Grass hedges for the protection of sloping lands from runoff and soil loss: An example from Northern China

Simulated rainfall was applied during three 1-h “runs” (dry run, wet run and very wet run) to evaluate the effects of rain intensity (14, 22 and 36 mm/h), protective grass hedges (two different grasses: Pennisetum alopecuroides and Arundinella hirta) and slope gradients (5%, 10%, 15% and 20%) on overland flow and soil loss. Plots without grass hedges were used as controls. The soil in the plots was a loam covered with soybean plants. Grass hedges substantially reduced overland flow (65–88% reduction for Pennisetum and 15–38% for Arundinella) and soil loss (decreased by 77–84% in the case of Pennisetum and by 21–61% for Arundinella), and protection with P. alopecuroides hedges showed a higher efficiency than A. hirta. Corresponding to hedge protection, rain intensity and slope were positively correlated to runoff and soil loss. Soil loss and runoff were significantly and positively but non-linearly correlated: a multiplicative model gave better fittings than linear models in all cases (s = exp(−5.40537 + 1.55017 × ln (r)), R2 = 80.08%). In conclusion, grass hedges resulted an effective conservation measure for runoff and soil loss control; in particular P. alopecuroides appears to be a suitable species for application in conditions in northern China.