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A critical evaluation of the Kentucky phosphorus index
- Bolster, Carl H.
- Transactions of the Kentucky Academy of Science. 2011 v.72 no.1 pp. 46
- Natural Resources Conservation Service, agricultural management models, agricultural soils, fertilizer rates, losses from soil, nonpoint source pollution, nutrient management, phosphorus, phosphorus fertilizers, risk, soil erosion, waterways, Kentucky
- The U.S. Department of Agriculture's Natural Resource Conservation Service (USDA-NRCS) is currently revising its 590 Nutrient Management Conservation Standard. As part of this revision, USDA-NRCS is considering requiring states to test the accuracy of their phosphorus (P) indices using either measured P loss data or simulated P loss data generated from process-based models. The objective of this study was to critically evaluate the KY P index by comparing index output with simulated P loss data obtained from a validated P loss model. Furthermore, the general formulation of the index was evaluated against current research on the processes controlling P transport in the environment. Results suggested that in some areas the index does a good job in assigning P loss risk; however, this analysis also showed some important deficiencies in the index, primarily the neglect of important factors known to affect P loss (e.g., soil erosion and P application rates) and how the different factors in the index are weighted. To reduce the amount of P that is exported from agricultural fields to waterways within Kentucky, resources should be devoted to revising the KY P index to address these limitations as well as developing long-term monitoring sites where the P index and more process-based models can be evaluated against measured P loss data.