Research progress on the regulatory mechanisms of crop roots on N₂O production and emissions in rhizosphere soil

Agricultural land is a major source of nitrous oxide (N₂O). N₂O emissions are not only affected by agricultural management measures but are also closely related to the growth of crop roots. Root self-metabolism affects the formation and reduction of N₂O in the rhizosphere soil and subsequently affects N₂O emissions from farmland. The rhizosphere is an important interface of root-soil-microbial interactions and is the most direct and intense key area where roots affect soil N₂O emissions. It is also a hotspot for soil N₂O production in farmlands, and its share in farmland N₂O emissions is prominent. Therefore, studies have widely focused on the mechanisms by which roots influence rhizosphere N₂O emissions. In this study, relevant research was comprehensively reviewed to evaluate the research progress on the intensity of the influence of crop root growth on N₂O emissions in farmland soil and the regulatory mechanisms of N₂O production and emissions in the rhizosphere microdomain. Existing difficulties in studying the influence of crop root growth on N₂O production and emissions in rhizosphere microdomain soil were also analyzed. Future related research is warranted. The effect of root systems on N₂O emissions from farmlands is complicated and involves many factors. Many studies have shown that factors such as fertilizer application amount and type, soil nitrogen content and form, temperature, humidity, and light intensity can affect the water and nutrients extracted from soil, the conduction and secretion of photosynthetic products to the roots by regulating root growth, and change the rhizosphere microdomain aeration status and nutrients, such as the carbon and nitrogen sources that microorganisms depend on for survival. Furthermore, the community structure, quantity, and activity of rhizosphere microorganisms and their distribution in the soil are affected, which mediates the nitrification and denitrification processes of these microorganisms and affects N₂O generation, reduction, and emission in the rhizosphere soil. Considering the influence of many factors, crop root growth can promote or inhibit soil N₂O production and emission, and the direction and strength of its effects affect the overall N₂O emission budget in farmland ecosystems. Therefore, it is necessary to study the regulatory effect of crop roots on soil N₂O emissions and their feedback mechanisms on global warming, which is of great importance in reducing the uncertainty of global N₂O emission predictions and mitigating the impact of human activities on global climate change.