IARRP team discovers using green manure to increase rice field productivity while lowering net global warming potential
The Innovation Team of Fertilizer and Fertilization Technology of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS), found that using green manure can increase rice field productivity while reducing net global warming potential.
The findings were published in the Journal of Environmental Management under the title "Paddy fields can gain high productivity with low net global warming potential by utilizing green manure".
In recent years, the comprehensive assessment of net global warming potential by combining greenhouse gas emissions from farmland with soil carbon storage has become mainstream. Increasing carbon input through proper crop rotation, cover crops during fallow periods, and other methods can effectively enhance soil carbon sequestration in farmland, reducing the greenhouse effect. The role of green manure in regulating soil carbon transformation processes and expanding soil carbon pools has been widely confirmed. The combined use of milk vetch and rice straw can reduce losses in carbon conversion processes, increase soil active organic carbon and total organic carbon content. However, the increased input of more organic materials may lead to increased greenhouse gas emissions. There is currently controversy regarding greenhouse gas emissions from milk vetch application in rice fields. Therefore, it is necessary to study the soil carbon sequestration and greenhouse gas emission patterns under the combined use of milk vetch and rice straw to clarify the net global warming potential of vetch application in rice fields.
The research found that after seven years of milk vetch application, the annual soil carbon sequestration rates under milk vetch and milk vetch-rice straw combined treatments increased by 492 and 1437 kg/ha/year compared to winter fallow, respectively. The net global warming potential of the vetch treatment significantly decreased by 6343 and 4208 kg CO2-eq/ha compared to the rice straw treatment and milk vetch-rice straw combined treatment. The increase in soil carbon sequestration under the vetch-rice straw combined treatment completely offset the increase in global warming potential caused by straw returning. In the green manure-early rice-late rice rotation system, milk vetch application did not significantly increase the emission of methane (CH4), the main greenhouse gas. Instead, it significantly reduced the net greenhouse gas emission intensity by increasing rice yield and annual soil carbon sequestration rates. Under the combined use of milk vetch and rice straw, the increase in soil soluble carbon and nitrogen stimulated the activity of methane-producing bacteria, leading to increased CH4 emissions. However, the increase in soil organic carbon under the combined use completely offset the CH4 emissions caused by straw returning, while also reducing the cumulative emissions of CO2 and N2O, thereby lowering the net global warming potential. Therefore, incorporating green manure into rice planting systems is an effective strategy to increase rice field productivity and mitigate the greenhouse effect.
Doctoral student Li Shun from the College of Resources and Environmental Sciences at Nanjing Agricultural University and Researcher Nie Jun from the Soil and Fertilizer Research Institute of Hunan Academy of Agricultural Sciences are the co-first authors of this paper. Researcher Cao Weidong from the Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, and Associate Professor Gao Songjuan from Nanjing Agricultural University are the co-corresponding authors. The research was supported by the National Key Laboratory for Efficient Utilization of Arid and Semi-arid Farmland in Northern China, the National Natural Science Foundation of China (32072678, 32202616, 32202609, 32101854), the National Key Research and Development Program of the Fourteenth Five-Year Plan (2021YFD1700200), and the National Green Manure Industry Technology System (CARS-22).
【Citation】: Li, S., Nie, J., Liang, H., Zhou, G., Zhang, J., Liao, Y., Lu, Y., Tao, Y., Gao, S.,Cao, W., 2025. Paddy fields can gain high productivity with low net global warming potential by utilizing green manure. Journal of Environmental Management 377.
Original Link: https://doi.org/10.1016/j.jenvman.2025.124596