Adding Biochar can enhance the composting process through:
- Adding beneficial micro-organisms
- Accelerating the composting process
- Reducing GHG emissions
- Reducing ammonia loss
- Serving as a bulking agent
- Reducing odor
At adequate doses, Biochar has been found to accelerate the composting process - mainly through improving the homogeneity and structure of the mixture and stimulating microbial activity in the composting mix. This increased activity translates to increased temperatures and a shorter overall time requirement for compost development.
Terra Preta was most likely formed by mixing of charring residues (Biochar) with biogenic wastes from human settlements (excrements and food wastes including bones and ashes) which were microbially converted to a biochar-compost-like substrate. Thus, co-composting of biochar and fresh organic materialis likely to have a number of benefits. Examples are enhanced nutrient use efficiency, biological activation of biochar and better material flow management and a higher and long-term C sequestration potential. From the compost point of view, there is evidence that biochar as a bulking agent improves oxygen availability and hence stimulates microbial growth and respiration rates. Pyrolysis condensates adsorbed to biochar initially provoked increased respiration rates in soils which most likely occur also during composting. Biochar in compost provides habitats for microbes, thereby enhancing microbial activity. Reported increased moisture absorption of biochar-amended composts with beneficial effects on the composting process.
A common problem during the composting of manure is the formation of big lumps upon drying that stops the process. The addition of 3% (mass basis) of Biochar to poultry manure co‐composted with straw was able to significantly reduce the formation of big lumps in the pile, improving the composting process and the overall structure of the final compost.
For further information on using Biochar as a compost additive, please read the linked document from the International Biochar Initiative.