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BIOCHAR & Organic

BIOCHAR & Organic Agriculture By: Jeff Schahczenski, NCAT/ATTRA Thanks to Wikipedia we can now more easily understand the meaning of “movements”. To paraphrase these definitions, a movement is a set of diverse scientific, social, economic, technological and political topics and activities surrounding a common theme or issue. After lurking in the world of biochar for many years, I feel confident in saying that biochar is a movement. But what is biochar? The range of topics and issues surrounding biochar are immense and unwieldly. If you don’t believe me, just check out the 2015 second edition of the book, Biochar for Environmental Management: Science: science, technology and implementation, edited by Biochar leaders Johannes Lehmann and Stephen Joseph. Biochar Definition Minimum C Content Section 14513.5 of CA Department of Food and Agriculture’s code: “Biochar” means materials derived from thermochemical conversion of biomass in an oxygen-limited environment containing at least 60 percent carbon. At least 60 percent carbon. This 928 page tome is only the tip of the iceberg on the many, many topics related to biochar. To try and keep up with this monster of a subject, join the many listserves and website related to the International Biochar Initiative, IBI. “Biochar: A solid material obtained from thermo-chemical conversion of biomass in an oxygen-limited environment.” The organic carbon content of biochar must be higher than 10% of the dry mass (DM). Biochar materials are divided into 3 grades based on increasing organic carbon content. Biochar is here defined as a charcoal-like substance that is pyrolysed from sustainable obtained biomass under controlled conditions and which is used for any purpose which does not involve its rapid mineralization to CO2. Pyrolysis The biochar's carbon content must be higher than 50% of the dry mass (DM). Pyrolysed organic matter with a carbon content lower than 50% are classified as Bio-Carbon-Minerals (BCM). But what is this movement—inspiring miraculous substance called biochar? Why might it be important to sustainable and organic agriculture? The type of feedstock, and the time and temperature of pyrolysis influence biochar characteristics. Photo courtesy of International Biochar Initiative. 14 Organic Famer August/September 2018

The definition of sustainable biochar is more about its creation and intended application than it is about its composition. Biochar is created through an energy-conversion process called pyrolysis. Pyrolysis is the combustion of biomass in the complete or near absence of oxygen. Biochar can technically be made from any biomass product (wood, manure, grasses, and crop residues). The outputs of pyrolysis are, heat, biochar, oils, and gases—all possible sources of potentially renewable energy. The amount and quality of these outputs depend on the type (or combination) of biomass used and the processing conditions under which it is produced (time and temperature). Recently, the IBI, has created a voluntary international standard for biochar which again speaks mostly to issues of its creation. This standard attempts to settle issues of biochar definition and product testing and assure safety in its use. The use of biochar in certified organic agriculture production is allowed under the National Organic Program (NOP). However, the biomass sources must be from untreated plant or animal material. Biochar from manure is prohibited. This prohibition is a bit perplexing and unfortunate because there is some evidence that biochar made from manures may have additional crop production benefits. Indeed, the quality of biochar used as a soil amendment for agriculture is highly dependent on the type of biomass used and generally is of greater benefit if the pyrolysis process was done slowly and at a lower temperature (known as “slow pyrolysis”). Biochar and Fertility Scientists still don't have a full understanding of how biochar provides fertility for crops, but the following provides a good summary of what research has suggested to date: • Biochars have variable and often limited plant-nutrient content. Pyrolysis removes at least half of the N (nitrogen) content of the original feedstock (North, 2015), yet may concentrate cations such as potassium (K) and calcium (Ca), depending on ash content of the biochar product. For example a Swiss Biochar product contained 0.8 percent potash (K2O) (Schmidt and Niggli, 2015), which would deliver 160 pounds of K2O per acre in a 10-ton-per-acre application. Biochars made with manure generally have higher nutrient content than plant-based biochars. • Biochar enhances soil fertility primarily by providing cation exchange capacity (CEC); reducing leaching losses of nitrate, phosphate, and other anion nutrients, improving soil structure and moisture-holding capacity, and enhancing soil biology (Blanco-Canqui, 2017; Petersen- Rockney, 2015; Wilson, 2014). • The availability of nutrients to crops made possible by biochar is likely enhanced if the biochar is blended with compost, manure, or synthetic fertilizer before application. Biochar combined with synthetic nitrogen increased wheat yields in Oregon (Machado et al., 2017). Blending biochar in this way is often referred to as “charging” the biochar and would not be allowable in organic production systems. Continued on Page 16 FREE online tutorials on soil health, produce safety, and more There are many types of biochar being sold, so it’s important to research what rates and application techniques are appropriate for your operation. Organic growers should check with their certifying agency if they’re not sure about a biochar product meets NOP guidelines. Photo courtesy of google images. How can ATTRA help you? Trusted technical assistance for your ag challenges August/September 2018 15