Abstract：
Straw return is an effective measure to promote sustainable agriculture by significantly improving soil fertility. At present, few studies have been conducted on the most effective carbon enhancing management measures for various crops. Therefore, we conducted a meta-analysis using data collected from 184 literature sources, comprising 3297 data sets to analyze the carbon increase effects of straw returning in three main crops (rice, maize, and wheat) in China and to explore the influence mechanism of natural factors, soil properties, straw return measures, and cropping systems on the carbon enhancement effect. The study showed that straw return significantly increased soil organic carbon and the rate of increase was higher for wheat at 15.88% (14.74%-17.03%) than for rice at 12.7% (11.5%-13.91%) and maize at 12.42% (11.42%-13.42%), with varying degrees of improvement in other soil physicochemical properties. Natural factors have the greatest impact on the carbon increasing effect of rice fields, reaching 28.8%, especially at temperature between 10 °C and 15 °C, less than 800 mm precipitation, low latitude, and short frost-free period. Maize and wheat are most affected by soil properties, reaching 41% and 34.5% respectively. Furthermore, field management practices also play a pivotal role, organic carbon increasing obviously was observed when the C/N ratio of exogenous nutrients is bigger than 20 with the low initial organic matter. Shallow tillage and less than 7.5 t hm-2 straw returning with 3-10 years to the field are ideal for rice and maize. Crop rotation, especially in drylands, increased soil organic carbon more significantly than continuous. The results of our analysis can provide valuable insights into the effect of straw return on carbon increase. In the future, the soil carbon can be improved by adopting rational cropping patterns and straw return measures with taking into account climate and soil characteristics for different crops.
摘要：
秸秆还田是通过显著提高土壤肥力促进可持续农业的有效措施。目前,关于各种作物最有效的碳增强管理措施的研究很少。因此,我们使用从184个文献来源收集的数据进行了荟萃分析，包括3297个数据集，用于分析三种主要作物(水稻，玉米,和小麦）在中国，并探索自然因素的影响机制，土壤性质，秸秆还田措施,和种植系统对碳的增强作用。研究表明，秸秆还田显著增加了土壤有机碳，小麦的增幅为15.88%(14.74%-17.03%)，高于水稻的12.7%(11.5%-13.91%)和玉米的12.42%(11.42%-13.42%)，其他土壤理化性质均有不同程度的改善。自然因素对稻田增碳效应的影响最大,达到28.8%,特别是在10°C至15°C的温度下，降水量小于800毫米，低纬度,无霜期短。玉米和小麦受土壤性质影响最大,分别达到41%和34.5%。此外，现场管理实践也起着举足轻重的作用，当外源养分的C/N比大于20时，有机碳明显增加，初始有机质较低。浅耕和少于7.5thm-2的秸秆还田3-10年是水稻和玉米的理想选择。作物旋转，尤其是在旱地,土壤有机碳比连续增加更显著。我们的分析结果可以为秸秆还田对碳增加的影响提供有价值的见解。在未来,通过采取合理的种植模式和秸秆还田措施，同时考虑不同作物的气候和土壤特性，可以提高土壤碳含量。
