In certain situations, Virginia and Pennsylvania continue to allow the land application of organic waste to be nitrogen-based, guaranteeing a massive over-application of both nitrogen and phosphorus and proving that agricultural economic concerns continue to trump concerns about water quality.
Pollution is an externality and its real cost is never accounted for. In Virginia, dairy manure is applied assuming that 35 percent of the nitrogen is available to the next crop because it takes time for microbes to decompose the organic material in the waste and release the nutrients for plant uptake.
What happens to the other 65 percent of the nitrogen? Unless nitrogen fertilizers are considerably reduced for subsequent crops — which is not required and rarely done — much of the excess nitrogen is pollution. It is easy to understand why animal waste — poultry litter, sewage sludge and manure — accounts for half of all agricultural nutrient pollution, or a little more than a quarter of Bay nutrient pollution because less than half of the disposed nitrogen and phosphorus ends up in the crop.
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