Biochar is charcoal used as a soil amendment for both carbon sequestration and soil health benefits. Biochar is a stable solid, rich in carbon, and can endure in soil for thousands of years.[1] Like most charcoal, biochar is made from biomass via pyrolysis. Biochar is under investigation as a viable approach for carbon sequestration,[1] as it has the potential to help mitigate global warming and climate change.[2][3]

Biochar is recognized as offering a number of soil health benefits. The extremely porous nature of biochar is found to be effective at retaining both water and water-soluble nutrients. Biochar is hygroscopic. Thus it is a desirable soil material in many locations due to its ability to attract and retain water. This is possible because of its porous structure and high specific surface area.[67] As a result, nutrients such as phosphate, and agrochemicals are retained for the plants benefit. Plants are therefore healthier, and less fertilizer leaches into surface or groundwater. Soil biologist Elaine Ingham indicates[42] the extreme suitability of biochar as a habitat for many beneficial soil micro organisms.

Biochar can improve water quality, reduce soil emissions of greenhouse gases, reduce nutrient leaching, reduce soil acidity, and reduce irrigation and fertilizer requirements.[47] Biochar was also found under certain circumstances to induce plant systemic responses to foliar fungal diseases and to improve plant responses to diseases caused by soilborne pathogens.[48][49][50]