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A field study was completed to compare the effects of land application methods, swine growth stage, and varying flow rates following the application of varying amounts of swine manure to 0.75-m by 2.00-m long plots. Three different manure sources were used to represent key different growth stages including growers, finishers, and sows and gilts. The different swine manures were applied in May and Jun 2011 to meet a 1 year nitrogen (N) requirement for corn. Three different land application methods were used to apply the swine manure, broadcast, incorporation, and injection. Runoff water quality was measured during three 30 minute simulated rainfall events. Following the third and final simulated rainfall even, inflow was added at the top of the plots to simulate increased slope length. Application method significantly affected dissolved phosphorus (DP) transport but did not affect the transport of particulate phosphorus (PP), total phosphorus (TP), NO3-N, NH4-N, or total nitrogen (TN). The disking and injection application methods resulted in significantly lower DP transport than that of the broadcast method. The growth stage significantly affected DP transport but was not found to significantly affect PP or TP transport. Growth stage also significantly affected NH4-N and TN transport but did not affect the transport of NO3-Nnutrient transport rate was found to increase in a linear fashion with increasing runoff rate.
Another paper evaluated the effectiveness of a narrow grass hedge in reducing nutrient runoff loads following land application of swine manure. Swine manure was applied to 0.75-m wide by 4.00 m long plots established on an Arksarben silty clay loam located in southeast Nebraska. Manure treatments consisted of no manure application and manure application to meet the 1, 2, or 3 year nitrogen (N) requirements for corn. Runoff water quality was measured during three 30 minute simulated rainfall events. Following the third and final simulated rainfall event, inflow was added at the top of the plot to simulate increased slope length. The narrow grass hedge did not significantly affect runoff nutrient transport. Varying nitrogen application rate also did not significantly affect runoff nutrient transport. The grass hedge significantly reduced electrical conductivity (EC) measurements from 0.78 to 0.73 dS m-1 and pH values from 8.16 to 7.85. Overland flow rate did significantly affect nutrient transport rates which increased in a linear fashion with increasing runoff rate. A narrow grass hedge did not significantly reduce runoff loads of N and P following swine slurry application.
Advisor: John E. Gilley