How much is soil nitrous oxide emission reduced with biochar application? An evaluation of meta‐analyses
How much is soil nitrous oxide emission reduced with biochar application? An evaluation of meta‐analyses
复制标题
DOI：
10.1111/gcbb.13003
复制
发表时间：
2022-09
期刊：
影响因子：
--
通讯作者：
N. Kaur;C. Kieffer;Wei Ren;D. Hui
中科院分区：
文献类型：
--
作者：
N. Kaur;C. Kieffer;Wei Ren;D. Hui
氧化亚氮（N2 O）是仅次于二氧化碳和甲烷的第三大温室气体，农田是土壤N2 O排放的地球化学热点。为减少土壤N2 O及其他温室气体排放，已采用气候智慧型农业措施，包括生物炭应用。已经进行了许多关于生物炭应用的研究，但这些研究的结果并不确定。为了解决这个问题，Meta分析，一种综合多项独立研究结果的定量综述，已被广泛使用。不同Meta分析的结果也不同，但很少进行评价。在这项研究中，我们评估了生物炭应用对土壤N2 O排放影响的Meta分析。提出了一个总平均响应比（RR）来估计整体效应以及实验设置、生物炭和土壤性质以及农业实践的影响。我们发现2014年至2022年间发表了18篇Meta分析论文。样本量（出版物或实验）从小于30到大于1000不等，平均样本量为275。除1项研究外，所有研究均计算RR。虽然四项Meta分析没有发现生物炭应用对土壤N2 O排放量的显着影响，但所有其他分析都报告了土壤N2 O排放量的减少，但幅度范围为-10.5%至54.8%。综合这些Meta分析的所有结果，我们发现生物炭的应用总体上显着减少了38.8%的土壤N2 O排放。在一年半之前，影响随实验持续时间的增加而增加，一年半之后则减小。生物质炭的施用量和碳氮比对生物质炭对土壤N2 O排放的影响较大。这项研究表明，虽然Meta分析提供了更全面和更好的估计，但这些研究之间的不一致性可能需要进一步评估。基于Meta分析的总平均RR可能比单一Meta分析更准确和更具代表性。
Nitrous oxide (N2O) is the third important long‐lived greenhouse gas next to carbon dioxide and methane and croplands are considered biogeochemical hotspots of soil N2O emissions. To reduce soil N2O and other greenhouse emissions, climate‐smart agricultural practices including biochar application have been applied. Many studies have been conducted with biochar application but results from these studies are not conclusive. To address this issue, meta‐analysis, a quantitative review that synthesizes results from multiple independent studies, has been widely used. The results from different meta‐analyses also differ but are seldomly evaluated. In this study, we evaluated meta‐analyses on the effects of biochar application on soil N2O emissions. A grand mean response ratio (RR) was further proposed to estimate an overall effect and the impacts of experiment setting, properties of biochar and soil, and agricultural practices. We found 18 meta‐analysis papers were published between 2014 and 2022. Sample size (publications or experiments) varied from less than 30 to more than 1000, with a mean sample size of 275. RR was calculated in all studies except one. While four meta‐analyses did not find a significant effect of biochar application on soil N2O emissions, all others reported reductions of soil N2O emissions, but the magnitude ranged from −10.5% to −54.8%. Synthesizing all results from these meta‐analyses, we found that biochar application overall significantly reduced the soil N2O emissions by 38.8%. The impacts increased with experimental duration till one and half years and reduced after that. Biochar application rate and C:N ratio had large influence on the effects of biochar application on soil N2O emissions. This study demonstrated that while meta‐analysis provides a more comprehensive and better estimation, the inconsistence among these studies may need to be further evaluated. A grand mean RR based on meta‐analyses could be more accurate and representative than single meta‐analysis.