Climate Change Mitigation in Agronomy

Concept & Importance

• Definition (IPCC): Mitigation of climate change refers to human interventions to reduce sources or enhance sinks of greenhouse gases (GHGs).
• Agriculture contributes 20–25% of global GHG emissions (India ~18–20%).
• Major agricultural GHGs:
  • CO₂ → soil degradation, land use change, fossil fuel burning.
  • CH₄ → rice paddies, livestock (enteric fermentation).
  • N₂O → fertilizer application, manure mismanagement.

Goal of mitigation in agronomy = low-carbon farming systems that maintain yield & ensure sustainability.

Major Mitigation Strategies in Agronomy

(A) Soil Carbon Sequestration

• Most important & long-term mitigation pathway.
• Mechanisms: Conversion of atmospheric CO₂ → Soil Organic Carbon (SOC).
• Practices:
  • Conservation Agriculture (CA) → Zero tillage + crop residue retention → improves SOC, lowers CO₂ emission.
  • Green manuring & cover crops → add organic matter.
  • Agroforestry systems → carbon storage in biomass + soil.
  • Biochar application → stable carbon form, enhances SOC.
  • Organic amendments (FYM, compost, crop residues).

(B) Nutrient Management

• N₂O emissions = main issue with fertilizers.
• Mitigation through:
  • 4R Nutrient Stewardship: Right source, Right dose, Right time, Right method.
  • Site-Specific Nutrient Management (SSNM).
  • Neem-coated urea, slow-release fertilizers.
  • Nitrification inhibitors (e.g., DCD, nitrapyrin).
  • Integrated Nutrient Management (INM) → balance of organic & inorganic fertilizers.
  • Biofertilizers (Rhizobium, Azospirillum, PSB, Azolla in rice).

(C) Water Management

• Rice is the biggest source of CH₄ → managing water reduces emissions.
• Practices:
  • Alternate Wetting and Drying (AWD) → 30–50% reduction in CH₄.
  • System of Rice Intensification (SRI) → intermittent irrigation, reduces methane by ~25–30%.
  • Micro-irrigation (drip, sprinkler) → ↑ WUE, ↓ pumping energy.
  • Laser Land Leveling → uniform irrigation, saves 20–25% water.

(D) Crop Management

• Redesigning cropping systems to lower emissions:
  • Diversified cropping systems → legume rotations fix N biologically, reduce fertilizer need.
  • Stress-tolerant varieties (drought/heat/salt tolerant).
  • Short-duration varieties → avoid climate stress periods.
  • Intercropping & relay cropping → enhance resource use efficiency.
  • Direct Seeded Rice (DSR) → less water, lower CH₄.

(E) Energy Management

• Agriculture is energy-intensive → mechanization & pumps use fossil fuel.
• Practices:
  • Renewable energy use (solar pumps, wind, biogas).
  • Improved machinery efficiency (zero-till drills save diesel).
  • Use of crop residues as bioenergy instead of open burning.

(F) Residue & Waste Management

• Stubble burning = major GHG + pollution problem.
• Mitigation through:
  • In-situ residue management (mulching, incorporation with Happy Seeder).
  • Composting, vermicomposting.
  • Anaerobic digestion → biogas production.
  • Bioethanol & biodiesel from crop residues.

(G) Policy & Institutional Support

• National Action Plan on Climate Change (NAPCC, 2008) → 8 missions.
• National Mission on Sustainable Agriculture (NMSA) → soil health, water efficiency, climate-smart farming.
• NICRA (National Innovations on Climate Resilient Agriculture, ICAR, 2011) → adaptive & mitigation technologies in climate-vulnerable districts.
• Carbon credit mechanisms under UNFCCC → Clean Development Mechanism (CDM).

Quick Exam-Oriented Factsa

• Agriculture → 18–20% of India’s GHG emissions.
• Rice fields contribute ~20% of global CH₄ emissions.
• Zero tillage wheat in IGP saves ~30 L diesel/ha + reduces CO₂.
• Residue retention prevents ~1.5 t C loss/ha annually.
• SRI → reduces methane emission by ~25–30%.
• AWD in rice → reduces CH₄ without yield penalty.

Quick Points to Remember

General

• Agriculture contributes 18–20% of India’s total GHG emissions.
• Major sources: Rice paddies (CH₄), fertilizer use (N₂O), residue burning & fuel use (CO₂).
• IPCC (2014 report) → Soil carbon sequestration is the most cost-effective mitigation option in agriculture.

Soil Carbon Sequestration

• Zero tillage with residue retention → increases Soil Organic Carbon (SOC) by 0.1–0.3 t C/ha/year.
• Biochar → stable form of carbon, can sequester for >100 years.
• Agroforestry → sequesters 1.5–3.5 t C/ha/yr in tropical systems.

Water & Crop Management

• AWD in rice → reduces methane by 30–50%.
• SRI → lowers CH₄ emission by 25–30% with higher WUE.
• Direct Seeded Rice (DSR) → saves ~15–20% irrigation water, lowers methane emissions.
• Legume-based rotations → reduce fertilizer N use by 25–30%.

Nutrient Management

• Nitrification inhibitors (like DCD) → reduce N₂O by 30–40%.
• Neem-coated urea → improves N-use efficiency by 10–15%.
• INM (organic + inorganic) reduces GHG intensity per unit yield.

Energy & Residue Management

• Zero tillage wheat in IGP → saves 30 L diesel/ha, reduces 80 kg CO₂/ha.
• Residue burning in India releases >140 million tonnes CO₂/year.
• Residue incorporation or mulching prevents ~1.5 t C loss/ha annually.
• Bioenergy (biogas, bioethanol) reduces dependence on fossil fuels.

Policy Support

• NAPCC (2008) → National Action Plan on Climate Change.
• NMSA → National Mission on Sustainable Agriculture.
• NICRA (2011, ICAR) → climate-resilient & mitigation practices in vulnerable districts.
• Carbon credits & CDM (Clean Development Mechanism) support adoption globally.

In India, practices like AWD in rice, zero tillage in wheat, residue retention, and INM are proven low-cost mitigation options that reduce GHG emissions while sustaining productivity.