Nutrient Runoff Following Manure Application

A field study was completed to measure the effects of varying flow rate on nutrient transport following the application of varying amounts of beef cattle manure to plots containing either no-residue or a wheat residue cover. Beef cattle manure was applied and incorporated into the soil in May 2010 to meet zero, one, two, four or eight year corn phosphorus requirements. Simulated rainfall events were applied in June and July 2010. The presence of a crop residue cover significantly increased the transport of dissolved phosphorus, total phosphorus, NO3-N, NH4-N, and total nitrogen in runoff but decreased soil loss. Multiple year manure applications may be economically wise but can contribute to elevated nutrient levels in runoff, especially the four and eight year manure application rates. Increasing runoff rates simulating longer slopes also increased nutrient transport in runoff. Another study was conducted to measure the effectiveness of a narrow wheat strip in reducing runoff nutrient transport. Beef cattle manure was applied at rates needed to meet a zero, one, two or four year corn phosphorus requirement. Simulated rainfall events were applied the same week the manure was added. Excessive amounts of manure were added after the initial tests were completed to meet 8, 12, 16, or 20 year corn phosphorus requirements. This was done to determine the effects of excessive manure application on runoff nutrient transport. The wheat strip significantly reduced the mean transport of DP, NO3-N, NH4-N, and TN in runoff. The wheat strip also reduced EC of runoff, particularly when excessive amounts of manure were applied. Manure rate significantly affected measurements of DP, PP, TP, NH4-N, TN and EC. Runoff rates significantly affected each of the measured runoff water quality parameters. When excessive manure amounts were applied to meet the 8, 12, 16, or 20 year crop P requirements, DP, PP, TP, and NH4-N transport generally increased as application rates increased. The results indicate that wheat strips can reduce N and P transport in runoff