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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Water Quality and Ecology Research » Research » Research Project #441148

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

Location: Water Quality and Ecology Research

Project Number: 6060-13660-008-038-I
Project Type: Interagency Reimbursable Agreement

Start Date: Jul 31, 2021
End Date: Jul 30, 2026

Objective:
Quantify nutrients in alluvial soils and characterize properties related to stability of P pools to determine legacy P hotspots. Conduct reach-scale tracer and nutrient uptake experiments to estimate rates of P uptake and release, and the role of vegetation and residence time in nutrient dynamics. Explore the degree of P saturation along a landscape gradient in watersheds with stacked conservation practices and watersheds without conservation practices.

Approach:
The project will take a two phased approach, informed always by modeling but building off of empirical work that we initiate in phase 1, which will support well-documented watershed modeling in phase 2. This agreement covers work for Phase 1 in the following areas: Characterize legacy P sources in research watersheds, with locally derived, and common, methods. This will involve sampling soils and sediments, hopefully around areas where there are experiments and monitoring (esp. nested). Some samples will be analyzed at a common lab per methods TBD. We will also use existing models (SWAT, APEX, AnAgNPS, SPARROW, others) to inform our decisions on metrics so that they may be implemented later. The emphasis will be on P characterization, but sediment budgeting/sourcing should be encouraged. Assess long-term (>5 yr) Edge-of-Field and small watershed data to assess contributions of new/recent/incidental vs. old/legacy/chronic sources. Legacy P partners and others (CEAP watershed) will contribute data. Data will be analyzed per routines lifted from WRTDS or by other methods. Advance management recommendations to comprehensively address legacy P and nonlegacy P sources, including to be used as scenarios by watershed modelers. Conduct reach-scale tracer and nutrient uptake experiments to estimate rates of P uptake and release and the role of vegetation and residence time in nutrient dynamics. Explore the degree of P saturation along a landscape gradient in watersheds with stacked practices, such as Beasley Lake watershed, and in watersheds without conservation practices, such as Roundaway Lake watershed.