Based on long-term conservation tillage experiments at Dingxi in the rain-fed field of western Loess Plateau in Gansu province, we investigated the effects of four types of tillage methods, including conventional tillage(T), no tillage no stubble retention (NT),no tillage with stubble retention(NTS) conventional tillage with stubble retention(TS), on soil organic carbon, soil labile organic carbon, soil microbial biomass carbon, carbon pool management and four kinds of soil enzymes involved in carbon cycling were invertase, diastase, cellulase and peroxidase. Aanalysis of the relationship between soil organic carbon and labile carbon fractions and soil enzymes showed that compared with T treatment NTS improved soil organic carbon, soil active organic carbon, soil microbial biomass carbon and carbon pool management index,by 16.3%, 28.26%, 41.88%, 37.04%, respectively. Compared with T, NTS, TS, NT improved the soil invertase, diastase, cellulase, peroxidase activities in 0~30 cm depth of soil, invertase activity were increased by 33.84%, 21.59%, 25.15%, diastase activity by 20.90%, 13.43%, 12.69%, cellulase activity by 39.13%, 17.39%, 4.34%, peroxidase activity by 7.81%, 2.08%, 3.65%. Soil invertase, diastase, cellulase, peroxidase and labile organic carbon fractions and carbon pool management index were significantly positive correla-tion. With the increase in invertase activities, it was benefit to increase the concentration of total organic carbon, soil labile organic carbon and soil microbial biomass carbon, and the invertase played a vital role in the accumulating of soil organic carbon pool, soil cellulase has great effect on soil organic carbon and soil labile organic carbon. Peroxidase favourable for the accumulation of total organic carbon. No tillage with straw cover is suitable for the healthy and stable development of the farmland ecosystem in this region as an important way to reduce losses for carbon pool. |