by Sam Maupin, Horticulturist at The Brothers Greenhouses, February 2014, Port Orchard, Wash.
Biochar is a product that has been used by farmers for tens of thousands of years, and is currently gaining popularity for a myriad of reasons. It is created when organic matter is heated in anaerobic conditions resulting in a charred material that is little more than a hollow carbon structure. Benefits of biochar production are leading greenhouse growers to incorporate this technology in various facets of production. Utilizing heat created in biochar production to grow crops is a significant economic incentive for greenhouse managers. When biochar is carefully incorporated in soil or growing media, it brings physical, chemical and biological benefits for crop production. Ecological benefits of biochar production have the potential to bring political and social support, if they are communicated effectively. The undeniable upside of biochar technology has that potential to impact farming the way the electric car has impacted the auto industry.
Heating costs are one of the greatest expenses for greenhouse growers. Most growers rely on natural gas heat, despite high volatility in prices. Heat created during biochar production can be used to reduce or eliminate dependence on natural gas. When wood chips or other agricultural byproducts are heated without exposure to oxygen they release volatile gas, a process called pyrolysis. This gas can be collected and burned to create the heat that drives the pyrolysis process. When this happens inside a greenhouse, or in concert with a boiler system, the heat becomes useful for crop production. Because the organic material itself is not burned, carbon dioxide is not released, and emissions are relatively clean.
Biochar suitable for soil incorporation should have physical properties that benefit soil structure, and chemical properties that are safe for agricultural production. Incorporating biochar increases organic matter in soil. This tends to benefit water relations such as drainage and water-holding capacity. It also increases cation exchange capacity, meaning the soil can hold more nutrients. It should be considered that nutrients held tightly by biochar may not be readily available to plants, but they will also be less likely to be leached from soils and lost. Increased organic matter is generally beneficial for soil micro biotic activity. The hollow carbon structure of charred wood acts like coral reef for microbes that work symbiotically with plants to deliver nutrients and resist pathogens. On a basic level biochar can serve as a cheap bulking agent in growing media, but it also has the potential to benefit long-term soil productivity.
Turning the tide on global pollution is becoming increasingly important. Biochar represents another way for greenhouse growers to take a step toward sustainability. Biochar is incredibly stable. When plants convert carbon dioxide to cellulose, they are creating a carbon sink. When the cellulose is charred it becomes stabilized, preventing the carbon from becoming gas contributing to global climate change. This is a winning model in a hypothetical carbon-credits market, and in public relations. Biochar production creates energy from local fuel sources and reduces reliance on controversial fuels like natural gas, oil and coal. Promoting a positive environmental image will also increase customer appreciation of products grown.