain to determine their soil properties and water-stable aggregates (WSA) between 4.75-2.00 mm, 2.00-1.00 mm, 1.00-0.50 mm, 0.50-02.5 mm and <0.25 mm. The relative distributions of soil organic carbon (SOC), total nitrogen and available ...

  3. Effects of reclaimed water irrigation and nitrogen fertilization on the chemical properties and microbial community of soil

    DEFF Research Database (Denmark)

    Guo, Wei; Andersen, Mathias Neumann; Qi, Xue-bin

    2017-01-01

    physicochemical properties and microbial community structure in soils irrigated with reclaimed water and receiving varied amounts of N fertilizer. The results indicated that the reclaimed water irrigation increased soil electrical conductivity (EC) and soil water content (SWC). The N treatment has highly...... of microbial communities using either clean or reclaimed water for irrigation indicated that the type of irrigation water may have a greater influence on the structure of soil microbial community than N fertilizer treatment. Based on a canonical correspondence analysis (CCA) between the species of soil......The ecological effect of reclaimed water irrigation and fertilizer application on the soil environment is receiving more attention. Soil microbial activity and nitrogen (N) levels are important indicators of the effect of reclaimed water irrigation on environment. This study evaluated soil...

  4. Criterion 4: Conservation and maintenance of soil and water resources

    Science.gov (United States)

    Stephen R. Shifley; Francisco X. Aguilar; Nianfu Song; Susan I. Stewart; David J. Nowak; Dale D. Gormanson; W. Keith Moser; Sherri Wormstead; Eric J. Greenfield

    2012-01-01

    Soils are the fundamental resource enabling land to provide a wide array of benefits. Both humans and wildlife rely on soils for the production of life-sustaining nourishment and shelter. Soil is important to society because it supports plants that supply food, fibers, drugs, and other essentials and because it filters water and recycles wastes.The factors that affect...

  5. Effect of Two Halophyte Plants Irrigated with Saline Water on Soil Salinization under Different Soil Type

    International Nuclear Information System (INIS)

    Abdel-Sabour, M. F.; Rizk, M. A.; Abdel Aziz, A.; Moustafa, S. M.; Eigala, A. M.; Abuo El-Naga, H.

    2007-01-01

    A lysimeter experiment was conducted to evaluate the impact of saline water irrigation at three levels namely, fresh water (0.3), 4 and 8 dS/m on salt accumulation and its effect on different soil types. The tested halophyte plants were Kallar grass and Atriplex (Salt bush). The tested soil types were sandy, calcareous and clayey soils. Irrigating the soil with saline water (either 4 or 8 dS/m) resulted in increasing salinity levels in soil profile with different orders of magnitude, depending on the soil type layer and the cultivated plant. Kallar grass seems limit the accumulation of salts in soil profile, compared to Atriplex at any tested soil. This may be attributed to its root effect on soil profile such as dispersed soil matrix and improved soil structure, which provide channels for solute movement through the profile under halophyte cultivation. Calculating the SAR average values for each irrigation treatment (18 values) showed significant increase in soil SAR values, especially under Kallar grass compared to Atriplex. The highest SAR values were observed in the case of clayey soil. However, the relevant SAR values under Atriplex cultivation were always lower. Values for SAR were always higher in the saline clayey > calcareous > sandy soils

  6. Nitrogen uptake and fertilizer nitrogen use efficiency of wheat under different soil water conditions

    International Nuclear Information System (INIS)

    Wang Baiqun; Zhang Wei; Yu Cunzu

    1999-01-01

    The pot experiment was conducted to study the effects of soil water regime and fertilizer nitrogen rate on the yields, nitrogen uptake and fertilizer nitrogen utilization of wheat by using 15 N tracer method. The results showed that the aboveground biomass, stem yield and grain yield increased with the increase of soil moisture in the fertilizer nitrogen treatments. All the yield increased with the increase of the fertilizer nitrogen rate in the soil water treatments. It was found that both soil water regime and fertilizer nitrogen rate significantly influenced the amount of nitrogen uptake by wheat according to the variance analysis. The amount of nitrogen uptake increased with the rise of the soil moisture in fertilizer nitrogen treatments and the amount also increased with the increase of the urea nitrogen rate in the soil water regime. Soil water regimes not only had an impact on nitrogen uptake but also had a close relationship with soil nitrogen supply and fertilizer nitrogen use efficiency. The soil A values decreased in urea treatment and increased with the rise of the soil moisture in the combination treatment of urea with pig manure. The fertilizer nitrogen use efficiency rose with the rise of the soil moisture in the same fertilizer nitrogen treatment. The fertilizer nitrogen use efficiency of the urea treatment was 13.3%, 27.9% and 32.3% in the soils with 50%, 70% and 90% of the field water capacity, respectively. The fertilizer nitrogen use efficiency in the combination treatment of urea with pig manure was 20.0%, 29.9% and 34.4% in the soils of above three levels, respectively. It was concluded that the low soil moisture restricted urea nitrogen use efficiency (UNUE) and the UNUE could be raised by combination treatment of urea with manure in the soil of enough moisture

  7. Modifying soil water status and improving stand establishment in a water repellent soil using surfactant coated seed.

    Science.gov (United States)

    Kostka, Stanley; Lampe, Mark; van Mondfrans, Jan; Madsen, Matthew; McMillan, Mica

    2015-04-01

    Surfactant seed coating (SSC) is a technology being developed cooperatively by scientists at the USDA, Agricultural Research Service and Aquatrols to improve stand establishment in water repellent soils, particularly under arid conditions. Early SSC studies have demonstrated that surfactant coatings can dramatically increase soil water content, turfgrass density, cover, and biomass for Kentucky bluegrass, tall fescue and perennial ryegrass sown in water repellent soils under greenhouse conditions. However, in these studies, surfactant loads were excessive (≥ 40 wt% of seed mass). The objective of the current study was to ascertain if a lower surfactant treatment level (10 wt%) would improve emergence and stand establishment in a severely water repellent sandy soil under field conditions. Research was conducted on a golf course near Utrecht, NL. At the time of planting water drop penetration time (WDPT) of the soil was approximately 300 s, indicating severe water repellency. Chewings fescue (Festuca rubra subsp. commutata) seed was treated with ASET-4001 surfactant at a loading rate of 10 wt% using two different proprietary coating procedures (US Patent Application 20100267554). The two different ASET-4001 coatings were compared against untreated seed in a randomized complete block design with four replicates. In order to maximize abiotic stresses, the only applied water came from rainfall. Assessments of stand establishment were made every 7-14 days for three months using a subjective visual assessment of percent grass cover and sward quality based on a 1-10 scale (where 10 is best). At six months post-sowing, 20 mm x 300 mm soil cores were randomly removed from each plot and soil wetting front depth measured. Improved emergence of the surfactant coated seeds over the untreated seeds began to appear 7 days after sowing. However, there were no differences between the two SSC treatments. Establishment was influenced by weather conditions. From mid-June to early

  8. Modeling and Prediction of Soil Water Vapor Sorption Isotherms

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per

    2015-01-01

    Soil water vapor sorption isotherms describe the relationship between water activity (aw) and moisture content along adsorption and desorption paths. The isotherms are important for modeling numerous soil processes and are also used to estimate several soil (specific surface area, clay content.......93) for a wide range of soils; and (ii) develop and test regression models for estimating the isotherms from clay content. Preliminary results show reasonable fits of the majority of the investigated empirical and theoretical models to the measured data although some models were not capable to fit both sorption...... directions accurately. Evaluation of the developed prediction equations showed good estimation of the sorption/desorption isotherms for tested soils....

  9. Soil-water contact angle of some soils of the Russian Plane

    Science.gov (United States)

    Bykova, Galina; Tyugai, Zemfira; Milanovskiy, Evgeny; Shein, Evgeny

    2016-04-01

    INTRODUCTION Soil wettability affects the aggregate water resistance, the movement of moisture and dissolved substances, preferential flows, etc. There are many factors affecting the soil's wettability (the content of organic matter (OM), soil's mineralogical composition, particle size distribution), so it can reflect changes in the soil, including results of human impact. The quantitative characteristic of soil wettability is a contact angle (CA), its measurement is a new and difficult problem because of the complexity, heterogeneity and polydispersity of the object of investigation. The aim of this work is to study soil-water CA of some soils of the Russian Plane. MATERIALS AND METHODS The objects of study were sod-podzolic (Umbric Albeluvisols Abruptic, Eutric Podzoluvisols), grey forest non-podzolised (Greyic Phaeozems Albic, Haplic Greyzems), typical Chernozems (Voronic Chernozems pachic, Haplic Chernozems) - profiles under the forest and the arable land, and the chestnut (Haplic Kastanozems Chromic, Haplic Kastanozems) soils. The CA's determination was performed by a Drop Shape Analyzer DSA100 by the static sessile drop method. For all samples was determined the content of total and organic carbon (OC and TC) by dry combustion in oxygen flow. RESULTS AND DISCUSSION There is CA increasing from 85,1° (5 cm) to 40-45° (deeper, than 45 cm) in the sod-podzolic soil; OC content is changed at the same depths from 1,44 to 0.22%. We can see the similar picture in profiles of chernozems. In the forest profile the highest OC content and CA value are achieved on the surface of profile (6,41% and 78,1°), and by 90 cm these values are 1.9% and 50.2°. In the chernozem under the arable land the OC content is almost two times less and the profile is more wettable (from 50° to 19° at 5 and 100 cm). Corresponding with the OC content, the curve describing changes of CA in the profile of grey forest soil is S-shaped with peaks at 20 and 150 cm (81,3° and 70° respectively

  10. Investigating the Relationship Between Soil Water Mobility and Stable Isotope Composition with Implications for the Ecohydrologic Separation Hypothesis

    Science.gov (United States)

    Shuler, J.; McNamara, J. P.; Benner, S. G.; Kohn, M. J.; Evans, S.

    2017-12-01

    The ecohydrologic separation (ES) hypothesis states that streams and plants return different soil water compartments to the atmosphere and that these compartments bear distinct isotopic compositions that can be used to infer soil water mobility. Recent studies have found isotopic evidence for ES in a variety of ecosystems, though interpretations of these data vary. ES investigations frequently suffer from low sampling frequencies as well as incomplete or missing soil moisture and matric potential data to support assumptions of soil water mobility. We sampled bulk soil water every 2-3 weeks in the upper 1 m of a hillslope profile from May 2016 to July 2017 in a semi-arid watershed outside Boise, ID. Twig samples of three plant species were also collected concurrently. Plant and soil water samples extracted via cryogenic vacuum distillation were analyzed for δ2H and δ18O composition. Soil moisture and soil matric potential sensors were installed at five and four depths in the profile, respectively. Shallow bulk soil water was progressively enriched in both isotopes over the growing season and plotted along a soil evaporation line in a plot of δ2H versus δ18O. Plant water during the growing season plotted below both the Local Meteoric Water Line and soil evaporation line. Plant water isotopic composition could not be traced to any source sampled in this study. Additionally, soil moisture and matric potential data revealed that soils were well-drained and that mobile soil water was unavailable throughout most of the growing season at the depths sampled. Soil water isotopic composition alone failed to predict mobility as observed in soil moisture and matric potential data. These results underscore the need for standard hydrologic definitions for the mobile and immobile compartments of soil water in future studies of the ES hypothesis and ecohydrologic processes in general.

  11. Multifractal detrended fluctuation analysis in examining scaling properties of the spatial patterns of soil water storage

    Directory of Open Access Journals (Sweden)

    A. Biswas

    2012-03-01

    Full Text Available Knowledge about the scaling properties of soil water storage is crucial in transferring locally measured fluctuations to larger scales and vice-versa. Studies based on remotely sensed data have shown that the variability in surface soil water has clear scaling properties (i.e., statistically self similar over a wider range of spatial scales. However, the scaling property of soil water storage to a certain depth at a field scale is not well understood. The major challenges in scaling analysis for soil water are the presence of localized trends and nonstationarities in the spatial series. The objective of this study was to characterize scaling properties of soil water storage variability through multifractal detrended fluctuation analysis (MFDFA. A field experiment was conducted in a sub-humid climate at Alvena, Saskatchewan, Canada. A north-south transect of 624-m long was established on a rolling landscape. Soil water storage was monitored weekly between 2002 and 2005 at 104 locations along the transect. The spatial scaling property of the surface 0 to 40 cm depth was characterized using the MFDFA technique for six of the soil water content series (all gravimetrically determined representing soil water storage after snowmelt, rainfall, and evapotranspiration. For the studied transect, scaling properties of soil water storage are different between drier periods and wet periods. It also appears that local controls such as site topography and texture (that dominantly control the pattern during wet states results in multiscaling property. The nonlocal controls such as evapotranspiration results in the reduction of the degree of multiscaling and improvement in the simple scaling. Therefore, the scaling property of soil water storage is a function of both soil moisture status and the spatial extent considered.

  12. Biochar particle size, shape, and porosity act together to influence soil water properties.

    Science.gov (United States)

    Liu, Zuolin; Dugan, Brandon; Masiello, Caroline A; Gonnermann, Helge M

    2017-01-01

    Many studies report that, under some circumstances, amending soil with biochar can improve field capacity and plant-available water. However, little is known about the mechanisms that control these improvements, making it challenging to predict when biochar will improve soil water properties. To develop a conceptual model explaining biochar's effects on soil hydrologic processes, we conducted a series of well constrained laboratory experiments using a sand matrix to test the effects of biochar particle size and porosity on soil water retention curves. We showed that biochar particle size affects soil water storage through changing pore space between particles (interpores) and by adding pores that are part of the biochar (intrapores). We used these experimental results to better understand how biochar intrapores and biochar particle shape control the observed changes in water retention when capillary pressure is the main component of soil water potential. We propose that biochar's intrapores increase water content of biochar-sand mixtures when soils are drier. When biochar-sand mixtures are wetter, biochar particles' elongated shape disrupts the packing of grains in the sandy matrix, increasing the volume between grains (interpores) available for water storage. These results imply that biochars with a high intraporosity and irregular shapes will most effectively increase water storage in coarse soils.

  13. Hydrological balance and water transport processes of partially sealed soils

    Science.gov (United States)

    Timm, Anne; Wessolek, Gerd

    2017-04-01

    With increased urbanisation, soil sealing and its drastic effects on hydrological processes have received a lot of attention. Based on safety concerns, there has been a clear focus on urban drainage and prevention of urban floods caused by storm water events. For this reason, any kind of sealing is often seen as impermeable runoff generator that prevents infiltration and evaporation. While many hydrological models, especially storm water models, have been developed, there are only a handful of empirical studies actually measuring the hydrological balance of (partially) sealed surfaces. These challenge the general assumption of negligible infiltration and evaporation and show that these processes take place even for severe sealing such as asphalt. Depending on the material, infiltration from partially sealed surfaces can be equal to that of vegetated ones. Therefore, more detailed knowledge is needed to improve our understanding and models. In Berlin, two partially sealed weighable lysimeters were equipped with multiple temperature and soil moisture sensors in order to study their hydrological balance, as well as water and heat transport processes within the soil profile. This combination of methods affirms previous observations and offers new insights into altered hydrological processes of partially sealed surfaces at a small temporal scale. It could be verified that not all precipitation is transformed into runoff. Even for a relatively high sealing degree of concrete slabs with narrow seams, evaporation and infiltration may exceed runoff. Due to the lack of plant roots, the hydrological balance is mostly governed by precipitation events and evaporation generally occurs directly after rainfall. However, both surfaces allow for upward water transport from the upper underlying soil layers, sometimes resulting in relatively low evaporation rates on days without precipitation. The individual response of the surfaces differs considerably, which illustrates how

  14. Net carbon allocation in soybean seedlings as influenced by soil water stress at two soil temperatures

    International Nuclear Information System (INIS)

    McCoy, E.L.; Boersma, L.; Ekasingh, M.

    1990-01-01

    The influence of water stress at two soil temperatures on allocation of net photoassimilated carbon in soybean (Glycine max [L.] Merr.) was investigated using compartmental analysis. The experimental phase employed classical 14 C labeling methodology with plants equilibrated at soil water potentials of -0.04, -0.25 and -0.50 MPa; and soil temperatures of 25 and 10C. Carbon immobilization in the shoot apex generally followed leaf elongation rates with decreases in both parameters at increasing water stress at both soil temperatures. However, where moderate water stress resulted in dramatic declines in leaf elongation rates, carbon immobilization rates were sharply decreased only at severe water stress levels. Carbon immobilization was decreased in the roots and nodules of the nonwater stressed treatment by the lower soil temperature. This relation was reversed with severe water stress, and carbon immobilization in the roots and nodules was increased at the lower soil temperature. Apparently, the increased demand for growth and/or carbon storage in these tissues with increased water stress overcame the low soil temperature limitations. Both carbon pool sizes and partitioning of carbon to the sink tissues increased with moderate water stress at 25C soil temperature. Increased pool sizes were consistent with whole plant osmotic adjustment at moderate water stress. Increased partitioning to the sinks was consistent with carbon translocation processes being less severely influenced by water stress than is photosynthesis

  15. Dual permeability soil water dynamics and water uptake by roots in irrigated potato fields

    DEFF Research Database (Denmark)

    Dolezal, Frantisek; Zumr, David; Vacek, Josef

    2007-01-01

    Water movement and uptake by roots in a drip-irrigated potato field was studied by combining field experiments, outputs of numerical simulations and summary results of an EU project (www.fertorganic.org). Detailed measurements of soil suction and weather conditions in the Bohemo-Moravian highland...

  16. Utilization of Weibull equation to obtain soil-water diffusivity in horizontal infiltration

    International Nuclear Information System (INIS)

    Guerrini, I.A.

    1982-06-01

    Water movement was studied in horizontal infiltration experiments using laboratory columns of air-dry and homogeneous soil to obtain a simple and suitable equation for soil-water diffusivity. Many water content profiles for each one of the ten soil columns utilized were obtained through gamma-ray attenuation technique using a 137 Cs source. During the measurement of a particular water content profile, the soil column was held in the same position in order to measure changes in time and so to reduce the errors in water content determination. The Weibull equation utilized was excellent in fitting water content profiles experimental data. The use of an analytical function for ν, the Boltzmann variable, according to Weibull model, allowed to obtain a simple equation for soil water diffusivity. Comparisons among the equation here obtained for diffusivity and others solutions found in literature were made, and the unsuitability of a simple exponential variation of diffusivity with water content for the full range of the latter was shown. The necessity of admitting the time dependency for diffusivity was confirmed and also the possibility fixing that dependency on a well known value extended to generalized soil water infiltration studies was found. Finally, it was shown that the soil water diffusivity function given by the equation here proposed can be obtained just by the analysis of the wetting front advance as a function of time. (Author) [pt

  17. Soil-water repellency characteristic curves for soil profiles with organic carbon gradients

    DEFF Research Database (Denmark)

    Wijewardana, Nadeeka Senani; Müller, Karin; Møldrup, Per

    2016-01-01

    Highlights •Water repellency at different soil organic carbon (SOC) contents was measured. •Repellency was restricted to the top 20 cm of the soil profiles. •The sessile drop method is highly sensitive at high SOC contents. •We proposed six repellency parameters for repellent soils. •Functions...

  18. Soil variability and effectiveness of soil and water conservation in the Sahel.

    NARCIS (Netherlands)

    Hien, F.G.; Rietkerk, M.; Stroosnijder, L.

    1997-01-01

    Sahelian sylvopastoral lands often degrade into bare and crusted areas where regeneration of soil and vegetation is impossible in the short term unless soil and water conservation measures are implemented. Five combinations of tillage with and without mulch on three crust type/soil type combinations

  19. [Effects of brackish water irrigation on soil enzyme activity, soil CO2 flux and organic matter decomposition].

    Science.gov (United States)

    Zhang, Qian-qian; Wang, Fei; Liu, Tao; Chu, Gui-xin

    2015-09-01

    Brackish water irrigation utilization is an important way to alleviate water resource shortage in arid region. A field-plot experiment was set up to study the impact of the salinity level (0.31, 3.0 or 5.0 g · L(-1) NaCl) of irrigated water on activities of soil catalase, invertase, β-glucosidase, cellulase and polyphenoloxidase in drip irrigation condition, and the responses of soil CO2 flux and organic matter decomposition were also determined by soil carbon dioxide flux instrument (LI-8100) and nylon net bag method. The results showed that in contrast with fresh water irrigation treatment (CK), the activities of invertase, β-glucosidase and cellulase in the brackish water (3.0 g · L(-1)) irrigation treatment declined by 31.7%-32.4%, 29.7%-31.6%, 20.8%-24.3%, respectively, while soil polyphenoloxidase activity was obviously enhanced with increasing the salinity level of irrigated water. Compared to CK, polyphenoloxidase activity increased by 2.4% and 20.5%, respectively, in the brackish water and saline water irrigation treatments. Both soil microbial biomass carbon and microbial quotient decreased with increasing the salinity level, whereas, microbial metabolic quotient showed an increasing tendency with increasing the salinity level. Soil CO2 fluxes in the different treatments were in the order of CK (0.31 g · L(-1)) > brackish water irrigation (3.0 g · L(-1)) ≥ saline water irrigation (5.0 g · L(-1)). Moreover, CO2 flux from plastic film mulched soil was always much higher than that from no plastic film mulched soil, regardless the salinity of irrigated water. Compared with CK, soil CO2 fluxes in the saline water and brackish water treatments decreased by 29.8% and 28.2% respectively in the boll opening period. The decomposition of either cotton straw or alfalfa straw in the different treatments was in the sequence of CK (0.31 g · L(-1)) > brackish water irrigation (3.0 g · L(-1)) > saline water treatment (5.0 g · L(-1)). The organic matter

  20. Dielectric Relaxation of Bound Water versus Soil Matric Pressure

    NARCIS (Netherlands)

    Hilhorst, M.A.; Dirksen, C.; Kampers, F.W.H.; Feddes, R.A.

    2001-01-01

    The electrical permittivity of soil is a function of the water content, which facilitates water content measurements. The permittivity of soil is also a function of the frequency of the applied electric field. This frequency dependence can be described by the relationship between the dielectric

  1. Soil water use by Ceanothus velutinus and two grasses.

    Science.gov (United States)

    W. Lopushinsky; G.O. Klock

    1990-01-01

    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,...

  2. Estimation of Soil Water Retention Curve Using Fractal Dimension ...

    African Journals Online (AJOL)

    ADOWIE PERE

    2017-12-01

    Dec 1, 2017 ... approaches to model transient water and solute transport in the vadose zone are based on the. Richards equation. To solve this equation, the knowledge of the soil hydraulic properties, namely, the soil water retention curve (SWRC) and the unsaturated hydraulic conductivity is required and on the other ...

  3. Comparison of soil water potential sensors: a drying experiment

    NARCIS (Netherlands)

    Degre, Aurore; Ploeg, van der M.J.; Caldwell, Todd; Gooren, H.P.A.

    2017-01-01

    The soil water retention curve (WRC) plays a major role in a soil’s hydrodynamic behavior. Many measurement techniques are currently available for determining the WRC in the laboratory. Direct in situ WRC can be obtained from simultaneous soil moisture and water potential readings covering a wide

  4. Linkages between forest soils and water quality and quantity

    Science.gov (United States)

    Daniel G. Neary; George G. Ice; C. Rhett Jackson

    2009-01-01

    The most sustainable and best quality fresh water sources in the world originate in forest ecosystems. The biological, chemical, and physical characteristics of forest soils are particularly well suited to delivering high quality water to streams, moderating stream hydrology, and providing diverse aquatic habitat. Forest soils feature litter layers and...

  5. Movement of Irrigation Water in Soil from a Surface Emitter

    Directory of Open Access Journals (Sweden)

    Ibrahim Abbas Dawood

    2016-09-01

    Full Text Available rickle irrigation is one of the most conservative irrigation techniques since it implies supplying water directly on the soil through emitters. Emitters dissipate energy of water at the end of the trickle irrigation system and provide water at emission points. The area wetted by an emitter depends upon the discharge of emitter, soil texture, initial soil water content, and soil permeability. The objectives of this research were to predict water distribution profiles through different soils for different conditions and quantify the distribution profiles in terms of main characteristics of soil and emitter. The wetting patterns were simulated at the end of each hour for a total time of application of 12 hrs, emitter discharges of 0.5, 0.75, 1, 2, 3, 4, and 5 lph, and five initial volumetric soil water contents. Simulation of water flow from a single surface emitter was carried out by using the numerically-based software Hydrus-2D/3D, Version 2.04. Two approaches were used in developing formulas to predict the domains of the wetted pattern. In order to verify the results obtained by implementing the software Hydrus-2D/3D a field experiment was conducted to measure the wetted diameter and compare measured values with simulated ones. The results of the research showed that the developed formulas to express the wetted diameter and depth in terms of emitter discharge, time of application, and initial soil water content are very general and can be used with very good accuracy.

  6. Estimating water retention curves and strength properties of unsaturated sandy soils from basic soil gradation parameters

    Science.gov (United States)

    Wang, Ji-Peng; Hu, Nian; François, Bertrand; Lambert, Pierre

    2017-07-01

    This study proposed two pedotransfer functions (PTFs) to estimate sandy soil water retention curves. It is based on the van Genuchten's water retention model and from a semiphysical and semistatistical approach. Basic gradation parameters of d60 as particle size at 60% passing and the coefficient of uniformity Cu are employed in the PTFs with two idealized conditions, the monosized scenario and the extremely polydisperse condition, satisfied. Water retention tests are carried out on eight granular materials with narrow particle size distributions as supplementary data of the UNSODA database. The air entry value is expressed as inversely proportional to d60 and the parameter n, which is related to slope of water retention curve, is a function of Cu. The proposed PTFs, although have fewer parameters, have better fitness than previous PTFs for sandy soils. Furthermore, by incorporating with the suction stress definition, the proposed pedotransfer functions are imbedded in shear strength equations which provide a way to estimate capillary induced tensile strength or cohesion at a certain suction or degree of saturation from basic soil gradation parameters. The estimation shows quantitative agreement with experimental data in literature, and it also explains that the capillary-induced cohesion is generally higher for materials with finer mean particle size or higher polydispersity.

  7. Fate of triclocarban during soil aquifer treatment: Soil column studies

    KAUST Repository

    Essandoh, H. M K

    2010-04-01

    There are current concerns about the presence of persistent chemicals in recharge water used in soil aquifer treatment systems. Triclocarban (TCC) has been reported as a persistent, high production volume chemical with the potential to bioaccumulate in the environment. It is also known to have adverse effects such as toxicity and suspected endocrine disruption. This study was carried out to study the fate of TCC in soil aquifer treatment (SAT) through laboratory simulations in a soil column. The system performance was evaluated with regards to TCC influent concentration, sand (column) depth, and residence time. Results obtained confirmed the ability of SAT to reduce TCC concentrations in wastewater. Sorption and biodegradation were responsible for TCC removal, the latter mechanism however being unsustainable. The removal efficiency was found to be dependent on concentration and decreased over time and increased with column depth. Within the duration of the experimental run, TCC negatively impacted on treatment performance through a reduction in COD removals observed in the column. © IWA Publishing 2010.

  8. A Simple Beta-Function Model for Soil-Water Repellency as a Function of Water and Organic Carbon Contents

    DEFF Research Database (Denmark)

    Karunarathna, Anurudda Kumara; Kawamoto, Ken; Møldrup, Per

    2010-01-01

    WR(θ) models is still lacking. In this study, a simple empirical beta function was suggested to describe the effect of changing soil-water content on the change of WR given as apparent contact angle (α) measured by the molarity of ethanol droplet (MED) method. The beta function for predicting α......Soil-water content (θ) and soil organic carbon (SOC) are key factors controlling the occurrence and magnitude of soil-water repellency (WR). Although expressions have recently been proposed to describe the nonlinear variation of WR with θ, the inclusion of easily measurable parameters in predictive......(θ) is based on measurement of WR on air-dry soil and three additional model parameters: the water contents at which the maximum WR (highest α) occurs and where WR ceases (α = 90 degrees), and the maximum α value. The MED data for three data sets from literature comprising WR measurements across moisture...

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

    Directory of Open Access Journals (Sweden)

    Erik eBraudeau

    2014-10-01

    Full Text Available 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.

  10. Plant growth-promoting rhizobacteria (PGPR) reduce evaporation and increase soil water retention

    Science.gov (United States)

    Zheng, W.; Zeng, S.; LaManna, J.; Bais, H.; Jin, Y.

    2017-12-01

    Enhancement of plant drought stress tolerance by plant growth promoting rhizobacteria (PGPR) has been increasingly documented in the literature. However, most studies to date have focused on PGPR-root/plant interactions; very little is known about PGPR's role in mediating physiochemical and hydrological changes in the rhizospheric soil that may impact plant drought stress tolerance. Our study seeks to advance mechanistic understanding of PGPR- mediated biophysical changes in the rhizospheric soil that may contribute to plant drought stress tolerance in addition to plant responses. In this study, we measured soil water retention characteristics, hydraulic conductivity, and water evaporation in soils with various textures (i.e., pure sand, sandy soil, and loam) as influenced by a PGPR (Bacillus subtilis strain UD1022) using the instrument HYPROP©. All PGPR-treated soils held more water, had reduced conductivity, and reduced evaporation rate compared to their corresponding controls. While changes in evaporation behavior, i.e., the transition from Stage I to Stage II, due to PGPR addition, occurred in all soils, they differed with soil texture: PGPR prolonged Stage I (but at lower evaporation rate than control) in the pure sand while the bacteria shortened Stage I in the other two soils. These results indicate that PGPR affects evaporation by modifying soil capillarity and wettability that control liquid phase continuity and capillary forces that sustain Stage I evaporation. SEM images show that PGPR promoted aggregation in the pure sand due to EPS production and biofilm formation. On the other hand, modification of soil wettability by EPS/biofilm thus water phase continuity and capillary driving forces likely dominated the PGPR effects in the other two soils. These findings improve our understanding of rhizosphere functions and have implications in developing biotechnologies using PGPR to increase soil water retention, which would help sustain agricultural production

  11. Effects of soil water depletion on the water relations in tropical kudzu

    Directory of Open Access Journals (Sweden)

    Adaucto Bellarmino de Pereira-Netto

    1999-07-01

    Full Text Available Tropical kudzu (Pueraria phaseoloides (Roxb. Benth., Leguminosae: Faboideae is native to the humid Southeastern Asia. Tropical kudzu has potential as a cover crop in regions subjected to dryness. The objective of this paper was to evaluate the effect of soil water depletion on leaflet relative water content (RWC, stomatal conductance (g and temperature (T L in tropical kudzu. RWC of waterstressed plants dropped from 96 to 78%, following a reduction in SWC from 0.25 to 0.17 g (H2O.g (dry soil-1.Stomatal conductance of stressed plants decreased from 221 to 98 mmol.m-2.s-1, following the reduction in soil water content (SWC. The day after re-irrigation, g of water stressed plants was 15% lower than g of unstressed plants. Differences in T L between waterstressed and unstressed plants (deltaT L rose linearly from 0.1 to 2.2ºC following progressive water deficit. RWC and T L of waterstressed plants paralled RWC and T L of unstressed plants the day after reirrigation. The strong decrease in SWC found in this study only induced moderate water stress in tropical kudzu. In addition, tropical kudzu recover rapidly from the induced water stress after the re-irrigation.

  12. Soil Erosion: Advanced Crop and Soil Science. A Course of Study.

    Science.gov (United States)

    Miller, Larry E.

    The course of study represents the last of six modules in advanced crop and soil science and introduces the agriculture student to the topic of soil erosion. Upon completion of the two day lesson, the student will be able to: (1) define conservation, (2) understand how erosion takes place, and (3) list ways of controlling wind and water erosion.…

  13. Role of water repellency in aggregate stability of cultivated soils under simulated raindrop impact

    Science.gov (United States)

    Kořenková, Lucia; Matúš, Peter

    2015-07-01

    Soil aggregate stability (AS) is an important indicator of soil physical quality. For the purpose of this research it was hypothesized that particular properties such as water repellency (WR) influence soil aggregation and AS. Directly after sampling, WR was detected for three soils, after a week of air-drying two of these soils still showed some resistance to penetration by a water drop placed on the surface (WDPT test). The study examines AS of air-dried texturally different aggregates of size 0.25-0.5 mm taken from surface layers (5-15 cm depth) of six agriculturally used soils. The procedure involves exposure of soil aggregates to direct impact of water drops. Results showed that soil AS increases in order: cutanic Luvisol (siltic) Chernozem < calcic mollic Fluvisol < mollic grumic Vertisol (pellic) < mollic Fluvisol (calcaric) < gleyic Fluvisol (eutric). Gradual increase in AS can be explained by the increase in soil organic matter content and its hydrophobic properties. Although WR has been most commonly observed in soils under forests and grass cover, the results confirmed that cultivated soils may also create water-stable aggregates, especially in the case when their organic matter induces WR under particular moisture conditions.

  14. Structure stability and water retention near saturation characteristics as affected by soil texture, and polyacrylamide concentration

    Science.gov (United States)

    Mamedov, Amrakh I.; Ekberli, Imanverdi A.; Ozturk, Hasan S.; Wagner, Larry E.; Norton, Darrell L.; Levy, Guy J.

    2017-04-01

    Studying the effects of soil properties and amendment application on soil structure stability is important for the development of effective soil management and conservation practices for sustaining semi-arid soil and water quality under climate change scenarios. Two sets of experiments were conducted to evaluate the effects of soil texture and soil amendment polyacrylamide (PAM) rate on soil structural stability expressed in terms of near saturation soil water retention and aggregate stability using the high energy (0-5 J kg-1) moisture characteristic (HEMC) method. Contribution of (i) soil type were assessed using 30 soil samples varying in texture from sandy to clay taken from long term cultivated lands, covering a range of crop and land management practices, and (ii) anionic PAM concentration (0, 10, 25, 50, 100 & 200 mg l-1) were tested on selected loam and clay soils. The water retention curves of slow and fast wetted soil samples were characterized by a modified van Genuchten (1980) model that provides (i) model parameters α and n, which represent the location of the inflection point and the steepness of the S-shaped water retention curves, and (ii) a composite soil structure index (SI =VDP/MS; VDP-volume of drainable pores, MS-modal suction). The studied treatments had, generally, considerable effects on the shape of the water retention curves (α and n). Soil type, PAM concentration and their interaction had significantly effects on the stability indices (SI, VDP and MS) and the model parameters (α and n). The SI and α increased, and ndecreased exponentially with the increase in soil clay content and PAM concentration, but the shape of curves were soil texture and management dependent, since predominant changes were observed in the various range of studied macropores (pore size > 60 μm). An exponential type of relationship existed between SI and α and n. Effect of PAM contribution and wetting condition was more pronounced in the loam soil at low PAM

  15. Modeling the soil system: Bridging the gap between pedology and soil-water physics

    Science.gov (United States)

    Braudeau, Erik; Mohtar, Rabi H.

    2009-05-01

    The biological and geochemical processes in soil such as organic matter mineralization, microbiological activity, and plant alimentation can be accurately assessed and modeled only with the knowledge of the thermodynamic status of the soil medium where these processes take place. However, current soil water models do not define and characterize the soil structure or the thermodynamic state of the soil water interacting with this structure. This article presents a new paradigm in characterizing and modeling the organized soil medium and the physical properties resulting from this organization. It describes a framework of the modeling approach as a contribution to the General Systems theory. The basic concept of Representative Elementary Volume (REV) in soil physics and hydrology was transformed into the concept of Structure Representative Volume (SREV) which takes into account the hierarchical organization of the structured soil medium. The pedostructure is defined as the SREV of the soil medium and this concept is at the basis of the new paradigm including variables, equations, parameters, and units in soil physics, in a similar way that the REV is at the basis of the continuous porous media mechanics applied to soils. The paradigm allows for a thermodynamic characterization of the structured soil medium with respect to soil water content then bridging the gap between pedology and soil physics. We show that the two points of view (REV and SREV) are complementary and must be used in the scaling of information. This approach leads to a new dimension in soil-water properties characterization that ensures a physically based modeling of processes in soil and the transfer of information from the physical scale of processes (pedostructure or laboratory measurements scale) to the application scale of the other disciplines (modeling and mapping scale).

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

    International Nuclear Information System (INIS)

    Waugh, W.J.

    1989-05-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Waugh, W.J.

    1989-05-01

    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.

  18. Determination of antibiotic residues in manure, soil, and surface waters

    Science.gov (United States)

    Christian, T.; Schneider, R.J.; Farber, H.A.; Skutlarek, D.; Meyer, M.T.; Goldbach, H.E.

    2003-01-01

    In the last years more and more often detections of antimicrobially active compounds ("antibiotics") in surface waters have been reported. As a possible input pathway in most cases municipal sewage has been discussed. But as an input from the realm of agriculture is conceivable as well, in this study it should be investigated if an input can occur via the pathway application of liquid manure on fields with the subsequent mechanisms surface run-off/interflow, leaching, and drift. For this purpose a series of surface waters, soils, and liquid manures from North Rhine-Westphalia (Northwestern Germany) were sampled and analyzed for up to 29 compounds by HPLC-MS/MS. In each of the surface waters antibiotics could be detected. The highest concentrations were found in samples from spring (300 ng/L of erythromycin). Some of the substances detected (e.g., tylosin), as well as characteristics in the landscape suggest an input from agriculture in some particular cases. In the investigation of different liquid manure samples by a fast immunoassay method sulfadimidine could be detected in the range of 1...2 mg/kg. Soil that had been fertilized with this liquid manure showed a content of sulfadimidine extractable by accelerated solvent extraction (ASE) of 15 ??g/kg dry weight even 7 months after the application. This indicates the high stability of some antibiotics in manure and soil.

  19. Simulating soil-water movement through loess-veneered landscapes using nonconsilient saturated hydraulic conductivity measurements

    Science.gov (United States)

    Williamson, Tanja N.; Lee, Brad D.; Schoeneberger, Philip J.; McCauley, W. M.; Indorante, Samuel J.; Owens, Phillip R.

    2014-01-01

    Soil Survey Geographic Database (SSURGO) data are available for the entire United States, so are incorporated in many regional and national models of hydrology and environmental management. However, SSURGO does not provide an understanding of spatial variability and only includes saturated hydraulic conductivity (Ksat) values estimated from particle size analysis (PSA). This study showed model sensitivity to the substitution of SSURGO data with locally described soil properties or alternate methods of measuring Ksat. Incorporation of these different soil data sets significantly changed the results of hydrologic modeling as a consequence of the amount of space available to store soil water and how this soil water is moved downslope. Locally described soil profiles indicated a difference in Ksat when measured in the field vs. being estimated from PSA. This, in turn, caused a difference in which soil layers were incorporated in the hydrologic simulations using TOPMODEL, ultimately affecting how soil water storage was simulated. Simulations of free-flowing soil water, the amount of water traveling through pores too large to retain water against gravity, were compared with field observations of water in wells at five slope positions along a catena. Comparison of the simulated data with the observed data showed that the ability to model the range of conditions observed in the field varied as a function of three soil data sets (SSURGO and local field descriptions using PSA-derived Ksat or field-measured Ksat) and that comparison of absolute values of soil water storage are not valid if different characterizations of soil properties are used.

  20. Conservation of peat soils in agricultural use by infiltration of ditch water via submerged drains: results of a case study in the western peat soil area of The Netherlands

    Science.gov (United States)

    van den Akker, Jan J. H.; Hendriks, Rob F. A.

    2017-04-01

    About 8% of all soils in The Netherlands are peat soils which almost all drained with ditches and mainly in agricultural use as permanent pasture for dairy farming. The largest part of the peat meadow area is situated in the densely populated western provinces South- and North-Holland and Utrecht and is called the Green Heart and is valued as a historic open landscape. Conservation of these peats soil by raising water levels and converting the peat meadow areas mainly in very extensive grasslands or wet nature proved to be a very costly and slow process due to the strong opposition of farmers and many others who value the open cultural historic landscape and meadow birds. The use of submerged drains seems to be a promising solution acceptable for dairy farmers and effective in diminishing peat oxidation and so the associated subsidence and CO2 emissions. Oxidation of peat soils strongly depends on the depth of groundwater levels in dry periods. In dry periods the groundwater level can be 30 to 50 cm lower than the ditchwater level, which is 30 - 60 cm below soil surface. Infiltration of ditchwater via submerged drain can raise the groundwater level up to the ditchwater level and diminish the oxidation and associated subsidence and CO2 emissions with at least 50%. Since 2003 several pilots with submerged drains are started to check this theoretical reduction and to answer questions raised about water usage and water quality and grass yields and trafficability etcetera. In our presentation we focus on the results of a pilot in South-Holland concerning the hydrological aspects, however, include results from the other pilots to consider the long term aspects such as the reduction of subsidence. The use of submerged drains proves to be promising to reduce peat oxidation and so subsidence and CO2 emissions with at least 50%. Grass yields are more or less equal in parcels with versus parcels without submerged drains. Trafficability in wet periods is better and trampling

  1. The Effect of Vegetation on Soil Water Infiltration and Retention Capacity by Improving Soil Physiochemical Property in Semi-arid Grassland

    Science.gov (United States)

    A, Y.; Wang, G.

    2017-12-01

    Water shortage is the main limiting factor for semi-arid grassland development. However, the grassland are gradually degraded represented by species conversion, biomass decrease and ecosystem structure simplification under the influence of human activity. Soil water characteristics such as moisture, infiltration and conductivity are critical variables affecting the interactions between soil parameters and vegetation. In this study, Cover, Height, Shannon-Wiener diversity index, Pielou evenness index and Richness index are served as indexes of vegetation productivity and community structure. And saturated hydraulic conductivity (Ks) and soil moisture content are served as indexes of soil water characters. The interaction between vegetation and soil water is investigated through other soil parameters, such as soil organic matter content at different vertical depths and in different degradation area (e.g., initial, transition and degraded plots). The results show that Ks significantly controlled by soil texture other than soil organic matter content. So the influence of vegetation on Ks through increasing soil organic content (SOM) might be slight. However, soil moisture content (SMC) appeared significantly positive relationship with SOM and silt content and negative relationship with sand content at all depth, significantly. This indicated that capacity of soil water storage was influenced both by soil texture and organic matter. In addition, the highest correlation coefficient of SMC was with SOM at the sub-surficial soil layer (20 40 cm). At the depth of 20 40 cm, the soil water content was relatively steady which slightly influenced by precipitation and evaporation. But it significantly influenced by soil organic matter content which related to vegetation. The correlation coefficient between SOM and SMC at topsoil layer (0 20 cm) was lowest (R2=0.36, pwater content not only by soil organic matter content but also the other influential factors, such as the root

  2. SALTMED model as an integrated management tool for water, crop, soil and N-fertilizer water management strategies and productivity: field and simulation study

    OpenAIRE

    Ragab, R.; Battilani, A.; Matovic, G.; Stikic, R.; Psarras, G.; Chartzoulakis, K.

    2015-01-01

    This paper is a follow-up from a paper which described the SALTMED model. In this paper the focus is on the model application,using data of tomato and potato from field experiments in Italy, Greece (Crete) and Serbia. Drip full irrigation, drip deficit irrigation, drip as partial root drying (PRD), sprinkler and furrow irrigation were used in the 3-yr experiment between 2006 and 2008. In drip-irrigated experiments, the drip line was 10–12 cm below the surface. Dry matter, final yield, soil mo...

  3. Spatial distribution of soil water repellency in a grassland located in Lithuania

    Science.gov (United States)

    Pereira, Paulo; Novara, Agata

    2014-05-01

    Soil water repellency (SWR) it is recognized to be very heterogeneous in time in space and depends on soil type, climate, land use, vegetation and season (Doerr et al., 2002). It prevents or reduces water infiltration, with important impacts on soil hydrology, influencing the mobilization and transport of substances into the soil profile. The reduced infiltration increases surface runoff and soil erosion. SWR reduce also the seed emergency and plant growth due the reduced amount of water in the root zone. Positive aspects of SWR are the increase of soil aggregate stability, organic carbon sequestration and reduction of water evaporation (Mataix-Solera and Doerr, 2004; Diehl, 2013). SWR depends on the soil aggregate size. In fire affected areas it was founded that SWR was more persistent in small size aggregates (Mataix-Solera and Doerr, 2004; Jordan et al., 2011). However, little information is available about SWR spatial distribution according to soil aggregate size. The aim of this work is study the spatial distribution of SWR in fine earth (Geoderma, 118, 77-88. Wessel, A.T. (1988) On using the effective contact angle and the water drop penetration time for classification of water repellency in dune soils, Earth Surfaces Process. Landforms, 13, 555-562, 1988.

  4. Impact of water saturation level on arsenic and metal mobility in the Fe-amended soil.

    Science.gov (United States)

    Kumpiene, Jurate; Ragnvaldsson, Daniel; Lövgren, Lars; Tesfalidet, Solomon; Gustavsson, Björn; Lättström, Anders; Leffler, Per; Maurice, Christian

    2009-01-01

    The impact of water saturation level (oxidizing-reducing environment) on As and metal solubility in chromium, copper, arsenic (CCA)-contaminated soil amended with Fe-containing materials was studied. The soil was mixed with 0.1 and 1 wt% of iron grit (Fe(0)) and 1, 7 and 15 wt% of oxygen scarfing granulate (OSG, a by-product of steel processing). Solubility of As and metals was evaluated by a batch leaching test and analysis of soil pore water. Soil saturation with water greatly increased As solubility in the untreated as well as in the Fe-amended soil. This was related to the reductive dissolution of Fe oxides and increased concentration of As(III) species. Fe amendments showed As reducing capacity under both oxic and anoxic conditions. The cytotoxicity of the soil pore water correlated with the concentration of As(III). The Fe-treatments as well as water saturation of soil were less significant for the solubility of Cu, Cr and Zn than for As. The batch leaching test used for waste characterization substantially underestimated As solubility that could occur under water-saturated (anaerobic) conditions. In the case of soil landfilling, other techniques than Fe-stabilization of As containing soil should be considered.

  5. Holistic irrigation water management approach based on stochastic soil water dynamics

    Science.gov (United States)

    Alizadeh, H.; Mousavi, S. J.

    2012-04-01

    Appreciating the essential gap between fundamental unsaturated zone transport processes and soil and water management due to low effectiveness of some of monitoring and modeling approaches, this study presents a mathematical programming model for irrigation management optimization based on stochastic soil water dynamics. The model is a nonlinear non-convex program with an economic objective function to address water productivity and profitability aspects in irrigation management through optimizing irrigation policy. Utilizing an optimization-simulation method, the model includes an eco-hydrological integrated simulation model consisting of an explicit stochastic module of soil moisture dynamics in the crop-root zone with shallow water table effects, a conceptual root-zone salt balance module, and the FAO crop yield module. Interdependent hydrology of soil unsaturated and saturated zones is treated in a semi-analytical approach in two steps. At first step analytical expressions are derived for the expected values of crop yield, total water requirement and soil water balance components assuming fixed level for shallow water table, while numerical Newton-Raphson procedure is employed at the second step to modify value of shallow water table level. Particle Swarm Optimization (PSO) algorithm, combined with the eco-hydrological simulation model, has been used to solve the non-convex program. Benefiting from semi-analytical framework of the simulation model, the optimization-simulation method with significantly better computational performance compared to a numerical Mote-Carlo simulation-based technique has led to an effective irrigation management tool that can contribute to bridging the gap between vadose zone theory and water management practice. In addition to precisely assessing the most influential processes at a growing season time scale, one can use the developed model in large scale systems such as irrigation districts and agricultural catchments. Accordingly

  6. Variability in chemistry of surface and soil waters of an ...

    African Journals Online (AJOL)

    Water chemistry is important for the maintenance of wetland structure and function. Interpreting ecological patterns in a wetland system therefore requires an in-depth understanding of the water chemistry of that system. We investigated the spatial distribution of chemical solutes both in soil pore water and surface water, ...

  7. Soil water movement in the unsaturated zone of an inland arid region: Mulched drip irrigation experiment

    Science.gov (United States)

    Han, Dongmei; Zhou, Tiantian

    2018-04-01

    Agricultural irrigation with trans-basin water diversion can effectively relieve the water paucity in arid and semi-arid regions, however, this may be accompanied by eco-environmental problems (e.g., saline soils, rising groundwater levels, water quality problems). The mechanism of soil water movement under irrigation in the unsaturated zone of arid regions is a key scientific problem that should be solved in order to evaluate agricultural water management and further improve current irrigation practices. This study investigated the impact of drip irrigation on soil water movement in the unsaturated zone of a cotton field in an inland arid region (the Karamay Agricultural Development Area), northwest China. Combining in situ observational physical data with temporal variation in stable isotopic compositions of soil water, we described the soil water flow system and mechanism in severe (Plot 1) and mild (Plot 2) saline-alkali cotton fields. The infiltration depths are 0-150 cm for both plots. Drip irrigation scheduling makes no significant contribution to local groundwater recharge, however, groundwater can move into the unsaturated zone through capillary rise during cotton flowering and boll periods. Plot 2 is less prone to having secondary soil salinization than Plot 1 due to the existence of a middle layer (approximately 100 cm thick), which elongated the distance between the root zone and aquifer. Rise in the water table (approximately 60 cm for Plot 1 and 50 cm for Plot 2) could be caused by lateral groundwater flow instead of vertical infiltration. We estimated the soil water storage changes in the unsaturated zone and proposed a conceptual model for deciphering the movement process of soil water. This study provides a scientific basis for determining the rise of groundwater levels and potential development of saline soils and improving agricultural water management in arid regions.

  8. Rainfall simulation and Structure-from-Motion photogrammetry for the analysis of soil water erosion in Mediterranean vineyards

    NARCIS (Netherlands)

    Prosdocimi, Massimo; Burguet, Maria; Prima, Di Simone; Sofia, Giulia; Terol, Enric; Rodrigo Comino, Jesús; Cerda Bolinches, Artemio; Tarolli, Paolo

    2017-01-01

    Soil water erosion is a serious problem, especially in agricultural lands. Among these, vineyards deserve attention, because they constitute for the Mediterranean areas a type of land use affected by high soil losses. A significant problem related to the study of soil water erosion in these areas

  9. How big is the influence of biogenic silicon pools on short-term changes in water-soluble silicon in soils? Implications from a study of a 10-year-old soil-plant system

    Science.gov (United States)

    Puppe, Daniel; Höhn, Axel; Kaczorek, Danuta; Wanner, Manfred; Wehrhan, Marc; Sommer, Michael

    2017-11-01

    The significance of biogenic silicon (BSi) pools as a key factor for the control of Si fluxes from terrestrial to aquatic ecosystems has been recognized for decades. However, while most research has been focused on phytogenic Si pools, knowledge of other BSi pools is still limited. We hypothesized that different BSi pools influence short-term changes in the water-soluble Si fraction in soils to different extents. To test our hypothesis we took plant (Calamagrostis epigejos, Phragmites australis) and soil samples in an artificial catchment in a post-mining landscape in the state of Brandenburg, Germany. We quantified phytogenic (phytoliths), protistic (diatom frustules and testate amoeba shells) and zoogenic (sponge spicules) Si pools as well as Tiron-extractable and water-soluble Si fractions in soils at the beginning (t0) and after 10 years (t10) of ecosystem development. As expected the results of Tiron extraction showed that there are no consistent changes in the amorphous Si pool at Chicken Creek (Hühnerwasser) as early as after 10 years. In contrast to t0 we found increased water-soluble Si and BSi pools at t10; thus we concluded that BSi pools are the main driver of short-term changes in water-soluble Si. However, because total BSi represents only small proportions of water-soluble Si at t0 ( 5 µm) only amounted to about 16 % of total Si contents of plant materials of C. epigejos and P. australis at t10; thus about 84 % of small-scale and/or fragile phytogenic Si is not quantified by the used phytolith extraction method. Analyses of small-scale and fragile phytogenic Si structures are urgently needed in future work as they seem to represent the biggest and most reactive Si pool in soils. Thus they are the most important drivers of Si cycling in terrestrial biogeosystems.

  10. Validation of a spatial–temporal soil water movement and plant water uptake model

    KAUST Repository

    HEPPELL, J.

    2014-06-01

    © 2014, (publisher). All rights reserved. Management and irrigation of plants increasingly relies on accurate mathematical models for the movement of water within unsaturated soils. Current models often use values for water content and soil parameters that are averaged over the soil profile. However, many applications require models to more accurately represent the soil–plant–atmosphere continuum, in particular, water movement and saturation within specific parts of the soil profile. In this paper a mathematical model for water uptake by a plant root system from unsaturated soil is presented. The model provides an estimate of the water content level within the soil at different depths, and the uptake of water by the root system. The model was validated using field data, which include hourly water content values at five different soil depths under a grass/herb cover over 1 year, to obtain a fully calibrated system for plant water uptake with respect to climate conditions. When compared quantitatively to a simple water balance model, the proposed model achieves a better fit to the experimental data due to its ability to vary water content with depth. To accurately model the water content in the soil profile, the soil water retention curve and saturated hydraulic conductivity needed to vary with depth.

  11. Soil water erosion under different cultivation systems and different fertilization rates and forms over 10 years

    Directory of Open Access Journals (Sweden)

    Ildegardis Bertol

    2014-12-01

    Full Text Available The action of rain and surface runoff together are the active agents of water erosion, and further influences are the soil type, terrain, soil cover, soil management, and conservation practices. Soil water erosion is low in the no-tillage management system, being influenced by the amount and form of lime and fertilizer application to the soil, among other factors. The aim was to evaluate the effect of the form of liming, the quantity and management of fertilizer application on the soil and water losses by erosion under natural rainfall. The study was carried out between 2003 and 2013 on a Humic Dystrupept soil, with the following treatments: T1 - cultivation with liming and corrective fertilizer incorporated into the soil in the first year, and with 100 % annual maintenance fertilization of P and K; T2 - surface liming and corrective fertilization distributed over five years, and with 75 % annual maintenance fertilization of P and K; T3 - surface liming and corrective fertilization distributed over three years, and with 50 % annual maintenance fertilization of P and K; T4 - surface liming and corrective fertilization distributed over two years, and with 25 % annual maintenance fertilization of P and K; T5 - fallow soil, without liming or fertilization. In the rotation the crops black oat (Avena strigosa , soybean (Glycine max , common vetch (Vicia sativa , maize (Zea mays , fodder radish (Raphanus sativus , and black beans (Phaseolus vulgaris . The split application of lime and mineral fertilizer to the soil surface in a no-tillage system over three and five years, results in better control of soil losses than when split in two years. The increase in the amount of fertilizer applied to the soil surface under no-tillage cultivation increases phytomass production and reduces soil loss by water erosion. Water losses in treatments under no-tillage cultivation were low in all crop cycles, with a similar behavior as soil losses.

  12. Suitability of seven species of soil-inhabiting invertebrates for testing toxicity of pesticides in soil pore water

    NARCIS (Netherlands)

    Ronday, R.; Houx, N.W.H.

    1996-01-01

    This study assessed the suitability of seven species of soil invertebrates for toxicologically testing pesticides in water. Requirements were that the organisms must survive in water, be easy to handle, be easy to breed, be sensitive to pesticides, and show unambiguous toxicological effects. The

  13. Validation of water sorption-based clay prediction models for calcareous soils

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Razzaghi, Fatemeh; Moosavi, Ali

    2017-01-01

    . The low organic carbon content of the soils and the low fraction of low-activity clay minerals like kaolinite suggested that the clay content under-predictions were due to large CaCO3 contents. Thus, for such water-sorption based models to work accurately for calcareous soils, a correction factor......Soil particle size distribution (PSD), particularly the active clay fraction, mediates soil engineering, agronomic and environmental functions. The tedious and costly nature of traditional methods of determining PSD prompted the development of water sorption-based models for determining the clay...... fraction. The applicability of such models to semi-arid soils with significant amounts of calcium carbonate and/or gypsum is unknown. The objective of this study was to validate three water sorption-based clay prediction models for 30 calcareous soils from Iran and identify the effect of CaCO3...

  14. Impacts of soil conditioners and water table management on phosphorus loss in tile drainage from a clay loam soil.

    Science.gov (United States)

    Zhang, T Q; Tan, C S; Zheng, Z M; Welacky, T W; Reynolds, W D

    2015-03-01

    Adoption of waste-derived soil conditioners and refined water management can improve soil physical quality and crop productivity of fine-textured soils. However, the impacts of these practices on water quality must be assessed to ensure environmental sustainability. We conducted a study to determine phosphorus (P) loss in tile drainage as affected by two types of soil conditioners (yard waste compost and swine manure compost) and water table management (free drainage and controlled drainage with subirrigation) in a clay loam soil under corn-soybean rotation in a 4-yr period from 1999 to 2003. Tile drainage flows were monitored and sampled on a year-round continuous basis using on-site auto-sampling systems. Water samples were analyzed for dissolved reactive P (DRP), particulate P (PP), and total P (TP). Substantially greater concentrations and losses of DRP, PP, and TP occurred with swine manure compost than with control and yard waste compost regardless of water table management. Compared with free drainage, controlled drainage with subirrigation was an effective way to reduce annual and cumulative losses of DRP, PP, and TP in tile drainage through reductions in flow volume and P concentration with control and yard waste compost but not with swine manure compost. Both DRP and TP concentrations in tile drainage were well above the water quality guideline for P, affirming that subsurface loss of P from fine-textured soils can be one critical source for freshwater eutrophication. Swine manure compost applied as a soil conditioner must be optimized by taking water quality impacts into consideration. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  15. Effects of Vermicompost and Water Treatment Residuals on Soil Physical Properties and Wheat Yield

    Science.gov (United States)

    Ibrahim, Mahmoud M.; Mahmoud, Essawy K.; Ibrahim, Doaa A.

    2015-04-01

    The application of vermicompost and water treatment residuals to improve the physical properties in the salt affected soils is a promising technology to meet the requirements of high plant growth and cost-effective reclamation. Therefore, the aim of this study was to investigate the effect of vermicompost and its mixtures with water treatment residuals on selected physical properties of saline sodic soil and on wheat yield. The treatments were vermicompost, water treatment residuals, vermicompost + water treatment residuals (1:1 and 2:1 wet weight ratio) at levels of 5 and 10 g dry weight kg-1 dry soil. The considered physical properties included aggregate stability, mean weight diameter, pore size distribution and dry bulk density. The addition of vermicompost and water treatment residuals had significant positive effects on the studied soil physical properties, and improved the grain yield of wheat. The treatment of (2 vermicompost + 1 water treatment residuals) at level of 5 g kg-1 soil gave the best grain yield. Combination of vermicompost and water treatment residuals improved the water treatment residuals efficiency in ameliorating the soil physical properties, and could be considered as an ameliorating material for the reclamation of salt affected soils.

  16. Biochar effects on wet and dry regions of the soil water retention curve of a sandy loam

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Moldrup, Per; Sun, Zhencai

    2014-01-01

    Reported beneficial effects of biochar on soil physical properties and processes include decreased soil density, and increased soil water transport, water holding capacity and retention (mainly for the wet region). Research is limited on biochar effects on the full soil water retention curve (wet...... and dry regions) for a given soil and biochar amendment scenarios. This study evaluates how biochar applied to a sandy loam field at rates from 0 to 50 Mg ha−1 yr–1 in 2011, 2012, or both years (2011+2012) influences the full water retention curve. Inorganic fertilizer and pig slurry were added to all...... treatments. Six months after the last biochar application, intact and disturbed soil samples were collected for analyses. Soil water retention was measured from −1 kPa to −100 kPa using tension tables and ceramic plates and from −10 MPa to −480 MPa using a Vapor Sorption Analyzer. Soil specific area...

  17. Creation of Soil Water and Physical data base and its inclusion in a new version of GIS of Soil Resources Attributive Table

    International Nuclear Information System (INIS)

    Kolev, Boyko

    2013-01-01

    For better using of GIS of Soil Resources a new version of the attributive table formation was created. This makes possible soil, physical, and water properties to be included into the table. The simulation procedure for soil hydro-physical properties determination was realized by using the soil particle size distribution data only. This develops a calculation algorithm for soil water content dynamic monitoring, which was realized for some of Bulgarian soils. The main aims of the study are: To demonstrate the usefulness of the new version of the attributive table formation. To show how the simulation model can be applied for environment conditions monitoring and agricultural production management. Keywords: environment conditions, simulation model, soil moisture at field capacity, wilting point, effective soil water content, particle size distribution

  18. Studying the hydrological cycle in the Iberian Peninsula using the LEAFHYDRO LSM: Influence of groundwater dynamics on soil moisture and land-atmosphere coupling. Impacts of artificial water extraction in the regional water cycle, including land-surface f

    Science.gov (United States)

    Martinez, A.; Miguez-Macho, G.

    2012-04-01

    We perform long-term (10 year) simulations over the Iberian Peninsula at 2.5 km resolution with the LEAFHYDRO LSM, which includes groundwater dynamics and river routing. Atmospheric forcing comes from ERA-interim and a regional high-resolution analysis of precipitation over Spain and Portugal. The model simulates the coupled evolution of the groundwater, land surface (soil moisture and vegetation) and river reservoirs and we validate the simulation with all available observations of river flow and water table depth. In an experiment, we impose an artificial water extraction rate from the groundwater reservoir based on observations and estimations of irrigation withdrawals and we investigate the impact on the regional water cycle. The extraction rates induce a depression of the water table that over the years becomes quite significant and that matches observed decreasing rates of water table levels. The depressed water table discontinues groundwater input into rivers and the stream flow is diminished notably, in particular during the dry summer. Moreover, in areas with semiarid climate where the water table was naturally relatively shallow and connected to soil moisture and vegetation, which include most of the agricultural areas inland Spain, the depression of the water table has a significant impact on soil moisture and land-surface fluxes, with a decrease of root zone soil water availability and evapotranspiration and increasing water stress for the vegetation. The land hydrology alteration is more pronounced in the summer when there is an absence of precipitation, and as the model shows, through the induced changes in land-surface fluxes can potentially have a noticeably impact on the regional climate.

  19. Fate and persistence of 14C pesticide residues in different soils: effects of 14C pesticide contaminated run-off soil water on biological systems. Part of a coordinated programme on isotopic-tracer-aided studies of agrochemical residue - soil biota interactions

    International Nuclear Information System (INIS)

    Lichtenstein, E.

    1982-09-01

    The interaction of selected fungicides, herbicides and N-fertilizers with microorganisms in cranberry soils and their effects on the degradation of 14 C-phenyl-parathion were investigated. Incubation of soils with parathion of p-nitrophenol for 4 days, followed by the addition of 14 C-parathion resulted after 24 h in an enhanced degradation of the insecticide to 14 CO 2 (34-39% of the applied radiocarbon as opposed to 2% in controls) and also in an increased binding of 14 C to the soil. The fungicide captafol inhibited the degradation of soil-applied 14 C-parathion as evidenced by a reduction of both 14 CO 2 evolution and 14 C-bound residues. Maneb and benomyl suppressed the degradation of 14 C-parathion to 14 CO 2 but not the formation of bound residues. Addition of 2,4-D to 14 C-parathion treated soil also resulted in an increased persistence of the insecticide. Studies conducted with the insecticide and (NH 4 ) 2 SO 4 , NH 4 NO 3 , KNO 3 or urea showed that under all experimental conditions the total amounts of 14 C recovered were similar, yet the distribution of 14 C-compounds into benzene-soluble, water-soluble and bound residues was not. This possibly indicated a change in the pathway of 14 C-parathion degradation. The insecticide was most persistent in soils containing (NH 4 ) 2 SO 4 , as demonstrated by a recovery of 29% of the applied radiocarbon in benzene-soluble form. Analyses by TIC of this benzene extraction phase revealed the presence of 14 C-parathion, 14 C-p-aminophenol and 14 C-aminoparathion

  20. Amending greenroof soil with biochar to affect runoff water quantity and quality

    International Nuclear Information System (INIS)

    Beck, Deborah A.; Johnson, Gwynn R.; Spolek, Graig A.

    2011-01-01

    Numbers of greenroofs in urban areas continue to grow internationally; so designing greenroof soil to reduce the amount of nutrients in the stormwater runoff from these roofs is becoming essential. This study evaluated changes in extensive greenroof water discharge quality and quantity after adding biochar, a soil amendment promoted for its ability to retain nutrients in soils and increase soil fertility. Prototype greenroof trays with and without biochar were planted with sedum or ryegrass, with barren soil trays used as controls. The greenroof trays were subjected to two sequential 7.4 cm/h rainfall events using a rain simulator. Runoff from the rain events was collected and evaluated. Trays containing 7% biochar showed increased water retention and significant decreases in discharge of total nitrogen, total phosphorus, nitrate, phosphate, and organic carbon. The addition of biochar to greenroof soil improves both runoff water quality and retention. - Highlights: → Biochar in green roof soil reduces nitrogen and phosphorus in the runoff. → Addition of biochar reduces turbidity of runoff. → Addition of biochar reduces total organic carbon content in runoff by 67-72%. → Biochar improves water retention of saturated soil. - In this controlled laboratory experiment, greenroof soil was amended by the addition of biochar, which reduced the water runoff concentration of nitrogen, phosphorus, and organic carbon.

  1. Amending greenroof soil with biochar to affect runoff water quantity and quality

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Deborah A.; Johnson, Gwynn R. [Portland State University, Mechanical and Materials Engineering, POB 751, Portland, OR 97207 (United States); Spolek, Graig A., E-mail: graig@cecs.pdx.edu [Portland State University, Mechanical and Materials Engineering, POB 751, Portland, OR 97207 (United States)

    2011-08-15

    Numbers of greenroofs in urban areas continue to grow internationally; so designing greenroof soil to reduce the amount of nutrients in the stormwater runoff from these roofs is becoming essential. This study evaluated changes in extensive greenroof water discharge quality and quantity after adding biochar, a soil amendment promoted for its ability to retain nutrients in soils and increase soil fertility. Prototype greenroof trays with and without biochar were planted with sedum or ryegrass, with barren soil trays used as controls. The greenroof trays were subjected to two sequential 7.4 cm/h rainfall events using a rain simulator. Runoff from the rain events was collected and evaluated. Trays containing 7% biochar showed increased water retention and significant decreases in discharge of total nitrogen, total phosphorus, nitrate, phosphate, and organic carbon. The addition of biochar to greenroof soil improves both runoff water quality and retention. - Highlights: > Biochar in green roof soil reduces nitrogen and phosphorus in the runoff. > Addition of biochar reduces turbidity of runoff. > Addition of biochar reduces total organic carbon content in runoff by 67-72%. > Biochar improves water retention of saturated soil. - In this controlled laboratory experiment, greenroof soil was amended by the addition of biochar, which reduced the water runoff concentration of nitrogen, phosphorus, and organic carbon.

  2. Effects of added organic matter and water on soil carbon sequestration in an arid region.

    Directory of Open Access Journals (Sweden)

    Liming Lai

    Full Text Available It is generally predicted that global warming will stimulate primary production and lead to more carbon (C inputs to soil. However, many studies have found that soil C does not necessarily increase with increased plant litter input. Precipitation has increased in arid central Asia, and is predicted to increase more, so we tested the effects of adding fresh organic matter (FOM and water on soil C sequestration in an arid region in northwest China. The results suggested that added FOM quickly decomposed and had minor effects on the soil organic carbon (SOC pool to a depth of 30 cm. Both FOM and water addition had significant effects on the soil microbial biomass. The soil microbial biomass increased with added FOM, reached a maximum, and then declined as the FOM decomposed. The FOM had a more significant stimulating effect on microbial biomass with water addition. Under the soil moisture ranges used in this experiment (21.0%-29.7%, FOM input was more important than water addition in the soil C mineralization process. We concluded that short-term FOM input into the belowground soil and water addition do not affect the SOC pool in shrubland in an arid region.

  3. Assessment of the soil water content temporal variations in an agricultural area of Galicia (NW Spain)

    Science.gov (United States)

    Mestas-Valero, Roger Manuel; Miras-Avalos, Jose Manuel; Paz-González, Antonio

    2010-05-01

    The direct and continuous assessment of the temporal variation on soil water content is of paramount importance for agricultural practices and, in particular, for the management of water resources. Soil water content is affected by many factors such as topography, particle size, clay and organic matter contents, and tillage systems. There are several techniques to measure or estimate soil water content. Among them, Frequency Domain Reflectometry (FDR) stands out. It is based on measuring the dielectrical constant of the soil environment. This technique allows to describe water dynamics in time and space, to determine the main patterns of soil moisture, the water uptake by roots, the evapotranspiration and the drainage. Therefore, the aim of this study was to assess the daily variation of soil water content in the root-influenced zone in plots devoted to maize and grassland as a function of the soil water volumetric content. The studied site is located in an experimental field of the Centre for Agricultural Research (CIAM) in Mabegondo located in the province of A Coruña, Spain (43°14'N, 8°15'W; 91 masl). The study was carried out from June 2008 to September 2009 in a field devoted to maize (Zea mays, L.) and another field devoted to grassland. The soil of these sites is silt-clay textured. Long-term mean annual temperature and rainfall figures are 13.3 °C and 1288 mm, respectively. During the study period, maize crop was subjected to conventional agricultural practices. A weekly evaluation of the phenological stage of the crop was performed. An EnviroSCAN FDR equipment, comprising six capacitance sensors, was installed in the studied sites following the manufacturer's recommendations, thus assuring a proper contact between the probe and the soil. Soil water content in the root-influenced zone (40 cm depth in grassland and 60 cm depth in maize were considered) was hourly monitored in 20 cm ranges (0-20 cm, 20-40 cm, and 40-60 cm) using FDR. Evaluations were

  4. Catch crops impact on soil water infiltration in vineyards

    Science.gov (United States)

    Cerdà, Artemi; Bagarello, Vincenzo; Iovino, Massimo; Ferro, Vito; Keesstra, Saskia; Rodrigo-Comino, Jesús; García Diaz, Andrés; di Prima, Simone

    2017-04-01

    Bagarello, V., Castellini, M., Di Prima, S., & Iovino, M. (2014). Soil hydraulic properties determined by infiltration experiments and different heights of water pouring. Geoderma, 213, 492-501. Bagarello, V., Elrick, D. E., Iovino, M., & Sgroi, A. (2006). A laboratory analysis of falling head infiltration procedures for estimating the hydraulic conductivity of soils. Geoderma, 135, 322-334. Ben Slimane, A., Raclot, D., Evrard, O., Sanaa, M., Lefevre, I., & Le Bissonnais, Y. (2016). Relative contribution of Rill/Interrill and Gully/Channel erosion to small reservoir siltation in mediterranean environments. Land Degradation and Development, 27(3), 785-797. doi:10.1002/ldr.2387 Cerdà, A. (1996). Seasonal variability of infiltration rates under contrasting slope conditions in southeast spain. Geoderma, 69(3-4), 217-232. Cerdà, A. (1999). Seasonal and spatial variations in infiltration rates in badland surfaces under mediterranean climatic conditions. Water Resources Research, 35(1), 319-328. doi:10.1029/98WR01659 Cerdà, A. (2001). Effects of rock fragment cover on soil infiltration, interrill runoff and erosion. European Journal of Soil Science, 52(1), 59-68. doi:10.1046/j.1365-2389.2001.00354.x Cerdà, A., Morera, A. G., & Bodí, M. B. (2009). Soil and water losses from new citrus orchards growing on sloped soils in the western mediterranean basin. Earth Surface Processes and Landforms, 34(13), 1822-1830. doi:10.1002/esp.1889 di Prima, S., Lassabatère, L., Bagarello, V., Iovino, M., & Angulo-Jaramillo, R. (2016). Testing a new automated single ring infiltrometer for Beerkan infiltration experiments. Geoderma, 262, 20-34. Iovino, M., Castellini, M., Bagarello, V., & Giordano, G. (2016). Using static and dynamic indicators to evaluate soil physical quality in a sicilian area. Land Degradation and Development, 27(2), 200-210. doi:10.1002/ldr.2263 Laudicina, V. A., Novara, A., Barbera, V., Egli, M., & Badalucco, L. (2015). Long-term tillage and cropping system effects on

  5. Predicting Soil-Water Characteristics from Volumetric Contents of Pore-Size Analogue Particle Fractions

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Møldrup, Per; Tuller, Markus

    *-model) for the SWC, derived from readily available soil properties such as texture and bulk density. A total of 46 soils from different horizons at 15 locations across Denmark were used for models evaluation. The Xw-model predicts the volumetric water content as a function of volumetric fines content (organic matter......Modelling water distribution and flow in partially saturated soils requires knowledge of the soil-water characteristic (SWC). However, measurement of the SWC is challenging and time-consuming, and in some cases not feasible. This study introduces two predictive models (Xw-model and Xw...... (organic matter, clay, silt, fine and coarse sand), variably included in the model depending on the pF value. The volumetric content of a particular soil particle size fraction was included in the model if it was assumed to contribute to the pore size fraction still occupied with water at the given p...

  6. The Impact of magnetic water treatment on salt distribution in a large unsaturated soil column

    Directory of Open Access Journals (Sweden)

    Vladimir Zlotopolski

    2017-12-01

    Full Text Available The use of saline water for crop production leads to soil salinization. Magnetically-treated water (MTW has been used for many years and has shown promise in leaching some ions from soil. At the same time, results have been inconsistent and somewhat controversial. In this study, we used large unsaturated columns (diameter 15 cm and length 90 cm to determine: 1 salt distributions at depths of up to 90 cm after adding magnetically-treated, saline water to soil; 2 whether MTW could reduce the rate of accumulation of salts (measured by EC in soil, and; 3 whether MTW could increase the leaching effect of soluble salts below root zones compared to control. The soil tested had a lower salt content compared to the water, a real-world scenario often faced when farmers elect to switch from higher-cost municipal water sources to ground water sources that have a higher saline content. Results indicated that the rate of salt accumulation was greater in the control group at the 30–60 cm depth. At the same time, the salt content at the 90 cm depth was greater in the MTW column. The results have shown that MTW changes the distribution of salts between soil layers reducing their content in the upper layers which are more important for agriculture. Keywords: Magnetic water treatment, Agriculture, Soil, Irrigation water

  7. The impact of agriculture terraces on soil organic matter, aggregate stability, water repellency and bulk density. A study in abandoned and active farms in the Sierra de Enguera, Eastern Spain.

    Science.gov (United States)

    Cerdà, Artemi; Burguet, Maria; Keesstra, Saskia; Prosdocimi, Massimo; Di Prima, Simone; Brevik, Erik; Novara, Agata; Jordan, Antonio; Tarolli, Paolo

    2016-04-01

    Soil erosion, land degradation, lack of organic matter, erodible soils, rock outcrops… are a consequence of the human abuse and misuse of the soil resources. And this is a worldwide environmental issue (Novara et al., 2011; Vanlauwe et al., 2015; Musinguzi et al., 2015; Pereira et al., 2015; Mwagno et al., 2016). Agriculture terraces are a strategy to reduce the soil erosion, improve the soil fertility and allow the ploughing (Cerdà et al., 2010; Li et al., 2014). Although this idea is well accepted there are few scientific evidences that demonstrate that soils in the terraced areas are more stable, fertile and sustainable that the soil in non terraced areas. In fact, the ploughing in comparison to the abandoned or not ploughed land results in the soil degradation (Lieskovský and Kenderessy, 2014; Gao et al., 2015; Parras-Alcántara et al., 2014). This is mainly due to the lack of vegetation that increase the surface runoff (Cerdà et al., 1998; Keesstra et al., 2007). And why is necessary to develop also in terraced landscapes soil erosion control strategies (Mekonnen et al., 2015a; Mekonnen et al., 2015b; Prosdocimi et al., 2016). Our objective was to assess the soil organic matter content (Walkley and Black, 1934), the soil bulk density (ring method), the aggregate stabilility (drop impact) and the water repellency (Water Drop Penetration Time test) in four study sites in the Sierra de Enguera. Two sites were terraced: one abandoned 40 years before the measurements and the other still active with olive crops. And two control sites non-terraced. We used the paired plot strategy to compare the impact of terracing and abandonment. At each site we collected randomly 50 soil samples at 0-2 cm, 4-6 and 8-10 cm depth. At each sampling point 100 WDPT measurements where carried out, and one sample for the bulk density, and one for the organic matter, and one for the soil aggregate stability were collected. The soil surface samples shown the largest differences. The

  8. Effect Of Soil Properties On The Geochemical Speciation Of Arsenic In Contaminated Soils: A Greenhouse Study

    Science.gov (United States)

    Sharma, S.; Sarkar, D.; Datta, R.

    2005-05-01

    Land-applied arsenical pesticides have contributed elevated soil arsenic (As) levels. Many baseline risk assessments As-contaminated sites assume that all As present in the soil is bioavailable, thereby potentially overestimating the actual health risk. However, risk from As exposure is associated only with those forms of As that are potentially extractable by the human gastrointestinal juices. It has been demonstrated that As may exist in several geochemical forms depending on soil chemical properties, which may or may not be bioavailable. The current study aims at addressing the issue of soil variability on As bioavailability as a function of soil physico-chemical properties in a greenhouse setting involving dynamic interactions between soil, water and plants. Four different soils were chosen based on their potential differences with respect to As reactivity: Immokalee, an acid sand with low extractable Fe/Al, having minimal arsenic retention capacity; Millhopper, an acid sandy loam with high extractable Fe/Al oxides; Pahokee Muck soil with 85% soil organic matter (SOM) as well as high Fe/Al content; and Orelia soil with high clay and Fe/Al content. Soils were amended with sodium arsenate (675 and 1500 mg/Kg). Rice (Oryza sativa) was used as the test crop. A sequential extraction scheme was employed to identify the geochemical forms of As in soils (soluble, exchangeable, organic, Fe/Al-bound, Ca/Mg-bound, residual) immediately after spiking; after 3 mo; and after 6 mo of equilibration time. Concentrations of these As forms were correlated with the in-vitro bioavailable As fractions to identify those As fractions that are most likely to be bioavailable. Results from this study showed that there was little to no plant growth in the contaminated soils. Sequential extractions of the soil indicated that arsenic is strongly adsorbed onto soil amorphous iron/aluminum oxides, and the degree of arsenic retention is a direct function of equilibration time.

  9. Soil management system for water conservation and mitigation of global change effect

    Science.gov (United States)

    Ospina, A.; Florentino, A.; Lorenzo, V.

    2012-04-01

    One of the main constraints in rained agriculture is the water availability for plant growth which depends largely on the ability of the soil to allow water flow, infiltration and its storage. In Venezuela, the interaction between aggressive climatic conditions, highly susceptible soils and inadequate management systems have caused soil degradation which together with global change threatened the food production sustainability. To address this problem, we need to implement conservationist management strategies that improve infiltration rate, permeability and water holding capacity in soil and reduce water loss by protecting the soil surface. In order to study the impact of different management systems on soil water balance in a Fluventic Haplustept, the effects of 11 years of tillage and crops rotation management were evaluated in a long term field experiment located in Turén (Portuguesa state). The evaluated tillage systems were no tillage (NT) and conventional tillage (CT) and crop rotation treatments were maize (Zea mays)-cotton (Gossypium hirsutum) and maize-bean (Vigna unguiculata). Treatments were established in plots arranged in a randomized block design with three replicates. The gravimetric moisture content was determined in the upper 20 cm of soil, at eight different sampling dates. Results showed increased in time of the water availability with the use of tillage and corn-cotton rotation and, better protection of the soil against raindrop impact with crop residues. Water retention capacity also increased and improved structural condition on soil surface such as infiltration, storage and water flow distribution in the rooting zone. We conclude that these strategies of land use and management would contribute to mitigate the climate change effects on food production in this region of Venezuela. Key words: Soil quality; rained agriculture; plant water availability

  10. Increased ambient air temperature alters the severity of soil water repellency

    Science.gov (United States)

    van Keulen, Geertje; Sinclair, Kat; Hallin, Ingrid; Doerr, Stefan; Urbanek, Emilia; Quinn, Gerry; Matthews, Peter; Dudley, Ed; Francis, Lewis; Gazze, S. Andrea; Whalley, Richard

    2017-04-01

    Soil repellency, the inability of soils to wet readily, has detrimental environmental impacts such as increased runoff, erosion and flooding, reduced biomass production, inefficient use of irrigation water and preferential leaching of pollutants. Its impacts may exacerbate (summer) flood risks associated with more extreme drought and precipitation events. In this study we have tested the hypothesis that transitions between hydrophobic and hydrophilic soil particle surface characteristics, in conjunction with soil structural properties, strongly influence the hydrological behaviour of UK soils under current and predicted UK climatic conditions. We have addressed the hypothesis by applying different ambient air temperatures under controlled conditions to simulate the effect of predicted UK climatic conditions on the wettability of soils prone to develop repellency at different severities. Three UK silt-loam soils under permanent vegetation were selected for controlled soil perturbation studies. The soils were chosen based on the severity of hydrophobicity that can be achieved in the field: severe to extreme (Cefn Bryn, Gower, Wales), intermediate to severe (National Botanical Garden, Wales), and subcritical (Park Grass, Rothamsted Research near London). The latter is already highly characterised so was also used as a control. Soils were fully saturated with water and then allowed to dry out gradually upon exposure to controlled laboratory conditions. Soils were allowed to adapt for a few hours to a new temperature prior to initiation of the controlled experiments. Soil wettability was determined at highly regular intervals by measuring water droplet penetration times. Samples were collected at four time points: fully wettable, just prior to and after the critical soil moisture concentrations (CSC), and upon reaching air dryness (to constant weight), for further (ultra)metaproteomic and nanomechanical studies to allow integration of bulk soil characterisations with

  11. Integrating water by plant roots over spatially distributed soil salinity

    Science.gov (United States)

    Homaee, Mehdi; Schmidhalter, Urs

    2010-05-01

    In numerical simulation models dealing with water movement and solute transport in vadose zone, the water budget largely depends on uptake patterns by plant roots. In real field conditions, the uptake pattern largely changes in time and space. When dealing with soil and water salinity, most saline soils demonstrate spatially distributed osmotic head over the root zone. In order to quantify such processes, the major difficulty stems from lacking a sink term function that adequately accounts for the extraction term especially under variable soil water osmotic heads. The question of how plants integrate such space variable over its rooting depth remains as interesting issue for investigators. To move one step forward towards countering this concern, a well equipped experiment was conducted under heterogeneously distributed salinity over the root zone with alfalfa. The extraction rates of soil increments were calculated with the one dimensional form of Richards equation. The results indicated that the plant uptake rate under different mean soil salinities preliminary reacts to soil salinity, whereas at given water content and salinity the "evaporative demand" and "root activity" become more important to control the uptake patterns. Further analysis revealed that root activity is inconstant when imposed to variable soil salinity. It can be concluded that under heterogeneously distributed salinity, most water is taken from the less saline increment while the extraction from other root zone increments with higher salinities never stops.

  12. Water-stability of soil aggregates in relation to selected properties

    International Nuclear Information System (INIS)

    Mbagwu, J.S.C.; Bazzoffi, P.; Unamba Oparah, I.

    1995-03-01

    The stability of soil aggregates in water is an important soil physical property for evaluating the potential of agricultural soils to erode and elucidating the mechanisms of soil erosion. In this study we used aggregates from 15 surface soil samples in Italy to evaluate the influence of intrinsic soil physical, chemical and mineralogical properties on aggregates stability (AS). The aim was to develop a model for predicting AS from a subset of these soil properties. The index of stability used is the mean-weight diameter of water-stable aggregates (MWD). The model developed with soil physical properties alone explained just 42% of variance in MWD and predicted AS in only 20% of test soils. The model developed with mineralogical properties alone explained 70% of variance in MWD and predicted AS in 60% of the test soils. The chemical properties - based model explained 90% of variance in MWD and predicted AS in 80% of the test soils. The best-fit model was developed with soil properties from the physical, chemical and mineralogical subsets. It explained 98% of variance in MWD and predicted AS in 100% of the test soils. This model shows that the most important soil properties which influence the AS of these soils include ratio of total sand to clay, concentrations of iron oxide, magnesium oxide, organic matter, silica/alumina ratio, chlorite, feldspar and muscovite. This indicates that fairly good estimates of the relative stability of these aggregates in water and hence of their potential to erode, requires a knowledge of the physico-chemical and mineralogical properties. (author). 40 refs, 4 tabs

  13. Non-destructive estimates of soil carbonic anhydrase activity and associated soil water oxygen isotope composition

    Science.gov (United States)

    Jones, Sam P.; Ogée, Jérôme; Sauze, Joana; Wohl, Steven; Saavedra, Noelia; Fernández-Prado, Noelia; Maire, Juliette; Launois, Thomas; Bosc, Alexandre; Wingate, Lisa

    2017-12-01

    The contribution of photosynthesis and soil respiration to net land-atmosphere carbon dioxide (CO2) exchange can be estimated based on the differential influence of leaves and soils on budgets of the oxygen isotope composition (δ18O) of atmospheric CO2. To do so, the activity of carbonic anhydrases (CAs), a group of enzymes that catalyse the hydration of CO2 in soils and plants, needs to be understood. Measurements of soil CA activity typically involve the inversion of models describing the δ18O of CO2 fluxes to solve for the apparent, potentially catalysed, rate of CO2 hydration. This requires information about the δ18O of CO2 in isotopic equilibrium with soil water, typically obtained from destructive, depth-resolved sampling and extraction of soil water. In doing so, an assumption is made about the soil water pool that CO2 interacts with, which may bias estimates of CA activity if incorrect. Furthermore, this can represent a significant challenge in data collection given the potential for spatial and temporal variability in the δ18O of soil water and limited a priori information with respect to the appropriate sampling resolution and depth. We investigated whether we could circumvent this requirement by inferring the rate of CO2 hydration and the δ18O of soil water from the relationship between the δ18O of CO2 fluxes and the δ18O of CO2 at the soil surface measured at different ambient CO2 conditions. This approach was tested through laboratory incubations of air-dried soils that were re-wetted with three waters of different δ18O. Gas exchange measurements were made on these soils to estimate the rate of hydration and the δ18O of soil water, followed by soil water extraction to allow for comparison. Estimated rates of CO2 hydration were 6.8-14.6 times greater than the theoretical uncatalysed rate of hydration, indicating that CA were active in these soils. Importantly, these estimates were not significantly different among water treatments, suggesting

  14. Water potential distribution in the testing soil column

    International Nuclear Information System (INIS)

    Yao Laigen; Zhao Yingjie

    2000-01-01

    The author explains the water potential distribution in the testing soil column under artificial sprinkling condition and confirm that the nuclide migration is carried out under the unsaturated condition. Knowing well the situation of water permeation in the unsaturated zone is one of main research works. The testing material and size of soil column used is very similar to the No.4 soil column for nuclide migration test. Under the same sprinkling condition as simulation test for nuclide migration, the water potential distribution in the soil column was measured. The test result shows that during the test process in upper 40 cm scope of soil column the unsaturated condition is kept from beginning to end

  15. Assessment of ecological security based on soil and water conservation: a case study from Gansu Province, China

    Science.gov (United States)

    Li, Z. J.; Tian, Q.; Song, L. L.

    2016-08-01

    In this study, the analytic hierarchy process (ahp), ecological security index(S) and PSR model were used to evaluate Gansu's ecological security based on the large number of survey data. The results indicated that Gansu's ecological security index increased from 0.31 in 1986 to 0.66 in 2013, which reflected ecological security was in sensitive state (0.7༞S≥⃒0.5). The main reason was that national policy on protecting the ecological environment has played a crucial role, especially the national project of returning farmland to forest and grass carried out in recent years. Moreover, the environmental issues such as the higher PM2.5, sand storms and climate extremes, had significantly improved people's environmental awareness in the study area. The regional difference of ecological security index was significant in Gansu Provinces, and the part of Yangtze river basin was higher than the part of Yellow River basin, whiles the in-land river basin was the lowest value. In a world, Gansu's ecological security had improved in recent years, but there was strong need for paying more attention to policy for ecological environment protection and increasing the propaganda to ensure the Gansu's ecological security in the future. This study will provide a scientific basis for the sustainable development of regional social economy and ecological environment.

  16. EVALUATION OF A SIMULATOR MODEL FOR PREDICTING SOIL-WATER CHARACTERISTICS OF SELECTED AGMCULTURAL FIELDS

    Directory of Open Access Journals (Sweden)

    H. E. Igbadun

    2011-06-01

    Full Text Available The ability of the Soil Water Characteribtics-Hydraulic Calculator (SWC-HPC model in predicting soi-water agricultural fields in Zaria, Nigeria, was tested and reprted in this study. The goal was to establish the predictability and reliability of the nodel, and hence, its use in determining water characteristics of soils in the stud/ area. Forty soil samples collected from four irrigation sites were used in the valuation. The soils particle size distribution (specifically, percent clay and sand and organic matter contents were inputted into the model to simulate soil moistur; status at saturation, field capacity and wilting point, soil bulk density and saturated hydraulic conductivity. The model outputs were statistically compared with observed parameters from laboratory tests using root mean square error (RMSE, c< ^efficient of variation (CV, modeling efficiency (EF and coefficient of residual mass (CRM. The model accurately simulated the observed bulk densities of the soil tested, satisfactorily simulated soil moisture content at field capacity, and mot lerately simulated moisture content at saturation and wilting point. The model lowever, poorly simulated saturated hydraulic conductivity of the soils tested. The SWC-HPC may therefore be used only to simulate soil bulk densities and moistui e status at saturation, field capacity and wilting point in the study locations.

  17. Untangle soil-water-mucilage interactions: 1H NMR Relaxometry is lifting the veil

    Science.gov (United States)

    Brax, Mathilde; Buchmann, Christian; Schaumann, Gabriele Ellen

    2017-04-01

    Mucilage is mainly produced at the root tips and has a high water holding capacity derived from highly hydrophilic gel-forming substances. The objective of the MUCILAGE project is to understand the mechanistic role of mucilage for the regulation of water supply for plants. Our subproject investigates the chemical and physical properties of mucilage as pure gel and mixed with soil. 1H-NMR Relaxometry and PFG NMR represent non-intrusive powerful methods for soil scientific research by allowing quantification of the water distribution as well as monitoring of the water mobility in soil pores and gel phases.Relaxation of gel water differs from the one of pure water due to additional interactions with the gel matrix. Mucilage in soil leads to a hierarchical pore structure, consisting of the polymeric biohydrogel network surrounded by the surface of soil particles. The two types of relaxation rates 1/T1 and 1/T2 measured with 1H-NMR relaxometry refer to different relaxation mechanisms of water, while PFG-NMR measures the water self-diffusion coefficient. The objective of our study is to distinguish in situ water in gel from pore water in a simplified soil system, and to determine how the "gel effect" affects both relaxation rates and the water self-diffusion coefficient in porous systems. We demonstrate how the mucilage concentration and the soil solution alter the properties of water in the respective gel phases and pore systems in model soils. To distinguish gel-inherent processes from classical processes, we investigated the variations of the water mobility in pure chia mucilage under different conditions by using 1H-NMR relaxometry and PFG NMR. Using model soils, the signals coming from pore water and gel water were differentiated. We combined the equations describing 1H-NMR relaxation in porous systems and our experimental results, to explain how the presence of gel in soil affects 1H-NMR relaxation. Out of this knowledge we propose a method, which determines in

  18. Modeling of soil water content and soil temperature at selected U.S. and central European stations using SoilClim model

    Science.gov (United States)

    Hlavinka, P.; Trnka, M.; Balek, J.; Zalud, Z.; Hayes, M.; Svoboda, M.; Eitzinger, J.

    2009-04-01

    Within the presented study the SoilClim model was tested through various climatic and soil conditions. SoilClim model enables to estimate reference and actual evapotranspiration from defined vegetation cover and consequently the soil water content within two defined layers (named as Moisture control section I and II) could be deduced. The soil temperature in 0.5 m depth is also estimated (on the basis of simple empirical model). Mentioned outputs could be additionally used for identification of soil climate regimes (both Hydric and Thermic) within selected location. The SoilClim works in daily step and needs daily maximum and minimum air temperature, global radiation, precipitation, air humidity and wind speed as input. The brief information about soil layers (field capacity, wilting point, depth) and vegetation cover is necessary. The algorithm for reference evapotranspiration is based on Penman-Monteith method. The main aim of the study was to assess accuracy and suitability of the SoilClim for simulation of soil water content in the two defined layers and temperature in 0.50 m depth. For this purpose the seven stations through central U.S. were selected (by twos from Nebraska, Iowa and Kansas and one from South Dakota). Used measurements were observed from 2004 to 2008. The central European region was represented by Austrian Lysimetric station Gross-Enzersdorf. The data within three different soil profiles and for various crop covers (spring barley, winter wheat, maize and potato) from 1999 to 2004 were used. During introduced reserch SoilClim provided reasonable results of soil moisture for both layers against lysimetric measurements. Agreement between measured and estimated water content (30 days averages) could be described by coefficient of determination (R2) which varied from 0.45 to 0.75. The Mean Bias Error (MBE) for values in daily step was from -12.87 % to 20.66 % and Root Mean Square Error (RMSE) varied from 14.49 % to 34.76 %. The modeling efficiency

  19. Bioremediation of PAH polluted soils: column studies

    Energy Technology Data Exchange (ETDEWEB)

    Hallberg, R.O. [Dept. of Geology and Geochemistry, Stockholm Univ., Stockholm (Sweden); Trepte, B.S. [Angpannefoereningen AB, Stockholm (Sweden)

    2003-07-01

    Background. Due to spills, discharges and leakage, the gaswork site at Husarviken in Stockholm is today the largest (36 ha) creosote-contaminated site in Sweden. The main pollutants are creosote, lead and mercury. The remediation costs are estimated to be as high as US $125 million. It is thus of great interest to find more cost effective remediation methods. Objectives. The aim of this study was to investigate i) if the addition of NTA, EDTA, nitrate, iron and dry yeast would enhance the bioremediation rate of a complex organic pollutant like PAH and, if so, at what concentrations they would be most efficient, ii) the effect on PAH reduction when larger dimensions of the column is used to diminish the effect of water passing along the sides of the column, iii) long-term effects on the reduction of PAH in field-contaminated soil with high concentrations. Materials and Methods. Creosote-contaminated soil from the Husarviken gaswork site was treated with aerated water in column experiments at room temperature. Three column experiments were performed in 2 and 100 L of homogenised soil samples percolated by recirculating flushing water. Fluoranthene was analysed as a representative of the overall degradation of PAH in the columns. (orig.)

  20. Hydraulic redistribution of soil water by neotropical savanna trees.

    Science.gov (United States)

    Fabian G. Scholz; Sandra J. Bucci; Guillermo Goldstein; et al.

    2002-01-01

    The magnitude and direction of water transport by the roots of eight dominant Brazilian savanna (Cerrado) allowed bidirectional measurements of sap flow. The patterns of sap flow observed during the dry season in species with dimorphic roots systems were consistent with the occurrence of hydraulic redistribution of soil water, the movement of water from moist to drier...

  1. Percolation theory and its application for interpretation of soil water retention curves

    International Nuclear Information System (INIS)

    Kodesova, R.

    2004-01-01

    The soil porous system has traditionally been deduced from the soil-water retention curve with the assumption of homogeneity and free accessibility of pores, defined as capillary tubes, from the sink/source of water. But real soil fabric is mostly characterized by aggregates. In this case, the soil porous system cannot be modeled as a homogeneous one. To examine the differences between homogeneous and heterogeneous soil porous systems, we studied two types of soils: sandy soil and coarse sandy soil. We applied image processing filters and the ARC/INFO Grid module to analyze pore sizes in both soils from their electron microscope images taken at two different magnifications. We used the resulting pore-size distribution data to generate 3-D porous media consisting of pores and throats. The homogeneous pore structure was created as a mono-modal pore-throat network with one pore-size distribution. The heterogeneous pore structure was designed as a bi-modal pore-throat network with two pore-size distributions, where the pore sizes were hierarchically arranged in the nodes of the network. We applied the percolation model to simulate water and air displacement in these networks. The distribution of water in the nodes of the networks was studied increasing/decreasing steps of pressure head and the drainage and wetting branches of the retention curves were evaluated. The soil-water retention curves modeled for the mono-modal and bi-modal porous systems had different characters. The simulated shape of the retention curve in the mono-modal case was close to the step-like form of a retention curve characteristic of unstructured soil. The shape of the simulated retention curve in the bi-modal case was smoother, more gradual, and closer to the shape of the retention curve of a real, structured soil. (author)

  2. Spatio-temporal effects of soil and bedrock variability on grapevine water status in hillslope vineyards.

    Science.gov (United States)

    Brillante, Luca; Bois, Benjamin; Mathieu, Olivier; Leveque, Jean

    2014-05-01

    Hillslope vineyards show various and complex water dynamics between soil and plants, and in order to gain further insight into this phenomenon, 8 grapevine plots were monitored during three vintages, from 2010 to 2013, on Corton Hill, Burgundy, France. Plots were distributed along a topolithosequence from 330 to 270 metres a.s.l. Grapevine water status was monitored weekly by surveying water potential, and, at the end of the season, by the use of the δ13C analysis of grape juice. Soil profile of each plot was described and analysed (soil texture, gravel content, organic carbon, total nitrogen, pH, CEC). Soil volumetric humidity was measured weekly, using TDR probes. A pedotransfer function was developed to transform Electrical Resistivity Imaging (ERI) into soil volume wetness and therefore to spatialise and observe variation in the Fraction of Transpirable Soil Water (FTSW). During the three years of monitoring, grapevines experienced great variation in water status, which ranged from low to considerable water deficit (as expressed by pre-dawn leaf water potential and δ13C analysis of grape juice). With ERI imaging, it was possible to observe differences in water absorption pattern by roots, in different soils, and at different depth. In addition, significant differences were observed in grapevine water status in relation to variations in the physical characteristics of the terroir along the hillslope (i.e. the geo-pedological context, the elevation etc.). Grapevine water behaviour and plant-soil water relationships on the hillslope of Corton Hill have been extensively characterised in this study by ultimate technologies, allowing to present this terroir as a very interesting example for future generalisation and modelling of the hillslope vineyard water dynamics.

  3. Soil and water conservation practices in the savanna of northern ...

    African Journals Online (AJOL)

    Adoption of soil and water conservation measures by farmers is low since these measures tend to be labour intensive, costly and have a more long term effect. The need to conserve soil resources for greater productivity and protect the environment from degradation is of utmost priority. This paper reviews some of the ...

  4. Estimation of Soil Water Retention Curve Using Fractal Dimension ...

    African Journals Online (AJOL)

    ADOWIE PERE

    2018-02-10

    Feb 10, 2018 ... particle size distribution has fractal properties. Hence, fractal model can be used to estimate the soil water retention curve. Thus determining the DSWRC from SWRC experimental data, establishing a relationship among DSWRC and soil readily available characteristics (i.e. clay, silt and sand contents and.

  5. Water magnetization and phosphorus transport parameters in the soil

    Directory of Open Access Journals (Sweden)

    Tarcila N. Generoso

    Full Text Available ABSTRACT There are scientific studies describing changes in properties of the water when subjected to the action of a magnetic field, which may favor the availability of some nutrients in the soil solution. Some nutrients, although they are essential to the process of crop development, can be sources of pollution for watercourses and soil. The aim of this study was to evaluate the effect of water magnetization on transport parameters of the phosphate ion in a Red Latosol (RL and in a Quartzarenic Neosol (QN. Saturated leaching columns were connected to bottles containing KH2PO4 solutions. In RL, there were significant differences in phosphorus (P transport parameters, related to the retardation factor (R and distribution coefficient (Kd. For the others, Peclet number (Pe, dispersive-diffusion coefficient (D and dispersivity (λ, there were no significant differences in the comparison between the treatments with magnetized and non-magnetized water. In QN, there were statistical differences in R and Kd. For the other parameters, Pe, D and λ, there were no statistical differences between treatments.

  6. Effect of some soil physical properties on water holding capacity, neutron probe calibration and salt movement

    International Nuclear Information System (INIS)

    Razzouk, A.

    2010-01-01

    This study was conducted in tow areas representing in silty soil in Southern Syria (Dra'a), loamy and sandy soil in Eastern Syria (Deir Al zour) to compare the soil effect on the calibration of the neutron probe, correlation coefficient, soil characteristics curve, soil solution content of nitrates, potassium and sodium for the estimation of the optimum sampling time of soil solution by porous ceramic cups. Regression analysis results showed that the three soils curves, in which the soil contained the lowest content of clay had a high correlation coefficient and decreased with increasing the clay content. Whereas, the correlation coefficient in sandy soil was 0.96 while decreased to 0.79 in silty soil. The hydraulic head increased with decreasing the water content, which was obvious in the three soils characteristic curves. The NO 3 content decreased due to the plants roots absorption and leaching to deeper layers, while the NO 3 content in the surfaces layer significantly decreased in the sandy soil. Results showed that equilibrium between the soil solution and the NO 3 content in the solution in porous cups occurred within 8 days. (author)

  7. Water repellency and hydraulic conductivity of forest soils as influenced by management practices

    Science.gov (United States)

    Wahl, N. A.; Bens, O.; Hüttl, R. F.

    2003-04-01

    For soils under both agricultural and forest use, management and tillage practice have significant influence on different hydraulic properties. It is therefore supposed, that management practices are capable of altering surface runoff, water retention and flooding risk of river catchments. Soil water repellency (hydrophobicity) can adversely affect soil hydrological properties, e.g. reduce infiltration capacity and induce preferential flow, thus enhancing the overall risk of flooding in river catchment areas. Hydrophobic effects are especially pronounced in coniferous forest soils. Investigations were carried out on several study plots in the German Northeastern Lowlands, located app. 50 km NE of Berlin in Brandenburg. The predominant soil in the study area is a weakly podsolic Cambisol from glacifluvial deposits with a distinct texture in the range of medium sized sand. The four stands investigated represent different stages of forest transformation, in a sense of a "false" chronosequence and are made up of populations of Pinus sylvestris and Fagus sylvatica of different ages. Infiltration was measured with a tension infiltrometer (hood infiltrometer) and a single ring infiltrometer at the soil surface. Water repellency was quantified with the water drop penetration time (WDPT) test, for determining the persistence of water repellency, and the ethanol percentage (EP) test, for measuring the severity/degree of water repellency. Soil samples from the four forest plots and different soil depths (0--160 cm) were used for the experiments. During the different stages of forest transformation, the types, forms, and quantities of soil organic matter and humus present are changed. Consequently, the production and supply of water repellent substances vary according to the stand structure of the different experimental plots. The results indicate that for the studied sandy forest soils, the overall infiltration capacity of the plots is low due to the textural composition. The

  8. Elevated carbon dioxide: impacts on soil and plant water relations

    National Research Council Canada - National Science Library

    Kirkham, M. B

    2011-01-01

    .... Focusing on this critical issue, Elevated Carbon Dioxide: Impacts on Soil and Plant Water Relations presents research conducted on field-grown sorghum, winter wheat, and rangeland plants under elevated CO2...

  9. Soil and Water Conservation Districts of New Mexico

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The New Mexico Soil and Water Conservation District (SWCD) shapefile includes forty-seven boudaries which cover each SWCD throughout the State.

  10. Water flow in soil from organic dairy rotations

    DEFF Research Database (Denmark)

    Lamandé, Mathieu; Eriksen, Jørgen; Krogh, Paul Henning

    2017-01-01

    and fertilizer practice on the movement of water through sandy loam soil profiles were investigated in managed grassland of a dairy operation. Experiments using tracer chemicals were performed, with or without cattle slurry application, with cutting or grazing, in the 1st and the 3rd year of ley, and in winter...... rye. Each plot was irrigated for an hour with 18·5 mm of water containing a conservative tracer, potassium bromide; 24 h after irrigation, macropores >1 mm were recorded visually on a horizontal plan of 0·7 m2 at five depths (10, 30, 40, 70 and 100 cm). The bromide (Br−) concentration in soil was also...... by the grazing regime. Infiltrating water may bypass the soil matrix under similar or more extreme conditions than in the current experiment. Such hydraulic functioning in the grazing regime is expected to reduce the risk of leaching of nitrate contained in soil water....

  11. A comparison of simulation models for predicting soil water dynamics in bare and vegetated lysimeters

    Energy Technology Data Exchange (ETDEWEB)

    Link, S.O.; Kickert, R.N.; Fayer, M.J.; Gee, G.W.

    1993-06-01

    This report describes the results of simulation models used to predict soil water storage dynamics at the Field Lysimeter Test Facility (FLTF) weighing lysimeters. The objectives of this research is to develop the capability to predict soil water storage dynamics with plants in support of water infiltration control studies for the Hanford Permanent Isolation Barrier Development Program. It is important to gain confidence in one`s ability to simulate soil water dynamics over long time periods to assess the barrier`s ability to prevent drainage. Two models were compared for their ability to simulate soil water storage dynamics with and without plants in weighing lysimeters, the soil water infiltration and movement (SWIM) and the simulation of production and utilization of rangelands (SPUR-91) models. These models adequately simulated soil water storage dynamics for the weighing lysimeters. The range of root mean square error values for the two models was 7.0 to 19.8. This compares well with the range reported by Fayer et al. (1992) for the bare soil data sets of 8.1 to 22.1. Future research will test the predictive capability of these models for longer term lysimeter data sets and for historical data sets collected in various plant community types.

  12. Relating the onset of reduction to degree of soil water saturation ...

    African Journals Online (AJOL)

    Relating the onset of reduction to degree of soil water saturation. Kimberly Smith, Cornelius W van Huyssteen. Abstract. Literature does not indicate the degree of water saturation at which reduction is expected to occur. This study therefore aimed to determine the degree of water saturation (S) at which reduction is initiated.

  13. Processes preventing nocturnal equilibration between leaf and soil water potential in tropical savanna woody species.

    Science.gov (United States)

    Sandra Bucci; Fabian G. Scholz; Guillermo Goldstein; Frederick C. Meinzer; Jose A. Hinojosa; William A. Hoffman; Augusto C. Franco

    2004-01-01

    The impact of nocturnal water loss and recharge of stem water storage on predawn disequilibrium between leaf (ΨL) and soil (Ψ S) water potentials was studied in three dominant tropical savanna woody species in central Brazil (Cerrado). Sap flow continued throughout the night during the dry season and...

  14. Uncoupling between soil and xylem water isotopic composition: how to discriminate mobile and tightly-bound water?

    Science.gov (United States)

    Martín Gómez, Paula; Aguilera, Mònica; Pemán, Jesús; Gil Pelegrín, Eustaquio; Ferrio, Juan Pedro

    2014-05-01

    As a general rule, no isotopic fractionation occurs during water uptake and water transport, thus, xylem water reflects source water. However, this correspondence does not always happen. Isotopic enrichment of xylem water has been found in several cases and has been either associated to 'stem processes' like cuticular evaporation 1 and xylem-phloem communication under water stress 2,3 or to 'soil processes' such as species-specific use of contrasting water sources retained at different water potential forces in soil. In this regard, it has been demonstrated that mobile and tightly-bound water may show different isotopic signature 4,5. However, standard cryogenic distillation does not allow to separate different water pools within soil samples. Here, we carried out a study in a mixed adult forest (Pinus sylvestris, Quercus subpyrenaica and Buxus sempervirens) growing in a relatively deep loamy soil in the Pre-Pyrenees. During one year, we sampled xylem from twigs and soil at different depths (10, 30 and 50 cm). We also sampled xylem from trunk and bigger branches to assess whether xylem water was enriched in the distal parts of the tree. We found average deviations in the isotopic signature from xylem to soil of 4o 2o and 2.4o in δ18O and 18.3o 7.3o and 8.9o in δ2H, for P.sylvestris, Q.subpyrenaica and B.sempervirens respectively. Xylem water was always enriched compared to soil. In contrast, we did not find clear differences in isotopic composition between xylem samples along the tree. Declining the hypothesis that 'stem processes' would cause these uncoupling between soil and xylem isotopic values, we tested the possibility to separate mobile and tightly-bound water by centrifugation. Even though we could separate two water fractions in soils close to saturation, we could not recover a mobile fraction in drier soils. In this regard, we welcome suggestions on alternatives to separate different soil fractions in order to find the correspondence between soil and

  15. Effects of ashes from a Brazilian savanna wildfire on water, soil and biota: An ecotoxicological approach.

    Science.gov (United States)

    Oliveira-Filho, Eduardo C; Brito, Darlan Q; Dias, Zelia M B; Guarieiro, Mayara S; Carvalho, Esther L; Fascineli, Maria L; Niva, Cintia C; Grisolia, Cesar K

    2018-03-15

    Wildfire is very common in Brazilian savannas, and its effects on water, soil and aquatic/soil organisms are poorly understood. In this study, we observed the effects of fire, especially of ashes, on surface soil and subsurface water in a typical Brazilian savanna (Cerrado sensu strictu) for one year. Soil analyses (pH, organic matter content, potential acidity, K, Ca, Mg and P) and subsurface water analyses (NO 3- , PO 4 3- Mg 2+ , Ca 2+ and K + ) were assessed. We evaluated the ecotoxicological effects of ashes on three different endpoints and species, in fish Danio rerio (embryonic development), aquatic snail Biomphalaria glabrata (reproduction) and a soil species Enchytraeus sp. (reproduction). We found a higher amount of exchangeable cations and organic matter content in short-term fire effects on soil, but the higher availability of nutrients did not affect the soil pH in field plots. The effects of ashes on soil and subsurface water did not persist for one-year post-fire, except for organic matter content in burned areas. No toxic effects were observed on hatching success and incidences of developmental abnormalities in D. rerio embryos. However, ash input had adverse effects on reproduction in snails and enchytraeids. We reported a statistically significant decrease in snail eggs exposed to the 50g.L -1 and 100g.L -1 of ashes after four weeks (pfires on soil and aquatic biota in tropical savannas. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. STUDY OF A SOIL WITH SWELLING AND SHRINKING PHENOMENA

    Directory of Open Access Journals (Sweden)

    G. Rogobete

    2012-12-01

    Full Text Available Vertisols are deep clayey soils, with more than 45 % clay, dominated by clay minerals, such as smectites, that expand upon wetting and shrink upon drying. The most important physical characteristics of Vertisols are a low hydraulic conductivity and stickiness when wet and high flow of water through the cracks when dry. They become very hard when dry and in all the time are difficult to work. During the rainy season, the cracks disappear and the soil becomes sticky and plastic with a very slippery surface which makes Vertisols in – trafficable when wet. Water movement in soil that change volume with water content is not well understood and management of swelling soil remains problematic. Swelling or shrinking result in vertical displacement of the wet soil, which involves gravitational work and contributes to an overburden component to the total potential of the soil water. Many swelling soil crack and the network of cracks provides pathways for rapid flow of water which prejudice application of theory based on Darcian flow. One – dimensional flow of water in a swelling system requires material balance equation for both the aqueous and solid phases. The analytical data offers some values particle – size distribution, compression, swelling degree and pressure, plasticity index, elastic modulus, triaxial shear, angle of shear and load carrying capacity in order to realize a foundation study for some constructions.

  17. The long-term effects of alfalfa on soil water content in the Loess ...

    African Journals Online (AJOL)

    Soil desiccation is the most serious problem in forest vegetations and grassland, which lead to widespread land degradation in the Loess Plateau of China. The soil water variations at 0 to 1000 cm depth of different vegetations were studied to explore the hydrological effects of vegetations and determine the optimal length ...

  18. Converging patterns of uptake and hydraulic redistribution of soil water in contrasting woody vegetation types.

    Science.gov (United States)

    F.C. Meinzer; J.R. Brooks; S. Bucci; G. Goldstein; F.G. Scholz; J.M. Arren

    2004-01-01

    We used concurrent measurements of soil water content and soil water potential (Ψsoil) to assess the effects of Ψsoil on uptake and hydraulic redistribution (HR) of soil water by roots during seasonal drought cycles at six sites characterized by differences in the types and amounts of woody vegetations and...

  19. Advances in treatment methods for uranium contaminated soil and water

    International Nuclear Information System (INIS)

    Navratil, J.D.

    2002-01-01

    Water and soil contaminated with actinides, such as uranium and plutonium, are an environmental concern at most U.S. Department of Energy sites, as well as other locations in the world. Remediation actions are on going at many sites, and plans for cleanup are underway at other locations. This paper will review work underway at Clemson University in the area of treatment and remediation of soil and water contaminated with actinide elements. (author)

  20. Field, laboratory and estimated soil-water content limits

    African Journals Online (AJOL)

    2005-01-21

    Jan 21, 2005 ... pressure pot (-50 and -100 kPa) and pressure chamber at -1 500. kPa and the soil-water content was .... -10 kPa, a pressure pot was used for matric potentials between. -50 and -100 kPa and a pressure chamber .... In clay soils, since the pore-size distribution is more uniform, more of the water is adsorbed, ...

  1. Pollutants impact bioassay from waters and soils in Banat region

    Directory of Open Access Journals (Sweden)

    Crina Laura Mosneang

    2014-12-01

    Full Text Available Analyses of water and soil samples by chemical methods identified the quantities of chlorides, nitrates and phosphates by comparison with the maximum limits of law. Acute toxicity tests on zebra fish embryos is an alternative test of water samples around swine farms in Banat region, because embryos are not subject to animal protection legislation during experiments. The use of Eisenia fetida earthworms as pollution indicators allowed assessment of avoidance behavior of potentially polluting soils collected from different distances from farms.

  2. Calibration precision of capacitance and neutron soil water content gauges in arid soils

    International Nuclear Information System (INIS)

    Waugh, W.J.; Baker, D.A.; Kastens, M.K.; Abraham, J.A.

    1996-01-01

    Resonant frequency capacitance (RFC) gauges have been marketed as a replacement for neutron thermalization (NT) gauges for monitoring soil water content in access tubes. Regulatory restrictions have increased the cost of maintaining and operating NT gauges. Commercial RFC gauges have performed satisfactorily for some agronomic applications when tested in relatively uniform or recompacted soil profiles. We compared the calibration statistics of RFC and NT gauges in three heterogeneous arid soils initially for all data, and then for data post stratified by texture, bulk density, and salinity. Our experimental design included measurements of soil water profiles in paired wet and dry plots, one at field capacity and the other near the seasonal low. Coefficients of determination (r 2 ) for linear calibrations of the RFC gauge ranged from 0.19 to 0.85. The response of the resonant frequency difference measured by the RFC probe to soil water content (θ) was masked by sensitivity primarily to soil salinity, but also to soil bulk density (ρ) and soil texture. The RFC gauge performed best in a thick sandy loam soil with low salinity levels and fairly uniform p. Values of r 2 for linear calibrations of the NT gauge versus θ ranged from 0.84 to 0.94. The NT gauge calibrations were little influenced by soil salinity, ρ, or soil texture. Standard errors of θ estimates [SE(Eθ)] were up to 7 times higher for the RFC gauge than for the NT gauge (0.025–0.093 and 0.014–0.026 cm 3 cm‐3 for RFC and NT gauges, respectively). These results support continued use of NT gauges for soil water monitoring in access tubes at undisturbed arid sites. (author)

  3. The soil water balance in a mosaic of clumped vegetation

    Science.gov (United States)

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

    2014-05-01

    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

  4. Sudbury soils study : industry perspective

    International Nuclear Information System (INIS)

    Watson, G.

    2009-01-01

    This presentation presented the industry perspective of a soils study conducted by Vale Inco to assess the risk of mining activities in the Sudbury region to human health and the environment. The study was comprised of extensive soil collection and analysis; a review of historical soils data; and extensive human health and ecological risk assessments. Extensive sampling was also conducted on air, dust, and locally-produced foods. The human health risk assessment (HHRA) study was conducted and administered by a multi-stakeholder technical committee attended by the public. A public advisory committee was also formed by Vale Inco to disseminate scientific information to the community. Scientific data obtained in the study were also peer-reviewed by an independent expert review panel comprised of leading specialists in human health, toxicology, speciation, and risk assessment. The study showed that the identified risks were over-estimated in the interest of protecting human health. The study demonstrated to the mining company that multi-stakeholder risk assessments with community involvement are expensive and time-consuming. Risk assessment methods and standard practices are conservative, and may determine risks that aren't always attributable to the proponent. It was concluded that risk assessment progress and results must be clearly and frequently communicated with the public. The presentation emphasized that companies must take time to listen to the public and consider the priorities of communities in the region. tabs., figs

  5. Water retention and availability in soils of the State of Santa Catarina-Brazil: effect of textural classes, soil classes and lithology

    Directory of Open Access Journals (Sweden)

    André da Costa

    2013-12-01

    Full Text Available The retention and availability of water in the soil vary according to the soil characteristics and determine plant growth. Thus, the aim of this study was to evaluate water retention and availability in the soils of the State of Santa Catarina, Brazil, according to the textural class, soil class and lithology. The surface and subsurface horizons of 44 profiles were sampled in different regions of the State and different cover crops to determine field capacity, permanent wilting point, available water content, particle size, and organic matter content. Water retention and availability between the horizons were compared in a mixed model, considering the textural classes, the soil classes and lithology as fixed factors and profiles as random factors. It may be concluded that water retention is greater in silty or clayey soils and that the organic matter content is higher, especially in Humic Cambisols, Nitisols and Ferralsol developed from igneous or sedimentary rocks. Water availability is greater in loam-textured soils, with high organic matter content, especially in soils of humic character. It is lower in the sandy texture class, especially in Arenosols formed from recent alluvial deposits or in gravelly soils derived from granite. The greater water availability in the surface horizons, with more organic matter than in the subsurface layers, illustrates the importance of organic matter for water retention and availability.

  6. Plant-available soil water capacity: estimation methods and implications

    Directory of Open Access Journals (Sweden)

    Bruno Montoani Silva

    2014-04-01

    Full Text Available The plant-available water capacity of the soil is defined as the water content between field capacity and wilting point, and has wide practical application in planning the land use. In a representative profile of the Cerrado Oxisol, methods for estimating the wilting point were studied and compared, using a WP4-T psychrometer and Richards chamber for undisturbed and disturbed samples. In addition, the field capacity was estimated by the water content at 6, 10, 33 kPa and by the inflection point of the water retention curve, calculated by the van Genuchten and cubic polynomial models. We found that the field capacity moisture determined at the inflection point was higher than by the other methods, and that even at the inflection point the estimates differed, according to the model used. By the WP4-T psychrometer, the water content was significantly lower found the estimate of the permanent wilting point. We concluded that the estimation of the available water holding capacity is markedly influenced by the estimation methods, which has to be taken into consideration because of the practical importance of this parameter.

  7. Predicting Soil-Air and Soil-Water Transport Properties During Soil Vapor Extraction

    DEFF Research Database (Denmark)

    Poulsen, Tjalfe

    designing and operating remediation systems. Simple and accurate models for estimating soil properties from soil parameters that are easy to measure are useful in connection with preliminary remedial investigations and evaluation of remedial technologies. In this work simple models for predicting transport...... properties of undisturbed soil from more easily measurable soil properties are developed. The importance of soil properties with respect to contaminant migration during remediation by soil vapor extraction (SVE) in the unsaturated zone was investigated using numerical simulations....

  8. Effects of Biochar on Adsorption Characteristics of Water-soluble Fluorine in Tea Garden Soil

    Directory of Open Access Journals (Sweden)

    SUN Yong-hong

    2017-06-01

    Full Text Available The adsorption characteristics of water-soluble fluoride with application of biochar in tea garden soil was studied by indoor culture test. The results showed that the adsorption quantity and adsorption rate of water-soluble fluorine decreased gradually with the increase of biochar amounts in tea garden soil. The isothermal adsorption of Langmuir equation, Freundlich equation and Temkin equation could be better used to describe the adsorption law of water-soluble fluorine, and the Freundlich equation had the best fitting curve. With the increase of biochar content of soil, the net amount of fluoride adsorption reduced gradually. The adsorption kinetics of fluoride in soil was characterized by fast adsorption and slow reaction stages. The equilibrium time was less than 120 min for the rapid increase of adsorption, 0.25% and 0.50% biomass carbon content treatments of the soil reached to equilibrium after 1 440 min. The results of theoretic calculation were in good agreement with experimental adsorption quantity by dual constant equation, Elovich equation and first order kinetics equation, which could accurately describe the adsorption process of water-soluble fluorine in soil with biochar. The increase of soil pH with the addition of biochar was closely related to the decrease of maximum adsorption quantity, adsorption intensity and net adsorption quantity of water-soluble fluorine in tea garden soil.

  9. Effects of biochar, waste water irrigation and fertilization on soil properties in West African urban agriculture.

    Science.gov (United States)

    Häring, Volker; Manka'abusi, Delphine; Akoto-Danso, Edmund K; Werner, Steffen; Atiah, Kofi; Steiner, Christoph; Lompo, Désiré J P; Adiku, Samuel; Buerkert, Andreas; Marschner, Bernd

    2017-09-06

    In large areas of sub-Saharan Africa crop production must cope with low soil fertility. To increase soil fertility, the application of biochar (charred biomass) has been suggested. In urban areas, untreated waste water is widely used for irrigation because it is a nutrient-rich year-round water source. Uncertainty exists regarding the interactions between soil properties, biochar, waste water and fertilization over time. The aims of this study were to determine these interactions in two typical sandy, soil organic carbon (SOC) and nutrient depleted soils under urban vegetable production in Tamale (Ghana) and Ouagadougou (Burkina Faso) over two years. The addition of biochar at 2 kg m -2 made from rice husks and corn cobs initially doubled SOC stocks but SOC losses of 35% occurred thereafter. Both biochar types had no effect on soil pH, phosphorous availability and effective cation exchange capacity (CEC) but rice husk biochar retained nitrogen (N). Irrigation with domestic waste water increased soil pH and exchangeable sodium over time. Inorganic fertilization alone acidified soils, increased available phosphorous and decreased base saturation. Organic fertilization increased SOC, N and CEC. The results from both locations demonstrate that the effects of biochar and waste water were less pronounced than reported elsewhere.

  10. Dynamic soil water repellency during infiltration of water, ethanol, and aqueous ethanol solutions in post wildfire soils

    Science.gov (United States)

    Beatty, Sarah; Smith, James

    2015-04-01

    Contact angle dynamics, the temporal dependence of repellency, and the persistence of repellency are all terms used to describe dynamic changes in soil water repellency with time. Studied over varied spatial and temporal scales, much remains to be known about dynamic soil water repellency and its role during infiltration. Of those approaches used to characterize dynamic soil water repellency and develop mechanistic insight, tension infiltration has become an important one. Removing positive pore water pressures through tension infiltration facilitates the observation of infiltration initiated by capillary pull and experimentally eliminates one of the competing mechanisms that generates non-uniqueness. This makes tension infiltrometers and the data they generate uniquely sensitive to (primary) changes in contact angles and fractional wettability. Changes, which are subsumed when positive pore water pressures are the primary drivers of infiltration, as is the case during ponded infiltration in water repellent soils. One pressing challenge, however, is that analytical approaches, based on idealized wettable-system principles (e.g. 0° and/or static contact angles), yield suspect results in non-wetting / fractionally wettable / dynamic systems. Consequently, complex infiltration behaviours, and linkages between fundamental process oriented understanding and real-world problems, remain poorly understood. This persistently impedes our ability to accurately describe, model, and predict flow in water repellent systems. To help address this knowledge gap, this work presents suites of in situ field (3D) and laboratory (1D) experimental data collected in naturally repellent post wildfire soils using tension infiltrometers (4.4cm and 8cm, respectively) and different infiltrating fluids. In the field, 49 infiltration tests using water, ethanol (95%), and Molarity of Ethanol Drop (MED)-derived aqueous ethanol solutions indicated that early- and late-time infiltration behaviours

  11. Pollution Status of Pakistan: A Retrospective Review on Heavy Metal Contamination of Water, Soil, and Vegetables

    Directory of Open Access Journals (Sweden)

    Amir Waseem

    2014-01-01

    Full Text Available Trace heavy metals, such as arsenic, cadmium, lead, chromium, nickel, and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. In addition to these metals, copper, manganese, iron, and zinc are also important trace micronutrients. The presence of trace heavy metals in the atmosphere, soil, and water can cause serious problems to all organisms, and the ubiquitous bioavailability of these heavy metal can result in bioaccumulation in the food chain which especially can be highly dangerous to human health. This study reviews the heavy metal contamination in several areas of Pakistan over the past few years, particularly to assess the heavy metal contamination in water (ground water, surface water, and waste water, soil, sediments, particulate matter, and vegetables. The listed contaminations affect the drinking water quality, ecological environment, and food chain. Moreover, the toxicity induced by contaminated water, soil, and vegetables poses serious threat to human health.

  12. Pollution status of Pakistan: a retrospective review on heavy metal contamination of water, soil, and vegetables.

    Science.gov (United States)

    Waseem, Amir; Arshad, Jahanzaib; Iqbal, Farhat; Sajjad, Ashif; Mehmood, Zahid; Murtaza, Ghulam

    2014-01-01

    Trace heavy metals, such as arsenic, cadmium, lead, chromium, nickel, and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. In addition to these metals, copper, manganese, iron, and zinc are also important trace micronutrients. The presence of trace heavy metals in the atmosphere, soil, and water can cause serious problems to all organisms, and the ubiquitous bioavailability of these heavy metal can result in bioaccumulation in the food chain which especially can be highly dangerous to human health. This study reviews the heavy metal contamination in several areas of Pakistan over the past few years, particularly to assess the heavy metal contamination in water (ground water, surface water, and waste water), soil, sediments, particulate matter, and vegetables. The listed contaminations affect the drinking water quality, ecological environment, and food chain. Moreover, the toxicity induced by contaminated water, soil, and vegetables poses serious threat to human health.

  13. Development of soil water regime under spruce stands

    Directory of Open Access Journals (Sweden)

    Tužinský Ladislav

    2017-06-01

    Full Text Available The aim of this paper is to analyse the water regime of soils under spruce ecosystems in relation to long-lasting humid and drought periods in the growing seasons 1991-2013. The dominant interval humidity in observing growing seasons is semiuvidic interval with soil moisture between hydro-limits maximal capillary capacity (MCC and point of diminished availability (PDA. Gravitationally seepage concentrated from accumulated winter season, water from melting snow and existing atmospheric precipitation occurs in the soil only at the beginning of the growing season. The supplies of soil water are significantly decreasing in the warm climate and precipitant deficient days. The greatest danger from drought threatens Norway spruce during the summer months and it depends on the duration of dry days, water supply at the beginning of the dry days, air temperature and the intensity of evapotranspiration. In the surface layers of the soil, with the maximum occurrence of active roots, the water in semiarid interval area between hydro-limits PDA and wilting point (WP decreases during the summer months. In the culminating phase occurs the drying to moisture state with capillary stationary and the insufficient supply of available water for the plants. Physiological weakening of Norway spruce caused by set of outlay components of the water balance is partially reduced by delivering of water by capillary action from deeper horizons. In extremely dry periods, soil moisture is decreasing also throughout the soil profile (0-100 cm into the bottom third of the variation margin hydro-limits MCC-PDA in the category of capillary less moving and for plants of low supply of usable water (60-90 mm. The issue of deteriorated health state of spruce ecosystems is considered to be actual. Changes and developments of hydropedological conditions which interfere the mountain forests represent the increasing danger of the drought for the spruce.

  14. Modeling of Soil Water and Salt Dynamics and Its Effects on Root Water Uptake in Heihe Arid Wetland, Gansu, China

    Directory of Open Access Journals (Sweden)

    Huijie Li

    2015-05-01

    Full Text Available In the Heihe River basin, China, increased salinity and water shortages present serious threats to the sustainability of arid wetlands. It is critical to understand the interactions between soil water and salts (from saline shallow groundwater and the river and their effects on plant growth under the influence of shallow groundwater and irrigation. In this study, the Hydrus-1D model was used in an arid wetland of the Middle Heihe River to investigate the effects of the dynamics of soil water, soil salinization, and depth to water table (DWT as well as groundwater salinity on Chinese tamarisk root water uptake. The modeled soil water and electrical conductivity of soil solution (ECsw are in good agreement with the observations, as indicated by RMSE values (0.031 and 0.046 cm3·cm−3 for soil water content, 0.037 and 0.035 dS·m−1 for ECsw, during the model calibration and validation periods, respectively. The calibrated model was used in scenario analyses considering different DWTs, salinity levels and the introduction of preseason irrigation. The results showed that (I Chinese tamarisk root distribution was greatly affected by soil water and salt distribution in the soil profile, with about 73.8% of the roots being distributed in the 20–60 cm layer; (II root water uptake accounted for 91.0% of the potential maximal value when water stress was considered, and for 41.6% when both water and salt stress were considered; (III root water uptake was very sensitive to fluctuations of the water table, and was greatly reduced when the DWT was either dropped or raised 60% of the 2012 reference depth; (IV arid wetland vegetation exhibited a high level of groundwater dependence even though shallow groundwater resulted in increased soil salinization and (V preseason irrigation could effectively increase root water uptake by leaching salts from the root zone. We concluded that a suitable water table and groundwater salinity coupled with proper irrigation

  15. Grey water treatment by the slanted soil system with unsorted soil media.

    Science.gov (United States)

    Ushijima, Ken; Tanaka, Erina; Suzuki, Laís Yuko; Hijikata, Nowaki; Funamizu, Naoyuki; Ito, Ryusei

    2015-01-01

    This study evaluated the performance of unsorted soil media in the slanted soil treatment system, in terms of removal efficiency in suspended solids (SS), chemical oxygen demand (COD), linear alkylbenzene sulphonate (LAS) and Escherichia coli, and lifetime until clogging occurs. Unsorted soil performed longer lifetime until clogging than sorted fine soil. Removal of SS, COD, and LAS also performed same or better level in unsorted soil than fine soil. As reaction coefficients of COD and LAS were described as a function of the hydraulic loading rate, we can design a slanted soil system according to the expected hydraulic loading rate and the targeted level of COD or LAS in effluent. Regarding bacteria removal, unsorted soil performed sufficient reduction of E. coli for 5 weeks; however, the removal process occurred throughout all four chambers, while that of fine soil occurred in one to two chambers.

  16. Genotypic Diversity of Escherichia coli in the Water and Soil of Tropical Watersheds in Hawaii ▿

    Science.gov (United States)

    Goto, Dustin K.; Yan, Tao

    2011-01-01

    High levels of Escherichia coli were frequently detected in tropical soils in Hawaii, which present important environmental sources of E. coli to water bodies. This study systematically examined E. coli isolates from water and soil of several watersheds in Hawaii and observed high overall genotypic diversity (35.5% unique genotypes). In the Manoa watershed, fewer than 9.3% of the observed E. coli genotypes in water and 6.6% in soil were shared between different sampling sites, suggesting the lack of dominant fecal sources in the watershed. High temporal variability of E. coli genotypes in soil was also observed, which suggests a dynamic E. coli population corresponding with the frequently observed high concentrations in tropical soils. When E. coli genotypes detected from the same sampling events were compared, limited sharing between the soil and water samples was observed in the majority of comparisons (73.5%). However, several comparisons reported up to 33.3% overlap of E. coli genotypes between soil and water, illustrating the potential for soil-water interactions under favorable environmental conditions. In addition, genotype accumulation curves for E. coli from water and soil indicated that the sampling efforts in the Manoa watershed could not exhaust the overall genotypic diversity. Comparisons of E. coli genotypes from other watersheds on Oahu, Hawaii, identified no apparent grouping according to sampling locations. The results of the present study demonstrate the complexity of using E. coli as a fecal indicator bacterium in tropical watersheds and highlight the need to differentiate environmental sources of E. coli from fecal sources in water quality monitoring. PMID:21515724

  17. Infiltration and redistribution of water in soils

    International Nuclear Information System (INIS)

    Stroosnijder, L.

    1976-01-01

    The flow of the liquid phase through a soil can be predicted from pressure gradients. Different ways of predicting infiltration for irrigation of a basin were compared: numerical approximation; semi-analytical and analytical. A partly empirical equation was developed for description of rate of infiltration, after examination of existing equations. Under certain conditions, infiltration was influenced by under or over pressure of the trapped gas phase and by swelling of clays. Complex models for redistribution were of little value in practice, since they could not be generalized and required too many physical data about the soil. A scheme was developed that grouped techniques for estimating physical properties of soil, according to cost and expertise required. A new experimental technique based on gamma transmission is described for estimating the physical properties of the soil. (Auth.)

  18. Modeling of soil-water-structure interaction

    DEFF Research Database (Denmark)

    Tang, Tian

    to dynamic ocean waves. The goal of this research project is to develop numerical soil models for computing realistic seabed response in the interacting offshore environment, where ocean waves, seabed and offshore structure highly interact with each other. The seabed soil models developed are based...... as the developed nonlinear soil displacements and stresses under monotonic and cyclic loading. With the FVM nonlinear coupled soil models as a basis, multiphysics modeling of wave-seabed-structure interaction is carried out. The computations are done in an open source code environment, OpenFOAM, where FVM models...... of Computational Fluid Dynamics (CFD) and structural mechanics are available. The interaction in the system is modeled in a 1-way manner: First detailed free surface CFD calculations are executed to obtain a realistic wave field around a given structure. Then the dynamic structural response, due to the motions...

  19. An index for plant water deficit based on root-weighted soil water content

    Science.gov (United States)

    Shi, Jianchu; Li, Sen; Zuo, Qiang; Ben-Gal, Alon

    2015-03-01

    Governed by atmospheric demand, soil water conditions and plant characteristics, plant water status is dynamic, complex, and fundamental to efficient agricultural water management. To explore a centralized signal for the evaluation of plant water status based on soil water status, two greenhouse experiments investigating the effect of the relative distribution between soil water and roots on wheat and rice were conducted. Due to the significant offset between the distributions of soil water and roots, wheat receiving subsurface irrigation suffered more from drought than wheat under surface irrigation, even when the arithmetic averaged soil water content (SWC) in the root zone was higher. A significant relationship was found between the plant water deficit index (PWDI) and the root-weighted (rather than the arithmetic) average SWC over root zone. The traditional soil-based approach for the estimation of PWDI was improved by replacing the arithmetic averaged SWC with the root-weighted SWC to take the effect of the relative distribution between soil water and roots into consideration. These results should be beneficial for scheduling irrigation, as well as for evaluating plant water consumption and root density profile.

  20. EFFECT OF SOIL WATER POTENTIAL ON TRANSPIRATION RATE IN CUCUMBER PLANTS

    OpenAIRE

    Cho, Tosio; Eguchi, Hiromi; Kuroda, Masaharu; Tanaka, Akira; Koutaki, Masahiro; Ng, Ah Lek; Matsui, Tsuyoshi

    1985-01-01

    In an attempt to examine the effect of soil water potential (pF) on transpiration rate, leaf temperature of cucumber plants was measured under various conditions of soil water potential, and transpiration rate was calculated from heat balance of the leaf. Transpiration rate decreased with reduction in soil water potential; transpiration rate dropped at soil water potentials lower than pF 3.0. This fact suggests that the reduction in soil water potential restricts water uptake in roots and cau...

  1. Characterization of Soil-Water Retention with Coarse Fragments in ...

    African Journals Online (AJOL)

    The presence of coarse fragments can have profound impact on soil moisture retention characteristics. The study was conducted to assess the effects of coarse fragments on the moisture retention characteristics of 16 soil series, developed over five different parent materials in the Densu basin. Soil profiles were excavated ...

  2. Fingerlike wetting patterns in two water-repellent loam soils

    NARCIS (Netherlands)

    Dekker, L.W.; Ritsema, C.J.

    1995-01-01

    In soils with fingered flow, surface-applied solutes can reach the groundwater more rapidly than in the case of homogeneous wetting. This study was undertaken to demonstrate the occurrence of finger-like wetting patterns in a silt loam soil and a silty clay loam soil, and to investigate the

  3. Soil water dynamics and evapotranspiration of forage cactus clones under rainfed conditions

    Directory of Open Access Journals (Sweden)

    Thieres George Freire da Silva

    2015-07-01

    Full Text Available Abstract: The objective of this work was to evaluate soil water dynamics in areas cultivated with forage cactus clones and to determine how environmental conditions and crop growth affect evapotranspiration. The study was conducted in the municipality of Serra Talhada, in the state of Pernambuco, Brazil. Crop growth was monitored through changes in the cladode area index (CAI and through the soil cover fraction, calculated at the end of the cycle. Real evapotranspiration (ET of the three evaluated clones was obtained as the residual term in the soil water balance method. No difference was observed between soil water balance components, even though the evaluated clones were of different genus and had different CAI increments. Accumulated ET was of 1,173 mm during the 499 days of the experiment, resulting in daily average of 2.35 mm. The CAI increases the water consumption of the Orelha de Elefante Mexicana clone. In dry conditions, the water consumption of the Miúda clone responds more slowly to variation in soil water availability. The lower evolution of the CAI of the IPA Sertânia clone, during the rainy season, leads to a higher contribution of the evaporation component in ET. The atmospheric demand controls the ET of clones only when there is higher soil water availability; in this condition, the water consumption of the Miúda clone decreases more rapidly with the increase of atmospheric demand.

  4. Functional digital soil mapping for the prediction of available water capacity in Nigeria using legacy data

    NARCIS (Netherlands)

    Ugbaje, S.U.; Reuter, H.I.

    2013-01-01

    Soil information, particularly water storage capacity, is of utmost importance for assessing and managing land resources for sustainable land management. We investigated using digital soil mapping (DSM) and digital soil functional mapping (DSFM) procedures to predict available water capacity (AWC)

  5. The soil sulphate effect and maize plant (Zea mays L.) growth of sulphate reducing bacteria (SRB) inoculation in acid sulfate soils with the different soil water condition

    Science.gov (United States)

    Asmarlaili, S.; Rauf, A.; Hanafiah, D. S.; Sudarno, Y.; Abdi, P.

    2018-02-01

    The objective of the study was to determine the potential application of sulphate reducing bacteria on acid sulfate soil with different water content in the green house. The research was carried out in the Laboratory and Green House, Faculty of Agriculture, Universitas Sumatera Utara. This research used Randomized Block Design with two treatments factors, ie sulphate reducing bacteria (SRB) isolate (control, LK4, LK6, TSM4, TSM3, AP4, AP3, LK4 + TSM3, LK4 + AP4, LK4 + AP3, LK6 + TSM3, LK6 + AP4, LK6 + AP3, TSM4 + TSM3, TSM4 + AP4, TSM4 + AP3) and water condition (100% field capacity and 110% field capacity). The results showed that application of isolate LK4 + AP4 with water condition 110% field capacity decreased the soil sulphate content (27.38 ppm) significantly after 6 weeks. Application of isolate LK4 + AP3 with water condition 110% field capacity increased soil pH (5.58) after-week efficacy 6. Application of isolate LK4 with water condition 110% field capacity increased plant growth (140 cm; 25.74 g) significantly after week 6. The best treatment was application isolate LK4 with water condition 110% field Capacity (SRB population 2.5x108; soil sulphate content 29.10ppm; soil acidity 4.78; plant height 140cm; plant weight 25.74g).

  6. Effects of waste water irrigation on soil properties and soil fauna of spinach fields in a West African urban vegetable production system.

    Science.gov (United States)

    Stenchly, Kathrin; Dao, Juliane; Lompo, Désiré Jean-Pascal; Buerkert, Andreas

    2017-03-01

    The usage of inadequately processed industrial waste water (WW) can lead to strong soil alkalinity and soil salinization of agricultural fields with negative consequences on soil properties and biota. Gypsum as a soil amendment to saline-sodic soils is widely used in agricultural fields to improve their soil physical, chemical and hence biological properties. This study aimed at analysing the effects of intensive WW irrigation on the structure and composition of soil-dwelling arthropods on spinach fields (Spinacia oleracea L.) in a West African urban vegetable production system. We used gypsum as a soil amendment with the potential to alleviate soil chemical stress resulting in a potentially positive impact on soil arthropods. A total of 32 plots were established that showed a gradient in soil pH ranging from slight to strong soil alkalinity and that were irrigated with WW (n = 12) or clean water (CW; n = 20), including eight plots into which gypsum was incorporated. Our study revealed a high tolerance of soil-dwelling arthropods for alkaline soils, but spinach fields with increased soil electrical conductivity (EC) showed a reduced abundance of Hymenoptera, Diptera and Auchenorrhyncha. Arthropod abundance was positively related to a dense spinach cover that in turn was not affected by WW irrigation or soil properties. Gypsum application reduced soil pH but increased soil EC. WW irrigation and related soil pH affected arthropod composition in the investigated spinach fields which may lead to negative effects on agronomical important arthropod groups such as pollinators and predators. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Gonzales, Christopher; Baumgartl, Thomas; Scheuermann, Alexander

    2014-05-01

    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

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

    Science.gov (United States)

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

    2014-02-01

    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

  9. Multitracer studies for determining seepage water and anion movement in four types of soil using lysimeters with different functions and designs; Multitracer-Untersuchungen zur Bestimmung der Sickerwasser- und Anionenbewegung in vier Bodenformen bei Lysimetern unterschiedlicher Nutzung und Bauart

    Energy Technology Data Exchange (ETDEWEB)

    Knappe, S.; Russow, R. [UFZ - Umweltforschungszentrum Leipzig-Halle GmbH, Bad Lauchstaedt (Germany). Sektion Bodenforschung; Seeger, J. [Lysimeterstation Falkenberg (Germany)

    1999-02-01

    Lysimeter experiments based on the stable isotope tracer technique are a suitable means of examining the complex relationships governing water and material transport processes in the soil. The present paper reports on experiments in which water and nitrate movement was traced directly by means of lysimeters placed at different depths and using deuterium water and [{sup 15}N]N-nitrate for pulse marking. Extensive investigations carried out during the dissection of soil monoliths that had been used for many years in lysimeters offered an opportunity for stable isotope tracer studies aimed at determining seepage water and anion movement in undisturbed soils and, after dismantling the lysimeters, conducting soil analyses to find out more about the fate of nonpercolated tracers at various soil depths. Following other authors, bromide anions were additionally used as conservative tracers. [Deutsch] Zur Untersuchung der komplexen Zusammenhaenge des Wasser- und Stofftransportes im Boden bieten sich Lysimeterversuche unter Nutzung der stabilisotopen Tracertechnik an. In der vorliegenden Arbeit wird zunaechst ueber die direkte Verfolgung der Wasser- und Nitrat-Bewegung in tiefengestaffelten Lysimetern durch Pulsmarkierung mit Deuteriumwasser und [{sup 15}N]Nitrat berichtet. Im Rahmen von umfangreichen Untersuchungen bei der Zerlegung von langjaehrig in Lysimetern genutzten Bodenmonolithen bestand des weiteren die Moeglichkeit, stabilisotope Traceruntersuchungen zur Bestimmung der Sickerwasser- und Anionenbewegung an ungestoerten Boeden durchzufuehren und nach der Zerlegung der Lysimeter ueber entsprechende Analysen des Bodens Aussagen zum Verbleib der nicht perkolierten Tracer in verschiedenen Bodentiefen zu treffen. Zusaetzlich wurde dabei das von anderen Autoren bereits genutzte Bromid-Anion als sogenannter konservativer Tracer eingesetzt. (orig.)

  10. Dynamics of Soil Water Evaporation during Soil Drying: Laboratory Experiment and Numerical Analysis

    OpenAIRE

    Jiangbo Han; Zhifang Zhou

    2013-01-01

    Laboratory and numerical experiments were conducted to investigate the evolution of soil water evaporation during a continuous drying event. Simulated soil water contents and temperatures by the calibrated model well reproduced measured values at different depths. Results show that the evaporative drying process could be divided into three stages, beginning with a relatively high evaporation rate during stage 1, followed by a lower rate during transient stage and stage 2, and finally maintain...

  11. Study on speciation of rare earth elements in soil

    International Nuclear Information System (INIS)

    Wang Yuqi; Sun Jingxin; Chen Hongmin; Guo Fanqing; Wang Lijun; Zhang Shen

    1996-01-01

    The contents of rare earth elements (REE) in red soil, yellow brown soil and leached chernozem are studied. After extracted sequentially, REE in these soils are fractionated into seven forms, i.e., (I) water soluble, (II) exchangeable, (III) loosely bound to organic mater, (IV) bound to carbonate and specifically absorbed, (V) bound to Fe-Mn oxides, (VI) tightly bound to organic matter and (VII) residual forms. The contents of REE in every form are determined by NAA (neutron activation analysis). The results show that REE in soils mainly exist in residual form and REE in soluble forms are very limited (<7%)

  12. Fire and grazing effects on wind erosion, soil water content, and soil temperature.

    Science.gov (United States)

    Vermeire, Lance T; Wester, David B; Mitchell, Robert B; Fuhlendorf, Samuel D

    2005-01-01

    Selective grazing of burned patches can be intense if animal distribution is not controlled and may compound the independent effects of fire and grazing on soil characteristics. Our objectives were to quantify the effects of patch burning and grazing on wind erosion, soil water content, and soil temperature in sand sagebrush (Artemisia filifolia Torr.) mixed prairie. We selected 24, 4-ha plots near Woodward, OK. Four plots were burned during autumn (mid-November) and four during spring (mid-April), and four served as nonburned controls for each of two years. Cattle were given unrestricted access (April-September) to burned patches (erosion, soil water content, and soil temperature were measured monthly. Wind erosion varied by burn, year, and sampling height. Wind erosion was about 2 to 48 times greater on autumn-burned plots than nonburned plots during the dormant period (December-April). Growing-season (April-August) erosion was greatest during spring. Erosion of spring-burned sites was double that of nonburned sites both years. Growing-season erosion from autumn-burned sites was similar to nonburned sites except for one year with a dry April-May. Soil water content was unaffected by patch burn treatments. Soils of burned plots were 1 to 3 degrees C warmer than those of nonburned plots, based on mid-day measurements. Lower water holding and deep percolation capacity of sandy soils probably moderated effects on soil water content and soil temperature. Despite poor growing conditions following fire and heavy selective grazing of burned patches, no blowouts or drifts were observed.

  13. Impacts of thinning of a Mediterranean oak forest on soil properties influencing water infiltration

    Directory of Open Access Journals (Sweden)

    Di Prima Simone

    2017-09-01

    Full Text Available In Mediterranean ecosystems, special attention needs to be paid to forest–water relationships due to water scarcity. In this context, Adaptive Forest Management (AFM has the objective to establish how forest resources have to be managed with regards to the efficient use of water, which needs maintaining healthy soil properties even after disturbance. The main objective of this investigation was to understand the effect of one of the AFM methods, namely forest thinning, on soil hydraulic properties. At this aim, soil hydraulic characterization was performed on two contiguous Mediterranean oak forest plots, one of them thinned to reduce the forest density from 861 to 414 tree per ha. Three years after the intervention, thinning had not affected soil water permeability of the studied plots. Both ponding and tension infiltration runs yielded not significantly different saturated, Ks, and unsaturated, K−20, hydraulic conductivity values at the thinned and control plots. Therefore, thinning had no an adverse effect on vertical water fluxes at the soil surface. Mean Ks values estimated with the ponded ring infiltrometer were two orders of magnitude higher than K−20 values estimated with the minidisk infiltrometer, revealing probably soil structure with macropores and fractures. The input of hydrophobic organic matter, as a consequence of the addition of plant residues after the thinning treatment, resulted in slight differences in terms of both water drop penetration time, WDPT, and the index of water repellency, R, between thinned and control plots. Soil water repellency only affected unsaturated soil hydraulic conductivity measurements. Moreover, K−20 values showed a negative correlation with both WDPT and R, whereas Ks values did not, revealing that the soil hydrophobic behavior has no impact on saturated hydraulic conductivity.

  14. Contribution of macroporosity to water flux of a soil under different tillage systems

    Directory of Open Access Journals (Sweden)

    Carlos Germán Soracco

    2012-08-01

    Full Text Available In view of the importance of the macroporosity for the water transport properties of soils, its quantitative assessment is a challenging task. Measurements of hydraulic conductivity (K at different soil water tensions and the quantification of water-conducting macropores (θM of a soil under different tillage systems could help understand the effects on the soil porous system and related hydraulic properties. The purpose of this study was to assess the effects of Conventional Tillage (CT, Chisel Plow (CP and No Tillage (NT on θM and on K; and to quantify the contribution of macroporosity to total water flux in a loam soil. A tension disc infiltrometer was used at two soil water pressure heads (-5 cm, and 0 to infer θM and K, during fallow. Macroporosity was determined based on the flow contribution between 0 and -5 cm water potentials (K0, K5, respectively, according to the Hagen-Poiseuille equation. The K0 values were statistically higher for CT than for NT and CP. The K5 values did not differ statistically among treatments. The mean K values varied between 0.20 and 3.70 cm/h. For CT, θM was significantly greater than for CP and NT, following the same trend as K0. No differences in θM were detected between CP and NT. With CT, the formation of water-conducting macropores with persistence until post-harvest was possible, while under CP preparation, the water-conducting macropores were not persistent. These results support the idea that tillage affects the soil water movement mainly by the resulting water-conducting macropores. Future studies on tillage effects on water movement should focus on macroporosity.

  15. Estimation of root water uptake parameters by inverse modeling with soil water content data

    NARCIS (Netherlands)

    Hupet, F.; Lambot, S.; Feddes, R.A.; Dam, van J.C.; Vanclooster, M.

    2003-01-01

    In this paper we have tested the feasibility of the inverse modeling approach to derive root water uptake parameters (RWUP) from soil water content data using numerical experiments for three differently textured soils and for an optimal drying period. The RWUP of interest are the rooting depth and

  16. Connecting carbon and nitrogen storage in rural wetland soil to groundwater abstraction for urban water supply.

    Science.gov (United States)

    Lewis, David Bruce; Feit, Sharon J

    2015-04-01

    We investigated whether groundwater abstraction for urban water supply diminishes the storage of carbon (C), nitrogen (N), and organic matter in the soil of rural wetlands. Wetland soil organic matter (SOM) benefits air and water quality by sequestering large masses of C and N. Yet, the accumulation of wetland SOM depends on soil inundation, so we hypothesized that groundwater abstraction would diminish stocks of SOM, C, and N in wetland soils. Predictions of this hypothesis were tested in two types of subtropical, depressional-basin wetland: forested swamps and herbaceous-vegetation marshes. In west-central Florida, >650 ML groundwater day(-1) are abstracted for use primarily in the Tampa Bay metropolis. At higher abstraction volumes, water tables were lower and wetlands had shorter hydroperiods (less time inundated). In turn, wetlands with shorter hydroperiods had 50-60% less SOM, C, and N per kg soil. In swamps, SOM loss caused soil bulk density to double, so areal soil C and N storage per m(2) through 30.5 cm depth was diminished by 25-30% in short-hydroperiod swamps. In herbaceous-vegetation marshes, short hydroperiods caused a sharper decline in N than in C. Soil organic matter, C, and N pools were not correlated with soil texture or with wetland draining-reflooding frequency. Many years of shortened hydroperiod were probably required to diminish soil organic matter, C, and N pools by the magnitudes we observed. This diminution might have occurred decades ago, but could be maintained contemporarily by the failure each year of chronically drained soils to retain new organic matter inputs. In sum, our study attributes the contraction of hydroperiod and loss of soil organic matter, C, and N from rural wetlands to groundwater abstraction performed largely for urban water supply, revealing teleconnections between rural ecosystem change and urban resource demand. © 2014 John Wiley & Sons Ltd.

  17. Landscape scale assessment of soil and water salinization processes in agricultural coastal area.

    Science.gov (United States)

    Elen Bless, Aplena; Follain, Stéphane; Coiln, François; Crabit, Armand

    2017-04-01

    Soil salinization is among main land degradation process around the globe. It reduces soil quality, disturbs soil function, and has harmful impacts on plant growth that would threaten agricultural sustainability, particularly in coastal areas where mostly susceptible on land degradation because of pressure from anthropogenic activities and at the same time need to preserve soil quality for supporting food production. In this presentation, we present a landscape scale analysis aiming to assess salinization process affecting wine production. This study was carried out at Serignan estuary delta in South of France (Languadoc Roussillon Region, 43˚ 28'N and 3˚ 31'E). It is a sedimentary basin near coastline of Mediterranean Sea. Field survey was design to characterize both space and time variability of soil and water salinity through water electrical conductivity (ECw) and soil 1/5 electrical conductivity (EC1/5). For water measurements, Orb River and groundwater salinity (piezometers) were determined and for soil 1737 samples were randomly collected from different soil depths (20, 50, 80, and 120 cm) between year 2012 and 2016 and measured. In order to connect with agricultural practices observations and interviews with farmers were conducted. We found that some areas combining specific criteria presents higher electrical conductivity: positions with lower elevation (a.s.l), Cambisols (Calcaric) / Fluvisols soil type (WRB) and dominated clay textures. These observations combined with geochemical determination and spatial analysis confirm our first hypothesis of sea salt intrusion as the main driven factor of soil salinity in this region. In this context, identification of salinization process, fine determination of pedological specificities and fine understanding of agricultural practices allowed us to proposed adaptation strategies to restore soil production function. Please fill in your abstract text. Key Words: Salinity, Coastal Agriculture, Landscape, Soil, Water

  18. A global validation of the ASCAT Soil Water Index (SWI) with in situ data from the International Soil Moisture Network.

    Science.gov (United States)

    Paulik, C.; Naeimi, V.; Dorigo, W.; Wagner, W.; Kidd, R.

    2012-04-01

    Soil Moisture is an Essential Climate Variable and a key parameter in hydrology, meteorology and agriculture. Surface Soil Moisture (SSM) can be estimated from measurements taken by ASCAT onboard Metop-A and have been successfully validated by several studies (C. Albergel et.al. 2009 and 2012, M.Parrens et.al. 2012). Profile soil moisture, while equally important, can not be measured directly by remote sensing. The near real-time Soil Water Index (SWI) product, developed within the framework of the GMES project geoland2 aims to close this gap. It is produced from ASCAT SSM estimates using a two-layer water balance model which describes the relationship between surface and profile soil moisture as a function of time. It provides daily global data about moisture conditions for 8 characteristic time lengths representing different depths. The objective of this work was to assess the quality of the SWI data for different measurement depths. SWI data from January 1st 2007 until the end of 2010 was compared to in situ soil moisture data from 420 stations belonging to 22 observation networks which are available through the International Soil Moisture Network. These stations delivered 1331 station/depth combinations which were compared to the SWI values. After excluding observations made during frozen conditions the average significant correlation coefficients were 0.564 (min -0.684, max 0.955) while being greater than 0.3 for 88% of all station/depth combinations.

  19. The dependence of water potential in shoots of Picea abies on air and soil water status

    Directory of Open Access Journals (Sweden)

    A. Sellin

    Full Text Available Where there is sufficient water storage in the soil the water potential (Ψx in shoots of Norway spruce [Picea abies (L. Karst.] is strongly governed by the vapour pressure deficit of the atmosphere, while the mean minimum values of Ψx usually do not drop below –1.5 MPa under meteorological conditions in Estonia. If the base water potential (Ψb is above –0.62 MPa, the principal factor causing water deficiency in shoots of P. abies may be either limited soil water reserves or atmospheric evaporative demand depending on the current level of the vapour pressure deficit. As the soil dries the stomatal control becomes more efficient in preventing water losses from the foliage, and the leaf water status, in turn, less sensitive to atmospheric demand. Under drought conditions, if Ψb falls below –0.62 MPa, the trees' water stress is mainly caused by low soil water availability. Further declines in the shoot water potential (below –1.5 MPa can be attributed primarily to further decreases in the soil water, i.e. to the static water stress.Key words. Hydrology (evapotranspiration · plant ecology · soil moisture.

  20. Determination of soil parameters during the water horizontal infiltration and redistribution by gamma ray attenuation method and tensiometry

    International Nuclear Information System (INIS)

    Oliveira, J.C.M. de.

    1991-04-01

    The present work studies the water diffusivity and hydraulic conductivity in a Latossolo Roxo distrofico soil, during the water infiltration and redistribution processes. Variation water flow equations were utilized for the calculations. The data of wetting front positions and of soil water content profiles were obtained through the gamma ray attenuation from a 241-Am source, with 100 mCi activity detected by a standard electronic equipment of gamma spectrometry, with NaI CTD scintillation detector. From the soil water content data in function of space and time and from analytic models, the properties of soil water diffusivity and soil hydraulic conductivity were determined in the laboratory for the 0-10 cm and 10-25 soil layers. (author)

  1. The effects of Fire Disturbance on Soil Water Cycling of a Southeast Amazonian Forest

    Science.gov (United States)

    Santos, C.; Coe, M. T.; Trumbore, S.; Lefebvre, P.; Silverio, D. V.; Macedo, M.; Brando, P. M.

    2014-12-01

    Fire disturbances can reduce the capacity of tropical forests to cycle water from the soil to the atmosphere, but our understanding of this process remains poor. To address this gap, we studied the effects of fire-related changes in vegetation structure and dynamics on soil water cycling of a transitional forest located between Amazônia and Cerrado, Mato Grosso, Brazil. In particular, we measured monthly soil moisture (from 1 to 9 m depth) using seven soil water pits that were distributed across three 50-ha plots: a plot that represented an unburned control; a plot that was burned in 2004, 2007 and 2010; and, a plot that was burned annually from 2004 to 2010, with exception of 2008. Measurements of soil moisture began after the experimental fires of 2010 (in mid September) and continued until December 2013. We hypothesized that soil moisture would be higher in the burned plots than in the control due to fire-induced reductions in evapotranspiration. Our preliminary results provide only partial support for this hypothesis. We observed a high variability in soil moisture between treatments, among months, and across years. For example, the unburned control tended to hold more soil water throughout the soil profile in wet-season months. However, soil moisture tended to be higher in the experimentally burned plots during the driest months of the year (August and September), but this pattern was no consistant across drought and non-drought years. These results show that fires exert complex influences on the soil water cycling of this transitional forest, perhaps even promoting increased evapotranspiration in the burned plots due to reduced competition among trees for resources.

  2. Influence of drainage status on soil and water chemistry, litter decomposition and soil respiration in central Amazonian forests on sandy soils

    Directory of Open Access Journals (Sweden)

    Antônio Ocimar Manzi

    2011-04-01

    Full Text Available Central Amazonian rainforest landscape supports a mosaic of tall terra firme rainforest and ecotone campinarana, riparian and campina forests, reflecting topography-induced variations in soil, nutrient and drainage conditions. Spatial and temporal variations in litter decomposition, soil and groundwater chemistry and soil CO2 respiration were studied in forests on sandy soils, whereas drought sensitivity of poorly-drained valley soils was investigated in an artificial drainage experiment. Slightly changes in litter decomposition or water chemistry were observed as a consequence of artificial drainage. Riparian plots did experience higher litter decomposition rates than campina forest. In response to a permanent lowering of the groundwater level from 0.1 m to 0.3 m depth in the drainage plot, topsoil carbon and nitrogen contents decreased substantially. Soil CO2 respiration decreased from 3.7±0.6 µmol m-2 s-1 before drainage to 2.5±0.2 and 0.8±0.1 µmol m-2 s-1 eight and 11 months after drainage, respectively. Soil respiration in the control plot remained constant at 3.7±0.6 µmol m-2 s-1. The above suggests that more frequent droughts may affect topsoil carbon and nitrogen content and soil respiration rates in the riparian ecosystem, and may induce a transition to less diverse campinarana or short-statured campina forest that covers areas with strongly-leached sandy soil.

  3. Fate and transport of the β-adrenergic agonist ractopamine hydrochloride in soil-water systems.

    Science.gov (United States)

    Hakk, Heldur; Shelver, Weilin L; Casey, Francis X M

    2016-07-01

    The feed additive ractopamine hydrochloride was fortified at four concentrations into batch vials containing soils that differed in both biological activity and organic matter (OM). Sampling of the liquid layer for 14days demonstrated that ractopamine rapidly dissipated from the liquid layer. Less than 20% of the fortified dose remained in the liquid layer after 4hr, and recoveries of dosed ractopamine ranged from 8 to 18% in the liquid layer at 336hr. Sorption to soil was the major fate for ractopamine in soil:water systems, i.e., 42%-51% of the dose at 14days. The major portion of the sorbed fraction was comprised of non-extractables; a smaller fraction of the sorbed dose was extracted into water and acetone, portions which would be potentially mobile in the environment. Partitioning coefficients for all soils suggested strong sorption of ractopamine to soil which is governed by hydrophobic interactions and cation exchange complexes within the soil OM. Ractopamine degradation was observed, but to mostly non-polar compounds which had a higher potential than ractopamine to sorb to soil. The formation of volatiles was also suggested. Therefore, despite rapid and extensive soil sorption, these studies indicated a portion of ractopamine, present in manures used to fertilize soils, may be mobile in the environment via water-borne events. Copyright © 2016. Published by Elsevier B.V.

  4. Decreased DOC concentrations in soil water in forested areas in southern Sweden during 1987-2008.

    Science.gov (United States)

    Löfgren, Stefan; Zetterberg, Therese

    2011-04-15

    During the last two decades, there is a common trend of increasing concentrations of dissolved organic carbon (DOC) in streams and lakes in Europe, Canada and the US. Different processes have been proposed to explain this trend and recently a unifying hypothesis was presented, concluding that declining sulphur deposition and recovery from acidification, is the single most important factor for the long-term DOC concentration trends in surface waters. If this recovery hypothesis is correct, the soil water DOC concentrations should increase as well. However, long-term soil water data from Sweden and Norway indicate that there are either decreasing or indifferent DOC concentrations, while positive DOC trends have been found in the Czech Republic. Based on the soil water data from two Swedish integrated monitoring sites and geochemical modelling, it has been shown that depending on changes in pH, ionic strength and soil Al pools, the DOC solubility might be positive, negative or indifferent. In this study, we test the acidification recovery hypothesis on long-term soil water data (25 and 50cm soil depth) from 68 forest covered sites in southern Sweden, showing clear signs of recovery from acidification. The main aim was to identify potential drivers for the DOC solubility in soil solution by comparing trends in DOC concentrations with observed changes in pH, ionic strength and concentrations of Al(n+). As in earlier Swedish and Norwegian studies, the DOC concentrations in soil water decreased or showed no trend. The generally small increases in pH (median <0.3 pH units) during the investigation period seem to be counterbalanced by the reduced ionic strength and diminished Al concentrations, increasing the organic matter coagulation. Hence, opposite to the conclusion for surface waters, the solubility of organic matter seems to decrease in uphill soils, as a result of the acidification recovery. Copyright © 2011 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2014-05-01

    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

  6. Selected soil properties as indicators of soil water regime in the ...

    African Journals Online (AJOL)

    The morphological features and physicochemical properties of 14 soil profiles, representing the major soil types, were studied in the Cathedral Peak VI catchment of KwaZulu-Natal, South Africa. The soils are characterised by a high organic carbon content in the topsoil, red and yellow freely drained subsoils, and some ...

  7. Available water and the orange trees growth on soils of a toposequence of the Reconcavo Baiano

    International Nuclear Information System (INIS)

    Paiva, Arlicelio de Queiroz; Souza, Luciano da Silva; Ribeiro, Antonio Carlos; Costa, Liovando Marciano da; Santana, Marlete Bastos

    1997-01-01

    Aiming the study of the influence of available water in soils, at different depths, on the orange trees growth, the present work was carried out on a toposequence located at the Sapeacu-BA-Brazil municipality, with 190 m length and 0.097 mm -1 declivity. Due to the declivity and soils variations, the area was divided into three sectors with different constitutions. Weekly basis measurements of the soil water content have been performed, in the period of Dec 18, 1995 - Dec 18, 1996, at different depths, by using a neutron probe. The water considered as available was the stored water in the soil, at different depths, less the volumetric humidity under the -1,500 kPa

  8. Water and chloride transport in a fine-textured soil in a feedlot pen

    Science.gov (United States)

    Veizaga, E. A.; Rodríguez, L.; Ocampo, C. J.

    2015-11-01

    Cattle feeding in feedlot pens produces large amounts of manure and animal urine. Manure solutions resulting from surface runoff are composed of numerous chemical constituents whose leaching causes salinization of the soil profile. There is a relatively large number of studies on preferential flow characterization and modeling in clayed soils. However, research on water flow and solute transport derived from cattle feeding operations in fine-textured soils under naturally occurring precipitation events is less frequent. A field monitoring and modeling investigation was conducted at two plots on a fine-textured soil near a feedlot pen in Argentina to assess the potential of solute leaching into the soil profile. Soil pressure head and chloride concentration of the soil solution were used in combination with HYDRUS-1D numerical model to simulate water flow and chloride transport resorting to the concept of mobile/immobile-MIM water for solute transport. Pressure head sensors located at different depths registered a rapid response to precipitation suggesting the occurrence of preferential flow-paths for infiltrating water. Cracks and small fissures were documented at the field site where the % silt and % clay combined is around 94%. Chloride content increased with depth for various soil pressure head conditions, although a dilution process was observed as precipitation increased. The MIM approach improved numerical results at one of the tested sites where the development of cracks and macropores is likely, obtaining a more dynamic response in comparison with the advection-dispersion equation.

  9. Salinity controls on plant transpiration and soil water balance

    Science.gov (United States)

    Perri, S.; Molini, A.; Suweis, S. S.; Viola, F.; Entekhabi, D.

    2017-12-01

    Soil salinization and aridification represent a major threat for the food security and sustainable development of drylands. The two problems are deeply connected, and their interplay is expected to be further enhanced by climate change and projected population growth. Salt-affected land is currently estimated to cover around 1.1 Gha, and is particularly widespread in semi-arid to hyper-arid climates. Over 900 Mha of these saline/sodic soils are potentially available for crop or biomass production. Salt-tolerant plants have been recently proposed as valid solution to exploit or even remediate salinized soils. However the effects of salinity on evapotranspiration, soil water balance and the long-term salt mass balance in the soil, are still largely unexplored. In this contribution we analyze the feedback of evapotranspiration on soil salinization, with particular emphasis on the role of vegetation and plant salt-tolerance. The goal is to introduce a simple modeling framework able to shed some light on how (a) soil salinity controls plant transpiration, and (b) salinization itself is favored/impeded by different vegetation feedback. We introduce at this goal a spatially lumped stochastic model of soil moisture and salt mass dynamics averaged over the active soil depth, and accounting for the effect of salinity on evapotranspiration. Here, the limiting effect of salinity on ET is modeled through a simple plant response function depending on both salt concentration in the soil and plant salt-tolerance. The coupled soil moisture and salt mass balance is hence used to obtain the conditional steady-state probability density function (pdf) of soil moisture for given salt tolerance and salinization level, Our results show that salinity imposes a limit in the soil water balance and this limit depends on plant salt-tolerance mainly through the control of the leaching occurrence (tolerant plants exploit water more efficiently than the sensitive ones). We also analyzed the

  10. Partitioning of hydrophobic pesticides within a soil-water-anionic surfactant system.

    Science.gov (United States)

    Wang, Peng; Keller, Arturo A

    2009-02-01

    Surfactants can be added to pesticide-contaminated soils to enhance the treatment efficiency of soil washing. Our results showed that pesticide (atrazine and diuron) partitioning and desorbability within a soil-water-anionic surfactant system is soil particle-size dependent and is significantly influenced by the presence of anionic surfactant. Anionic surfactant (linear alkylbenzene sulphonate, LAS) sorption was influenced by its complexation with both the soluble and exchangeable divalent cations in soils (e.g. Ca2+, Mg2+). In this study, we propose a new concept: soil system hardness which defines the total amount of soluble and exchangeable divalent cations associated with a soil. Our results showed that anionic surfactant works better with soils having lower soil system hardness. It was also found that the hydrophobic organic compounds (HOCs) sorbed onto the LAS-divalent cation precipitate, resulting in a significant decrease in the aqueous concentration of HOC. Our results showed that the effect of exchangeable cations and sorption of HOC onto the surfactant precipitates needs to be considered to accurately predict HOC behavior within soil-water-anionic surfactant systems.

  11. An improved effective microorganism (EM) soil ball-making method for water quality restoration.

    Science.gov (United States)

    Park, Gun-Seok; Khan, Abdur Rahim; Kwak, Yunyoung; Hong, Sung-Jun; Jung, ByungKwon; Ullah, Ihsan; Kim, Jong-Guk; Shin, Jae-Ho

    2016-01-01

    Soil balls containing the so-called effective microorganisms (EM) have been applied to improve water quality of small ponds, lakes, and streams worldwide. However, neither the physical conditions facilitating their proper application nor the diversity of microbial community in such soil balls have been investigated. In this study, the application of 0.75% of hardener to the soil balls exerted almost neutral pH (pH 7.3) which caused up to a fourfold increased hardness of the soil ball. Moreover, the 0.75% of hardener in the soil ball also improved the water quality due to a significant reduction in dissolved oxygen, total phosphorus, and total nitrogen contents. Metagenomic analysis of the microbial community in the soil ball with 0.75% hardener was compared with control (traditional soil ball) through next-generation sequencing. The traditional soil ball microbial community comprised 96.1% bacteria, 2.7% eukaryota, and 1% archaea, whereas the soil ball with 0.75% hardener comprised 71.4% bacteria, 27.9% eukaryota, and 0.2% viruses. Additionally, metagenomic profiles for both traditional and improved soil balls revealed that the various xenobiotic biodegradation, such as those for caprolactam, atrazine, xylene, toluene, styrene, bisphenol, and chlorocyclohexane might be responsible for organic waste cleanup.

  12. Correction of resistance to penetration by pedofunctions and a reference soil water content

    Directory of Open Access Journals (Sweden)

    Moacir Tuzzin de Moraes

    2012-12-01

    Full Text Available The soil penetration resistance is an important indicator of soil compaction and is strongly influenced by soil water content. The objective of this study was to develop mathematical models to normalize soil penetration resistance (SPR, using a reference value of gravimetric soil water content (U. For this purpose, SPR was determined with an impact penetrometer, in an experiment on a Dystroferric Red Latossol (Rhodic Eutrudox, at six levels of soil compaction, induced by mechanical chiseling and additional compaction by the traffic of a harvester (four, eight, 10, and 20 passes; in addition to a control treatment under no-tillage, without chiseling or additional compaction. To broaden the range of U values, SPR was evaluated in different periods. Undisturbed soil cores were sampled to quantify the soil bulk density (BD. Pedotransfer functions were generated correlating the values of U and BD to the SPR values. By these functions, the SPR was adequately corrected for all U and BD data ranges. The method requires only SPR and U as input variables in the models. However, different pedofunctions are needed according to the soil layer evaluated. After adjusting the pedotransfer functions, the differences in the soil compaction levels among the treatments, previously masked by variations of U, became detectable.

  13. Assessing HYDRUS-2D model to estimate soil water contents and olive tree transpiration fluxes under different water distribution systems

    Science.gov (United States)

    Autovino, Dario; Negm, Amro; Rallo, Giovanni; Provenzano, Giuseppe

    2016-04-01

    comparison between measured and simulated soil water content and actual transpiration fluxes, under the hypothesis to neglect the contribute of the tree capacitance. Moreover, two different crop water stress functions and in particular the linear model proposed by Feddes et al. (1978) and the S-shape model suggested by van Genuchten et al. (1987), were considered. The result of the study evidenced that for the investigated crop and under the examined conditions, HYDRUS-2D model reproduces fairly well the dynamic of soil water contents at different distances from the emitters (RMSEOlive tree, HYDRUS-2D, Soil water content, Actual transpiration fluxes

  14. Rock outcrops redistribute water to nearby soil patches in karst landscapes.

    Science.gov (United States)

    Wang, Dian-Jie; Shen, You-Xin; Huang, Jin; Li, Yu-Hui

    2016-05-01

    The emergence of rock outcrops is very common in terrestrial ecosystems. However, few studies have paid attention to their hydrological role in the redistribution of precipitation, especially in karst ecosystems, in which a large proportion of the surface is occupied by carbonate outcrops. We collected and measured water received by outcrops and its subsequent export to the soil in a rock desertification ecosystem, an anthropogenic forest ecosystem, and a secondary forest ecosystem in Shilin, China. The results indicated that outcrops received a large amount of water and delivered nearly half of it to nearby soil patches by means of runoff. No significant difference was found in the ratio of water received to that exported to the soil by outcrops among the three ecosystems annually. When the outcrop area reaches 70 % of the ground surface, the amount of water received by soil patches from rock runoff will equal that received by precipitation, which means that the soil is exposed to twice as much precipitation. This quantity of water can increase water input to nearby soil patches and create water content heterogeneity among areas with differing rock emergence.

  15. Water management impacts rice methylmercury and the soil microbiome.

    Science.gov (United States)

    Rothenberg, Sarah E; Anders, Merle; Ajami, Nadim J; Petrosino, Joseph F; Balogh, Erika

    2016-12-01

    Rice farmers are pressured to grow rice using less water. The impacts of water-saving rice cultivation methods on rice methylmercury concentrations are uncertain. Rice (Oryza sativa L. cv. Nipponbare) was cultivated in fields using four water management treatments, including flooded (no dry-downs), alternating wetting and drying (AWD) (with one or three dry-downs), and furrow-irrigated fields (nine dry-downs) (n=16 fields). Anoxic bulk soil was collected from rice roots during the rice maturation phase, and rice grain was harvested after fields were dried. Total mercury and methylmercury concentrations were determined in soil and polished rice samples, and the soil microbiome was analyzed using 16S (v4) rRNA gene profiling. Soil total mercury did not differ between fields. However, compared to continuously flooded fields, soil and rice methylmercury concentrations averaged 51% and 38% lower in the AWD fields, respectively, and 95% and 96% lower in the furrow-irrigated fields, respectively. Compared to flooded fields, grain yield was reduced on average by soil and rice methylmercury and specific soil microbiomes. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Associations between soil texture, soil water characteristics and earthworm populations of grassland

    DEFF Research Database (Denmark)

    Holmstrup, Martin; Lamandé, Mathieu; Torp, Søren Bent

    2011-01-01

    The aim of the present study was to investigate the relationships between soil physical characteristics and earthworms in a regional-scale field study in Denmark. The earthworm populations along within-field gradients in soil texture were quantified at five field sites, representing dominant soil...... types of Denmark. Eleven earthworm species were found, but populations were mainly dominated by Aporrectodea tuberculata and A. longa. Despite considerable variation in soil parameters across the five study sites the results suggest that the biomass of anecic worms (or A. longa as a species......) was not causally associated with the soil parameters studied. This indicates that there must be other causal factors associated with the abundance (and composition) of anecic worms that are not among the soil texture and structure parameters studied. On the other hand, soil texture (Coarse sand) was associated...

  17. Soil water characteristics of Middle Pleistocene paleosol layers on ...

    African Journals Online (AJOL)

    Administrator

    2011-09-14

    Sep 14, 2011 ... to hold water and this was related to their soil structures and porosities. These differences could be due to the different conditions prevailing during their formation. Although, paleosols occur at various depths, certain deep-rooting plants can access the water they hold. Therefore, the SWCC of the individual ...

  18. Condensation of water vapour on moss-dominated biological soil ...

    Indian Academy of Sciences (India)

    mean temperature was negatively linearly related to amounts of water vapour condensation for both soil surfaces. The amount of water vapour condensation on BSC and dune sand can be described by the difference between air temperature and dew point with an exponential function, indicating that when the difference of ...

  19. Quantification of the Impact of Integrated Soil and Water ...

    African Journals Online (AJOL)

    The paper tries to evaluate the impact of integrated soil and water conservation measures on water availability in Mendae catchment (10.37 km2), which is located in the northeastern Tigray. Historical background of the catchment with respect to its land use was obtained from the local Bureau of Agriculture and Rural ...

  20. Retrieval of Soil Water Content in Saline Soils from Emitted Thermal Infrared Spectra Using Partial Linear Squares Regression

    Directory of Open Access Journals (Sweden)

    Lu Xu

    2015-11-01

    Full Text Available Timely information of soil water content is urgently required for monitoring ecosystem processes and functions at various scales. Although remote sensing has already provided many practical applications of retrieving soil moisture, it is largely limited to visible/near infrared or microwave domains and few studies have ever been conducted on the thermal infrared. In addition, soil salinization in arid land further complicates the situation when retrieving soil moisture from emitted spectra. In this study, we attempt to fill the knowledge gap by retrieving the soil moisture of saline soils with various salt contents. This was based on lab-controlled experiments for spectroscopy using a Fourier Transform Spectrometer (2–16 µm. Partial least squares regression (PLSR has been applied in analyses based on either original measured or first-order derivative spectra. The results revealed that the PLSR model using first-order derivative spectra, which had a determination coefficient (R2 of 0.71 and a root mean square error (RMSE of 3.3%, should be recommended for soil moisture estimation, judged from several statistical criteria. As thermal infrared wavelengths identified in this study are contained in several current available satellite sensors, the PLSR models should have great potential for large-scale application despite extensive validations are needed in future studies.

  1. Analytical reliability analysis of soil-water characteristic curve

    Directory of Open Access Journals (Sweden)

    Johari A.

    2016-01-01

    Full Text Available The Soil Water Characteristic Curve (SWCC, also known as the soil water-retention curve, is an important part of any constitutive relationship for unsaturated soils. Deterministic assessment of SWCC has received considerable attention in the past few years. However the uncertainties of the parameters which affect SWCC dictate that the problem is of a probabilistic nature rather than being deterministic. In this research, a Gene Expression Programming (GEP-based SWCC model is employed to assess the reliability of SWCC. For this purpose, the Jointly Distributed Random Variables (JDRV method is used as an analytical method for reliability analysis. All input parameters of the model which are initial void ratio, initial water content, silt and clay contents are set to be stochastic and modelled using truncated normal probability density functions. The results are compared with those of the Monte Carlo (MC simulation. It is shown that the initial water content is the most effective parameter in SWCC.

  2. [Effects of soil covering on solar greenhouse pepper water use efficiency and soil nitrate N and available phosphorus contents].

    Science.gov (United States)

    Zhou, Mao-juan; Liang, Yin-li; Chen, Jia-rui; Xiong, Ya-mei; Wei, Ze-xiu

    2007-06-01

    A greenhouse study on the effects of soil covering on pepper (Capsicum anmuum L.) water use efficiency and soil nitrate and available phosphorus contents showed that straw mulch + plastic film mulch could get the highest pepper yield water use efficiency (33.04 kg . m(-3)) and economic water use efficiency (50.22 yuan . m(-3)), followed by plastic film mulch, with the two parameters being 18.81 kg . m(-3) and 28.57 yuan . m(-3), respectively. Significant differences of nitrate N content in 0-20 cm soil layer were observed among different treatments. The control had the highest nitrate N content (50.33 mg . kg(-1)), followed by straw mulch (31.98 mg . kg(-1)) and straw + plastic film mulch (31.96 mg . kg(-1)), and plastic film mulch and applying water preserving agent. Compared with the control, soil covering could increase the nitrate N use efficiency of pepper, and decrease the accumulation of nitrate N in plough layer. In 0-20 cm soil layer, treatment plastic film mulch had the lowest available phosphorus content (0.72 mg . kg(-3)), and the second (0. 92 mg . kg(-1)) was the treatment straw + plastic film mulch. Treatments straw + plastic film mulch and plastic film mulch could increase pepper fruit yield and fertilizer use efficiency, and decrease fertilizer loss.

  3. Can control of soil erosion mitigate water pollution by sediments?

    Science.gov (United States)

    Rickson, R J

    2014-01-15

    The detrimental impact of sediment and associated pollutants on water quality is widely acknowledged, with many watercourses in the UK failing to meet the standard of 'good ecological status'. Catchment sediment budgets show that hill slope erosion processes can be significant sources of waterborne sediment, with rates of erosion likely to increase given predicted future weather patterns. However, linking on-site erosion rates with off-site impacts is complicated because of the limited data on soil erosion rates in the UK and the dynamic nature of the source-pathway-receptor continuum over space and time. Even so, soil erosion control measures are designed to reduce sediment production (source) and mobilisation/transport (pathway) on hill slopes, with consequent mitigation of pollution incidents in watercourses (receptors). The purpose of this paper is to review the scientific evidence of the effectiveness of erosion control measures used in the UK to reduce sediment loads of hill slope origin in watercourses. Although over 73 soil erosion mitigation measures have been identified from the literature, empirical data on erosion control effectiveness are limited. Baseline comparisons for the 18 measures where data do exist reveal erosion control effectiveness is highly variable over time and between study locations. Given the limitations of the evidence base in terms of geographical coverage and duration of monitoring, performance of the different measures cannot be extrapolated to other areas. This uncertainty in effectiveness has implications for implementing erosion/sediment risk reduction policies, where quantified targets are stipulated, as is the case in the EU Freshwater Fish and draft Soil Framework Directives. Also, demonstrating technical effectiveness of erosion control measures alone will not encourage uptake by land managers: quantifying the costs and benefits of adopting erosion mitigation is equally important, but these are uncertain and difficult to

  4. Statement on the Tianshui Experimental Site of Soil and Water Conservation in 1940s

    OpenAIRE

    YANG, Hongwei

    2013-01-01

    The Tianshui Experimental Site of Soil and Water Conservation was set up in 1942. Then the first construction broadcasted the thinking of soil and water conservation, and popularized the technologies of soil and water conservation and related plants. Their efforts established the foundation of the science of soil and water conservation with the first high-tech and high quality R&D team, and pushed the research of soil and water conservation building on the stage of systematization. All of thi...

  5. Activated soil filters for removal of biocides from contaminated run-off and waste-waters

    DEFF Research Database (Denmark)

    Bester, Kai; Banzhaf, Stefan; Burkhardt, Michael

    2011-01-01

    Building facades can be equipped with biocides to prevent formation of algal, fungal and bacterial films. Thus run-off waters may contain these highly active compounds. In this study, the removal of several groups of biocides from contaminated waters by means of an activated soil filter was studied...

  6. Soil, Groundwater, Surface Water, and Sediments of Kennedy Space Center, Florida: Background Chemical and Physical Characteristics

    Science.gov (United States)

    Shmalzer, Paul A.; Hensley, Melissa A.; Mota, Mario; Hall, Carlton R.; Dunlevy, Colleen A.

    2000-01-01

    This study documented background chemical composition of soils, groundwater, surface; water, and sediments of Kennedy Space Center. Two hundred soil samples were collected, 20 each in 10 soil classes. Fifty-one groundwater wells were installed in 4 subaquifers of the Surficial Aquifer and sampled; there were 24 shallow, 16 intermediate, and 11 deep wells. Forty surface water and sediment samples were collected in major watershed basins. All samples were away from sites of known contamination. Samples were analyzed for organochlorine pesticides, aroclors, chlorinated herbicides, polycyclic aromatic hydrocarbons (PAH), total metals, and other parameters. All aroclors (6) were below detection in all media. Some organochlorine pesticides were detected at very low frequencies in soil, sediment, and surface water. Chlorinated herbicides were detected at very low frequencies in soil and sediments. PAH occurred in low frequencies in soiL, shallow groundwater, surface water, and sediments. Concentrations of some metals differed among soil classes, with subaquifers and depths, and among watershed basins for surface water but not sediments. Most of the variation in metal concentrations was natural, but agriculture had increased Cr, Cu, Mn, and Zn.

  7. Structure-Dependent Water-Induced Linear Reduction Model for Predicting Gas Diffusivity and Tortuosity in Repacked and Intact Soil

    DEFF Research Database (Denmark)

    Møldrup, Per; Chamindu, Deepagoda; Hamamoto, Shoichiro

    2013-01-01

    but also on the local-scale variability of these. Different predictive models have been developed to estimate Dp in intact and repacked soil, but clear guidelines for model choice at a given soil state are lacking. In this study, the water-induced linear reduction (WLR) model for repacked soil is made...

  8. Mulch tillage for conserving soil water

    Science.gov (United States)

    Mulching is the practice of maintaining organic or inorganic materials on or applying them to the soil surface. It is an ancient practice, but through the years clean tillage that incorporated crop residues and also controlled weeds became the norm. Frequent and deep tillage often was promoted to co...

  9. Atrazine, triketone herbicides, and their degradation products in sediment, soil and surface water samples in Poland.

    Science.gov (United States)

    Barchanska, Hanna; Sajdak, Marcin; Szczypka, Kornelia; Swientek, Angelika; Tworek, Martyna; Kurek, Magdalena

    2017-01-01

    The aim of this study was to monitor the sediment, soil and surface water contamination with selected popular triketone herbicides (mesotrione (MES) and sulcotrione(SUL)), atrazine (ATR) classified as a possible carcinogen and endocrine disrupting chemical, as well as their degradation products, in Silesia (Poland). Seventeen sediment samples, 24 soil samples, and 64 surface water samples collected in 2014 were studied. After solid-liquid extraction (SLE) and solid phase extraction (SPE), analytes were determined by high-performance liquid chromatography (HPLC) with diode array detection (DAD). Ten years after the withdrawal from the use, ATR was not detected in any of the collected samples; however, its degradation products are still present in 41 % of sediment, 71 % of soil, and 8 % of surface water samples. SUL was determined in 85 % of soil samples; its degradation product (2-chloro-4-(methylosulfonyl) benzoic acid (CMBA)) was present in 43 % of soil samples. In 17 % of sediment samples, CMBA was detected. Triketones were detected occasionally in surface water samples. The chemometric analysis (clustering analysis (CA), single-factor analysis of variance (ANOVA), N-Way ANOVA) was applied to find relations between selected soil and sediment parameters and herbicides concentration. In neither of the studied cases a statistically significant relationship between the concentrations of examined herbicides, their degradation products and soil parameters (organic carbon (OC), pH) was observed.

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

    Science.gov (United States)

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

    2009-04-01

    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

  11. Changes in soil aggregate stability under different irrigation doses of waste water

    Science.gov (United States)

    Morugán, Alicia; García-Orenes, Fuensanta; Mataix-Solera, Jorge; Arcenegui, Victoria; Bárcenas, Gema

    2010-05-01

    Freshwater availability and soil degradation are two of the most important environmental problems in the Mediterranean area acerbated by incorrect agricultural use of irrigation in which organic matter is not correctly managed, the use of low quality water for irrigation, and the inefficiency of dose irrigation. For these reasons strategies for saving water and for the restoration of the mean properties of soil are necessary. The use of treated waste water for the irrigation of agricultural land could be a good solution to these problems, as it reduces the utilization of fresh water and could potentially improve key soil properties. In this work we have been studying, for more than three years, the effects on soil properties of different doses of irrigation with waste water. Here we show the results on aggregate stability. The study is located in an agricultural area at Biar (Alicante, SE of Spain), with a crop of grape (Vitis labrusca). Three types of waters are being used in the irrigation of the soil: fresh water (control) (TC), and treated waste water from secondary (T2) and tertiary treatment (T3). Three different doses of irrigation have been applied to fit the efficiency of the irrigation to the crop and soil type: D10 (10 L m-2 every week during 17 months), D50 (50 L m-2 every fifteen days during 14 moths) and D30 (30 L m-2 every week during 6 months up to present day). The results showed a clear decrease of aggregate stability during the period we used the second dose (D50) independent of the type of water used. That dose of irrigation and frequency produced strong wetting and drying cycles (WD) in the soil, and this is suspected to be the main factor responsible for the results. When we changed the dose of irrigation to D30, reducing the quantity per event and increasing the frequency, the soil aggregate stability started to improve. This dose avoids strong drying periods between irrigation events and the aggregate stability is confirmed to be slowly

  12. Scaling Soil Microbe-Water Interactions from Pores to Ecosystems

    Science.gov (United States)

    Manzoni, S.; Katul, G. G.

    2014-12-01

    The spatial scales relevant to soil microbial activity are much finer than scales relevant to whole-ecosystem function and biogeochemical cycling. On the one hand, how to link such different scales and develop scale-aware biogeochemical and ecohydrological models remains a major challenge. On the other hand, resolving these linkages is becoming necessary for testing ecological hypotheses and resolving data-theory inconsistencies. Here, the relation between microbial respiration and soil moisture expressed in water potential is explored. Such relation mediates the water availability effects on ecosystem-level heterotrophic respiration and is of paramount importance for understanding CO2 emissions under increasingly variable rainfall regimes. Respiration has been shown to decline as the soil dries in a remarkably consistent way across climates and soil types (open triangles in Figure). Empirical models based on these respiration-moisture relations are routinely used in Earth System Models to predict moisture effects on ecosystem respiration. It has been hypothesized that this consistency in microbial respiration decline is due to breakage of water film continuity causing in turn solute diffusion limitations in dry conditions. However, this hypothesis appears to be at odds with what is known about soil hydraulic properties. Water film continuity estimated from soil water retention (SWR) measureme