Location: Rangeland Resources & Systems Research
Project Number: 3012-61660-008-00-D
Project Type: In-House Appropriated
Start Date: Dec 7, 2015
End Date: Mar 6, 2017
Objective 1: WEPS: Validate untested science incorporated into WEPS for simulations of dryland crop rotations, tillage/no-tillage, organic soils, and residue cover, including the effects of within-field variability, against experimental data, and adjust algorithms where needed. Provide technology transfer of WEPS via data stewardship, data and algorithm documentation, and continual dialogue with NRCS. Sub-objective 1A. Evaluate and improve WEPS processes that define the surface state of erodibility through validation with existing datasets and field measurements. Sub-objective 1B. Evaluate an existing approach to simulate within-field variability of soils, crops, and management as sub-regions within WEPS. Objective 2: AgMIP: Characterize the temporal within-season, process-level understanding of the responses of soil, and soil-plant interactions to extreme precipitation and temperature events (including nighttime events), and how management practices modify the responses. Sub-objective 2A: Using the algorithms and data assembled by AgMIP collaborators, quantitatively assess the strengths and weaknesses of existing methods of simulating soil water, evapotranspiration (ET), crop water uptake (T), soil water evaporation (E), and water stress effects on leaf area, under a range of soil water conditions from full irrigation to drought and associated high temperatures during the crop season for different agro-climatic management conditions. Sub-objective 2B: Develop and test new concepts and algorithms that will enable better process-level understanding and quantification of diurnal fluctuations in ET in response to drought and high temperature during the growing season.
This research focuses on two main goals: 1) improve algorithms in the Wind Erosion Prediction System (WEPS) for temporal changes in the state of surface conditions and within-field variability for improved simulation of wind erosion; and 2) improve scientific approaches to predict evapotranspiration (ET) components under normal to drought and high temperature conditions as needed by the Agricultural Model Intercomparison and Improvement Project (AgMIP). In WEPS, the major components that determine the surface state of erodibility are the surface roughness, residue cover, aggregate size distribution and stability, soil moisture, and crusting. We will test WEPS algorithms against measured data from field sites and evaluate within-field variability by measuring the spatial changes of surface wind friction velocities. This research will improve the WEPS robustness and expand its utility to larger areas for NRCS and other users. For the second goal, we will evaluate various scientific approaches used in current AgMIP models to simulate ET processes, especially during drought and high temperature events, using existing datasets and identify the best approaches to improve AgMIP models. We will also collaborate to collect new data from field and growth chamber studies on leaf area, leaf water potential, stomatal conductance, and stem flow under drought and high temperature conditions to develop new concepts and algorithms for daily and hourly ET simulations. This research will improve crop models and the projection of climate change effects on crop water use and production. Outcomes of the project will enhance crop water use efficiency and reduce wind erosion.