Spatio-Temporal Dynamics of Greenhouse Gas Emissions among Four Types of Rice in China

Rice is not only the most basic staple crop, but also a major contributor to greenhouse gas emissions (GHGs). Negative emission options that can guarantee food security are urgently needed. In this study, we analyzed the temporal and spatial dynamics of GHGs from four types of rice in China, namely early indica rice, mid-season indica rice, late indica rice, and japonica rice, and estimated their mitigation potentials. The main results are fourfold. (1) The annual average GHGs per hectare was 4513.5 kg CO2-eq ha–1, increasing gradually from 2005 to 2020, while there was an opposite trend in annual average GHGs efficiency (0.4 kg CO2-eq yuan–1). The GHGs intensity was 0.9 kg CO2-eq kg–1 and remained constant in the same period. (2) The GHGs per unit (sowing area, output or output value) in central and southeastern China were higher than those in the north and west. (3) The GHGs per unit (area, yield or output value) of late indica rice were the highest while the corresponding values for japonica rice were the lowest. (4) The GHGs per hectare might be able to achieve a 20% reduction from the 2020 level, providing that cropland redistribution and mitigation measures are adopted. Finally, we put forward policy proposals and available measures for emission reduction to promote the sustainable development of agricultural systems.