Modeling Alternatives to Reduce Dairy Farm and Watershed Nonpoint Source Pollution

Management practices are available that may reduce sediment or phosphorus (P) loading to streams draining agricultural land. An evaluation of the long term effects of implementing one or more of these practices is needed. We used the Erosion Productivity Impact Calculator (EPIC) and Agricultural Non-Point Source (AGNPS) models to evaluate 20 management practices for sediment and P yields from 4 ha fields in a 1272 ha watershed of dairy farms. Five crop sequences [continuous corn (Zea mays L.) CC(OA)AAA, CC(OA)AAAA, CCC(OA)AAA, and CCCAAA; O, oat (Avena sativa L.); A, alfalfa (Medicago sativa L.)] combined with either fall moldboard plowing (mFMP), chisel plow (mFCP), no-till (mNT), or no-till substituting anhydrous ammonia for manure (aNT), were imposed on a toposequence of three Alfisols (.)