Effects of narrow grass hedges on nutrient transport from land application areas

The placement of stiff-stemmed grass hedges on the contour along a hill slope has been shown to decrease runoff nutrient transport. This study was conducted to measure the effectiveness of a narrow grass hedge in reducing runoff nutrient transport from plots with a range of soil nutrient values. Composted beef cattle manure was applied at dry weights of 0, 68, 105, 142, and 178 Mg ha^-1 to a silty clay loam soil and then incorporated by disking. Soil samples were collected 243 days later for analysis of water-soluble phosphorus (WSP), Bray and Kurtz No. 1 phosphorus (Bray-1 P), NO₃-N and NH₄-N. Three 30-min simulated rainfall events, separated by 24-hour intervals, were then applied. The transport of dissolved phosphorus (DP), total P (TP), NO₃-N, NH₄-N, total nitrogen (TN), runoff, and soil erosion were measured from 0.75 m wide × 4.0 m long plots. Compost application rate was found to significantly affect WSP, Bray-1 P, and NO₃-N content of the soil. The transport of DP, TP, NO₃-N, NH₄-N, TN, runoff and soil erosion was reduced significantly on the plots with a grass hedge. Mean runoff on the hedge and no-hedge treatments was 17 and 29 mm, respectively, and soil erosion rates were 0.12 and 1.48 Mg ha^-1. Compost application rate significantly affected the transport of DP, TP, and NO₃-N in runoff. The experimental results indicate that stiff-stemmed grass hedges, planted at selected down slope intervals, can significantly reduce the transport of nutrients in runoff from areas with a range of soil nutrient values.