Question: Nitrous oxide emissions from agriculture — sources, climate significance, and mitigation strategies
Introduction
Agriculture is a leading contributor to nitrous oxide (N₂O) emissions, a potent greenhouse gas with a global warming potential far exceeding CO₂, making its mitigation central to any credible climate-smart agriculture framework.
Body
1. Agricultural Soils as Primary N₂O Source
Agricultural soils, through microbial processes of nitrification and denitrification, constitute the largest single source of anthropogenic N₂O globally. Synthetic nitrogen fertilizer application accelerates these processes by increasing soil nitrogen availability, triggering excess emissions beyond crop uptake.
2. Climate Potency of N₂O
N₂O carries a Global Warming Potential approximately 265–298 times that of CO₂ over a 100-year horizon, as assessed by the IPCC. It also depletes stratospheric ozone, compounding its environmental significance beyond direct warming effects.
3. Enhanced Efficiency Fertilizers (EEFs) as Mitigation Tools
Nitrification inhibitors, urease inhibitors, and controlled-release fertilizers collectively form the EEF category. By slowing nitrogen transformation in soils, they reduce the substrate available for denitrification, thereby cutting N₂O emissions without proportionally reducing crop yields.
4. Nuanced Role of Leguminous Cover Crops
Leguminous cover crops fix atmospheric nitrogen, but their net effect on N₂O emissions is context-dependent. Well-managed legume integration can improve nitrogen use efficiency and reduce synthetic fertilizer demand, potentially lowering overall emissions — making the claim that they 'always increase' N₂O emissions incorrect.
5. Policy Relevance for India
India's Soil Health Card scheme and the Nano Urea initiative reflect early steps toward precision nutrient management. Scaling EEF adoption and integrating N₂O monitoring into national greenhouse gas inventories remain governance priorities under India's Nationally Determined Contributions.
Conclusion
Reducing agricultural N₂O demands a calibrated approach — combining precision fertilization, EEF deployment, and context-sensitive agronomic practices — rather than blanket prescriptions, ensuring food security and climate commitments are pursued simultaneously.
Word count: 247
PYQ 2024
Which one of the following is the correct description of "100 Million Farmers"?
PYQ
Consider the following statements regarding the 'Pradhan Mantri Krishi Sinchayee Yojana (PMKSY)':
1. It follows the principle of 'Har Khet Ko Pani, More Crop Per Drop'.
2. It was launched in 2015 by merging three existing schemes — Accelerated Irrigation Benefits Programme, Integrated Watershed Management Programme, and the On-Farm Water Management scheme.
3. The Watershed Development Component of PMKSY is implemented by the Ministry of Agriculture and Farmers' Welfare.
Which of the statements given above is/are correct?
PYQ
The concept of 'System of Rice Intensification (SRI)' is associated with which of the following features?
1. It requires more seeds per hectare compared to conventional rice cultivation.
2. It promotes aerobic soil conditions through intermittent irrigation rather than continuous flooding.
3. It has been shown to significantly reduce methane emissions from rice paddies.
4. It was originally developed by Henri de Laulanié in Madagascar.
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PYQ
With reference to 'Conservation Agriculture (CA)', consider the following statements:
1. CA is built on three principles: minimum soil disturbance, permanent soil cover, and crop rotation.
2. Zero-tillage is a component of minimum soil disturbance in CA and is associated with reduced carbon emissions from soils.
3. The Food and Agriculture Organization (FAO) estimates that CA is currently practiced on less than 5% of the global arable land.
Which of the statements given above is/are correct?
PYQ
The 'Voluntary Carbon Market' mechanism as applicable to agriculture involves which of the following?
1. Farmers receive carbon credits for adopting practices that sequester carbon in soil.
2. These credits are regulated and issued solely by the UNFCCC under its Clean Development Mechanism.
3. Biochar application, no-till farming, and agroforestry are among practices that can generate agricultural carbon credits.
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