Two experiments both of simulation under rainproof shelter and plot in field have been done to study the yieldresponse of corn to different treatments of water supply in Non-irrigated Plateau of Loess. The results show that

inthe field simulation column experiment

the biomass and the grain yield of corn are increased parabalically with theincreaseL of the soil moisture or the total water consumption

but the crop water use efficiency is hyperbolically de-creased with the increase of the total water consurnption

In the field plot experiment

the grain yield of corn is in-creased parabalically with the increase of the total water consumption too

the minimal crop water efficiency can bernade in the dry treatment

but the maximal crop water use efficiency can be rnade in the treatment of low watersupply(i.e

the irtigation quota is 70 mm per Mu)

with the increase of the irrigation(quota

the soil water depletionis decreased

and the percent age of soil water depletion in total is exponentially decreased.