September 26, 2023 | Nature Reviews Earth & Environment | Source |
Introduction: This collaborative review, conducted by researchers from 3 universities in China, University of Exeter (UK), UC Davis, (US), JIRCAS, IRRI and other institute across the globe, examines the spatial and temporal scales of greenhouse gas (GHG) emissions in rice cultivation, climate change effects, and potential mitigation strategies. Focusing on field-scale research, it assesses mitigation effectiveness of emission reductions and identifies key research gaps to improve emission estimates and enhance sustainability in rice agriculture.
Key findings: Rice paddy GHG emissions vary widely with agricultural practices, climate, and geography. While higher yields have reduced yield-scaled CHâ‚„ emissions, Nâ‚‚O emissions are rising with increased nitrogen use and non-continuous flooding (NCF). Climate change, particularly elevated COâ‚‚ and warming, is expected to further increase emissions, with China, India, and Indonesia as major contributors. Effective management strategies, identified as the following lists, are key to reducing rice paddy GHG emissions, outweighing the impact of climate and soil type.
- Rice Variety Selection: High-yielding, low-emission cultivars can reduce CHâ‚„ emissions by altering root oxygen release and rhizodeposition patterns.
- Water Management: Optimizing drying frequency, timing, and severity enhances GHG mitigation. NCF methods, such as AWD and mid-season drainage, reduce CHâ‚„ emissions by 53%, outweighing associated increases in soil carbon loss and Nâ‚‚O emissions.
- Organic Matter Management: Straw removal, composting, and optimized organic matter type, timing, and application reduce CHâ‚„ emissions while maintaining soil fertility. Biochar application further lowers both CHâ‚„ and Nâ‚‚O emissions.
- Nitrogen Management: Optimizing fertilizer use and adopting enhanced-efficiency fertilizers can cut Nâ‚‚O emissions by up to 60%, while targeted application methods improve overall nitrogen use efficiency.
- Tillage and Crop Establishment: No-till and direct seeding reduce CHâ‚„ emissions by 40–60% compared to conventional tillage. Ratoon cropping, which harvests a second crop from previous stubble, also influences GHG emissions.
- Emerging Practices: Lime application lowers CHâ‚„ emissions by 20% in acidic soils, while biochar, oxygen-releasing fertilizers, and microbial inoculations offer additional mitigation potential.
The study highlights the need for region-specific strategies to address CHâ‚„ emissions, improve data accuracy, and refine GHG models. Given the projected rise in GHG emissions, integrating multiple management practices and quantifying their interactions will be essential for reducing environmental impact while sustaining global rice production.
Figure | Potential mitigation strategies. Overview of management practices in rice agriculture to achieve high yields and low greenhouse gas (GHG) emissions.
