Role of Agriculture in 

Climate Change Mitigation

Role of Agriculture in Climate Change Mitigation

Agriculture emits other greenhouse gases, particularly  methane and nitrous oxide, in addition to carbon dioxide. While CO2 is the most significant greenhouse gas representing more than 80% of the GHG emissions in the United States, methane (CH4) and nitrous oxide (N2O) contribute to climate change impacts through their high Global Warming Potential (GWP). GWP is a measure of the amount of energy one tonne of the GHG will absorb relative to one tonne of carbon dioxide. Certain agricultural management practices can contribute to GHG emissions in the atmosphere.  

For example, application of fertilizers, growth of nitrogen fixing crops, livestock manure management, as well as irrigation and drainage choices can contribute to N2O emissions. Tillage and other forms of soil disturbance can speed up oxidation and microbial oxidation and respiration of soil carbon, leading to increased CO2 emissions. Livestock, particularly ruminants, can contribute to methane emissions through natural digestion, or enteric fermentation, and the producer's manure management practices. While some management practices can contribute to releasing GHG, when producers implement conservation or carbon farming practices, agricultural systems can begin to mitigate climate change through sequestering carbon naturally.  If widely adopted, improving soil fertility by maximizing soil organic matter through carbon farming practices can contribute to greater carbon gains than losses on working lands, and facilitate the CO2 removal from the atmosphere needed to slow or even counter the rise in global temperatures (6) 

Hansen et al. 2017 (9) 

‼️  Stop and Think: Observe the panels “Atmospheric CO2 without/with extraction”- How does extracting atmospheric CO2 change the levels even with a 2% increase in emissions?

Observe the "Global Surface Temperature" panels- How does the global temperature compare without CO2 extraction and an increase in emissions by 2% compared to with CO2 extraction and an increase in emissions by 2%?

All farming or ranching relies on solar energy and atmospheric carbon dioxide conversion into usable carbohydrates in the form of food crops, feed for livestock, biomass fuels, fiber, etc. A snapshot from the Bare Ranch Carbon Farm Plan, a case study in Module 2, demonstrates some carbon capture potential for 45 years of multiple conservation/carbon farming practices estimated using COMET-Planner, a greenhouse gas inventory tool designed for quantifying the GHG impacts of farm conservation scenarios.  

Throughout this curriculum, we will explore how carbon farming practices and planning through a carbon lens can lead to increased carbon sequestration, reduction in emissions, and other soil health co-benefits.  



For a learning extension, check out the Reversing Climate Change Podcast with Dr. Keith Paustian in the Resources tab. 

The GHG benefits of these practices were assessed using the COMET-Planner tool, which we will discuss in Module 2 as well. Some supporting practices, such as improving fence structures or water infrastructure for livestock, do not have a direct GHG benefit, but are necessary for practices that do have those GHG benefits. 

Discussion board: If you have any questions throughout Module 1, please use the discussion board to below to post.

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Principles of Healthy Soils

Citations

(1) Soil Management Bank. Australian Soil Management. 2019. https://www.australiansoil.com.au/soil-management-benefits (2) Follett, R., Mooney, S., Morgan, J., Paustian, K., Allen Jr., L., Archibeque, S., … Robertson, G. (2011). Carbon sequestration and greenhouse gas fluxes in agriculture: challenges and opportunities. Ames: Council for Agricultural Science and Technology (CAST). (3)Paustian, K., Six, J., Elliott, E. et al. Management options for reducing CO2 emissions from agricultural soils. Biogeochemistry 48, 147–163 (2000). https://doi.org/10.1023/A:1006271331703(4)L. E. Flint, A. L. Flint, M. A. Stern, A. Myer, W. Silver, C. F. Casey, F. Franco, K. Byrd, B. Sleeter, P. Alvarez, J. Creque, T. Estrada and D. Cameron, California's Fourth Climate Change Assessment, Increasing soil organic carbon to mitigate greenhuose gases and increase climate resiliency, 2018.(5)  J. Lavelle, F. Cotrufo, Soil carbon is a valuable resource, but all soil carbon is not created equal. The Conversation (2020), (available at https://theconversation.com/soil-carbon-is-a-valuable-resource-but-all-soil-carbon-is-not-created-equal-129175). (6) The Keeling Curve. The Keeling Curve (2020), (available at https://scripps.ucsd.edu/programs/keelingcurve/). (7) B. Deluisi, ESRL Global Monitoring Laboratory - Education and Outreach. Esrl.noaa.gov (2020), (available at https://www.esrl.noaa.gov/gmd/education/carbon_toolkit/basics.html). (8) Jonathan Sanderman, Tomislav Hengi, and Gregory J. Fiske. 2017. Soil carbon debt of 12,000 years of human land use. Proceedings of the National Academy of Sciences: Sep 2017, 114 (36) 9575-9580; DOI: 10.1073/pnas.1706103114(9)J. Hansen, M. Sato, P. Kharecha, K. V. Schuckmann, D. J.  Beerling, J. Cao, S. Marcott, V. Masson-Delmotte, M. J. Prather, E. J. Rohling, J. Shakun, P. Smith, A. Lacis, G. Russell and R. Ruedy, Earth System Dynamics, 2017, 8, 577–616.(10)Paustian, K., Lehmann, J., Ogle, S. et al. Climate-smart soils. Nature 532, 49–57 (2016). https://doi.org/10.1038/nature17174 (11) Hansen, J et al. : Young people's burden: requirement of negative CO2 emissions, Earth Syst. Dynam., 8, 577–616, , 2017