Biochar’s Role in Farming and Soil Health

Incorporation of biochar into farm soils improves soil quality, increases farm productivity, and reduces chemical needs.
By Stephen Smith and Russel Peterson | January 14, 2023

For most of the last century, modern farming has included heavy dependence on mechanical tilling, single crops, chemical fertilizers, herbicides and pesticides.  As a result, much of United States farmland soil is depleted of nutrients, natural soil microbes and organic matter, with continuing loss of top soil to wind and water erosion.  Farm productivity is further impacted by severe weather patterns.

According to a study by NASA and Columbia University, 77% of the entire West is experiencing severe to extreme drought, and 36 states and territories of the U.S. are in severe to exceptional drought conditions as of August 2022.  These problems are exacerbated by fertilizer and fuel shortages, and supply chain issues throughout the world. Farming practices and amendments that will improve soil quality, reverse chemical dependence, increase farm productivity, and make farming more resilient and sustainable are needed. 

National and international movements are now underway to “go green” by eliminating the use of chemicals and moving toward organic farming. However, as recently stated by a former USDA scientist, the change away from chemicals must involve a multiyear transition, rather than a one-size-fits-all, immediate and mandated change that could lead to Dust Bowl conditions and starvation due to crop failures. Fortunately, there is a path to regeneration of the soil that provides tools to bring it back to life while reducing greenhouse gases. Biochar is one of the tools that can help transform our existing state of agriculture, providing a net positive result not only for the soil, but to Earth as a whole.

Regenerative Farming to Improve Soil
Regenerative approaches to farming and soil health are methods that maintain or improve the soil characteristics important to current and future agricultural production and crop quality. Regenerative farming is not a new process, but an approach to cultivating land that increases the capacity of the soil to support plant growth and store carbon. By restoring ecosystem health and biodiversity, this approach aims to bring benefits including greater resilience in the face of drought and other extreme weather events, increased nutritional value in food, and increased profitability for farmers, all while helping to mitigate climate change. The regenerative agriculture movement has developed in recent years as a response to industrial agriculture’s tendency to reduce, rather than increase, soil fertility over time. As a result of mechanized tilling and heavy use of artificial fertilizers and pesticides, soil’s ability to hold on to nutrients has been diminished, thus reducing its agricultural productivity.

Regenerative farming seeks to undo this damage and regenerate soil damaged by conventional industrial farming practices.  Farming and soil management methods are used to restore natural levels of carbon, nutrients and biologic complexity to soil while the use of chemical herbicides, pesticides and most fertilizer is excluded or minimized.

Biochar is a uniquely stable form of carbon that has many properties that make it an attractive amendment for soil. Amending soil with biochar helps reduce nitrogen loss, phosphorus leaching, nitrous oxide production, ammonia volatilization, and GHG emissions.  Increased plant growth, water holding capacity, and resistance to drought are all positive results of biochar use. These qualities make biochar an amazing tool toward the regeneration of our soils. The incorporation of biochar accelerates the transition to healthy soil and increases the efficiency of plant uptake of nutrients, thus reducing the need for fertilizer. As regenerative farming continues, soil is improved as more organic matter is incorporated from cover crops, alternative crops, manure, biochar and other materials.

Sustainable farming involves farming methods that maintain soil quality for future use.  It differs from regenerative farming in that it assumes good soil, and seeks to maintain or gradually improve it year after year. Most of the same practices of regenerative farming are employed, only less aggressively.

A critical aspect of improving soil quality is to increase the organic content of soil.  Organic matter consists of degradable materials, such as roots, mulch, and compost, and nondegradable materials, such as char. Degradable materials are the food to feed the complex system of soil micro- and macro-organisms, ranging from bacteria and fungi to worms and insects.  These organisms break down the organic material to release nutrients needed by growing plants, while also loosening or aerating the soil and increasing its capacity to hold water needed by growing plants. Biochar is an excellent form of nondegradable carbon material. Production and incorporation of biochar into soil with appropriate additions of compost can improve short- and long-term soil health and farming productivity.  

Methods of Biochar Production
Biochar is produced by pyrolysis or gasification. In pyrolysis, organic material is heated to high temperatures in an oxygen-free environment with no combustion. In gasification, organic matter is heated to high temperature in a low oxygen environment, such that only partial combustion occurs. In either case, biochar is the remaining solid material. The biochar is black, mostly carbon and is not ash, but does contain some ash. Process temperatures range from 300 to over 1,000 degrees Celsius (572 to over 1,820 degrees Fahrenheit), but are generally in the range of 500 to 650 degrees C. As the temperature increases, less biochar remains and more gas is created.  In general, about one-third of the dry mass of material remains as biochar and about two-thirds are converted to gas. About half of that gas may be cycled to heat the pyrolysis process. 

There are various standards covering both the feed materials and the biochar product. Standards are applicable to biochar use, such as a soil amendment, and to its potential for sequestering carbon as a climate change mitigating (carbon credit) process. The International Biochar Initiative promotes the use of biochar for agriculture, as well as carbon sequestration. The IBI offers testing guidelines for biochar use in soil that are accepted as international quality standards. The IBI guide is intended to identify the characteristics of specific biochar products most important for use as an agricultural soil amendment.

Complementing the IBI is Puro.earth, a business that offers a business-to-business marketplace on NASDAQ to sell offsets to carbon dioxide (CO2) emissions.  Its website states that “Puro.earth focuses solely on verified, net-negative technologies that can remove carbon at an industrial scale and store it for a minimum of 50 years. Our innovation is harmonizing different methods of CO2 removal and turning them into digital tradable assets called CO2 Removal Certificates (CORCs).”  The standards that are applicable to biochar intended to qualify as CORCs for sale clearly allow feedstock of grown crops such as hemp, and waste wood materials such as pallets. The standards do not seem to allow waste treated wood.  However, the case for using creosote-treated railroad ties is justified, as creosote is an organic material that is destroyed by high-temperature pyrolysis. Thus, negotiation of this issue may be required. As of February 2022, the price of biochar CORCs was approximately €100/per metric ton of CO2.  Pricing for U.S.-created CORCs may be different.

Biochar Feedstocks, Chemistry and Characteristics
Hemp plants—which are not the same as marijuana—can be harvested and used to produce biochar. In addition to being a good biochar feedstock, hemp can be used for many products, including rope, fabric, human and animal food, and animal bedding. The roots of the plant remain after harvest to increase soil compost and water absorption, and improve texture.  Hemp grows rapidly, is drought tolerant, and absorbs approximately 9 to 13 metric tons of CO2 per hectare (4 to 6 tons per acre) harvested. Harvested hemp has low moisture content and produces a biochar with excellent qualities for soil improvement.

Wood is an excellent feedstock for biochar production. Waste or unusable wood is ideal due to its low cost and availability. Such wood materials may include trees killed by beetles, unwanted pallets, tree trimmings and used railroad ties. In order to minimize the cost and environmental impact of source materials, feedstocks will vary by specific location. Used railroad ties are produced in abundance, as U. S. railroads replace approximately 20 million ties per year. Disposition of ties is costly to railroads, so a local option transforming them to biomass is appealing. Railroad ties are mostly hardwood (generally oak), but in the western states may also be Douglas fir. Ties are mostly treated with creosote. Creosote is a hydrocarbon liquid derived from coal. In pyrolysis, creosote is broken down to its constituent elements of carbon and hydrogen that mainly contribute to the gas product. The wood is converted to gas and biochar.

Agricultural waste, such as chicken litter, manure or straw may be either mixed into the biochar or with the feedstock material prior to thermal conversion into biochar. Such additions may be used to improve characteristics of the biochar so that it can be even more beneficial to the soil.

Biochar characteristics vary greatly by input materials, pyrolysis temperature and other process variables. Generally, biochar from wood consists of approximately 60% to 90% carbon, 0.5% to 5% hydrogen, less than 1% nitrogen, 2% to 10% oxygen, and 5% ash (dirt).  If used railroad ties are utilized, the creosote is destroyed by the pyrolysis, so it is not present in the biochar or gas.

The energy efficiency of biochar production varies greatly from quite efficient to quite wasteful.  Heat recovery does not necessarily affect the biochar quality, but improves the life-cycle GHG benefit. Some processes release heat from the biomass into the atmosphere, while others are designed to capture energy from the gas portion of converted biomass and use it to produce beneficial heat energy.

Approximately two-thirds of the chemical energy (heat released by burning) of biomass becomes gas during conversion. In most gasification processes, some of this heat drives the conversion to biochar, but much of the heat and unburned gas is released. In many pyrolysis systems, some of the gas is also burned to provide indirect heat to convert biomass to biochar, and the remaining gas—about half—may be used for other processes such as heat or electricity, or sold as renewable natural gas.
Biochar lasts longer than 1,000 years in soil. It provides immediate benefits, including improved soil moisture holding capacity, better conditions for soil microbes, held and time-released nutrients to crops, and improved soil texture. The addition of biochar provides a head start in the transition to improved soil quality. 

Biochar in soil and hemp production are mutually beneficial. Hemp plants can be harvested and converted to biochar. Biochar in soil improves hemp growth.  Hemp plants add more biomass, aerate and loosen tight soil. 

Biochar in soil is carbon sequestration. Farmers, landowners and biochar producers may earn income by the sale of carbon credits or other financial systems, such as offered by Puro.earth.

Good, healthy soil generally benefits little from biochar application, while degraded, nutrient-poor soil—especially with limited water availability—is significantly improved. Some applications of biochar have yielded disappointing results. Thus, it is imperative that site-specific studies be conducted to evaluate both local soil and characteristics and amounts of potential biochar and other materials, in order to develop the recipe that maximizes soil health, productivity and carbon sequestration.

Our Plan
IND Hemp LLC intends to implement a project at Wolf Point Green LLC that will offer an example and lead the way toward improving farm soil and farm products and sequestering carbon, and in doing so, recycling waste materials. WPG will grow hemp to enrich and improve soil texture and organic content. Biochar will be produced and used on owned property and offered to neighboring farms to add organic matter to soil and sequester carbon. Biochar will be produced from used railroad ties, locally produced hemp, and potentially, other locally available organic materials. Such ties would otherwise be disposed in landfills or transported cross-country for combustion, resulting in more emissions to atmosphere. Additional renewable energy will be produced for local consumption.

Much of the farm soil in the U.S., including in northeast Montana, is degraded, resulting in lower farming production. IND Hemp intends to demonstrate how regeneration of soil will increase production and profits of farms. Regeneration will make farming more sustainable. Better soil improves farm finances, including making production more reliable and less susceptible to drought and heat. Putting more carbon into the soil results in less CO2 in the air, thus reducing global warming and generating carbon credits.

Growing hemp also can improve soil health and be part of sustainable farming. Hemp plants have deep root systems that improve soil structure, can increase soil carbon and provide carbon sequestration, while feeding and supporting the soil microbial biome.  Hemp can be grown as a primary crop or as a part of crop rotation.  Either way, it provides soil improvement and is mutually beneficial with biochar use. Biochar, potentially with compost, can be mixed into the top foot or so of soil with deep plowing. Thus, biochar addition and hemp culture synergistically improve soil health.
Further, the WPG project will demonstrate how phytoremediation (using plants to remediate soil) using biochar, hemp and sustainable farming practices can be used to restore oil-contaminated soils. The WPG site includes a former oil refinery with legacy contamination of soil by oil hydrocarbons. Through phytoremediation, the oil products will be degraded to their basic elements and the soil will be returned to a healthy, productive state.

Finally, but importantly, the process of making and using biochar will be designed and managed to monetize carbon sequestration to the extent practical in the location. Carbon credits or CORCs will be developed and marketed. For example, if the plant can process approximately 30 tons per year of biomass (about 370,000 ties per year), approximately $400,000 annually in carbon credits could be generated.

In conclusion, incorporation of biochar into farm soils improves soil quality, increases farm productivity, and reduces chemical needs. Biochar added to soil with the correct protocols can help reduce global warming and help generate income from carbon credits. Production of biochar from waste materials such as used railroad ties reduces demand for landfill capacity and reduces GHG emissions from landfills.  Biochar production and use can support the transformation of agriculture from chemical dependency to sustainability, while sequestering the CO2 that many believe threatens all of us and our world.

Authors: Stephen Smith
[email protected]

Russel Peterson
IND Hemp LLC
[email protected]