Regulation and mechanism of greenhouse gas emissions of circular agriculture ecosystem of planting and breeding in paddy

Rice is an important food crop in China and contributes immensely to ensuring food security, the national economy and the people's livelihood. Paddy fields make a significant fraction of greenhouse gases (GHG) emissions sources, including methane (CH₄) and nitrous oxide (N₂O). Therefore, controlling GHG emissions from rice fields is critical in mitigating global greenhouse effects. In recent years, the combination of planting and breeding in paddy has developed rapidly in China. The mode not only keeps a steady yield, increasing efficiency and promoting green development, but also changes the characteristics of GHG emissions and global warming potential (GWP) in paddy fields. Several combinations of planting and breeding in paddy (including rice-duck, rice-crayfish, rice-fish, rice-crab and rice-turtle) add niche and extend the food chain in rice paddy ecosystems. GHG emissions and GWP of the combination of planting and breeding in paddy are affected by the continuous movement and feeding activities of breeding organisms in the ecosystem with an appropriate mitigation of GHG emission. In order to provide theoretical and technical bases for GHG emissions mitigation, rice benefits increment and a healthy development of the combination of planting and breeding in paddy, this paper summarizes the characteristics of CH₄ and N₂O emissions and the effects of fertilizer and irrigation management and also explores available methods and research prospects used to reduce GHG emissions.