Background and context

Agriculture accounts for nearly half of global methane emissions, primarily from enteric fermentation, manure management, and rice cultivation. Reducing these emissions is essential to meet climate targets such as the Global Methane Pledge and the Paris Agreement. This report evaluates mitigation strategies based on technological readiness, cost-effectiveness, and potential co-benefits. It focuses on practical applications suited to regional production systems, especially in low- and middle-income countries.

Reducing enteric methane emissions

Enteric fermentation is the largest source of methane from agriculture, with beef cattle alone contributing 54% of such emissions. Improving feed efficiency—especially by increasing the digestibility of crop residues—can cut emissions by 8–44%. Dual-purpose crops and feed enrichment methods are effective and feasible in LMICs. Methane inhibition techniques include:

• 3-NOP: 16–41.6% reduction; cost of $144/tCO₂e.
• Asparagopsis: 26–98% reduction; costs up to $625/tCO₂e.
• Nitrates: Up to 30% reduction; $91/tCO₂e.
• Lipids: 3–17% reduction; $84/tCO₂e using waste oils.
• Plant secondary metabolites: 9–38% reduction; as low as $42/tCO₂e.

Other methods include methane vaccines (8–13%), genetic selection (15–25%), and wearable devices (up to 60%). These are less widely adopted and require further R&D, particularly for grazing systems and developing regions. Effective adoption depends on delivery mechanisms, regulation, and incentive structures.

Reducing methane emissions from manure management

Manure management systems, especially wet storage, emit methane under anaerobic conditions. Key interventions include:

• Solid-liquid separation: 25–62% reduction; $5–$24/tCO₂e.
• Anaerobic digestion: 17–85% reduction; high cost at $190–$240/tCO₂e.
• Aeration: 40–99% reduction; $16–$28/tCO₂e.
• Acidification: 47–89% reduction; $2–$17/tCO₂e.
• Flaring with impermeable covers: ~50% reduction; $17–$51/tCO₂e.

While digesters are effective, their cost and methane leakage risks require rigorous monitoring. Lower-cost alternatives such as acidification and separation offer viable options, particularly for small to medium farms. The report recommends targeted trials, improved emissions measurement, and financing mechanisms to scale adoption.

Reducing methane emissions from rice production

Rice cultivation contributes significantly to agricultural methane, with Asia accounting for ~85% of emissions. Continuous flooding is the primary driver. Effective strategies include:

• Mid-season drainage: 38–80% reduction.
• Alternate wetting and drying (AWD): 20–72% reduction.
• Drip irrigation: Up to 90% reduction in pilot trials.

Emerging approaches include replacing urea with ammonium-based fertilisers (23–50% reduction) and using nitrification inhibitors (8–58%). Some genetic interventions—such as low-methane rice varieties like SUSIBA—show promise, with up to 51% emission reductions in trials.

Mitigation effectiveness varies with soil type, irrigation infrastructure, and crop variety. The report highlights the need for technical planning, localised incentives, and expanded field validation to support uptake across diverse rice systems.