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W188: Characterization of Flow and Transport Processes in Soils at Different Scales

Annual/Termination Reports (SAES-422): [04/12/2002] [04/15/2003] [03/15/2004]

Date of Annual Report: 04/12/2002

Report Information:
  • Annual Meeting Dates: 01/03/02 to 01/04/02
  • Period the Report Covers: 01/2001 to 12/2001

    • Participants:

    URL: Copy of participant list
    Brief Summary of Minutes of Annual Meeting:
    The minutes of the annual meeting and a complete
    copy of the annual report may be found on the W-188 website.


    URL: Copy of minutes

    Accomplishments:
    Objective 1: To study relationships between flow and transport properties or processes
    and the spatial and temporal scales at which these are observed.

    The CA-Riverside field investigation of preferential flow patterns during moisture redistribution matured in 2001 and using a combination of soil sampling and dye trace photography found confirmation of their hypothesis that unstable flow begins at the draining front only after the initiation of redistribution which is characterized by a series of flow fingers. University of Minnesota in collaboration with Cornell University, Kazan University (Russia), and Wageningen University (Netherlands) used an
    extended Richards equation (REE) applied to linear stability analysis for three flow models in unsaturated porous media. The wetting front for the REE model is conditionally stable (stable for high frequency perturbations and unstable otherwise). Results of this work leads to existence of a wave-number for maximum amplification which relates to the dimensions of fingers in unstable flow alluded to in the Riverside work. Other research at UC-R involved fate of pesticides on golf greens and other turfgrass ecosystems. An important outcome included findings that the fraction of trichlorfon nor chlorpyrifos insecticides lost to leaching, volatilization and clipping was insignificant (< .06% of applied). Outcomes of other research contributing to Objective 1 included:
    7 USDA-USSL studied transport of volatile organic chemicals and developed analytical solutions that describe gas movement in layered soil profiles and predict gas flux and concentration. USSL researchers studied the critical area of pathogen transport. They found that pathogen transport was highly dependent on parasite size and soil pore characteristics.
    7 USDA-USSL studies have found multidimensional transient water flow models are limited in their applicability because root water uptake is generally treated as one-dimensional. In 2001, researchers developed a very flexible two-dimensional root water uptake model that allows spatial variations of water uptake as influenced by both non-uniform (i.e. drip irrigation) and uniform water application patterns. Collaborative research between USDA-USSL, University of Nevada Reno, and the Desert Research Institute addressed the development of fully coupled flow and geochemical numerical solvers to predict infiltration in mine-altered lands in Nevada. Target contaminants include arsenic, cyanide, and sulfates. The results are reducing contamination and developing cost-effective closure designs for operating mines.
    7 UC-Davis studied flow or transport processes across a range of spatial and temporal scales. They concluded that new instrumentation was needed to overcome inherent problems of uncertainties when changing between scales and the nonlinear nature of flow and transport processes in vadose zone hydrology.
    7 Iowa State University in collaboration with the Lawrence Berkeley National Lab studied effects of low connectivity on imbibition and solute transport in rock matrices. As predicted by percolation theory, they found that imbibition in sparsely connected porespaces is proportional to time0.26 as compared to time0.5 for cumulative mass imbibition.
    7 Iowa State University improved accuracy of water flow and solute transport predictions by developing a simple flow method to estimate hydraulic properties. North Dakota State University is pursuing collaborative research involving MT, MN, and SD on precision agriculture to develop nutrient management zones. This work is funded by a grant from the REEUSDA Initiative for Future Agriculture and Food Sources.
    7 Washington State University and the University of Delaware completed a comprehensive review article on fate and transport of viruses in the environment.

    OBJECTIVE 2: To develop and evaluate instrumentation and methods of analysis for characterization of flow and transport at different scales

    University of Arizona investigated water redistribution of subsurface water using borehole ground penetrating radar (BGPR). They concluded this to be a promising new method for water content profiling that rivals neutron probe for depth and spatial resolution. Other significant accomplishments under this objective included:
    7 USDA-USSL developed a rapid and sensitive method to measure the permeability of new low-permeability films for used during soil fumigation. Combination of methodology and improved agricultural film covers will reduce fumigant emissions and increase efficacy of the pesticide.
    7 Tension infiltrometers are widely and successfully used to measure hydraulic properties in soil, but not in fractured rock media. USSL has developed a new instrument that appears to meet the requirement for fractured rock.
    7 USDA-USSL scientists studied the rate-dependence of unsaturated hydraulic characteristics using steady state and transient flow analysis. They found that water entrapment and pore blockage play a significant role in hydraulic conductivity at high flow rates. They also evaluated the computer program "Rosetta" that uses a number of pedotransfer functions for quicker and cheaper estimates of water retention and hydraulic conductivity. It is available for use by researchers and consultants at http://www.ussl.ars.usda.gov/MODELS/MODELS.HTM
    7 USSL research described non-equilibrium flow in soils that has implications for the accelerated movement of fertilizers, pesticides, non-aqueous liquids, and other pollutants. Their approach using laboratory soil cores fitted with tensiometers, combined a numerical solution of governing flow equation (using a modification of HYDRUS-1D) with a Marquardt-Levenberg optimization. Their analysis of flow response demonstrated significant non-equilibrium flow.
    7 Colorado State University developed a new continuous flow method that allows estimation of wetting/draining hydraulic conductivity and moisture retention functions over the entire range of plant available soil water. They determined the continuous flow method is ideally suited for evaluating fundamental problems is soil water flow such as temporal variation and spatial scaling of soil hydraulic properties. University of Idaho and Utah State University collaborated on analytical solutions for prediction of sample scale unsaturated hydraulic conductivity derived from pore-scale processes in matrix and structural pore domains.
    7 Iowa State University developed a method to measure subsurface water fluxes using a heat pulse sensor and a simpler mathematical relationship that replaces the cumbersome mathematical analysis previously required.
    7 Kansas State University determined that the dual-probe heat-pulse (DPHP) method could be used to measure near surface volumetric water content and that forced convection did not limit the function depending on DPHP configuration in the soil.
    7 Montana State University and Utah State University improved in situ measurements of soil hydraulic properties that increase accuracy and efficiency in soil and water management. North Dakota State University improved the design of the automated tension infiltrometers by installing a single differential transducer. Measurement precision was increased by two orders of magnitude. NDSU also developed a new method of describing soil water retention curves using a flexible smooth function.
    7 Washington State University and Decagon utilized freezing experiments in a new method to determine moisture characteristics in porous media. Network analyzer measurements were made to determine the dielectric properties of frozen porous media as a function of frequency and temperature. WSU also tested the use of dyes in the vadose zone to visualize flow pathways in soils.
    7 USDA-CPRL (Bushland, TX) is estimating hydraulic properties in soils using a disc infiltrometer and in situ measurements of infiltration. They found inverse optimization of parameter offers an economical means to infer soil hydraulic properties from in situ measurements. USDA-CPRL also found that soil layering affected this method of estimating hydraulic conductivity. USDA-CPRL has an ongoing comparison of soil moisture sensors at Bushland. In particular, they are evaluating alternatives to the neutron probe by testing the Sentek EnviroSCAN, Sentek Diviner 2000, Trime T3 tube probe, Delta-T Profiler, and a sheathed TDR probe with the neutron probe. It appears that site-specific calibration will be required for many of these and accuracy still may not approach the neutron probe.

    OBJECTIVE 3: To apply scale-appropriate methodologies for the management of soil and water resources.

    UC-Riverside conducted studies of total maximum daily loads (TMDLs) in agricultural and nursery operations in cooperation with private sector growers to focus on control of sediment movement from the fields during overhead irrigation. In another agricultural project, UC-Riverside found that application of polymers to improve soil physical conditions reduces soil erosion but also can influence adsorption of pesticides and their eventual movement through soil profiles. UC-Davis developed a two- and three-dimensional root uptake model and incorporated it into their flow model. The simulated and measured water content values resulted in R2 values of 0.94 to 0.99, the model is extremely flexible, and allows spatial variation of water uptake as influenced by uniform and non-uniform water application.
    USDA-ARS Colorado studied several management practices on soil-plant processes including furrow irrigation and N banding on plant growth and N leaching, evaporation and rain infiltration, reconsolidation on soil water storage, and wheel compaction on permeability, porosity, and water retention. Other research included:
    7 ARS-CO scientists have incorporated their research findings into the Root Zone Water Quality Model (RZWQM) which is now available for application.
    7 Iowa State and USDA Tilth Lab have collaborated on a number of studies related to crop yield and N management. Multiple discriminate analysis of corn yield in a 32 ha field using cluster analysis allowed deciphering of spatiotemporal patterns into four yield clusters. A second project found tillage-induced barriers or localized compaction and dome (LCD) show potential for reducing N use and nitrate leaching in the Corn Belt.
    7 Montana State University in collaboration with CSIRO Land and Water (Australia), evaluated the efficacy of deep drains in lowering shallow saline water tables to maintain suitable rooting zone conditions for wheat. This research will have significant implications for Montana crop-fallow rotations.
    MSU also studied soil water implication for invasive weed species and their capacity for utilizing deeper sources of moisture than native plant species.
    7 North Dakota State University is using a novel approach for predicting field scale solute transport. A mechanistic-stochastic model was used to predict field-scale solute concentrations by integrating all possible velocities in individual stream tubes. They verified the model using fluorinated benzoic acid tracers under field conditions.
    7 USDA-ARS and NDSU investigated transport of bioactive chemicals (i.e. antibiotics, hormones, etc.). They concluded hormones testosterone and estradiol were strongly adsorbed by soils and were transported by a colloidal mechanism, while sulfa-based antibiotics were very mobile indicating ion repulsion.

    Impact Statements:
    1. A major problem that recurs in soils, soil water, and ground water is describing flow and transport of solutes in a complex media with very large spatial and temporal variability. Researchers participating in W-188 have shown that developing an understanding of and management strategies for the unsaturated soil zone near the surface offers the best opportunity to prevent or at least limit pollution of groundwater by chemical and biological agents from agricultural and industrial sources.
    2. Surface runoff problems from commercial nurseries was partially solved using vegetation filter strips as a demonstration of Management Practices that minimize off-site movement of nutrients and other contaminants.
    3. The Root Zone Water Quality Model (RZWQM) was made available for application and has been used for crop growth, effects of management, and environmental impact under a variety of situations such as: Midwest and Colorado cropping systems, tile drainage in Iowa, basin irrigation, manure management in Colorado and Arkansas, and water stress responses in Colorado. A user-friendly interface is being marketed commercially.
    4. Turf professionals recognize that chemicals used to control turfgrass pests can be harmful to plants and animals that live in and around ponds, streams, and lakes surrounding golf courses. Studies by W-188 scientists demonstrated that, when applied according to label, trichlorfon and chlorpyrifos was not found to leach, volatilize, or be removed by clipping.
    5. W-188 research has contributed significantly to mining company's ability to meet regulatory bonding requirements. In NV, research addressing development of fully coupled flow and geochemical numerical solvers to predict infiltration in mine-altered lands and the fate of such contaminants as cyanide, arsenic, and sulfates. Results are reducing contamination and developing cost-effective closure designs for operating mines.
    Last Modified: unknown

    Date of Annual Report: 04/15/2003

    Report Information:
  • Annual Meeting Dates: 01/05/03 to 01/08/03
  • Period the Report Covers: 01/2002 to 12/2002

    • Participants:
    Brief Summary of Minutes of Annual Meeting:
    The minutes of the annual meeting and a complete copy of the annual report, including all 2002 publications, may be found on the W-188 website at: http://www.soilsci.ndsu.nodak.edu/w188

    Accomplishments:
    Objective 1: To study relationships between flow and transport properties or processes and the spatial and temporal scales at which these are observed. Accomplishments: UC-Davis studied flow or transport processes across a range of spatial and temporal scales. Various numerical studies demonstrated that scaling theory and inverse modeling can be applied in concert, whereby scale-appropriate and effective soil hydraulic functions were optimized. Field trials by UC-Riverside researchers included development of best management practices for nitrogen fertilization of turfgrass (a major source of urban contamination of ground water) to minimize leaching losses under irrigated conditions. . Other field research included 17 field trials over a range of soil series and textures investigated stability theory for predicting three dimensional flow distribution. Concerns for environmental contamination and public health led USDA-USSL scientists to study processes and mechanisms that affect pesticide emissions from fields via volatilization. A model was developed for methyl bromide that included chemical transport in the vapor phase. Outcomes show that combinations of plastic vapor barriers and soil amendments can be effective in reducing pesticide vapor emissions. USDA-USSL scientists studied release behavior of pathogens (oo cyst) from animal waste. Their conception model predicts pathogen numbers based on dissolved manure concentration, initial pathogen concentration, and release efficiency of pathogens. These models benefit the public and agricultural agencies by predicting potential pollution for farming operations. This research is needed to develop management criteria to control soil and water contamination. Other significant research under this objective included: USDA-USSL scientists demonstrated that fluid flow and chemical transport occurs regularly in the capillary fringe (CF) including both vertical and horizontal flow velocities. This work suggests that CF may be much more significant in influencing the natural geochemical and microbial conditions in the transition zone between unsaturated and saturated groundwater flow. USDA-ARS CO scientists investigated the relationship between spatial soil water and crop yields and within-field variability related to landscape attributes, finding that predictions of spatial patterns of crop yield in semi-arid regions from topographic information are a prerequisite for ongoing research to aid site-specific land management decisions. Delaware researchers studied soil characteristics such as organic matter (OM) and layered double hydroxides (LDH) effects on virus retention and transport. The collective results indicated that OM-virus interactions were dependent on the nature of the OM (i.e. electrostatic vs hydrophobic) and LDHs were effective sorbents under most environmental conditions. DE , WSU, and Pacific Northwest National Laboratory (PNNL) studied Cs transport as affected by soil colloids. Results indicated that under otherwise identical conditions, the efficiency of colloid-facilitated Cs transport was greater in contaminated than uncontaminated transport media. University of MN studies investigated unstable flow in water repellent soils. Research at the NV Desert Research Institute centered on groundwater contamination from large gold ore heap leach facilities. Large and small gravity-pan lysimeters were used to measure infiltration collection efficiency and found no difference due to pan size despite evidence that large fractions of macropore flow had occurred. Results indicated that leaching efficiency of gold production spoils was significantly below that desired. North Dakota State University continued an 11-year study, which monitors NO3 N concentrations in subsurface water in a center-pivot irrigated field. They found as soil moisture increased through irrigation, the availability and mobility of N increased resulting in a flush of nitrate through the soil profile and the peak nitrate concentration decreased as the observation went deeper into the profile. NDSU investigated fate and transport of bioactive hormones and antibiotics from livestock waste. Hormones such as testosterone have potential to move through organic-rich portions of soil and contaminate groundwater. PNNL have developed several new approaches for quantifying spatial and temporal heterogeneities affecting water and solute transport in field soils. Investigating simulated tank leaks, researchers obtained data sets elucidating new theories and models of vadose zone transport. These approaches were successfully applied to a variety of infiltration experiments.
    OBJECTIVE 2: To develop and evaluate instrumentation and methods of analysis for characterization of flow and transport at different scales
    University of Arizona continued ongoing flow and transport studies at the Maricopa research center using bromide tracers. Various methodologies were used to postulate, compare, and rank conceptual models of unsaturated flow and transport under three different textural layering. Other significant accomplishments under this objective included:
    UC-Davis used a combined TDR-tensiometer probe that could be used to determine soil water retention curves in both laboratory and field conditions by including a coiled TDR probe around the porous cup of a standard tensiometer. The advantages was the simultaneous measurement of soil water matric potential at the same spatial location within the same soil volume. A new method to study substrate Ployacrylamide (PAM) was devised by UC Riverside scientists using a modified method of N-bromination of amide groups. This technique will serve as a tool to improve PAM applications to soil and facilitate PAM-related research. Colorado State University is applying a continuous flow method for rapid measurement of soil hydraulic conductivity and moisture retention functions including hysteresis. This new method allows estimation of wetting/draining hydraulic conductivity and moisture retention functions over the entire range of plant available soil water. University of Idaho and University of Connecticut collaborated on analytical solutions for prediction of sample scale unsaturated hydraulic conductivity derived from pore-scale processes in matrix and structural pore domains. withgreat potential for prediction of permeability of clay sand mixtures. Work is continuing. Kansas State University working with CSRIO Land and Water characterized the effective measurement scale for thermal sensors. They developed a method that allows application of spatial weighting functions used to quantify thermal properties including functions for volumetric heat capacity as measured by dual-probe heat-pulse (DPHP). Montana State University and Sweden evaluated a new shaft-mounted TDR probe. The new design may be used to measure both dielectric constant and bulk electrical conductivity of soils and is extremely useful in monitoring fertilizer status, solute distribution and transport, and other processes important to agricultural activity. Montana State and University of Connecticut scientists continued research evaluating variation in soil water characteristics of uniform, homogenized soil samples within and among laboratories. . DRI Nevada research focused on approaches to analyze site conditions and characterize hydraulic properties in both saturated and unsaturated media using natural soil water tracers (i.e. chlorides and nitrates). USDA-CPRL (Bushland, TX) are estimating hydraulic properties in soils using a disc infiltrometer for in situ measurements of infiltration used conjointly with TDR soil water measurements. Measurement with diagonally placed probes (30 degrees from horizontal) minimized errors associated with assuming a uniform weighting of water content within the sampling volume. USDA-CPRL has an ongoing comparison of soil moisture sensors at Bushland. In particular, they are evaluating alternatives to the neutron probe by testing the Sentek EnviroSCAN, Sentek Diviner 2000, Trime T3 tube probe, Delta-T Profiler, and a sheathed TDR probe with the neutron probe. Utah State University, University of Connecticut and the Space Dynamic Laboratory worked on the development of a gas diffusion system for the International Space Station for potential use in a bioregenerative life support system. Washington State University is developing a freezing technique that will be able to determine soil moisture characteristics in porous media. PNNL WA developed a vadose zone water flux meter consisting of a buried wick-lysimeter that passively controls the tension at the base of the lysimeter. The resolution of the fluxmeter is 0.1 mm of water and will be commercially available in 2003.
    OBJECTIVE 3: To apply scale-appropriate methodologies for the management of soil and water resources.
    UC-Riverside conducted studies to identify mitigation practices to improve water quality of surface runoff from commercial nurseries. Vegetative filter strips consisting of Canna lilies in concrete lined channels proved very effective in reducing N content of waters leaving the nursery. Other research included:
    UC Davis inversely applied models to obtain effective soil hydraulic properties at widely different spatial scales. They utilized scaling factors to estimate hydraulic properties in water district scales of square mile size. Iowa State and USDA Tilth Lab have collaborated on a study of three methods for determining corn yield potential zones from 6 years of data. The methods included: cluster analysis of multiple year yield data, cluster analysis of easily measured field attributes, and multiple regression analysis of the field attributes. All three methods were effective and highlighted the importance of landscape position and in delineating areas of similar yield potential. They are also evaluating the use of the cluster analysis to identify effective N management zones within fields. Montana State University researchers used four 25 to 60 ha farm fields to evaluate the relationship between topography (digital elevation models) and soil water content (neutron probe). They regressed compound topographic index (CTI) against soil water content and could find no consistent pattern for regions across sites for a given soil depth. They concluded that more location-specific soil, climate, and terrain information will be required to reliably predict spatial soil water status within farmers fields. MT, MN, SD, and ND collaborated on a study of the effectiveness of nutrient management zone determination methods for the Northern Plain agriculture. An on-farm replicated study evaluated three different methods of nutrient management (uniform application, variable rate application based on bare soil imaging, and variable rate based on cluster analysis). Cluster analysis showed spatial patterns that could then be used to develop nutrient management zones within fields. This approach will allow farmers to more precisely apply nutrients for optimum yields avoiding over application. PNNL studied interactions between microbial dynamics and transport processes in soils that have applied applications such as wastewater treatment, bioremediation, and oilfield recovery operations. University of Wyoming studied surfactant enhances remediation of denser-than water nonaquaous phase liquids (DNAPL) using stochastic analysis of soil spatial variability and heterogeneity. Randomly generated permeability fields were incorporated into the UTCHEM model to simulate DNAPL transport in heterogeneous media and stochastic analysis conducted based on the results. The study would provide useful information to design strategies for the characterization and remediation of nonaquaous phase liquid contaminated soils with spatial variability and herterogeneity.

    Impact Statements:
    1. Description models of flow and transport were used to establish nitrogen best management practices for a wide range of field situations ranging from fertilizer runoff from turfgrasses to an 11-year study for corn under center-pivot irrigation.
    2. A combination of plastic vapor barriers and soil amendments can be effective barriers to pesticide vapor emissions. Criteria were developed for controlling pathogen contamination off groundwater by assessing potential rather than remediation.
    3. W-188 scientists in collaboration with NASA developed a gas diffusion system for the International Space Station for use in a bioregenerative life support system.
    4. CO research results indicate that the prediction of spatial patterns of crop yields in semi-arid regions from topographic information are a prerequisite for ongoing research to aid site-specific land management.
    5. High levels of hormones and antibiotics in cattle operations in land applied manure were found to move through organic-rich soil contaminating groundwater
    6. Numerous new instruments and methods for studying flow and solute transport in soils were developed.
    7. The complex solutions described in the above listed accomplishments are somewhat difficult to summarize in terms of direct impact on stakeholders. However, the information generated by this project has far reaching impacts that will be transferred to users through applied research and extension outlets.Selected examples include
    Last Modified: unknown

    Date of Annual Report: 03/15/2004

    Report Information:
  • Annual Meeting Dates: 01/05/04 to 01/07/04
  • Period the Report Covers: 01/2003 to 12/2003

    • Participants:
    Brief Summary of Minutes of Annual Meeting:
    The minutes of the annual meeting and a complete copy of the annual report, including all 2003 publications, may be found on the W-188 website at: http://www.soilsci.ndsu.nodak.edu/w188

    Accomplishments:
    Objective 1: To study relationships between flow and transport properties or processes and the spatial and temporal scales at which these are observed.
    Accomplishments: UC-Davis research used the inverse method and physically based three-dimensional distributed model combined with measured tile drainage data from a 9700 ha trial to study soil hydraulic properties. Measured drainage data were of limited benefit in identifying soil hydraulic properties while the dominant hydrology of the site was best predicted by drain system properties and preferential flow. UC Riverside researchers found that, unlike expectations, prescribed ground fires near Lake Tahoe did not result in elevated phosphorus transport to surface streams and eventually to the lake. Other research found that mineral weathering occurred at slower rates on steep north facing slopes in alpine watersheds. This resulted in more susceptibility to negative impacts of atmospheric deposition in basins with a high percent of cold steep slopes. UC Riverside researchers continued nitrogen BMPs for irrigated turfgrass. To date, ammonium nitrate and Polyon (slow release) N source produced best turfgrass quality and NO3- - and NH4+-N concentrations below the root zone were maintained at less than 1 ppm. Other studies continued on management of N runoff from urban nurseries to reduce contamination of coastal waters and lakes. USDA-USSL scientists studied processes and mechanisms that affect pesticide emissions from fields via leaching. Use of ammonium thiosulfate and dissolved organic matter reduced mobility and leaching of pesticides. Other research investigated volatilization, degradation, and diffusion of propargyl bromide (3BP) in a bed-furrow fumigation system. They found that irrigation and higher initial soil moisture were more important in reducing volatilization than plastic tarp. USSL developed a colloid straining model that looked at retention and attachment. The results indicated that straining occurred when the ratio of the colloid and median grain diameters was > 0.5%. Other significant accomplishments under Objective 1 included: Delaware (UD) researchers studied soil characteristics (hydrophilic vs hydrophobic surfaces) as they affect virus retention and transport under unsaturated flow. They found significant interactions between ionic strength, virus type, and water content. Iowa State University (IA) researchers studied solute transport in a tile-drained field using TDR and found that TDR probes may be used to nondestructively determine soil surface transport properties which, in turn, can predict chemical leaching. This methodology is being used to assess the impact of different management practices on solute leaching. University of Minnesota continued work with Non-Equilibrium Richards Equation (NERE) as it affects finger velocity and saturation profile. They completed a low order stability analysis that showed the predictability of instability based on specific initial saturation. Researchers at Montana State and U Connecticut are working together to quantify the primary physical influences on microbial habitats and activities in unsaturated soils. Results in 2003 did not indicate a strong consistent change in microbial community composition in response to texture and wetness. They found higher microbial cell densities at higher diffusion potentials (lower matrix potential). Research at the NV Desert Research Institute continued on groundwater contamination from large gold ore heap leach facilities. A large-scale field experiment consisting of 27 collection lysimeters was conducted at the Placer Dome Gold Acres Mine to better understand surface infiltration and preferential flow in mine wastes. After a 90-day irrigation period followed by a 30 day drain down, results indicated that heterogeneity in the heap material was the dominant factor in controlling the variation in observed trough lysimeter fluxes and variations in application rate was shown by numerical simulation withHYDRUS-2D to be relatively unimportant in explaining the variance in lysimeter flux. North Dakota State University continued investigations of fate and transport of bioactive hormones and antibiotics from livestock waste. Results using transport models evaluated 17B-estradiol and testosterone and found 1) Both were strongly sorbed by soil and 2) estradiol decomposed readily to safe metabolites while testosterone remained intact and represents a greater risk to subsurface water quality. Utah State University in collaboration with U Connecticut studied water flow in microgravity performed with a KC-135 aircraft in parabolic flight. They found air entrapment in the absence of gravity is a significant factor affecting transport processes. Models developed from these studies will advance our understanding of soil physics in extra-terrestrial environments such as the Moon and Mars. PNNL have developed several new approaches for quantifying spatial and temporal heterogeneities affecting water and solute transport in field soils. WSU evaluated hydraulic conductivities under three management systems (natural prairie, conventional till, and no till) and found much high conductivity in the natural system and that 27 years of no till could restore the original soil conductivity.
    OBJECTIVE 2: To develop and evaluate instrumentation and methods of analysis for characterization of flow and transport at different scales.
    Selected accomplishments under this objective include: University of Arizona published studies describing unsaturated flow through spherical inclusions and through multiple circular inclusions which proved to be important in assessing percolation profiles of agricultural chemicals through soil profiles. UA also developed a new calibration procedure for neutron probes in determining water content in deep and layered vadose zones. UC Riverside is developing a nitrate hazard index for irrigated crops in the southwest. It will allow farm advisors and growers to adopt BMP that will reduce nitrate leaching. UCR researchers studying carbon cycling found that 1)it takes 10 ?15 years for cultivation to significantly change C turnover rates from that of native soil and 2) carbon sequestration in rice paddy soils in China well below what its potential is if sustainable agricultural principals were applied. USDA-USSL compared field drip irrigation data with HYDRUS-2D simulations and found the HYDRUS-2D water distribution predictions accurately described the actual measured water content. Other studies addressed dielectric loss on resonant frequency of capacitance probe sensors. University of Idaho evaluated hydraulic properties of swelling clay soils using a flexible wall permeameter and volume change apparatus. Iowa State University developed a number of laboratory techniques to improve current state-of-the-art measurements of dielectric spectra of soils using a vector network analyzer, soil water flow using a heat pulse technique and dual-probe heat-pulse (DPHP),and lastly new techniques for determining soil volumetric heat capacity. Montana State advanced measuring capabilities using TDR and evaluating variation in the measurement of soil water retention using water properties rather than a surrogate liquid. A second project evaluated variation in soil water retention measurements among research and commercial laboratories. DRI Nevada research in 2003 included evaluation of large-scale lysimeters in field scale flux experiments, improved methods for conducting aquifer tests, scaling approaches to estimating ET from wetlands in desert environments, and completed field work on overland flow characterization by refining existing methodologies to better delineate volume runoff per unit area and soil nutrient flux. USDA-CPRL are estimating hydraulic properties in soils using a disc infiltrometer for in situ measurements of infiltration used conjointly with TDR soil water measurements. Measurement with diagonally placed probes (30 degrees from horizontal) minimized errors associated with assuming a uniform weighting of water content within the sampling volume. USDA-CPRL has an ongoing comparison of soil moisture sensors at Bushland. In particular, they are evaluating alternatives to the neutron probe by testing the Sentek EnviroSCAN, Sentek Diviner 2000, Trime T3 tube probe, Delta-T Profiler, and a sheathed TDR probe with the neutron probe. Utah State University , University of Connecticut and the Space Dynamic Laboratory developed a gas diffusion system for the International Space Station for potential use in a bioregenerative life support system. Washington State University developed a freezing technique that will be able to determine soil moisture characteristics in porous media. A prototype instrument is being modified for commercial production. PNNL WA developed a vadose zone water flux meter consisting of a buried wick-lysimeter that passively controls the tension at the base of the lysimeter. The resolution of the fluxmeter is 0.1 mm of water and was commercially available in 2003.
    OBJECTIVE 3: To apply scale-appropriate methodologies for the management of soil and water resources. UC-Riverside investigated physical and hydraulic properties of sodic soils having different mineralogy and found that there is no significant effect of SAR on the ECa of vermiculite or smectite while the differences were more pronounced in kaolinite. UC Davis inversely applied models to obtain effective soil hydraulic properties at widely different spatial scales. They utilized scaling factors to estimate hydraulic properties in water district scales of square mile size. Montana State University researchers investigated soil physical properties that may account for a devastating invasion of knapweed and found no correlation between soil physical properties or water-use efficiency and knapweed establishment. DRI Nevada researchers studied hydraulic and nutrient management properties of the Sierran basin and Mojave National preserve. The later showed that increasing surface age (50 to 100,000 years) resulted in a 100-fold decline in saturated hydraulic conductivity. NDSU, SDSU, Minnesota, and Montana collaborated on a precision agriculture study of effectiveness of nutrient management for the Northern Plain agriculture. An on-farm replicated study evaluated different methods of nutrient management. Last year they found that N loss to leaching was 26 kg N/ha on the nutrient managed half of field compared to 270 kg N/ha on farmer managed side. WSU studied desert landform evolution in the Mojave Desert through deduction of the evolution of the Holocene and Pleistocene period. Using water erosion prediction models (WEPP)they identified two periods within the Holocene period with distinct erosion characteristics and shed new light on current state of Mohave Desert landform evolution.

    Impact Statements:
    1. W-188 scientists developed a model for methyl bromide of chemical transport in the vapor phase and showed that combinations of plastic vapor barriers and soil amendments were effective in reducing pesticide vapor emissions. This work was intended to help producers keep existing, effective chemical controls that are environmentally sound
    2. W-188 scientists developed watershed scale models for studying water drainage and solute transport in the San Joaquin Valley, geochemical transport in the Lake Tahoe basin, and transport properties and preferential flow in gold mining wastes in Nevada
    3. W-188 research evaluated methods to address soil retention, solute transport, and fate of chemical toxins, biological contaminants (viruses, hormones, etc) and other contaminants resulting from agricultural practices, mining disturbances, fires, and other man-caused and natural contamination. The work not only defined the scope of the problems but also suggested management practices to alleviate them
    4. W-188 scientists developed numerous new instruments and methods for studying flow and transport in soils ranging from single multifunctional sensors for simultaneous measurements of soil water and thermal properties to utilization of the HYDROUS-2D model designing drip irrigation management properties
    5. W-188 scientists developed and demonstrated the use of a dual-probe heat-pulse technique for monitoring water content as an inexpensive alternative to time domain reflectometry (TDR);;
    6. Impact 6. W-188 scientists developed and made commercially available a water fluxmeter and a prototype instrument to measure freezing and moisture characteristics of porous media
    7. Impact 7. W-188 scientists used methods that included: cluster analysis of multiple year yield data, cluster analysis of easily measured field attributes, and multiple regression analysis of the field attributes. While not perfect, the discriminant functions were able to capture the major characteristics of the yield cluster distribution across the field and suggests this approach may be useful to agronomists for management with or without detailed spatial data.
    Last Modified: unknown
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