About Immature and Unfinished Composts

Compost which undergoes adequate decomposition will normally result in a product that favours plant growth, improves soil fertility and potentially suppresses soil-borne pathogens. Under some circumstances, however, compost may not fully mature, meaning it does not undergo sufficient breakdown to become stable and growth promoting. Such composts may not only be odorous, they may also be "phytotoxic", and will suppress plant growth. The primary cause of the retardation is oxygen deprivation of root zone and direct damage via volatile organic acids present in unripe compost. Such composts often have a Solvita Index of less than 5, indicating very high respiration rate, and may have a high ammonia index as well.

The images below show composts in varying states of maturity and their effects on container plants. Photo 1 (tomatoes) shows: Left- immature (Solvita 3) compost and right- mature ( Solvita 7 ) compost. The second picture shows roots of Sorghum grass in Solvita #7 compost (left) and immature Solvita #4 compost on the right.