Scientists are reporting that biochar, which is a material that the Amazonian Indians used to enhance soil fertility centuries ago, has the potential in the modern world to help slow global climate change. Mass production of biochar could capture carbon that otherwise would wind up in the atmosphere as carbon dioxide, the main greenhouse gas. Their report appears in ACS’ Environmental Science & Technology, a bi-weekly journal.
It has only recently been realized that pyrogenic carbon or biochar or charcoal, can make up a significant fraction of the organic carbon in soils and sediments. As such, it is an important but poorly understood portion of the global carbon cycle. Biochar also may be useful as an additive to soils to enhance fertility.
Biochar is a high carbon, fine grained residue which used to be produced using centuries old techniques by smoldering biomass (i.e., covering burning biomass with soil and letting it smolder).
Biochar can be used as a soil amendment to affect plant growth yield, improve water quality, reduce leaching of nutrients, reduce soil acidity, and reduce irrigation and fertilizer requirements. These properties are very dependent on the properties of the biochar, and may depend on regional conditions including soil type, temperature, and humidity.
Kelli Roberts and colleagues note that biochar is charcoal produced by heating wood, grass, cornstalks or other organic matter in the absence of oxygen. The heat drives off gases that can be collected and burned to produce energy. It leaves behind charcoal rich in carbon. Amazonian Indians mixed a combination of charcoal and organic matter into the soil to improve soil fertility, a fact that got the scientists interested in studying biochar’s modern potential.
The ACS study involved a life cycle analysis of biochar production, a comprehensive cradle-to-grave look at its potential in fighting global climate change and all of the possible consequences of using the material. It concludes that several biochar production systems have the potential for being an economically viable way of sequestering carbon while producing renewable energy and enhancing soil fertility
For further information please see: http://pubs.acs.org/doi/full/10.1021/es902266r