| The surface application of manure to forages may increase environmental risk if applied at inappropriate times of the year or at excessive rates. A long-term (10-yr) field study evaluated the effect of spring, summer, early fall and late fall manure applications on forage yield, nutrient utilization and soil nutrient status. Time of year of manure application did not significantly affect the parameters examined. Yields were higher on the dykeland site, however, the response to manure addition was greater on the upland site. Annual manure applications based on nitrogen (N). oversupplied phosphorous (P) about 1.5 x . There was no significant difference in the amount of N and P below 30cm in: plots which received either manure or fertilizer at the high rate, or no amendment. Environmentally neutral rates of manure addition could achieve estimated maximum economic yields (approximately 90% of maximum yield). |
