Affectability of time to runoff and runoff coefficient in small laboratory plots to application of organic mulch

Nowadays, organic mulches are used as protective cover for the soil surface.This study in order to investigate the effect of protective cover straw Colza on the components of start time and runoff coefficient in loam – sandy soil in laboratory scale and using a rain simulation with an intensity of 50 mm / h with a 10-minute duration has been done. For this purpose, three levels of protective cover of straw Colza one control treatment  with four levels of moisture, were considered in three replications. The results showed that the application of protective cover of straw Colza would increase and decrease respectively, start time and runoff coefficient. Increasing the level of protective coating in each of the moisture levels increased and decreased, the start time and the runoff coefficient, so that the treatment without protective coating with a moisture content of 30 percent had the lowest starting time and the maximum runoff coefficient with values equal to 28 seconds, and 19 percent and 75 percent of protective cover with dry air humidity had the highest starting time and the lowest runoff coefficient with values equal to 635 seconds and 4percent. Increasing the level of moisture reason increases the runoff coefficient and decreases its onset time, but by applying the protective cover of straw Colza its intensity has decreased. Organic mulch cause delay in occurrence and reduces the amount of runoff coefficient.