Submitted to: Final Report to USDA-NRCS
Publication Type: Other
Publication Acceptance Date: 4/1/2004
Publication Date: 4/1/2004
Citation: Sharpley, A.N., Beegle, D., Jokela, W., Kleinman, P.J., Leytem, A.B., Maguire, R., Myers, J., Weld, J.L. 2004. An evaluation of the Virginia Phosphorus Index. Final Report to USDA-NRCS, Virginia State Office, 1606 Santa Rosa Blvd., Suite 209, Richmond, VA. 30 p. Interpretive Summary: The Natural Resources Conservation Service requested that a panel of experts review and comment on Virginia's proposed Phosphorus (P) Index. Three main areas of concern as related to the P Indexing procedure - workload, technical, and subjectivity - were addressed by the panel. Acceptance of an underlying principle that the P Index is a risk assessment tool and not a quantitative P loss model goes a long way toward addressing and resolving many issues raised about P Index implementation. The fact that the P Index is a risk assessment tool provides the user (i.e., farmer) flexibility in addressing potential P-management issues. Although it is recognized that determination of site vulnerability to P loss with the P Index involves about two hours per field (most of which involves calculating erosion), this is a one-time commitment, and any subsequent annual assessment will involve appreciably less time. Technical support of all aspects of the P Index is being continuously updated as research becomes more available. Finally, Index subjectivity can be minimized through proper technical and in-field training. The Panel was unanimous in its support of the P Indexing approach in developing P-based nutrient management strategies. The other two options available--agronomic and environmental soil P testing--are scientifically unsupportable by themselves in terms of assessing the risk of P loss and are a disservice to our customers (farmers and general public) given the wealth of sound research that has been conducted over the last 20 years.
Technical Abstract: The Natural Resources Conservation Service requested that a panel of experts review and comment on Virginia's proposed Phosphorus (P) Index. This report documents the comments of all panel members and is divided into three main areas of concern as related to the P Indexing procedure--workload, technical, and subjectivity. The workload are, in terms of acquiring information needed to conduct a P Index site assessment, is a one-time issue. Once all the basic site properties are collected, only management changes from year to year are needed. Thus, subsequent site assessments are going to be very easy and quick to conduct. This parallels the initial workload of developing a conservation plan. Inclusion of a simple screening tool (e.g., soil test P and distance to stream) in the P Index will reduce the number of fields that would be considered for a complete evaluation, and thus, workload. Technical support of all aspects of the P Index is being continuously updated as research becomes more available. Overall, the best way to minimize subjectivity is through proper technical and in-field training on the use of the P Index. This could be developed by Virginia Tech and the Natural Resources Conservation Service personnel. Several states in the Northeast U.S. have successfully implemented training programs that could be used as models for Virginia. Future issues must be dealt with by a Virginia-based advisory board that should be comprised of P Index developers, plan writers, and customers.