Designing An Ethylene-Neutral Biochar As a Substitute for Vermiculite In the Horticulture Industry.

Designing an ethylene-neutral biochar as a substitute for vermiculite in the horticulture industry Will Fulton1, John Miedema2,3, Fred Prahl1, Markus Kleber1 1. Oregon State University 2. Pacific Northwest Biochar Initiative 3. Thompson Timber/Starker Forests, Philomath, OR Abstract In 2008, the American nursery industry used approximately 21,500 metric tons of exfoliated, mined vermiculite as a potting medium amendment. Approximately 40% of the vermiculite used in America is imported, mostly from South Africa and China. We propose that biochars could be used as a substitute for vermiculite by nurseries. All mined materials are finite resources, and therefore subject to price increase, whereas the source of biochar feedstocks, the human-generated waste stream, expands exponentially with the population. Additionally, on-farm biochar production can be achieved while simultaneously mitigating heating costs. After initial thermal input, pyrolysis evolves gases that can fuel maintenance of its own temperature requirements, while also heating greenhouses. Before nurseries begin substituting biochar for vermiculite, they must know with confidence what chemical compounds specific biochars bring to their houses. Ethylene is a plant hormone which ordinarily occurs in low concentrations in most plant systems. However, its importance as a plant hormone varies from plant to plant, from time to time, and in a host of complex ways that have the potential to interfere with the expected development patterns of nursery plants. Researchers have discovered that some biochars can stimulate soil ethylene emissions. The chemical and physical characteristics of biochar are subject to variations which appear to derive from differences of feedstock or pyrolysis or post-manufacture handling. Our experiment tests biochar feedstocks from locally available waste streams, pyrolyzed at different temperatures, and treated with different post-production handling regimens, in order to determine the requirements for nursery safe biochars.