This is the umbrella term for the use of natural compounds to stimulate biological activity in the soil. These compounds range from compost teas (concocted after an analysis of the soil for deficiencies), worm ‘juice’ (active enzymes created from worm castings), Biosolids which is treated human effluent and needs to be plowed into the soil for hygene and odour reasons (not a favourite of carbon farmers), Nitrohumus (treated human effluent, needs no ploughing) etc.