A whole composting process contains 4 necessary stages:

  1. Heating stage. In the early stage of composting, the microorganisms in composting are mainly mesophilic and aerobic. They start the fermentation process of composting, and decompose organic substances (such as simple sugars, starch, protein, etc.) under aerobic conditions, and generate a lot of heat. The composting temperature is continuously increased from 20℃ to 40℃.
  2. High temperature stage. With the increase of temperature, the thermophilic microorganism gradually replaced the medium temperature type and played a leading role. The temperature continued to rise, reaching above 50℃in a few days, and entered the high temperature stage.
  3. Cooling stage. When the high temperature stage lasted for a certain period of time, most of cellulose, hemicellulose and pectin had been decomposed, and the complex components which were difficult to decompose and the newly formed humus were left. The microbial activity was weakened and the temperature gradually decreased. When the temperature drops below 40℃, mesophilic microorganisms become the dominant species.
  4. Maturity stage. After composting, the volume of compost is reduced, and the temperature of compost decreases to a little higher than the air temperature. At this time, the compost should be compacted to cause anaerobic state and weaken the mineralization of organic matter, so as to maintain the compost.