Limitation Factors to the Yield of Winter Wheat Growing on Non-irrigated Land in Heilonggang Area

The effects of irrigation and fertilizer on the yield of winter wheat growing on non-irrigated land in Heilonggang region with different pattern of annual rainfall from 1989 to 1993 were conducted.The results show that fertilizer is very important to the yield of winter wheat and poor soil is the main Limiting factor in normal and wet years.In dry years shortage of water is the main limitation factor,applied one time irrigation the yield could be doubled.On basis of one time irrigation,100kg/ha for N and 70 kg/ha for P₂O₅ dressing could also double the yield.Then increasing fertilizer is an important mean to improve non-irrigated winter wheat yield in this area.