Its value for the home gardener is that it retains moisture and fertilizer in the soil. I mix it in at the same time as I am working in fertilizer. The Biochar “hosts” these vital nutrients until my plants are ready to use them. It has a neutral pH and I can store bags of it easily.
The larger picture is that Biochar, also called “dark earth,” “soil carbon,” or “terra preta,” is considered by some as another potential tool to help combat climate change. It is made by burning organic crop, wood, and yard wastes, or manures, at very high temperatures and allowing it to decompose in the absence of oxygen, a process known as pyrolysis.
This ancient soil-building method creates humus-rich soil that stores large amounts of carbon that might otherwise be released into the atmosphere. It’s also good for your garden!
If you’re interested in learning a lot more about Biochar, I refer you to the book, Terra Preta: How the World’s Most Fertile Soil Can Help Reverse Climate Change and Reduce World Hunger, Ute Scheub and her co-authors are among those who believe that increasing the humus content of soils worldwide by 10 percent within the next 50 years could reduce atmospheric CO2 concentrations to pre-industrial levels.