Contour grass strips for soil erosion control on steep lands: a laboratoryevaluation

The effectiveness of Festuca ovina and Poa pratensis as contour grass strip s for erosion control was examined in a laboratory experiment for an erodib le sandy loam soil on 21, 25 and 29% slopes. No significant differences (P < 0.05) were observed in runoff between the plots with grass strips and bar e soil but significant differences in soil loss were recorded. Both grasses reduced erosion in the early part of the simulated storms by pending water behind the barrier, filtering sediment and causing deposition within the p onded area. The I! pratensis barrier was less rigid and became flattened un der submergence in the later part of the storms. Runoff flowed over the gra ss strip forming rills on the slope below, which then cut back and undermin ed the barrier. These barriers resulted in as much soil loss as bare soil t owards the end of the storms on all three slopes. The F. ovina was effectiv e in controlling erosion on the 21% and 25% slopes but not on the 29% slope .