通过秸秆还田(SR)提高土壤有机碳(SOC)已被广泛推荐为气候智能型农业的一种有希望的做法。许多研究已经调查了秸秆还田对SOC含量的相对影响,而秸秆还田在积累SOC存量方面的规模和效率仍不确定。这里,我们提出了SR引起的SOC变化的幅度和效率的综合,使用一个数据库,包括全球115个地点的327个观察结果。秸秆还田使SOC增加3.68±0.69(95%置信区间,CI)MgCha-1,相应的C效率为20.51±9.58%(95%CI),其中<30%是由秸秆C输入直接贡献的。SR引起的SOC变化幅度随着秸秆C输入和实验持续时间的增加而增加(P<0.05)。然而,在这两个解释因素下,C效率显着降低(P<0.01)。发现免耕和轮作可以增强SR引起的SOC增加,无论是规模还是效率。与碱性和有机贫瘠的土壤相比,在酸性和富含有机物的土壤中,秸秆回流所吸收的碳更多。机器学习随机森林(RF)算法表明,秸秆投放量是控制秸秆还田规模和效率的最重要单因素。然而,当地农业管理和环境条件共同决定了SR引起的SOC存量变化的空间差异。这需要通过优化环境条件良好的地区的农业管理,农民可以积累更多的碳,而负面影响很小。通过阐明多个局部因素的重要性和相对重要性,我们的研究结果可能有助于制定针对特定地区的秸秆还田政策,将SOC增量及其环境成本整合在一起。
Enhancing soil organic carbon (SOC) through straw return (SR) has been widely recommended as a promising practice of climate-smart agriculture. Many studies have investigated the relative effect of straw return on SOC content, while the
magnitude and efficiency of straw return in building up SOC stock remain uncertain. Here, we present an integrative synthesis of the
magnitude and efficiency of SR-induced SOC changes, using a database comprising 327 observations at 115 sites globally. Straw return increased SOC by 3.68 ± 0.69 (95 % Confidence Interval, CI) Mg C ha-1, with a corresponding C efficiency of 20.51 ± 9.58 % (95 % CI), of which <30 % was contributed directly by straw-C input. The
magnitude of SR-induced SOC changes increased (P < 0.05) with increasing straw-C input and experiment duration. However, the C efficiency decreased significantly (P < 0.01) with these two explanatory factors. No-tillage and crop rotation were found to enhance the SR-induced SOC increase, in both
magnitude and efficiency. Straw return sequestrated larger amount of C in acidic and organic-rich soils than in alkaline and organic-poor soils. A machine learning random forest (RF) algorithm showed that the amount of straw-C input was the most important single factor governing the
magnitude and efficiency of straw return. However, local agricultural managements and environmental conditions were together the dominant explanatory factors determining the spatial differences in SR-induced SOC stock changes. This entails that by optimizing agricultural managements in regions with favorable environmental conditions the farmer can accumulate more C with minor negative impacts. By clarifying the significance and relative importance of multiple local factors, our findings may aid the development of tailored region-specific straw return policies integrating the SOC increment and its environmental side costs.