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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Research Project #441262

Research Project: Contribution of Legacy P to Watershed Outcomes -UoM

Location: Soil and Water Management Research

Project Number: 5062-12130-008-037-A
Project Type: Cooperative Agreement

Start Date: Nov 1, 2021
End Date: Jun 30, 2026

The general objective of this two-phase project is to discern the potential contribution of legacy P sources to watershed P discharges and dynamics in the Upper Mississippi River Basin watershed.

1. Rely on existing datasets to characterize farm-scale P budgets and quantify edge- of-field losses. We will compile available field characterization and monitoring data from relevant participants in Minnesota’s Discovery Farm program. Flow, sediment, and phosphorus data from edge-of-field monitoring for both surface and subsurface tile runoff will be used to characterize field- and farm-scale exports of P over temporal scales ranging from event to annual. Farm-level inputs and outputs will be compiled from available records or estimated with accepted methods in order to develop farm-level P budgets including estimated contributions to/from legacy P. We will select one farm for more detailed characterization and soil sampling in support of the broader multi-site efforts of this Legacy P project. We have tentatively identified a site within the Le Sueur River basin which is managed in a two-year corn and soybean rotation typical for much of the Upper Midwestern United States. Long-term watershed monitoring data from this location will be used for contrasting P budgets across different spatial scales. 2. Compile data from existing watershed monitoring efforts to characterize P export at the watershed scale. A range of watersheds located in the Upper Mississippi River Basin are routinely monitored for flow and P export. Monitored watersheds vary in size, climate, land use, and physiographic setting and will provide insight into processes that are not present at the field or farm scale but can be very important for their influence on watershed P export.