Effect size and duration of recommended management practices on carbon sequestration in paddy field in Yangtze Delta Plain of China: A meta-analysis

Increasing evidence has shown that recommended management practices (RMPs) benefit carbon sequestration in cropland soils, but the differences in the effect size and duration between RMPs are not well documented, especially in paddy fields where multiple cropping systems are in use. In order to select feasible techniques and develop effective strategies for soil organic carbon (SOC) management for long-term sustainable rice production that promote environmental health, we conducted a meta-analysis to compare the carbon sequestration effects based on size and duration of several common RMPs; using in the Yangtze Delta Plain of eastern China. The meta-analysis data base included 26 long-term field experiments with 86 paired trials. The mean depth of soil sampling in all trials was 16.5 cm. Results showed that there were significant effects from applications of crop residue and animal manure applications on levels of carbon sequestration. Crop residue additions and animal manure applications increased SOC by 0.41 Mg ha(-1) yr(-1) and 0.34 Mg ha(-1) yr(-1) on average during the experiment period, respectively. In contrast, reduced/no tillage practices had no effect on levels of carbon sequestration in the study area. Crop residue additions and animal manure applications will enhance SOC, but only over periods of about 20 and 40 years, respectively. Significantly greater effect of RMPs on carbon sequestration occurred in a triple cropping system incorporating with double rice than that in double cropping system with only a single rice season. The above results suggest that increases in organic matter, such as additions of crop residues and animal manure to soils may have great effects on carbon sequestration in paddy fields in the research area. (C) 2009 Elsevier B.V. All rights reserved.