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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Research Project #441152

Research Project: Contribution of Legacy P to Watershed Outcomes - Phase 1 - SWMU

Location: Soil and Water Management Research

Project Number: 5062-12130-008-036-I
Project Type: Interagency Reimbursable Agreement

Start Date: Sep 1, 2021
End Date: Jul 30, 2026

To identify and quantify legacy P in the Upper Mississippi River Basin.

The approach is two-pronged, investigate 1. Field- and Farm-scale P dynamics, and 2. Watershed-scale P dynamics. 1. Field- and Farm-scale P dynamics: 1a) Utilize existing datasets to characterize farm-scale P budgets and quantify edge-of-field losses. In Minnesota and Wisconsin, extension programs work with farmers to characterize their operations and monitor environmental outcomes. Through this program, there are multi-year datasets available for several farms located within the Upper Mississippi River Basin. We will compile available field characterization and monitoring data from relevant participants in Minnesota’s 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. 1b) Detailed site characterization and analysis of a selected extension participant. Based on preliminary results from existing datasets, 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. 2. Watershed-scale P dynamics: 2a) 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. We will build upon previous efforts by updating a database of watershed scale P export and expanding it to include other monitored watersheds in the Upper Mississippi River Basin. 2b) Evaluate effectiveness of conservation practices at the small watershed scale. Data collected for the ARS in-house project from two paired small-scale watersheds, (roughly 270 ha each) for the purpose of evaluating conservation practice impact on water quality will be used to complement our field- and large watershed-scale efforts (objectives 1a and 2a).