Abstract: 【Objective】In order to improve the water use efficiency under conservation tillage, we study the effects of subsoiling on soil moisture under no-tillage.【Method】A field experiment of 40cm subsoiling under no-tillage was conducted from 2005 to 2006. Based on the observational data of soil moisture and crop yield, the physical basis of subsoiling for water conservation and yield increase was analyzed. 【Result】The results showed that: during oats growth season, 0-100cm soil water storage under subsoil was more than no-tillage. In the 0-100cm soil depth, the soil moisture in 50-100cm under subsoiling were more compared with no-tillage, which increased with the soil depth increasing when it’s dry; decreased with the soil depth increasing when it’s rainy. Compared with no-tillage, Subsoiling can reduce the water consumption of oats in the 0-50 cm soil layer and improve the efficient use of water in the 50-100cm soil layer by root system. Subsoiling increased the yield by 18.29％ average increase rate in two years. Subsoiling increased water use efficiency by 16.8% average increase rate in two years. The effects of subsoiling for water conservation and yield increase was affects by precipitation, well-proportioned rainfall was better to increase yield and water use efficiency. Meanwhile, subsoiling decreased bulk density, which increased the available precipitation.【Conclusion】Subsoiling contained more soil moisture and improved water use efficiency. The The effects of subsoiling for water conservation and yield increase was affects by precipitation and soil bulk density.

Key words: no-tillage, subsoiling, water conservation, yield increase