Purpose
This project was started to work with regional CIG projects to calibrate and harmonize Phosphorus Indices across the U.S., demonstrate their accuracy in identifying the magnitude and extent of phosphorus loss risk, and provide suggestions to refine or improve existing Indices. This research is important to provide consistency among state Phosphorus Indices and their subsequent recommendations.
What did we do?
We will combine and compare results from each of the four regional and state Phosphorus Index CIG-funded projects, in order to synthesize, summarize, and describe the science-based information and lessons learned from the individual Phosphorus Index assessment projects (i.e., Chesapeake Bay Watershed, Heartland Region, Southern States and Ohio Lake Erie Basin) and build a harmonized framework that yields consistent Phosphorus-based risk assessment across the U.S. by doing this, we plan to ensure that the refinement of Phosphorus Indices is grounded in the best available science, reflects local environmental and agronomic conditions, anticipates impacts to water quality and farm management, and provides consistent recommendations within and across varied physiographic regions of the U.S.
What have we learned?
Despite the success of the Phosphorus Index concept in state-level nutrient management planning strategies as part of the NRCS 590 Standard, there remain concerns about the effectiveness of the Indexing approach for attaining water quality goals. Different versions of the Phosphorus Index have emerged to account for regional differences in soil types, land management, climate, physiographic and hydrologic controls, manure management strategies, and policy conditions. Along with this development, differences in Phosphorus Index manure management recommendations under relatively similar site conditions have also emerged. To date, we have learned that the individual projects with slightly differing objectives have shown there to be a paucity of field measured runoff, against which to reliably compare Index performance. Thus, several off-the shelf and pre-calibrated models (e.g., APEX) were tested to provide adequate phosphorus runoff information to validate Indices. Use of off-the-shelf models can provide unreliable estimates of phosphorus runoff, while calibrate models can provide more reliable estimates when given adequate site information.
Future Plans
It is planned to have extend the research for one more year to the end of 2016 to continue model assessment, compile field runoff databases, conduct statistical and uncertainty analyses, and compile cross project findings.
Authors
Andrew Sharpley, Distinguished Professor, Division of Agriculture University of Arkansas System sharpley@uark.edu
Deanna Osmond, Professor and Soil Science Department Extension Leader; David Radcliff, Professor; Peter Kleinman, Research Leader; Doug Beegle, Distinguished Professor of Agronomy; John Lory, Associate Professor of Extension; and Nathan Nelson, Professor.
Additional information
Sharpley, A.N., D. Beegle, C. Bolster, L. Good, B. Joern, Q. Ketterings, J. Lory, R. Mikkelsen, D. Osmond, and P. Vadas. 2011. Revision of the 590 Nutrient Management Standard: SERA-17 Recommendations. Southern Cooperative Series Bulletin No. 412. Published by SERA-IEG-17, Virginia Tech. University, Blacksburg, VA. Available at https://sera17dotorg.files.wordpress.com/2015/02/590-sera-17-recommendations.pdf 2011.
Sharpley, A.N., D. Beegle, C. Bolster, L. Good, B. Joern, Q. Ketterings, J. Lory, R. Mikkelsen, D. Osmond, and P. Vadas. 2011. Revision of the 590 Nutrient Management Standard: SERA-17 Supporting Documentation. Southern Cooperative Series Bulletin No. 412. Published by SERA-IEG-17, Virginia Tech. University, Blacksburg, VA. Available at https://sera17dotorg.files.wordpress.com/2015/02/590-sera-17-recommendations.pdf
Sharpley, A.N., D.G. Beegle, C. Bolster, L.W. Good, B. Joern, Q. Ketterings, J. Lory, R. Mikkelsen, D. Osmond, and P.A. Vadas. 2012. Phosphorus indices: Why we need to take stock of how we are doing. J. Environ. Qual. 41:1711-1718.
Osmond, D.L., A.N. Sharpley, C. Bolster, M. Cabrera, S. Feagley, B. Lee, C. Mitchell, R. Mylavarapu, L. Oldham, F. Walker, and H. Zhang. 2012. Comparing phosphorus indices from twelve southern USA states against monitored phosphorus loads from six prior southern studies. J. Environ. Qual. 41:1741-1750.
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