ABSTRACT:
Historically phosphorus (P) was applied to cropland based on expected crop response and to correct soil nutrient deficiencies. As these deficiencies have become less common and animal production has intensified in many regions, concerns about surplus cropland P becoming a water resource pollutant have replaced historical concerns. To understand spatial and temporal changes in P surpluses, P budgets were developed for Pennsylvania cropland at approximately ten-year intervals from 1939 to 2002. The P balance, the difference between inputs to crop land (manure and fertilizer) and outputs (harvested crops), estimates the change in soil P storage plus P losses through runoff, erosion and leaching. Although the state-level P balance decreased since 1949, in 20 counties the maximum excess P occurred since 1992. Nutrient budgets, such as those developed for P in this research, can contribute to more informed strategies to reduce or prevent cropland P surpluses and thus reduce the risk to water quality.
Footnotes
Les E. Lanyon (deceased) was a professor of soil science and management, in the Department of Crop and Soil Sciences at the Pennsylvania State University, University Park, Pennsylvania. Kathleen E. Arrington is a research assistant in the Department of Soil Science at the University of Wisconsin-Madison in Madison, Wisconsin. Charles W. Abdalla is an associate professor of Agricultural and Environmental Economics in the Department of Agricultural Economics and Rural Sociology at Pennsylvania State University in University Park, Pennsylvania. Douglas B. Beegle is a professor of agronomy in the Department of Crop and Soil Sciences at Pennsylvania State University in University Park, Pennsylvania.
- Copyright 2006 by the Soil and Water Conservation Society
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