The thermal process that produces biochar is called pyrolysis (from the Greek, “pyro,” meaning fire and lysis,” meaning separation). During pyrolysis, the crucial trace elements found in plants (over 50 metals) become part of the carbon structure, thereby preventing them from being leached out while making them available to plants via root exudates and microbial symbiosis.
A range of organic chemicals are produced during pyrolysis. Some of these remain stuck to the pores and surfaces of the biochar and may have a role in stimulating a plant’s internal immune system, thereby increasing its resistance to pathogens.
The best method of loading nutrients is to co-compost the char. This involves adding 10-30% biochar (by volume) to the biomass to be composted. Co-composting improves both the biochar and the compost. The resulting compost can be used as a highly efficient substitute for peat in potting soil, greenhouses, nurseries and other special cultures.