Innovative manure solutions for sustainable dairy farming

This article is sponsored by Dairy Management Incorporated. 

As global attention intensifies on the need for climate action, the agricultural sector is increasingly in the spotlight, particularly concerning methane emissions — a potent greenhouse gas with significant impact on global warming. The world’s most preeminent leaders and scientists are converging on immediate and effective actions to mitigate one of the most challenging aspects of climate change.

According to the U.N. Food and Agriculture Organization, the global dairy industry accounts for about 3 percent of greenhouse gas emissions. As the world grapples with the challenges of sustainability and climate change, dairy farmers remain at the forefront, innovating and adapting. They have long stood as stewards of the land, with deeply rooted traditions of nurturing and preserving the natural resources entrusted to them. 

The U.S. dairy industry is exploring and implementing promising solutions in advanced manure management techniques. These innovative practices aim not only to reduce methane emissions but also to enhance overall farm sustainability and efficiency. And, as it turns out, they may also be part of the climate solution. 

Methane sources on dairy farms

Methane is emitted on dairy farms in two ways — enteric methane is produced in the cow’s rumen through its digestion process and released through their mouths; methane is also emitted through the decomposition of their manure. Today, manure accounts for about a third of the greenhouse gas emissions on a dairy farm in the United States, and reducing these emissions is possible with a variety of technologies.

But cow manure is not just waste, as many believe. When properly managed, it possesses remarkable value. Cow manure contains valuable nutrients such as nitrogen, phosphorus and potassium, which are needed for crops to grow, as well as fiber that can be used in other applications on-farm. However, in some situations, there is a need to store or transport manure longer distances for field application — and this can present logistical and environmental challenges. The good news is that technologies to address these challenges already exist. 

Transformative technologies

Anaerobic digesters often stand out as a solution when considering GHG emission reduction strategies on farms. In a digester, microbes break down cow manure and sometimes other organic waste, such as food waste, producing biogas, a renewable energy source that can offset fossil fuel use. According to USDA, there are approximately 8.9 million dairy cows in the United States. As of 2023, there are 290 digesters on U.S. dairy farms around the country, processing manure from 1.5 million cows. According to EPA data, this avoids approximately 7.2 million metric tons of CO₂ equivalent per year and produces about 2.42 million megawatt-hours (MWh) equivalent energy. It is important to note, digesters require significant capital investment, require substantial time and technical expertise to operate, and are not compatible with all farming systems.

Covered manure lagoon with methane-eliminating flare-off systems is another technology small and midsize dairies may be able to install to transform manure. Cap and flare technology involves covering manure storage units to capture the methane, which is then combusted (flared) to destroy it, preventing its release into the atmosphere. An Intergovernmental Panel on Climate Change model was used to estimate the methane reduction impact of covering manure storage to capture and flare the resulting methane. The total potential methane mitigation opportunity by region, and nationally, was estimated by integrating the projected methane reductions with the National Agriculture Statistics Service (NASS) 2017 Census data for the Midwest, Northeast and Southeast. Based on the analysis, if 100 percent of Midwest, Northwest and Southeast dairy operations with up to 999 milking cows were to adopt this cover and flare technology, the total magnitude of methane reduction would be approximately 6.4 to 11.6 million metric tons of CO₂ equivalent per year.

Vermiculture, also known as vermicomposting, presents another option for managing manure. Using the natural digestion capabilities of worms, this technology enables some farmers to transform manure into a valuable, nutrient-rich soil amendment. Vermicomposting also can reduce the environmental effects of manure-derived wastewater, offering a multifaceted solution to some dairy farmers. 

These three examples offer a glimpse into the diverse array of strategies dairy farmers are employing to manage manure and repurpose it as a valuable resource, while underscoring that no one-size-fits-all solution exists. 

Scaling solutions 

The challenge that remains for the dairy community is finding ways to make these technologies and practices affordable and accessible to all farms, regardless of farm size and/or geography. In part, that’s what the U.S. Dairy Net Zero Initiative is built to do — to support accelerated progress toward the industry’s environmental goals by advancing research and technology, on-farm pilots and new market development. 

One such example is the Dairy Soil and Water Regeneration project, in which researchers are measuring how different management practices and technologies — including the use of novel manure-based products — affect soil health and potentially reduces GHG emissions while improving water quality.

As we continue to navigate the challenges of sustainable agriculture and climate change, the role of innovative manure management technologies cannot be overstated. These practices not only show promise of a greener future but also ensure the economic viability of dairy farms across the globe.