Effect of Global Warming and Precipitation Change on Agricultural Soil Respiration

As an important part of terrestrial ecosystem, farmland ecosystem is important source/sink of atmospheric carbon dioxide. Exploring the effects of global warming and precipitation change on soil respiration (R_s) in agricultural fields and their driving mechanisms, is of great significance for the in-depth understanding of the carbon cycle in agricultural soil and the evaluation of the future carbon budget of agricultural ecosystems. This paper reviews the current status of research on the effects and driving mechanisms of warming and precipitation change and their interactions on farmland R_s, as well as the modelling of farmland R_s in recent years. The results show that: 1) short-term warming can enhance R_s in tropical, subtropical, and warm temperate farmland; long-term warming can increase R_s initially but may decrease with time. Warming has no significant effect on the R_s in cold climate farmland. 2) When there is water deficit in agricultural soil, precipitation can cause a strong R_s stimulation effect. Under the condition of soil wetness, precipitation has an inhibitory effect on R_s. 3) The coupling effect of warming and precipitation change on the impact of R_s in farmland depends on the ratio of soil water and heat factors. 4) The changes in soil properties, soil microorganisms, and crop productivity in farmland caused by warming and precipitation changes are the dominant factors and mechanisms controlling R_s. 5) At present, the simulation of R_s in farmland mostly uses empirical models with temperature and water as independent variables, which can hardly be applied to regional or global R_s research. In the future, long-term inter-site network observation experiments of R_s in farmland should be strengthened, regulatory mechanism of farmland R_s driven by crop-soil-microbe need to analyze deeply, and mechanism model of R_s in farmland under the coupling action of warming, precipitation change and its coupling effect should be constructed. It will improve the accuracy and reliability of earth system models in predicting the impacts of climate change on R_s.