Grass hedges to reduce overland flow and soil erosion

Overland flow and the consequent soil erosion are worldwide problems that are particularly acute in the Chinese Loess Plateau. Negative consequences are in situ erosion and land impoverishment, and even more serious damage such as physical and chemical pollution in downstream areas. Land impoverishment is due to the loss of fertile topsoil with its load of organic matter and nutrients. Nonetheless, the overland flowing water could be beneficial by helping to reduce the drought risk, if it could be controlled and encouraged to infiltrate the soil. Grass hedges are a cheap and effective structure for controlling overland flow and for filtering nutrients and pollutants, but research has mainly focused on their use in tropical, subtropical and Mediterranean environments. Here, two grass species were tested for their ability to reduce overland flow and soil erosion. Simulated rainfall was applied during sets of three 1-h runs to evaluate the effects of protective grass hedges. We tested two different grasses, Pennisetum alopecuroide and Arundinella hirta, under three rain intensities of 14, 22 and 36 mm h−1, and 5–20% slope gradients on overland flow and soil loss. Plots without grass hedges were used as control. Our results show that grass hedges reduced overland flow by 72% for Pennisetum and by 36% for Arundinella on average. Such native, non-invasive, perennial grasses proved to be very promising for use in conservation practices.