Rill erosion on a structurally degraded sandy loam surface soil
1993
Murphy, B.W. | Flewin, T.C. (New South Wales Conservation and Land Management Research Centre, Cowra (Australia))
The degree of rill erosion from a 0.65 ha site with a hardsetting red duplex soil having a structurally degraded surface soil was examined. The soil characteristics indicated that the soil was a structurally degraded soil with low aggregate stability (2.5 percent of total soil), very low organic matter levels (0.91 percent for 0-50 m) and relatively high bulk density (1.56 h per cu m). The low aggregate stability resulted in the rapid breakdown of soil aggregates and settling of the soil under rainfall causing surface crusting and low infiltration rates as well as decreasing depressional storage. This resulted in high runoff and rill erosion, considered to result from the combination of the poor structural condition of the soil, the tilled or loosened soil condition at the onset of the rainfall events, the duration and number of the low intensity rainfall events and the low evaporation rates between rainfall events. The results suggest that to reduce soil loss to acceptable levels under these conditions, it is necessary to adopt management practices that increase surface cover, maintain infiltration rates, reduce tillage and increase soil aggregate stability in combination with erosion control earthworks. The USLE equation should not be used to predict erosion for individual events or erosion resulting from concentrated flow; it should be used to estimate expected long-term soil loss under specific conditions.
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