Abstract: Biochar is a by-product from the combustion of biomass under limited oxygen conditions and is said to be a climate friendly process. Currently, there are a number of large-scale industrial processes available that can produce large quantities of biochar in an environmental friendly manner as a by-product of bioenergy systems. Unfortunately, at the smallholder scale the current technology is restricted to cooking stoves with limited information on their efficiency and capacity.
The raw biochar is very similar to charcoal and requires grinding to reduce its size prior to application. To date, there is little guidance on the best types of biomass to use (crop residues, dairy manure, urban waste, and wood, bioenergy crops such as miscanthus and switch grass) and the final particulate size required for soil application. A typical biochar size varies from less than 2mm to more than 20mm in diameter, but varies greatly with the type of biomass used and the pyrolysis process. Of potential concern is the black carbon produced at grinding and spreading.
Over the last ten years great interest has arisen in biochar, and is being advocated by many as a potential silver bullet that will help address the long-term problems of food insecurity and soil fertility decline in much of the drylands of the world, and even contribute to the mitigation of climate change.
Presenter: Anne-Sophie Rausch