ABSTRACT:
Phosphorus (P) based nutrient management regulations may affect the viability of agricultural enterprises in Pennsylvania. Identification of areas likely to be affected by impending P-based regulations will allow regulators and conservation officials to better target technical and financial assistance. A statewide GIS analysis based on an extensive soil testing database and available geospatial data (including land cover, streams, and livestock density) found that various regions of Pennsylvania would be affected by the P-index restrictions for different reasons. In the southeast and parts of the northeast, high soil test P levels associated with intensive animal agriculture required a full assessment of P source and transport factors under the P-index. In north- and south-central and southwest Pennsylvania, the P-index assessment was required because of the proximity of much of the region's farmland to surface waters. Additionally, nearly half of agronomic soil samples exceeded the optimum P level for crops, suggesting widespread over fertilization and an ongoing build up of soil P stocks. Soil P was found to increase with increasing animal density and the highest animal density areas had a large number of nutrient impaired streams. When samples were separated based on cover type, croplands exhibited the highest P levels, followed by grasslands and then pastures. Finally, a weighted combination of the percentage of soil samples exceeding 200 ppm P and the proportion of agricultural lands within 150 ft (45.7 m) of streams indicated that southeastern Pennsylvania, especially Lancaster County, would be most affected. How farm operators adapt to P-based nutrient management, via on- and off-farm strategies, will determine the severity of the impact and the necessity of government assistance.
Footnotes
Wilhem J. Kogelmann is a graduate assistant, Hangsheng (Henry) Lin is an assistant professor of hydropedology and soil hydrology, Douglas B. Beegle is a professor of agronomy, and Gary W. Petersen is a distinguished professor of soil and land resources in the Department of Crop and Soil Science at the Pennsylvania State University in University Park, Pennsylvania. Ray B. Bryant is a research leader in the U.S. Department of Agriculture-Agricultural Research Service, Pasture Systems and Watershed Management Research Unit in University Park, Pennsylvania. Ann M. Wolf is the director of the Agricultural Analytical Services Laboratory and an affiliate assistant professor of agronomy in the Department of Crop and Soil Science at the Pennsylvania State University in University Park, Pennsylvania.
- Copyright 2004 by the Soil and Water Conservation Society
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