Biochar Impact on Plant Resistance to Disease

Abstract

Since 2007, there has been the remarkable development worldwide of an agenda promoting the use of charcoal as a soil amendment. This agenda is based on four main pillars: (i) Renewable Energy Production: Charcoal (a solid energy product) is produced by thermally degrading biomass at temperatures above ~300oC in the absence of oxygen, a process known as pyrolysis. During biomass pyrolysis, gaseous (syngas consisting of H2, CH4, CO, CO2, and C2H4 and other small hydrocarbons) and liquid (bio-oil) energy products are also produced. The pyrolysis technology is poised to become part of an arsenal of technologies, including production of biodiesel from oil-rich crops, ethanol from cellulosic crops, and biogas from anaerobic digestion of wastes, for producing renewable energy from biomass. The goal is to replace some fossil fuels with these different biofuels in order to lower net greenhouse gas emissions and to diversify energy supplies. (ii) Waste Treatment: Many various wastes, including agricultural, forestry, food industry, and urban biomass wastes, can be treated by pyrolysis and thus converted into energy products. As a result, pyrolysis is considerably more versatile than biofuel technologies which require purpose-grown crops that compete with food production for resources. (iii) Soil Fertility: Charcoal used as a soil additive together with organic and inorganic fertilizers has the ability to signifi cantly improve soil fertility by improving soil physical and chemical attributes. Therefore, soil amendment by charcoal may help ward off soil degradation and restore already degraded soils, assisting in the establishment of sustainable food and fuel production in areas with severely depleted soils and scarce resources. (iv) Carbon Sequestration: Depending on feedstock and pyrolysis conditions, biochar is estimated to have a half-life in soil of hundreds to tens of thousands of years, leading to longterm, below-ground sequestration of carbon that originated as CO2 in the atmosphere. Moreover, addition of biochar to soil may reduce greenhousegas emissions from cultivated soils. These four pillars together constitute the “Charcoal Vision” (Laird 2008). To differentiate this 4-fold paradigm from the conventional view of charcoal solely as an energy product, a new name for it has emerged: BIOCHAR.