Does Pacific Northwest-Sourced Biochar Have a Future as a Soil Amendment in Annual Cropping Systems?

By Doug Finkelnburg, University of Idaho Extension

I recently had the pleasure of attending and presenting at the “Making and Using Biochar” workshop hosted by my colleague and Area Forestry Extension Educator Chris Schnepf in Sandpoint, Idaho. The program was designed to give foresters, forest owners, and agriculturists an introduction to biochar in forestry and agriculture and was an opportunity to see demonstrations of biochar production. The audience packed a large room at the Sandpoint Organic Agriculture Center and heard from experts on biochar production and use in USDA (United States Department of Agriculture) Forest Service funded projects.

The arguments for biochar use are compelling. Diverting what becomes an atmospheric carbon source—slash burning—into a net carbon sink—biochar—has several notable benefits from a soil health and climate change perspective. Our annually cropped soils in the Pacific Northwest are depleted of organic matter, following over one hundred years of tillage and erosion. Soil organic matter plays a critical role in crop production as a reservoir for plant available nutrients and water. As soils lose organic matter they become more reliant on synthetic fertilizers and less resilient to drought.  However, biochar adoption as a soil amendment in annually cropped agricultural systems faces several challenges to actually implement on-farm, and a better understanding of the agronomic effects and economic benefits over time is needed before we can realize its full potential.

Research into the benefits of biochar use in agroecosystems is very promising. A recent metanalysis has shown how biochar applications provide disease and pest management benefits to plants by altering soil microbial communities, promoting beneficial microorganisms, and suppressing plant pathogens. The physical structure of biochar also provides habitat for beneficial organisms, such as mycorrhizal fungi. A Utah State University Extension publication shows clearly how water holding capacity of soils growing silage corn and alfalfa was increased with biochar applications, although no clear crop yield benefits were discovered. In fact, crop yields decreased, although inconsistently, due to biochar application. This highlights our current knowledge gaps regarding the complex interactions within soils that govern nutrient availability when biochar is applied. Researchers are trying to fill in these knowledge gaps, drilling down into the effects of biochar on soil properties and wheat biomass under different fertility schemes, discovering new methods for measuring plant available water capacity in different biochar-soil mixes, co-composting biochar with compost materials to increase plant biomass and even building boutique biochars for environmental remediation.

But here is the biggest challenge with biochar as an agricultural amendment in annually cropped systems in the Pacific Northwest: high initial investment associated with its transportation and application. The cost of acquiring the  and integrating it into existing agricultural practices can be prohibitive for many farmers, particularly small-scale and resource-constrained ones. The high upfront costs often deter farmers from considering biochar as a viable option, even though its long-term benefits might outweigh the initial expenses. Currently, USDA-NRCS considers biochar amendments to cost almost $5,000/acre when applied in conservation programs. The estimated a 10-ton/acre biochar application to cost around $3,500/acre. As far as soil amendments go, growers can have trouble considering a $100/acre agricultural lime application and it is a much better-understood practice than biochar amendments. At these price points, biochar applications are not feasible on a landscape scale in annually cropped Pacific Northwest soils without support or incentives, especially since the time horizon over which the benefits play out is poorly understood. However, since biochar remains stable in soils for hundreds of years, policy makers may decide further subsidization makes sense.

So, does biochar have a future as a soil amendment in our annual cropping systems? While biochar holds great promise as a potential solution to address agricultural and environmental challenges, overcoming obstacles to its adoption will likely require more field scale applied research and subsequent knowledge dissemination, as well as policy support and incentives. With continued efforts and collaboration between researchers, policymakers, and agricultural stakeholders, biochar’s full potential as a valuable tool for sustainable agriculture and climate change mitigation can be unlocked for the benefit of both farmers and the environment.