| Abstrakt: |
[Objectives] The paper aims to explore the topsoil carbon sequestration potential size under different straw return modes in paddy fields in South China. [Methods] Based on the soil organic carbon data of 102 topsoil samples taken from 40 paddy field experiment sites in South China, we conducted a Meta-analysis to study the relative annual change of topsoil organic carbon content(RM), carbon sequestration duration and accumulation enhancement rates of soil organic carbon over the whole soil organic carbon sequestration period in paddy fields in South China under three straw return modes, conventional tillage with straw return(CTS) ,no tillage with straw return ( NTS) and rotary tillage with straw return (RTS). [Results] CTS, NTS and RTS could significantly increase the topsoil organic; carbon content in paddy fields in South China, and the RM under CTS,NTS and RTS were 0.42,0.37 and 0.64 g·kg-1, ·a-1 respectively. The highest RM among the three straw return modes was the RTS treatment ,which was about 1.7 times as large as that of the NTS treatment and 1.5 times as much as that of the CTS treatment. The average RM in double cropping system and triple cropping system under straw return treatments were 0.40 and 0.61 g·kg-1 ·a-1, respectively, which means straw return could increase the soil organic carlxm content no matter what kind of cropping system was adopted. In condition of the same straw return mode, the RM in triple cropping system was significantly higher than that in double cropping system, and the gap of RM between triple cropping system and double cropping system under NTS treatment was the highest of 2 times. While under CTS and RTS treatments, the gaps were 1.37 and 1.39 times which were slightly smaller than those under NTS treatment. The topsoil organic carbon accumulation rate decreased gradually with increasing time. The soil organic carbon sequestration duration of CTS, NTS and RTS were about 27, 44 and 30 years, respectively, and the NTS treatment was the longest among them. Accumulation enhancement rates of soil organic carbon for CTS,NTS and RTS over the whole soil organic carlxm sequestration period were about 15,8%,23.3% and 27.3%, respectively, and RTS treatment was the largest among them. [Conclusions] From the perspective of soil carbon sequestration in cropland, straw return with rotary tillage was more appropriate; than the other two straw return modes in paddy fields in South China. [ABSTRACT FROM AUTHOR] |
