Greenhouse Gas Emissions from Agricultural Soils: Sources and Mitigation Potential

Abstract

The anthropogenic emission of greenhouse gases (GHGs), that is, carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), is bringing about major changes to the global environment. Whereas most of the emissions come from combustion of fossil fuels and industrial processes, agriculture accounts for 10%–12% of the total anthropogenic emission of GHGs. Emissions from agriculture amount to 5.1–6.1 Gt CO₂-eq/year, including 3.3 Gt CO₂-eq/year as CH₄ and 2.8 Gt CO₂-eq as N₂O. Of the total non-CO₂ emissions from agriculture, N₂O emissions from soils and CH₄ emissions from enteric fermentation comprise 38% and 32%, respectively. Biomass burning, rice agriculture, and manure management account for 12%, 11%, and 7% of the emissions, respectively. Compared with 1990, agricultural emissions of CH₄ and N₂O have increased by nearly 17%, representing a mean emissions increase of about 60 Mt CO₂-eq/year. The adoption of improved management practices and mitigation technologies could help in reducing emissions. The strategies for lowering CO₂ emissions include reducing the global energy use, developing low- or no-carbon fuel, and sequestering CO₂ through natural and engineering techniques. Because engineering techniques are still in developmental stages, C sequestration in soil and vegetation is considered a viable option. Management practices that increase carbon input to the soil or reduce C loss, or both, lead to net carbon sequestration in soils. Appropriate water and nutrient management, cultural practices, and choice of crop cultivars can help reduce CH₄ emissions from rice fields. Practices that improve N-use efficiency can reduce N₂O emissions and indirectly reduce GHG emissions from N fertilizer manufacture. The global technical GHG mitigation potential from agriculture by 2030 is estimated to be 5.5–6.0 Gt CO₂-eq/year. Realizing this potential will require the adoption of best available management practices with reference to soil type and LU system.

Keywords:

• Adaptation
• best management practices
• carbon sequestration
• climate change
• global energy use
• greenhouse gases
• integrated nutrient management
• land-use changes(LUCs)
• mitigation techniques
• nitrogen-use efficiency
• no-carbon fuel

Acknowledgments

This article was modified and updated from “Greenhouse Gas Emission from Agricultural Soils: Sources and Mitigation Potential” (Chapter 5) in Combating Climate Change: An Agricultural Perspective, edited by Manjit S. Kang and Surinder S. Banga. Copyright 2013 by Taylor & Francis Group, LLC. Reprinted with permission.

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