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United States Department of Agriculture

Agricultural Research Service

Research Project: Improved Agricultural Management Practices to Reduce Adverse Impacts on Water Resources in Semi-Arid Regions Project Number: 2036-61000-015-01
Project Type: Specific Cooperative Agreement

Start Date: Sep 30, 2011
End Date: Sep 29, 2016

Objective:
(a) Determine the impact of soil characteristics (hydraulic conductivity- and pressure-moisture relationships), heat and water vapor transport and energy/mass exchanges (e.g., solar radiation, water) on soil water and chemical status (i.e., salinity, nutrients, trace elements) of the soil. (b) Test, and develop when necessary, sensors to measure soil water content covering the range from saturation to very dry conditions. (c) Test an improved non-isothermal, two-phase water flow model for simulating water movement and the accumulation and leaching of salts and trace elements in irrigated soils that was developed by Unit scientists in FY2010. (d) Relate this information to agronomic production and the protection of water resources. Ensure that this information can be incorporated into regional scale assessments of ground water quantity and quality that will be a focus of future research.

Approach:
(a) Conduct laboratory and field experiments to measure the status of soil water in semi arid regions over wetting and/or drying cycles. These experiments will elucidate the interactions between irrigation, water and water vapor movement in soil, and evaporation from soil during irrigation and drainage cycles and as affected by soil heating and solar energy inputs. Several methodologies for measuring soil water content will be tested and compared to gravimetric sampling (e.g. capacitance, TDR, psychometric). Obtain direct measurement of evaporation and sensible heat flux using the eddy covariance method. The information will be used to develop a measurement database, for model testing, and to obtain modeling uncertainty estimates for use in future regional scale salinity and nutrient assessments. (b) Test a newly develop non-isothermal water and solute transport model to elucidate the accuracy of simulated soil water content and evaporation. Compare simulation to field-scale soil water content and evaporation measurements. This research will include measurement of various soil physical properties, evapo-transpiration, heat transfer, energy balances and soil-atmospheric exchanges to characterize the moisture status of soils. Models will be tested and improved models will be developed, where necessary, to enable prediction of soil moisture status from saturated to very dry conditions.

Last Modified: 10/21/2014
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