Recently, the Qiyang Experimental Station at the Institute of Agricultural Resources and Regional Planning (IARRP), Chinese Academy of Agricultural Sciences (CAAS), made significant progress in evaluating the environmental consequences of combining green manure (Chinese milk vetch) and rice straw in double rice system. The findings were published in the Journal of Environmental Management under the title "Green manure and rice straw recycling: A triple-win for productivity, environmental sustainability and net ecosystem economic benefit."

Rice straw and green manure recycling are widely adopted practices for soil fertility improvement and yield enhancement in double-rice systems of southern China. However, their environmental consequences remain lacking.. To address this gap, the study employed a long-term field experiment at Qiyang Station and applied life cycle assessment (LCA) to quantify greenhouse gas (GHG) emissions, energy use efficiency, carbon footprint, and net ecosystem economic benefit under different residue residue recycling regimes.

The results showed that, compared with other residue recycling regimes (green manure recycling alone or early/late rice straw recycling alone), the the combination of green manure and early rice straw recycling significantly reduced CH₄ and N₂O emissions by 22.1%–33.9% and 18.5%–34.2%, respectively. Energy use efficiency increased by 6.8%–68%, the carbon footprint decreased by 110.4%–212.1%, and the net ecosystem economic benefit increased by 10.9%–112.1%.

Factor analysis indicated that this combined recycling regulates the soil carbon-to-nitrogen ratio, the abundance of genes associated with CH4 emissions (mcrA and pmoA) and ammonia oxidation genes (amoA), which contrabutes to reduce direct GHG emissions and carbon footprint.

This study provides important theoretical and practical guidance for optimizing the combined recycling of rice straw and green manure to achieve both yield increases and emission reductions in double-rice systems.

Figure 1. Carbon footprint and net ecosystem economic benefit based on life cycle assessment.

Nano Alemu Daba, an Ethiopian national and recent PHD graduate at the Institute of Agricultural Resources and Regional Planning, CAAS, and Associate Researcher Huang Jing are co-first authors. Researcher Zhang Huimin is the corresponding author. The study was supported by the State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, the National Natural Science Foundation of China, and the National Key Research and Development Program of China, among other projects.

Original article: https://doi.org/10.1016/j.jenvman.2025.128381