Nitrogen Use Efficiency is the percentage of applied Nitrogen sequestered in a crop. It is rarely better then 60%. In Chesapeake Bay, about 475 million pounds of Nitrogen fertilizer are purchased each year in VA, MD and PA, so 190 million pounds of Nitrogen are not sequestered in a crop and are released to the environment. That compares to about 240 million pounds of Nitrogen delivered to the Bay from all sources each year. Pollution by Nitrogen from chemical crop fertilization, and the disposal of animal waste by land application, are so overwhelming that pollution unrelated to crop fertilization doesn’t matter much. Pollution from chemical fertilizer can never be eliminated, but it can be significantly reduced by using “slow-release” products. In contrast, Nitrogen pollution from the disposal of animal waste by land application, with a Nitrogen Use Efficiency around 30% mandated by governments, can be eliminated. Current government regulations support waste producers and receivers and guarantee massive nutrient pollution. Unless chemical crop fertilization practices become much more efficient and the pollution caused by the disposal of animal waste by land application sanctioned by governments is stopped, there is no hope for significant improvement in Bay water quality.
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