Study on Soil Water Content Distributions in the Caragana-Grass Compound System

The present study was aimed to explore the dependences of soil water content distributions on the different sizes of belt spaces in the caragana-grass compound system in Siziwangqi county, Inner Mongolia. The soil water contents were measured at selected typical sample plots within the 5m, 10m and 16 m belt-space caragana -grass compound systems. The soil water contents in the 5m belt-space system were found to be the lowest among the three systems, to decrease with soil depth, also to decrease with distance from caragana belt, to vary greatly from month to month, and to decrease sharply in September due to the over consumption of soil water. The soil water contents in the 10m belt-space system were highest among the three systems, increased with the soil depth, fluctuated greatly from month to month, and also decreased sharply in September. The use of soil water by vegetation in this system was not close to its potential, nor is it balanced. The soil water contents in the 16m belt-space system were at median level among the three systems, were highest at the soil depth where the majority of roots locate, were relatively balanced in horizontal distribution, and had very small monthly changes. Therefore, the 16m belt-space caragana-grass compound system had the best soil water content distributions that enabled the full use of soil water by both caragana and within belt-space plants, and should be the one recommended for adoption in this area.