QUANTIFICATION OF THE EFFECT OF PEAT ON SOIL DETACHMENT BY RAINFALL

The relationship between soil detachment by rainfall and organic matter content was investigated for soils with different peat contents. Soil detachment was measured with splash cups and a rotating disc simulator was used to generate a 20 min storm of 81 mm h-1 intensity used for the experiment. In addition, detachment was also determined for rainfall durations of 4, 8, 12 and 16 min for seven of the test soils. Soil detachment generally reduced with increasing organic matter for all soils tested after 20 min rainfall as well as for those tested after other rainfall durations. For the latter soils, there was no unique equation to govern detachment reductions with organic matter for all the rainfall durations. Such a unique relationship was obtained by introducing a percentage soil detachment parameter. A good relationship was obtained between percentage soil detachment and peat cover and this was compared with similar existing relationships involving crop cover. The good relationship confirmed findings in an earlier paper that peat reduces detachment by having a mulching effect on the soil. The implication of using peat to reduce soil detachment by rainfall is discussed.