生物炭施用对农田土壤团聚体及有机碳影响的整合分析

生物炭作为一种土壤改良剂，已广泛用于农田土壤的改善.为明确生物炭对我国农田土壤固碳效应的影响，基于已公开发表的文献数据，利用Meta分析法研究生物炭施用在不同试验条件下对土壤团聚体、团聚体碳和土壤有机碳的响应.结果表明，与不施生物炭相比，施用生物炭显著增加土壤大团聚体比例（10.8%）和平均重量直径（MWD，13.3%），对土壤微团聚体和粉黏粒组分无显著作用；施用生物炭能够显著增加土壤各粒径团聚体碳和土壤总有机碳含量，土壤有机碳增幅为56.9%.通过亚组分析和Meta回归分析表明，华北地区施用生物炭土壤有机碳增幅最大（39.4%）；不同试验类型下施用生物炭均能显著提高土壤有机碳含量；相比不施肥，施肥条件下施用生物炭能显著改善土壤结构，提升土壤肥力；生物炭在施用>2 a条件下，能显著提高大团聚体比例（15.7%）、MWD （21.2%）、大团聚体碳（31.7%）和土壤有机碳含量（40.0%）；相比木材、木屑等原料制备的生物炭，农作物秸秆制备的生物炭对土壤的改良效果更佳；在高氮土壤中施用生物炭更有利于提高土壤团聚体稳定性.综上所述，生物炭施用可以改善土壤团聚结构，促进土壤有机碳积累，对农田肥力维持与提升具有重要意义.

Effect of Biochar on Agricultural Soil Aggregates and Organic Carbon: A Meta-analysis

As a soil amendment, biochar has been widely used to ameliorate agricultural soil. To ensure the effect of biochar on the carbon sequestration of farmlands in China, a Meta-analysis was carried out via collecting published literatures. We quantitatively analyzed the response of biochar application to soil aggregates, aggregate carbon, and soil organic carbon to different experimental conditions. The results showed that the application of biochar significantly increased the proportion of soil macroaggregates(10.8%) and MWD(13.3%) but had no significant effect on soil microaggregates and silty-clay compared with those in the non-biochar-added treatment. Moreover, biochar addition significantly increased soil organic carbon content(56.9%), with the largest increased area in North China(39.4%), and enhanced intra-aggregate carbon contents of each particle size. Biochar could significantly increase soil organic carbon content under different experimental designs. Compared with that under non-fertilization, biochar combined with fertilization could also significantly improve soil structure and soil fertility. We also found that more than two years of biochar application significantly increased the proportion of macroaggregates(15.7%), MWD(21.2%), macroaggregate carbon(31.7%), and soil organic carbon(40.0%). Meanwhile, biochar produced from crop straw had better soil improvement effects than that of wood and sawdust. Biochar applied in high-nitrogen soil was more beneficial to improve soil stability. Thus, we concluded that biochar could meliorate soil structure and promote the accumulation of soil organic carbon, which was of importance for the fertility maintenance and improvement of the farmland.