Research progress on the effect of soil fumigation on soil nitrogen cycles and functional microorganisms

Soil fumigation has been widely used with the advantages of high efficiency and broad spectrum, moreover, the broad spectrum of fumigants can not only kill the harmful organisms in the soil, but also affect the non-target microorganisms driving the circulation and transformation of various elements in the soil. Soil nitrogen cycle is an important hub connecting the atmosphere, soil and water, and the key processes related to the nitrogen cycle are mainly driven by microorganisms. Therefore, soil fumigation is bound to affect the material transformation in the nitrogen cycle. Existing research shows that the fumigant can significantly change the species and abundance of functional genes and microorganisms related to nitrogen cycles. In the short term, fumigation can improve soil nitrogen mineralization rate and increase the amount of accumulated nitrogen mineralization in the soil, but the nitrogen fixation, nitrification and denitrification process were suppressed, which could improve the utilization rate of nitrogen. This review summarized that the key processes of nitrogen fixation, mineralization, nitrification and denitrification in soil nitrogen cycle and the effects of functional microorganisms after fumigating with several commonly used fumigants to provide a basis for studying the environmental risks of soil fumigation.