Biocharcoal helps check global warming

Thursday 15 May 2008

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Farmers can be trained to make biochar from agricultural waste

depletion of organic matter in the soil and use of chemical fertilizers are increasingly becoming problems for farmers. Taking their cue from agricultural practices in the Amazon basin, scientists at Delaware University in the us conducted tests and found that charcoal derived from biomass--called biochar--increases soil fertility.

The researchers discovered that tribals in the central Amazon basin added charcoal (from animal bones and the bark of trees) to the soil, which made it extremely fertile. This method is about 1,500 years old. They presented the results at the 235th meeting of the American Chemical Society at New Orleans.

For the experiment, the researchers planted winter wheat in pots of soil and mixed 2 per cent biochar generated from tree leaves, corn stalk and wood chips in some pots and the others contained just soil.They found that soil with biochar showed improved germination and growth compared to regular soil. "The improved soil quality has a long-term effect. Once applied, it will remain for hundreds of years," says Mingxin Guo, the lead author. Besides being porous and having high nutrient and water retention capacities, biochar also boosts the carbon retaining capacity of the soil. This helps check global warming.

According to N Sai Bhaskar Reddy of the Geoecology Energy Organization, Hyderabad, using biochar is cost effective. Farmers can be trained to make charcoal from the biomass available in their fields and surroundings, he adds. During the traditional slash and burn method used in India, a lot of "accidental charcoal" is produced. However, not enough charcoal is produced since the process is not controlled, he says.

Reddy also refers to "charcoal fertilizers" as a novel way of improving the fertility of all kinds of soils. This prevents wasteful burning of millions of tonnes of biomass in the open fields after harvesting. Charcoal should be supplemented with soil microbes, vermi compost, mulch, micro-nutrients, sand, gypsum, fertilizers, silt, etc, he says.

Using biochar is not restricted to the Amazon basin. People have been using biochar knowingly or unknowingly in many parts of the world. The need is to create more awareness about the technique, says Reddy.

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