Protective Impact of Colza Straw (Brassica napus L.) on Runoff and Soil Loss Control Using Rainfall Simulation

Soil erosion is a global problem that seriously threatens soil and water resources. This research was conducted to study the effect of protection of colza straw on runoff and sediment yield from the laboratory plots using the rainfall simulator. Three coverage of 25, 50 and 75% of colza straw mulches and a control treatment (without coverage) were considered with three moisture levels of 15, 20 and 30% in three replications. The results showed that colza straw had a significant effect on runoff and sediment reduction. All moisture levels in three protective coverage levels decreased runoff volume by13.14, 26.29 and 31.52%, respectively, and sediment yield by 41.21, 72.4 and 78.78%, respectively. With increasing of protection coverages from no cover to the higher coverages, the trend of runoff and sediment yield decreased, so that the lowest amount of runoff (1821 ml) and sediment yield (58 g) were measured in the protective coverage of 75% with the moisture of 15%. The highest amount of runoff (5501 ml) and sediment yield (522 g) were observed in the control treatment at a moisture level of 30%. With increasing the moisture levels from the amount of runoff and sediment yield increased. Moreover, by applying the protective cover, runoff and sediment yield decreased at the same moisture levels.