[Effects of different maize straw-returning modes on the soil respiration in a winter wheat field]

By using static chamber-TGC method, an in situ observation was conducted in a 10-year conservation tillage winter wheat field to study the effects of different maize straw-returning modes on the soil respiration. The soil respiration had a significant positive correlation with the stubble height of maize straw, and two peaks were observed in wheat growth period. Under no tillage and no straw-returning, the soil respiration was 72.5% of that under no tillage with all straw-returning, and the soil respiration under conventional tillage and no straw- returning was 76.5% of that under conventional tillage with all straw-returning. The soil respiration was significantly positively correlated with the soil temperature and soil organic carbon at 20 cm depth, but no significant correlation with the soil organic carbon at 40 cm depth. A correlation was also observed between the soil respiration and soil moisture. The diurnal soil respiration in the treatments of all straw-returning presented a single-peak curve, with the peak at 18:00. There was a similar variation trend of soil temperature and soil respiration at the depth of 20 cm. Among the treatments of different straw-returning amounts, straw-returning with the stubble of 1 m height could reduce the soil respiration significantly, being a reasonable straw-returning mode.