According to the result of simulated runoff experiment in laboratory

the impact of the mineral nitrogen's transport with surface runoff and leaching are analyzed. It is validated that the straw coverage can greatly decrease soil erosion and reduce the velocity of flow on the loess slope. Therefore

the interaction between soil nitrogen and runoff is prolonged

which lead to more mineral nitrogen to be dissolved by runoff. However

the total amount of the mineral nitrogen loss by runoff is reduced. Compared with the result of bare land

the straw cover can be concluded that the infiltrative depths and amount of water and soil nitrate are added.