Manure from U.S. dairy and swine farms is a significant source of greenhouse gas emissions, primarily methane, which is over 80 times more potent than carbon dioxide over a 20-year period. Current manure management practices, dominated by wet storage systems such as lagoons and pits, create ideal conditions for methane-producing microbes, contributing over 1% of national emissions. While biogas digesters have received the most attention and funding, they only partially reduce methane emissions from manure storage, are expensive, and remain impractical for many small and medium-sized farms.

This paper examines promising alternative technologies, including solid-liquid separation, acidification, and manure aeration, that can significantly reduce methane emissions at lower costs and offer additional on-farm benefits like odor control, improved fertilizer value, manure handleability, and reduced lagoon maintenance. Despite their potential, adoption of these solutions in the U.S. is minimal due to limited field data, a lack of farmer incentives, and a narrow policy focus on digesters.

The analysis calls for expanded pilot programs, stronger measurement and reporting systems, and targeted financial and technical support to scale up these more efficient solutions. Broader adoption will require coordinated action among farmers, industry stakeholders, policymakers, and supply chain actors to close data gaps, fund on-farm trials, and create market and regulatory incentives. Without such efforts, mitigating methane emissions from manure management will be difficult.