Location: Soil Drainage Research
Project Number: 5080-13210-003-026-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Feb 1, 2022
End Date: Jan 31, 2026
Objective:
(1) Study phosporus (P)-transport mechanisms in tile drained fields by conducting flow-through experiments on surface and subsurface soils to characterize P adsorption and desorption behavior of soils as a function of texture, soil test phosphorus (STP), and flow rate (percolation rate);
(2) Modify Soil & Water Assessment Tool (SWAT) model source code governing transport of soluble P to tile drains by improving P transport through macropore flow; partitioning tile discharge pathway to macropore flow vs matrix flow; incorporating the soil matrix sorption/desorption model theory into SWAT;
(3) Conduct sensitivity analysis and validate the model improvements using edge-of-field monitoring data
Approach:
Dr. King: Lab, field and modeling approaches will be used to improve understanding phosphorus dynamics and simulation. The ARS portion will be field assessments and processes related to tile drainage. Data will be collected from the ARS edge-of-field network. Data includes discharge and phosphorus in surface and tile drainage from a subset of the edge-of-field sites. Data will be shared with partners to improve, calibrate, and validate field scale model predictions. Dr Penn: To test our central hypothesis we will conduct flow-through P desorption and adsorption experiments utilizing a short and long contact time (i.e., fast and slow flow rate) on a diverse group of high P soils collected from the Western Lake Erie Basin. Quantification of the impacts of flow rate and soil properties on dissolved P concentrations will then be reduced to useful equations that will be incorporated into SWAT for improving tile drainage routines.
