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Research Project: Sustaining Agroecosystems and Water Resources in the Northeastern U.S.

Location: Pasture Systems & Watershed Management Research

Title: The promise, practice and state of planning tools to assess site vulnerability to runoff phosphorus loss

Author
item Kleinman, Peter
item Sharpley, Andrew - University Of Arkansas
item Buda, Anthony
item Easton, Zachary - Virginia Polytechnic Institution & State University
item Lory, John - University Of Missouri
item Osmond, Deanna - North Carolina State University
item Radcliffe, David - University Of Georgia
item Nelson, Nathan - Kansas State University
item Veith, Tameria - Tamie
item Doody, Donnacha - Agri-Food And Biosciences Institute

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2017
Publication Date: 11/16/2017
Citation: Kleinman, P.J., Sharpley, A.N., Buda, A.R., Easton, Z.M., Lory, J.A., Osmond, D.L., Radcliffe, D.E., Nelson, N.O., Veith, T.L., Doody, D.G. 2017. The promise, practice and state of planning tools to assess site vulnerability to runoff phosphorus loss. Journal of Environmental Quality. 46(6):1243-1249. https://doi.org/10.2134/jeq2017.10.0395.
DOI: https://doi.org/10.2134/jeq2017.10.0395

Interpretive Summary: There are limited measured data for testing field-level decision support tools, like the Phosphorus Index, that show which fields and management practices cause risks of phosphorus loss. Recent studies have been trying to use complex simulation models as a substitute for measured data in testing the Phosphorus Index. We reviewed those recent studies and previous literature to determine how well the tools and models were doing in predicting phosphorus loss from fields. Also, we highlighted current questions that still exist in the research to help scientists determine most relevant areas for future study. In particular we found that new site assessment tools for phosphorus must undergo rigorous verification before being used in water quality planning. However, we also found that upgrades to the more complex models are continuing to improve our prediction of phosphorus loss and will lead to updated decision support tools.

Technical Abstract: Over the past 20 years, there has been a proliferation of phosphorus (P) site assessment tools for nutrient management planning, particularly in the United State. These decision support tools, range from the P Index to fate-and-transport models to weather-forecast based risk calculators. All require objective evaluation to ensure that they are effective in achieving intended benefits to protecting water quality. In the U.S., efforts have been underway to compare, evaluate and advance an array of P site assessment tools. Efforts to corroborate their performance using water quality monitoring data confirms previously-documented discrepancies between different P site assessment tools but also highlights a surprisingly strong performance of many versions of the P Index as a predictor of water quality. At the same time, fate-and-transport models, often considered to be superior in their prediction of hydrology and water quality due to their complexity, reveal limitations when applied to site assessment. Indeed, one consistent theme from recent experience is the need to calibrate highly parameterized models when transferred from one setting to another. As P site assessment evolves, new routines for fate-and-transport models show promise in better representing important aspects of P cycling and transport, and new classes of P site assessment tools help to move P site assessment from general, strategic goals to web-based tools supporting daily, operational decisions.