At the request of Chairman Hughes, Dr. Thomas A. Fretz, Dean of the University of Maryland College of Agriculture and Natural Resources, convened a group of scientists to advise the Commission on the current scientific thinking on the movement of nitrogen and phosphorus in an agricultural setting, alternatives for managing and controlling nutrients on farms and options for using and handling poultry litter. A copy of the Agricultural Science Group s Report, The Agricultural Perspective, is attached as Appendix 10. Portions of the Report are summarized and relied upon below. The Nutrient Management Program administered by the Maryland Department of Agriculture and the University of Maryland since the late 1980s has concentrated on assisting farmers to manage nitrogen. At the time of the establishment of the Program, nitrogen appeared to be more problematic than phosphorus, as it was thought that phosphorus losses could be controlled through soil erosion control measures.
Crops require varying amounts of phosphorus relative to nitrogen depending upon the crop produced.
The amount of phosphorus contained within organic sources of nutrients, such as manure, compared to the levels of nitrogen within the manure, does not usually correspond to the nutrient needs of crops. If these organic materials are used to meet the nitrogen needs of the crop, phosphorus is overapplied. If the use of the organic material is limited to the phosphorus needs of the crop, nitrogen is underapplied and commercial fertilizer must be added to meet the needs of the crop. Nitrogen and phosphorus behave differently in soil. A certain portion of nitrogen will volatilize and enter the atmosphere.