Biochar amendments maintain soil fertility

A colleague recently asked me about biochar. I have to confess, I had no idea what it was, so I looked it up online. According to the International Biochar Initiative, it is a burning process that yields a valuable soil amendment while providing a sink in the soil for greenhouse gases (CO2). This made me wonder if we as gardeners could just burn our crop and yard residues and put them back in the ground. However, the process is quite a bit more complex than that, because the burning has to take place without any oxygen present.

Biochar.org states that most carbon in soil is lost as greenhouse gas into the atmosphere when natural ecosystems are turned into agricultural land. With biochar, the idea is to burn vegetable matter waste, such as crop residues, to reduce the release of CO2 into the air while improving soil health. Putting this burned material, biochar, back into the soil can increase and maintain soil fertility. Using biochar prevents the leaching of nutrients, rather than allowing them to run off into rivers and groundwater. It stays in the soil a long time, outlasting composts, manures or unburned crop residue.

"Charcoal fertilization can permanently increase soil organic matter content and improve soil quality, persisting in soil for hundreds to thousands of years," said Mingxin Guo, Ph.D., and colleagues in a American Chemical Society report.

Biochar may be a solution to the global impact of farming operations, particularly the agriculture waste. Research and projects are still in the early stages, although it is thought that pre-Columbian Amazon natives used biochar to enhance their soils. It is thought to greatly benefit severely weathered or depleted soils with little organic matter. Microbes don't break it down. It may increase water retention. Using it may reduce the need for fertilizers. More research will say. Some reports suggest that it may only benefit plants that require higher potassium and pH levels.

A commercial production plant was built in Tennessee this past August, so gardeners may soon see it widely available. I found biochar suppliers and products online, including one inoculated with beneficial soil microbes. The manufacturer claims the product provides the following plant health benefits: improved soil drainage, more neutral pH, reduced soil compaction, increased nutrient cycling, greater retention of water In dry soils, improved germination and improved plant resistance to fungal disease, root-feeding nematodes and insect infestations. With all these wonderful claims, I think I better do more research.

JoAnne Skelly is the Carson City/Storey County Extension educator for University of Nevada Cooperative Extension and may be reached at skellyj@unce.unr.edu or 887-2252.