Based on natural rainfall erosion characteristic

the paper studied on soil crust formation on the slope farmland according to rainfall

runoff and rainfall runoff slope comprehensive methods in indoor. Some characteristics are found through measuring the crust hardness

bulk density and thickness of crust layer. In the process of soil crust forming

rainfall function is mainly impact

runoff function is mainly depositing and condensing

and their functions increase as rainfall intensity and depth of runoff increasing. But the function is also limited while slope degree increasing

the growth of crust is no good. On the whole

the function of rainfall is more powerful than runoff.