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Competency Area 6: Nutrient Management and Planning

PO 50. Compare surface application of manure and immediate incorporation of manure in terms of potential nutrient loss pathways, application rates to meet crop N guidelines, land base requirements, impact on soil test P, etc.

Manure contains organic N and inorganic N.  The latter can be lost as ammonia if manure is not incorporated.  Because of these losses, more manure needs to be applied to achieve the same available N.  This will result in larger P and K applications as well, leading to more rapid P and K soil test increases over time.  Surface application of nutrients also leaves them exposed to erosion and runoff events, potentially increasing losses to the environment.  While tillage reduces surface exposure of nutrients, it can increase erosion rates.  Many farms are limited in the acreage available over which to spread manure.  Overapplying manure leads to nutrient excesses and environmental losses.  It may become necessary to export manure nutrients in another way.