Alfalfa is often planted perennially in the Loess Plateau

which leads to the desiccation of deep soil layer.So

alfalfa is planted with four different patterns to lessen the formation of dried soil layer

which includes the halve sowing establishment

the intercrop establishment

the plastic film mulching establishment and the check establishment.The main results showed: the water storage of the plastic film mulching establishment was higher than the other three establishments in any time of the year.There is a very significant linear dependence between the available rainfall and replenishment of the soil water.The replenishment of plastic film mulching establishment is more obviously than the othr three establishments.The available rainfall replenish the active layer significantly.During the transition from spring to summer

the stable layer replenish the active layer significantly.There is a very significant linear dependence between the replenishment of stable layer and active layer of four establishments

but replenishments are different.