Effect of conservation tillage on soil microbial diversity in China: A Meta-analysis

A Meta-analysis of 42 published studies was conducted to ascertain the effects of conservation tillage no-tillage with no straw returning (NT), tillage with straw returning (TS), no-tillage with straw returning (NTS) on soil microbial diversity under different climatic types, soil quality, and test durations in China. The study examined the response of soil microbial diversity to conservation tillage, and at the same time evaluated the factors affecting soil microbial diversity. The results showed that compared with conventional tillage, conservation tillage significantly improved the Shannon and Simpson indices of soil microorganisms (P < 0.05), among which no-tillage with straw returning demonstrated the greatest increase in diversity, with an increase of 8.4% and 3.7%, respectively, compared to the control. The Shannon and Simpson diversity indices of bacteria in conservation tillage soil were higher than those in traditional tillage, and the Shannon and Simpson diversity indexes of fungi increased significantly in no-tillage with no straw returning soil, with an increase of 4.4% and 5.3%, respectively (P < 0.05). Soil microbial diversity is significantly affected by annual mean temperature and planted crops under traditional tillage with straw returning. No-tillage treatment in non-neutral soil with better soil environmental quality significantly increased soil microbial diversity (P < 0.05), and the effect of no-tillage on soil microbial diversity in the northern region of China was greater than that in other regions. Therefore, it is suggested that a conservation tillage system with no tillage as the core should be constructed in northern China, and straw returning management measures should be selected according to local conditions in different regions. Furthermore, the diversity of soil fungi and more indices of soil microbial diversity under conservation tillage should be studied.