One Kilo Per Cubic Meter

Or, for the folks on this side of the pond about 2 pounds per square yard, is the recommended application rate for char. The International Biochar Initiative (www.biochar-international.org/) has been working to not only spread the word about this important material, but has been researching the effectiveness of different application rates, ways to treat and enhance it and setting standards for char producers across the globe. The five years of research and development that I have put into char making and use has led me to understand many of the characteristics of the material. The way I make it is in a retort. Many other char producers use a TLUD (Top Lit Up Draft) burner. This allows some oxygen to enter the char burner and because this method produces lower quality char quickly, many like it for the obvious benefits of both speed and relative ease of making the char.

Many TULD units burn in less than an hour...the retort that I use takes at least three hours to convert the char to nearly pure carbon. In the retort system, no oxygen at all is allowed into the vessel and only volatile gasses are allowed to leave

The three main parts of the retort. Flameproof container Vent and Access Port.

The retort is a vessel that is nearly completely sealed from outside air. Other than venting the volatile gasses that are released by the dry organic matter, there are no places that air can be introduced to the vessel. Somewhat like a still, the retort contains the roasting material in  a container of some sort. The easiest, cheapest and most available retorts that I have found are simple cookie or cracker tins. I'm sure that virtually every second-hand store has them, steel tins are about as ubiquitous as any used, but useful item you can name. When using them to create char, you will need to punch a few holes in the lid, fill it with dry organic matter, then put it right in your fire pit, fire place or bonfire. Heating the material inside until it is hot enough to glow in the absence of oxygen is what transforms it to char. The retort I use holds five gallons of material, however, when it is reduced to char, it loses half the volume. No flame ever occurs inside the retort. As the volatile gasses escape through the vent or gaps around the access port, it burns off. The best indication of when the char is finished is that there will be no more flammable gasses escaping through the vent.

Because char is a natural product, some variation occurs, but the resulting char is roughly two and a half gallons once finished and it weighs about a kilo. This material is super light weight but has tremendous power to transform soils, healing them, and when the char is moisturized, mineralized, has nitrogen added and inoculated with healthy soil organisms, it is a powerful tool for restoration. In addition to sequestering carbon, biochar holds six times it's weight in water, sequesters carbon and slows the nutrient cycles withing the soil, providing habitat for billions of soil organisms. It is perhaps, hard to imagine, but char has sixteen acres of surface area per handful and the organisms that colonize these surfaces hold even more water in their cellular structure. Organisms, like us, are mostly water and their waste products are food for a cascade of other organisms, which can and do bring life to the soil.