Biochars are charcoal-like solid materials that can be added to soil to improve soil health. Biochar application as a soil amendment is one practice that can be implemented as part of a soil health management plan or conservation plan. Biochars can enhance the carbon impact of other soil health practices, like cover cropping and compost amendments. Applying biochars can improve your soil health by increasing soil organic matter, adjusting soil pH, supplying and conserving nutrients, improving soil water dynamics, and supporting soil biological function.

Biochars are made by heating biomass (e.g. wood, manure, crop residues, solid waste, etc.) in a high temperate, low oxygen specially designed furnace or kiln. This thermochemical process is called pyrolysis. The feedstocks and pyrolysis parameters (temperature, oxidation, residence time) impact the properties of the final biochar product, like the ash content, stability, and particle size. The final properties of biochars, like total carbon, stability of the carbon, nutrient content, and pH, impact how biochars react in soils. Post-production treatments, like steam activation, combining with synthetic fertilizers, with manure or compost, or other chemical or physical treatments, can also change biochars’ reactivity in soils. A complete biochar analysis, which includes the properties listed above, should be obtained from the biochar producer prior to designing the application plan.

Biochars add carbon to soil that is stable for 100s to 1000s of years and can be one natural solution for sequestering carbon and mitigating climate change. Biochars also improve soil water holding capacity and infiltration, soil structure, and crop yield. Additionally, biochars enhance plant growth which, in turn, absorbs more carbon dioxide from the atmosphere.

Biochars also provide economic benefits in agriculture systems by reducing fertilizer requirements, irrigation water requirements, and increasing crop yield. Estimates of economic impact will vary by operation, the cost of biochar application, and financial assistance level. As biochar markets and financial assistance programs continue to evolve, better economic analyses will be available.

Finally, biochar production results in byproducts that may be used as renewable fuels. Pyrolysis of organic waste materials/biomass can produce liquid and gaseous products as well as biochars. Those biooils and biofuels can be used by agriculture operations and other sectors of the economy.

Biochars can be added to soil as a stable carbon amendment through multiple processes. Biochars can be applied in cropping systems to the soil surface and incorporated like other soil amendments or they can be banded or injected, depending on the physical properties of the biochars. In perennial systems, like vineyards or orchards, or in container production, biochars can be applied with minimal incorporation or as part of a soil media mixture. The right application method is dependent on the physical properties and qualities of the biochar, which vary widely depending on the feedstock and pyrolysis process that was used to produce the biochar as well as any post-production treatment, and the production system.

Managing biochar applications for soil health and carbon sequestration requires matching the right biochar with the right soil at the right rate for the right purpose. You can work with a conservation professional to assess your soils, identify resource concerns, and develop a conservation plan to improve soil health and the resources on your land. If there is an existing resource concern that can be addressed through biochar application, the conservation professional you work with will help you decide which biochars and application methods are best for your soils and concerns. You can also use biochar decision support tools to select the best type of biochar and amendment rates for your soil.

Applying biochars with compost, manure or other amendments can ease application and reduce erosion risk by increasing the weight and moisture content of total amendment. An increase in weight and moisture can also reduce the risk of wind loss, especially when applying fine grained biochar. Best management practices include moistening the material before crushing it to reduce dust created during the process, and/or crushing the biochars inside closed bags. Mixing biochars with compost or manure will add moisture to the amendment mix and aid handling and application. Personal protective equipment should be considered when applying biochars to reduce exposure to dust sized particles.

The USDA Natural Resources Conservation Service (NRCS) provides financial and technical assistance to apply biochars on agricultural, forestry and other working lands. The Soil Carbon Amendment Conservation Practice Standard 336 (CPS 336) outlines the requirements of biochars, compost, and other carbon amendments to improve soil health and mitigate climate change. Financial assistance is designed around common application rates, including blended biochars and compost amendments. Many, but not all, states have this practice available in their Field Office Technical Guide. Technical guides are the primary scientific references for NRCS that guide planning efforts.

Federal, regional, and/or state Technical Service Providers can help you develop a conservation plan and find financial assistance. A conservation plan identifies natural resource concerns and prescribes a conservation practice standard to address each concern. If there is an existing resource concern that can be addressed through CPS 336, you can apply for reimbursement for the compost and or biochars procured through the NRCS Environmental Quality Incentives Program (EQIP). In addition to EQIP, the Regional Conservation Partnership Program (RCPP) may also offer financial assistance for CPS 336, but in order to receive financial assistance through RCPP the practice must be available in an active project in your region. In addition, some states offer financial assistance for biochar application.

Decision support is essential for proper implementation of biochar applications. It’s Important to know how biochars can improve soil conditions and to define the purpose of the application. The following decision support tools will help you assess the right biochars and application process for your soils.

USDA Web Soil Survey

The NRCS has incorporated a Dynamic Soil Properties Response to Biochar into the Web Soil Survey’s Soil Health Data Explorer. This tool uses the USDA soil survey data to determine the potential response to biochar applications rated from “unsuited” to “excellent”. This is a first-step screening tool and site-specific assessments of the potential response should be made before a final determination.

Pacific Northwest Biochar Atlas

The Pacific Northwest Biochar Atlas (the Atlas) is designed to provide guidance to farmers, gardeners, and other end-users on the potential benefits of biochars and to select biochar types and amendment rates. For users to get the most out of the Atlas, they should have their crop (species and nutrient requirements), soil (organic matter, nutrients, pH, CEC and texture) and biochar (total H%, total C%, available and total nutrients, CaCO₃ equivalent, particle size class) data to enter into the tool. Users should also be able to prioritize their goals for applying biochars from a drop-down menu (e.g., sequester carbon, increase water retention, increase soil pH). The Atlas also includes many other resources, supports biochar producers, and houses several case studies. The current area of focus is the Pacific Northwest region; however, a national expansion of the tool is underway with an anticipated release in 2025.

Biochar Selection Tool

The Biochar Selection Tool allows you to input data about your soils in order to select the best type of biochar and amendment rate.