免耕对农田土壤团聚体的影响研究：Meta分析

为明确免耕对农田土壤团聚体的影响，通过Meta分析整合已发表的116项研究，综合探究免耕对土壤团聚体粒径分布、平均重量直径（MWD）以及团聚体有机碳含量的影响.结果表明，与耕作相比，免耕显著提高土壤大团聚体占比（10.9%）和MWD（12.8%），减少黏粉粒占比（-15.5%），但对微团聚体及团聚体有机碳含量没有显著影响.亚组分析表明，免耕显著提高西北地区土壤大团聚体占比（17.6%），提高华北地区土壤团聚体MWD（15.4%）；在旱地及黏壤土中，免耕分别提高团聚体MWD效应值12.6%和18.4%；免耕提高大团聚体占比的效果随土壤pH值增加而增加；秸秆还田条件下，免耕显著提高土壤大团聚体占比（9.6%）及MWD（11.6%），秸秆移除后，免耕对团聚体的影响效应均不显著；在试验年限方面，短期免耕（< 5 a）显著提高土壤大团聚体比例，而长期免耕（> 10 a）提高团聚体MWD；在土壤深度方面，免耕仅能改善耕层（0~20 cm）土壤团聚体粒径分布及MWD，而对深层土壤（> 20 cm）团聚体没有影响.综上所述，免耕能够改善土壤团聚体粒径分布及稳定性，但对团聚体碳含量无显著影响.在实际生产中，要充分考虑生产区域、土壤性质和田间管理等因素，以达到有效改良土壤团聚体的目的.

Effect of No-tillage on Soil Aggregates in Farmland：A Meta Analysis

In order to clarify the impact of no-tillage on the quality of farmland soil aggregates in China and promote the adaptive application of no-tillage practices， a Meta-analysis was conducted by collecting data from 116 published studies. The effects of no-tillage on aggregate size distribution， mean weight diameter （MWD）， and aggregate-associated C were studied. The results showed that compared with that under tillage， no-tillage significantly increased the proportion of macroaggregates （10.9%） and MWD （12.8%） and decreased the proportion of clay and silt （-15.5%） but had no significant effect on soil microaggregate and aggregate-associated C. The subgroup and Meta regression analysis showed that no-tillage significantly increased the proportion of macroaggregates in Northwest China （17.6%） and MWD in North China （15.4%）. In upland and clay loam， no-tillage increased MWD by 12.6% and 18.4%， respectively. The effect of no-tillage on increasing the proportion of macroaggregates increased with the soil pH. When straw returned， no-tillage significantly increased the proportion of macroaggregates （9.6%） and MWD （11.6%）， but no significant effect of no-tillage on aggregates was found after straw removal. Regarding test duration， short-term （ < 5 a） no-tillage could significantly increase the proportion of macroaggregates， whereas long-term （ > 10 a） no-tillage could improve the MWD. In different soil layers， no-tillage could only significantly improve the aggregate size distribution and MWD in topsoil （0-20 cm） but had no effect in subsoil （ > 20 cm）. In summary， no-tillage could improve aggregate size distribution and stability but had no effect on aggregate-associated C. Production region， soil properties， field management methods， and other factors should be fully considered in production practice to effectively improve the quality of soil aggregates.