Narrow grass hedge effects on nutrient transport following swine slurry application

The effectiveness of a narrow grass hedge in reducing runoff nutrient loads following swine slurry application was examined. Slurry was applied to 0.75-m wide by 4.0-m long plots established on an Aksarben silty clay loam soil 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. The grass hedge did not significantly reduce runoff nutrient transport after the swine slurry which contained relatively small amounts of manure was applied. Increasing N application rate from a 1 year to a 3 year corn N requirement also did not result in a significant increase in N or phosphorus (P) loads in runoff. 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. The rates of transport of dissolved P, particulate P, and total P were each influenced by runoff rate and increased in a linear fashion from 7 to 25, 65 to 357, and 72 to 382 g ha^-1 min^-1, respectively. Runoff rate significantly affected rates of transport of NO ₃-N, NH₄-N, and total nitrogen which increased in a linear fashion from 273 to 1204, 30 to 47, and 323 to 1490 g ha^-1 min ^-1, respectively. Runoff rate is an important variable that should be considered when estimating nutrient transport following application of swine slurry containing relatively small amounts of nutrients.