ABSTRACT
Biochar use during composting can be a strategy to achieve high quality compost end products for agricultural or horticultural use with added economic value. Soils containing condensed aromatic black carbon (BC) are often richer in total organic carbon (OC) than soils without BC. In old charcoal-making places, the biochar application over time was not associated with nutrient-rich human waste inputs. Composting of organic wastes is a bio-oxidative process involving the mineralisation and partial humification of organic matter, leading to a stabilised final product with certain humic properties which should be free of phytotoxicity and pathogens. The same biochar and biochar composts produced at the Ithaka Institute and used for horticultural substrates or in the field trial were also used in a study conducted at the University of Geisenheim, Germany. The plant water availability' factor is of particular importance in poor sandy soils with a low water holding capacity. In summary, biochar as composting additive deserves future research and development.
