Biochar Solutions: Tackling Manure Pit Odor and Emissions at Shelburne Farms

Biochar delivery at Shelburne Farms

Project Overview

Shelburne Farms, located in Shelburne, Vermont, recently turned to an innovative way of utilizing biochar to tackle odor and potentially greenhouse gas emissions arising from their manure pits. With nearly 100,000 visitors a year, Shelburne Farms is an education nonprofit dedicated to building a sustainable future, and its historic campus is a working farm and forest. The integration of biochar into their soil and manure pits has shown significant promise in reducing odor and potentially lowering greenhouse gas emissions, providing a deeper understanding of the revolutionary benefits that biochar can offer to sustainable agriculture.

Manure Pit Emissions

Manure pits are commonly utilized by dairy and livestock farms to manage manure runoff and cleanout from barns and feedlots. While they improve water quality and provide fertilization for hay fields in upcoming growing seasons, they produce an unpleasant, persistent odor, which attracts flies, affecting both adjacent animal health and impacting visitors to the farm. According to Sam Dixon, the dairy manager at Shelburne Farms, biochar has knock-on benefits beyond odor control, “we had some challenges in the past with odor, but [were also] interested in their carbon footprint and reducing greenhouse gas emissions from the manure pits.” Former Carbon Drawdown Coordinator and lifelong Shelburne Farms resident Marshall Webb inspired their ambitious climate plan to meet net zero by 2028, and using biochar is a potentially valuable part of that strategy for them. This enthusiasm originated from his love for trees and soil.

Solution: Implementing Biochar

To reduce odor and potentially greenhouse gas emissions, Shelburne Farms needed to cover their manure pits and accelerate the decomposition of the manure, thereby reducing nitrous oxide (N2O) and other odor-forming gases that are a product of this process. After combing through some potential options, Marshall's passion for biochar led the farm to land on the product.   As Sam said, “we looked at various types of materials that people have used, like wood chips or straw, and we really felt like biochar…was the best material to use to create this permeable cover over the manure pit.”

Biochar is created by heating wood chips or other biomass in the absence of oxygen. This process, called pyrolysis, leaves behind a porous and lightweight charcoal-like material that is mostly carbon. These pores allow biochar to have an extremely large surface area, with one cubic inch of biochar having the same surface area as a football field. The addition of a layer of biochar on top of a manure pit forms a permeable cover while also allowing for more microbial activity per square foot of soil, therefore accelerating the decomposition process and reducing the odors emitted by the organic matter.

Biochar Implementation at Shelburne Farms

Shelburne Farms has been exploring various types of biochar for their manure pits for the past four seasons. This year, they implemented Standard Biocarbon’s biochar, which is derived only from spruce + fir sawmill residuals, creating a consistent product with an organic carbon content of over 90%, an ash content of less than 2%, and a pH value around 8. Sam noted some differences with the Standard Biocarbon biochar, stating that “while in the previous two years they had needed about 130 yards of biochar, with Standard Biocarbon’s product they only required 50 yards to achieve the same results.” The reason for this difference, according to Sam, “has to do with the bulk density of the material, [as] it’s much lighter and buoyant.” To apply the biochar, the process was easy. They simply “dumped the biochar in the pits and spread it out,” whereas in the past they had to “mix it in with the pump to get good coverage.”

Sam also mentioned that the biochar Shelburne Farms had been using previously had a much higher pH than the Standard Biocarbon biochar, which at 8% is very close to pH neutral, leaving little concern as to whether the pH of the soil could be disturbed.

Outcome

Shelburne Farms’ experience using Standard Biocarbon’s biochar has been very positive. As Sam emphasized, “it's been very successful in terms of reducing odor - it really cuts the smell.” The reduction in odor suggests to Sam that the biochar may be trapping greenhouse gases while also helping to “retain some of the nutrients and actually make the manure a better fertilizer.” While the farm is not currently directly measuring gas emissions, this assumption aligns with existing research on biochar’s ability to reduce methane gas emissions while retaining soil nutrients for crops.

Conclusion

The successful utilization of biochar at Shelburne Farms raises optimism about biochar's potential to increase the sustainability and productivity of farms nationwide. Shelburne Farms’ integration of biochar aligns with their long term climate goals, as well as serving as a model for agricultural operations nationwide seeking more sustainable practices. Sam is pleased with the results of Standard Biocarbon’s biochar so far and remains optimistic about future research on biochar in agriculture and improving soil health. He explained that liquid manure fertilizer can be harsh and acidic, and adding biochar can improve soil health and plant health. Dedicated to building a sustainable future, Shelburne Farms' innovative use of biochar highlights the potential of evolving traditional farming practices to tackle modern environmental challenges, setting an educational example for others to follow.

Relevant Links

Check out Shelburne Farm’s article on Biochar: https://shelburnefarms.org/about/news-and-stories/biochar-climate-solution