The United States agriculture sector is composed of nearly 2.1 million predominantly privately owned farms. Agriculture production occurs in all 50 states across the nation, while crop production is largely concentrated in California and the Midwest, with livestock production scattered throughout the country. In 2021, agriculture, food, and related industries contributed to 5.4% of the United States’ gross domestic product (GDP) providing 10.5% of U.S. employment. The main crops produced in the U.S. are corn, soybeans, wheat, and cotton. The market price of these crops contributes to relationships in other commodities, mainly in the livestock sector. Importantly, corn used to produce ethanol accounted for over 40% of U.S. corn use. In 2020, 228 million acres were designated for these four crops, contributing to roughly 27% of all agricultural land.
The agriculture sector in the United States contributes to 5.7% of global agriculture emissions with a Global Warming Potential of 20 years contributing 5.47 billion tons of CO2e20 from 2015-2021. Global Warming Potential (GWP) allows comparisons of the amount of energy 1 ton of gas has on the atmosphere in a given period. The main sub-sectors responsible for agriculture emissions in the U.S. are both enteric fermentation (the natural part of the digestive process in ruminant animals) contributing to 64.56% of emissions, and manure management contributing to 17.66%. These two sectors alone account for 4.48 billion metric tons of CO2e20, or 82% of agriculture emissions providing not only a great potential but a necessity to reduce emissions in agriculture.
Enteric fermentation provides the greatest potential to decrease agriculture emissions across the United States. Two ways enteric fermentation may be mitigated in the agriculture sector; improving the forage quality and dietary supplementation. Forage with higher starch, less fibre, and higher quality forage would assist in mitigating some of the emissions in this sector. Dietary modification provides the best chance of mitigating enteric emissions. Studies have shown that sunflowers and canola oil when added to forage can decrease emissions by 9-27%. Further studies have shown that seaweed supplemented in livestock feed may reduce enteric fermentation by up to 90%. An added benefit to growing seaweed for livestock increases carbon sequestration in oceans, provides habitats, and may reduce ocean acidification in the long term. There has been some adoption of these techniques but are still quite low due to the low economic benefits. Carbon offsets could potentially provide increased adoption however, market-based solutions to address climate change have often fallen short of their intended promise.
The second sub-sector providing the potential to decrease agriculture emissions is better manure management. Cornell University, through its extension service, has summarized quantifiable GHG mitigation practices for dairy manure storage. In larger operations, anaerobic digestion systems (methane digesters) may be used to capture methane and produce electricity and heat, however, the initial cost is estimated to be around $1.5 million for a 1000-cow farm perhaps pricing out many larger family farms. With smaller dairy operations, manure pits can be covered by an impermeable cover to allow methane (CH4) to be captured and burned off, producing CO2 as a byproduct; a much lower warming effect than methane. This mitigation process is estimated around $375,000 for 1000 cow farms. Again, the initial funding needed may price out many smaller farms without state and federal cost-sharing programs.
There is great potential to decrease emissions in the agriculture sector in order to address climate change. State and federal programs could assist in farms adopting better practices through improved affordability and design of manure pit cover and flare. The 2023 Farm Bill could also provide the pathways needed to reduce emissions in the agriculture sector in similar ways that the 2022 Inflation Reduction Act (IRA) affected emissions in the power sector. Keeping a close eye in 2023 and contacting representatives and senators imploring them to do more to combat climate change in order to stay under 1.5°C and stay on track with our climate pledges to the world.
This Post was submitted by Climate Scorecard US Country Manager Dave Schroeder