Impacts of Rice Cropping System Changes on Paddy Methane Emissions in Southern China

Abstract

Rice paddies are one of the main sources of anthropogenic terrestrial CH4. In recent decades, the substitution of single-cropping rice (SCR) for double-crop rice (DCR) has become more common in southern China. However, the concomitant impacts on CH4 emissions have not been quantified. We incorporated high-resolution rice cropping system maps into the CH4MOD model to calculate changes in CH4 emissions in southern China due to DCR conversion to SCR over the period 1990 to 2015. We find that a total planting area of 253.64 ×104 ha was converted from DCR to SCR. This conversion resulted in a 451.94 Gg reduction in CH4 emissions, accounting for 8.4% of CH4 emissions from paddies in China in 2015. The largest reduction was in the Middle–Lower Yangtze plain with high labor pressures. As urbanization continues, we project that the total CH4 emissions have the potential to decrease by between 17.1% and 9.2% under DCR conversion to SCR in southern China in the extreme and most likely scenarios, respectively. As farmers voluntarily move to SCR in response to labor scarcity, making full use of the land-use change trend of DCR to SCR may be an opportunity to reduce agricultural methane emissions, which is important for achieving Sustainable Development Goals (SDGs) and should be given more attention.

Relocating rice cultivation domestically is conducive to climate mitigation and land utilization without compromising food security

“…Assuming the TNC_B released 9,518.18 hectares are used to grow soybeans, there will be a 288% expansion in the domestic soybean output (i.e., an extra 13,890 tons), thus raising the soybean self-su ciency rate from less than 0.19% (for human consumption) and 2% (total demand) to 0.72% and 8.14%, respectively. Alternatively, growing eld corn, which can effectively reduce CH 4 emissions 22 , could help augment self-su ciency in animal feeds, cultivation of which is eligible for subsidies. The agricultural ministry estimated the net revenue per hectare of eld corn cultivation to be approximately NT$63,100, and this revenue is commensurate with that of the summer rice crop.…”

Eco-physiology and environmental impacts of newly developed rice genotypes for improved yield and nitrogen use efficiency coordinately

“…The model includes two sub-models: one for simulating the production of methanogenic substrates from root exudation and organic matter, and another for simulating CH4 production and emissions through rice plants and bubbles. It has been extensively validated and used worldwide, with minimal input data required (Bogner et al, 2000;Jiang et al, 2023).…”

Do Rice Farmers Have Knowledge of Greenhouse Gas (GHG) Emission Mitigation Strategies? New Evidence from Nigeria

“…Understanding farmers' knowledge of GHG emissions and mitigation strategies is among the crucial starting points for deciding what steps should be made to mitigate emissions from rice fields and produce rice in a cleaner environment. Some of the GHG emission mitigation strategies in rice field includes; alternate wetting and drying (AWD); system of rice intensification (SRI); changing tillage operations (CTO); Nitrogen Fertilizer Management (NFM); residue management (RM) and aerobic rice varieties (ARV) [12,13,14]. Substantial empirical evidence [9,11,13] exists on measuring and mitigating GHG emissions in rice fields in developed and developing countries and different researchers have analyzed the likely effects on rice production with various parameters.…”

“…Some of the GHG emission mitigation strategies in rice field includes; alternate wetting and drying (AWD); system of rice intensification (SRI); changing tillage operations (CTO); Nitrogen Fertilizer Management (NFM); residue management (RM) and aerobic rice varieties (ARV) [12,13,14]. Substantial empirical evidence [9,11,13] exists on measuring and mitigating GHG emissions in rice fields in developed and developing countries and different researchers have analyzed the likely effects on rice production with various parameters. Reducing GHG emissions and water use in rice fields is critical for combating climate change, and increasing the yield, income and standard of living of the farmers.…”