Effects of different conservation tillage measures on soil organic carbon pool in two sequence rotation systems of spring wheat and pease

A 5-year conservation tillage experiment was conduced in Lijiabu, Dingxi City of Gansu Province to study the effects of crop rotation and tillage on soil total carbon, active organic carbon, microbial biomass carbon and soil organic carbon pool management index. The results show that conventional tillage with straw mulching and conventional tillage, in which straw is plowed into soil, increase soil organic carbon, active organic carbon, microbial biomass carbon and soil carbon pool management index under both rotation sequences. Though zero-tillage increases soil carbon pool management index in 0 ~5 cm soil layer, it decreases index of the other soil layers. The findings then suggest that zero-tillage without straw mulching or straw plowing into the soil is non-sustainable for soil organic carbon management.