Biochar is a variety of charcoal which is used as a nutritional supplement for soil.

Biochar is basically charcoal. It can be made from almost any biological substance rich in carbon, such as wood, straw, various kinds of plant material, compost and so on. It is usually made from wood because wood has a structure with various sized holes in it, mostly for conducting water or sap in the tree, and these form places where micro flora can live. When biochar is made, it is not processed at a high temperature, so the physical structure of the wood is not lost.

Biochar benefits the soil by providing places for micro flora to life, holding water, and holding various nutrients to prevent them from washing away. The nutrients and water are available to plants with roots in or near the biochar, so it provides fertility to the soil.

Biochar also has the benefit of providing for carbon sequestration, which is valuable for taking carbon dioxide out of the air and helping with global warming.

Soil with biochar added is called terra preta.

Biochar is charcoal made from wood or other similar material such as straw, which has large holes in it from the water and sap carrying veins remaining. In order to retain the structure of the wood, it is made at low temperature.

Biochar provides places for micro flora to grow, and also holds water and nutrients that can be available for plants. Wnen mixed with soil, the result is terra preta.

To be used, it is added to the soil of a garden or farm field and mixed in. It should be mixed in gently so as to prevent worms from being killed. It might make up 5% to 10% of the soil when the job is done, but it should not all be mixed in at once. Two or three years of adding smaller amounts is better.

Once the biochar is in the soil, there should be no need to till. There should also be very little need to add fertilizer, though trace minerals might be added.

In the Amazon, where the soil is mostly very poor, there are patches of biochar several thousand years old. The poor soil remains poor in nature, but the patches of biochar build up thicker every year. This is because of the biological activity in the biochar.

3.08 tonnes of CO2 per tonne of pure carbon biochar.

James Bruges has written:

'Little Earth Book' -- subject(s): Effect of human beings on, Environmental degradation, Environmental responsibility, Global environmental change, Nature, Sustainable development

'The biochar debate' -- subject(s): Charcoal, Climatic changes, Carbon sequestration, Soil amendments, Ashes as fertilizer, Prevention

'The Little Earth Book--Countertop Display'