Chemical Index of Compost Maturity
- During composting, the unstable organic matter in the heap material is decomposed into carbon dioxide, water, minerals and stabilized organic matter, and the organic matter content of the heap material changes significantly, so the content of organic matter can be changed by the measurement of some parameters reflecting the change of organic matter (such as COD, BOD and VS) and the changes of some organic matter in composting process were used to characterize the degree of decay.
- In the process of biodegradation of compost, nitrogen-containing components are degraded to produce ammonia gas, and some ammonia gas is oxidized to nitrite and nitrate in the later stage of composting, so the degree of decay can be judged by the existence of nitrite or nitrate. And because the determination of these two indexes is relatively fast and simple, it has good practical value.
- The process of composting is accompanied by humification. It is an important method to evaluate the maturity of humic acid by studying the change of humification parameters. The results show that some parameters such asCEC (cation exchange capacity), HA, fulvic acid FA (humus HS, humic acid), FF and non-humus component NHF were used to evaluate the maturity of compost.
- Carbon source is the energy used by microorganisms, nitrogen source is the nutrient of microorganism, the change of carbon and nitrogen is one of the basic characteristics of composting, and C / N (solid phase) is the most commonly used parameter to evaluate the maturity of compost. It is also pointed out that the metabolism of microorganisms in the degradation of compost raw materials occurs in water soluble phase, so the index of water-soluble organic carbon / organic nitrogen can be used as the parameter of composting maturity.
- Organic acids exist widely in immature compost, and the maturity of compost can be evaluated by studying the changes of organic acids.
