Every day seems to bring another warning about contaminated food. While it is more challenging to make your own cheese, it is simple to grow produce at home. Even the smallest apartment can accommodate pots of herbs. A bigger balcony holds modest amounts of fruits like strawberries and vegetables such as beans or tomatoes. An actual garden has even more potential.

The next step is to use organic methods, ensuring a sustainable harvest. A new development may help gardeners. Biochar is created from slowly burned wood, producing a fine-grained charcoal. Like other methods of making charcoal, burning is necessary. But the wood source is different - biochar can be made from a huge variety of waste material such as sticks, leaves, yard trimmings, sawdust, wood chips, and used pallets.

As with so much these days, biochar is far from a new discovery. In fact, it has been used for thousands of years to improve farming. In Amazonia, it is called terra preta de indio. The recent experiment, conducted at Michigan Technological University, measured a staggering 880% increase in productivity. This seems to be due to biochar’s ability to hold water. When combined with soil, biochar sucks up water to be released when drier conditions prevail. Nutrients are also retained in the soil rather than being flushed away with runoff. In addition, biochar provides a surface for beneficial bacteria. Once in charcoal form, it is long-lasting and can persist for hundreds to thousands of years.

It does matter how biochar is produced. A horizontal barrel allows more efficient burning. After an initial ignition, the fuel is covered. Four or five hours later, at the equivalent to a simmer in cooking, the resulting material is allowed to sit and cool for a day. And voila, lightweight charcoal pieces. But wait, isn’t burning wood one of the contributors to unwanted emissions? As it turns out, the slow process releases significantly less carbon dioxide - only 50% compared to 80% normally. More research is necessary to fully investigate the findings, as the initial work was conducted relatively informally by undergraduates in a summer course.

Not only does biochar help to yield robust harvests and enrich the soil, but it also plays a role in climate change. It turns out that biochar sequesters carbon, reducing the amount emitted into the atmosphere. All those nutrients held in the soil also mean 50 to 80% less nitrous oxide (N2O) released into the air and less need for fertilizer.

Much of the current deforestation takes place through slash and burn techniques. Using forestry and agricultural waste to make biochar would be a substantial improvement. Production is simple and can be performed on a household scale. Even backyard gardeners and community gardens can use their prunings and weeds to feed a single char-producing barrel.

Photo credit: Gunnar3001@Flickr.com (http://www.flickr.com/photos/28688905@N06/2753219785/)