Biochar is defined as fine grained, carbon rich and porous product which is prepared by heating or pyrolysis of biomass. Preparation of biochar is in done without oxygen or limited amount of oxygen. Both physical and chemical composition of bio char depends upon the type of feedstock and pyrolysis process. The feedstock of biochar includes forest product, crop residue, animal and municipal waste , woods and manure etc. Plant based bio char consist of more carbon content and less nitrogen as compared to manure based bio char.  Composition of bio char consist of carbon, hydrogen, oxygen, nitrogen, sulfur. The proportion of nutrients varies with type of bio char.

High porosity if biochar helps to retain nutrients, water for long term in soil. It also protects the infestation of various types of soil microorganisms. It will store carbon for long term in soil as it prevents degradation of carbon. It also provides sodium, potassium, calcium and phosphorus as source of micronutrients to soil. Increase in soil porosity enhance the growth of soil microorganisms. It also increases the moisture content and air quantity of soil. Conversion of waste maintains crop diversity and prevents from deforestation.

Other benefit of biochar are given below.

Increased water retention capacity of soil

· Reduction in the leaching of water-soluble nutrients

 · Abatement in soil acidity

 · Reduced leaching of nitrogen into ground wate

r · Minimized emissions of nitrous oxide

Increased cation exchange capacity (CEC) of soil to improve soil fertility

 · Increased persistence of beneficial soil microbes

 · Influencing seed germination, early growth of seedlings and crop production

 · Increased earth-worm abundance, liming effect and priming effect

In comparison to burning, controlled carbonization converts even larger quantities of biomass organic matter into stable C pools which are assumed to persist in the environment over centuries. Apart from carbon sequestration, application of biochar in soils which reduces the emission of non-CO2 GHGs ,  N2O and CH4 emission from soil.