Abstract: Based on the measured data from the winter wheat fields in Zhengzhou of Henan Province, the vertical distribution of root length density (RLD) and root mass density (RMD) were analyzed. The results showed that the roots of winter wheat were centralized in upper soil layer. At the depth of 0-50 cm, the RLD and RMD occupied 57.% and 66.% of the total; while at 50-100 cm, they were 23.4% and 18.7%, respectively. The variation of RLD and RMD with soil depth accorded with exponential function. Considering of the root distribution and its water absorption, the feasible depth of soil available water at planting for winter wheat in Zhengzhou was 100 cm.

Key words: Steep slopeland, Soil moisture, Soil nutrients, Productivity, Spatial variability, Loessial semiarid region