Effects of short-term tillage managements on soil aggregation stability and carbon and nitrogen in the double-cropping rice system of Southern China

The effects of different short-term (7 years) tillage managements on soil aggregate stability and C and N distribution in the 0–10 and 10–20 cm layers in a double-cropping rice field of southern China were studied. The tillage experiment included four treatments: conventional tillage and straw returning (CT), rotary tillage and straw returning (RT), no-tillage and straw returning (NT), and rotary tillage with all straw removed from paddy field as a control (RTO). We found that mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregate under NT treatment increased by 31.54% and 27.22%, respectively, compared with RTO treatment. The dominant component particle size of paddy soil aggregates was >2 mm for all tillage treatments (51.07 ∼ 59.46%), and the C and N contribution rates in the 0–10 and 10–20 cm soil layers were 26.75% and 28.91%, respectively. Compared with RTO, soil organic carbon (SOC) in all particle-size aggregates at 0–10 cm layer with CT treatment increased by 33.07%, 43.04%, 36.00%, 26.56%, respectively. In conclusion, application of no-tillage with straw returning management was beneficial for the increase of soil aggregate stability and soil quality in the 0–10 cm layer of a double-cropping rice field in southern China.