CAST Report on the Potential for U.S. Agriculture to be Greenhouse Gas Negative
By: Don Mulvaney
The ASAS Public Policy Committee continually looks to share information which increases awareness of strategies and solutions for a more sustainable animal agricultural future. A recently released report “Potential for U.S. Agriculture to Be Greenhouse Gas Negative", assembled by the Council for Agricultural Science and Technology (CAST) in partnership with U.S. Farmers & Ranchers in Action (USFRA), examines strategies for reducing greenhouse gas (GHG) emissions within U.S. agriculture, particularly focusing on animal production systems. The report outlines how combining reduced GHG emissions from some agricultural activities with increased carbon sequestration in others could achieve GHG-negative agriculture. It also describes the research needed to help accomplish it. These complex systems are significant contributors to agricultural emissions, including enteric methane from ruminants and emissions from manure handling. According to the report, animal production accounts for nearly half of U.S. agricultural GHG emissions, with the primary emissions sources identified as feed production, enteric methane from ruminant digestion, and manure management.
Some of the findings on animal production in the report address ruminant feeding systems, manure management, sector-specific opportunities and challenges ahead. Ruminants (mainly cattle) release methane due to microbial fermentation in the rumen. To reduce these emissions, some mitigation strategies proposed were improving fiber digestibility the digestibility of feed which could lower methane production without impacting animal health or productivity. Secondly, increasing dietary lipids and using specific feed additives to inhibit methane-producing microbes have shown potential to reduce methane emissions by 20-40%, though economic feasibility remains a challenge. With regard to dealing with manure which is a significant emission source, particularly in confined operations. Potential interventions include adoptive use of anaerobic digesters to capture methane for use as a renewable marketable energy source, thereby turning waste into an asset. Another step is to create shortened storage times and aerobic digestion to decrease methane release. Along with the aforementioned strategies is the composting and liquid-solid separation as these methods can reduce GHGs and contribute to regenerative agriculture by providing high-quality organic fertilizers.
The report discusses sector-specific opportunities. Dairy systems offer high potential for carbon neutrality through improved feed production, nitrogen management, and enhanced digestibility of feeds. Methane capture from manure and dietary changes can lower emissions without reducing milk production. For grazing beef cattle, the focus is on improving forage quality, as this can impact enteric methane levels. Feedlot systems could also benefit from feed additives and better manure handling, similar to dairy systems. For pork and poultry systems, though efficient in feed-to-product conversion, they generate emissions mostly from manure. Therefore improved manure handling and energy-efficient housing could reduce their carbon footprints.
The report comments on challenges ahead of reaching GHG negative goals. First, is within adoption barriers. A significant obstacle for producers is the cost and perceived risk of implementing these technologies and infrastructural investments without solid evidence that they are economically viable and sustainable. Large-scale field research studies across diverse production systems are needed to provide reliable data that builds producer confidence. The report underscores the need for extensive research and economic analyses to ensure that these GHG mitigation practices are financially sustainable across different climate zones and animal production systems. In summary, the path to carbon neutrality within U.S. animal agriculture is a complex but feasible goal. By integrating targeted feed management, innovative manure handling, and energy-efficient practices, the sector can make substantial progress in reducing its GHG footprint. The process emphasizes a need for collaboration among researchers, producers, and policymakers as essential to develop practical, scalable solutions that support both environmental and economic sustainability in agriculture. Potential for U.S. Agriculture to Be Greenhouse Gas Negative" Report, hosted by the Council for Agricultural Science and Technology (CAST) in partnership with U.S. Farmers & Ranchers in Action (USFRA). For those interested in listening to a recording of a presentation on the report, it can be accessed at: https://youtu.be/HwCR5_N8D8Y.
