Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: 11/2/1999
Publication Date: N/A
Citation: Beegle, D., Sharpley, A.N. 1999. Approaches to managing phosphorus to protect the environment. Experiment Station Bulletins. Penn State Agronomic Field Diagnostic Clinic. Pennsylvania State University, College of Agricultural Sciences, Cooperative Extension, University Park, Pennsylvania. p. 42-46. Interpretive Summary:
Technical Abstract: A major issue in manure management policy today is whether nutrient management plans should be based on N or P. Both N and P can have a negative impact on water quality. A major concern with N is nitrate leaching from soil and contamination of ground water. High nitrate in ground water can have adverse health effects. Controlling the source of N is also important because it is very difficult to reduce N transport. The major concern with P is freshwater eutrophication. Biological activity of many surface water bodies is P limited. When P inputs are increased, algae and other plant growth are stimulated. The resulting eutrophication restricts the use of surface waters for aesthetics, fisheries, recreation, industry, and drinking water. In Pennsylvania, manure application guidelines and regulations are based on balancing N. However, the USDA and EPA have developed a Unified Strategy for Animal Feeding Operations (AFOs) to address water quality concerns related to nutrient management. The strategy proposes that all animal-feeding operations will have a comprehensive nutrient management plan by 2008. Concentrated animal feeding operations (CAFOs) will be required to have plans earlier as part of permitting requirements. An important part of this strategy is that it spells out how acceptable manure application rates will be determined in these plans. Both N and P must be considered in plans developed under this strategy. In this paper we outline the three options for determining appropriate phosphorus-based nutrient management plans; agronomic soil test P, environmental soil P thresholds, and P indexing of site vulnerability.