1988 Annual Report for LNE88-003
Role of Cereal Grain Cover Crops in Nitrogen Management for the Chesapeake Bay Region
Summary
Recently, there has been increasing concern about the impact of agricultural chemicals on groundwater resources. This is particularly true in the Chesapeake and Delaware Bay watersheds. One of the most prevalent issues is that of groundwater contamination with nitrate originating from soil fertility management practices. Nitrate in groundwater results from leaching of applied nitrogen, either directly or indirectly, and thus represents the loss of a resource required for crop production. For grain production of corn, recommended fertilizer rates are based on utilization efficiencies of approximately 60 percent, however, suboptimum growing conditions can reduce the percentage of applied nitrogen which is utilized by the crop to much lower levels. These inefficiencies have been recognized for some time but until the recent development of environmental issues, the unused portion of applied nitrogen was largely neglected. The development of agricultural management systems which focus on strategies for reducing the loss of nitrogen from the root zone must be considered.
Historically, cover crops were used to reduce soil erosion, fix nitrogen, and provide a source of forage in integrated agricultural systems. Since 1945, the development of relatively inexpensive inorganic fertilizers, and the concurrent spatial separation of livestock and grain production, has caused a dramatic reduction in the use of winter cover crops. Although much of the recent research on cover crops has focused on the use of legumes to supply nitrogen for future grain crops, long before nitrogen was recognized as a problem in the environment, scientists had documented the ability of cereal grain cover crops to reduce the leaching of nitrate from the root zone. However, the successful integration of cereal grain cover crops into current cropping systems will require an understanding of the dynamics of cover crop nitrogen uptake and remineralization in order to minimize nitrogen losses to the environment while providing maximum benefit to following grain crops. The proposed project will bring together research, extension, and private agencies and farmers in a five-year coordinated effort.
The project will be a cooperative effort between the University of Delaware, University of Maryland, Pennsylvania State University, and the Rodale Institute. Nitrate leaching under different cover crop management systems including dairy manure and forage production, poultry manure and irrigation, and continuous corn will be considered. Selected management practices will also be evaluated on two farms in Maryland, two in Delaware and two in Pennsylvania (total of six) to promote the use of cereal grain (rye) cover crops in nitrogen management. Results from the on-farm research and intensive plot research will be used to assess the economic impact of the different cover crop management practices on the farming system.
Objectives
(1) Evaluate the management of cereal grain (rye) cover crops to reduce the leaching of nutrients to groundwater and to optimize nitrogen recycling on the farm.
(2) Evaluate the economic impact of cereal grain (rye) cover crops on the farming system.
(3) Develop on-farm research to promote the use of cereal grain (rye) cover crops as a tool for nitrogen management.