ADVANCES IN AGRICULTURAL NUTRIENT RUNOFF CONTROLS

Progress has been relatively slow for reducing nitrate and phosphate losses from the Susquehanna River Watershed to the Chesapeake Bay. It was initially recognized that farmers on the well drained limestone soils of Southeastern Pennsylvania, especially Lancaster County, were land applying excessive N and P in the form of manures and commercial fertilizers. The objective of the authors has been to define ''the greatest agricultural production experiment of the century''. The farmers combined manures and commercial fertilizers on these lands over a period of 20 years and experienced a two fold increase in yields of different crops. While it has been relatively easy to convince the farmers to stop applying commercial fertilizers, reductions in nutrient loadings via a reduction in animal numbers per acre or per farm has not occurred. The authors and others have not proposed a reduction in dairy cows per acre because such reductions would not allow these producers to remain in business, and if we can't explain how these farmers were so successful in increasing production, we have little justification for asking that they be denied the technology they have developed. The data summarized below serve to justify the need for a program to increase cellulose and lignin carbon as bedding or direct application to land to increase the water holding capacities of the soils and immobilize an acceptable excess amount of manure N applied.