Abstract: To provide scientific basis for rational utilization of green manures in dryland cropping systems, we examined the characteristics of decomposition and nutrient release of green manure. Four types of green manures (including crimson clover, vetch, ryegrass and oat) were used for onsite decomposition incubation and their impacts on soil organic carbon and total nitrogen and crop yield were investigated in a spring maize system. All green manures decomposed rapidly in 0-14 d after incorporation, while the decomposing rate slowed down after six weeks. On the 42 d after the incorporation, the cumulative decomposition was more than 55% for all green manures, with a carbon releasing rate of 59.79%-74.75% and a nitrogen releasing rate of 60.79%-76.61%. On the 130 d after the incorporation, the cumulative decomposition rate was greater than 60% for all green manures, which was higher for leguminous green manure than gramineous green manure. Incorporation of green manures increased the contents of soil organic carbon and total nitrogen. Compared to the control without green manure, the incorporation of green manures increased maize yield by 2.21%-7.06%, with stronger effects of the leguminous green manures than gramineous green manure. In conclusion, leguminous green manure is more suitable for soil health and crop production in dryland cropping systems in northwest China.

Key words: green manure, decomposition, nutrient release, spring maize yield, soil fertility.