Effect of wheat straw on changing time to runoff and runoff coefficient in laboratory plots under rainfall simulation

The runoff and soil erosion is most basic of environmental, agricultural and food production problems in the world, that these had adverse effects on the natural ecosystems and man-managed. One of the most important factors of runoff and soil erosion control is using organic and inorganic mulches, that they have most role in runoff and soil erosion control. Therefore in this study, for studying time to runoff and runoff coefficient changes used from an organic mulch (wheat straw mulch) in laboratory conditions. The experiments was done using rainfall simulation, in slope of 30% and plot scale of 0.5 m2 with 3 replications, with two cover percent of 50 and 90% and rainfall intensities of 50 and 100 mm h-1 for 10 min and then the time to runoff and runoff coefficient rates measured. The results showed that in rainfall intensities of 50 and 90 mm h-1, the conservation treatment could increase and decrease time to runoff and runoff coefficient, respectively and the cover of 90% had more effect in increasing time to runoff and decreasing runoff coefficient. The enhancement percent of time to runoff in rainfall intensities of 50 and 100 mm h-1 (cover of 90%) was 102.37 and 70.80%, respectively. The reduction percent of runoff coefficient in rainfall intensities of 50 and 100 mm h-1 (cover of 90%) also was 36.58 and 27.31%, respectively. The effect of conservation treatment and rainfall intensity variables evaluated significant expect in the effect of rainfall intensity × conservation treatment.