Four periods of organic fertilizer fermentation

Composting is the process of mixing a certain proportion of compost base material and filler material, and under appropriate temperature, humidity and ventilation conditions, the organic matter is degraded by microorganisms to form stable humus and minerals, and the process of releasing heat, the composted product is is an organic fertilizer. Composting is a temperature-related fermentation process that includes four periods: heating period, high temperature period, cooling period and decomposing period.
1. Warming up period
During the heating period, the species of microorganisms are dominated by mesophilic microorganisms such as bacteria, fungi, and actinomycetes. They mainly decompose and utilize soluble substrates such as sugars and starches to release part of NH3 and release a large amount of heat. When the temperature reaches 25°C, mesophilic microorganisms multiply and grow rapidly, and can reach 40~45°C in about 20 hours. When the temperature exceeds 45~50°C, the compost enters a high temperature period.
2. High temperature period
As the temperature increases, mesophilic microorganisms gradually lose their activity, and are replaced by thermophilic microorganisms such as Bacillus and Actinomyces. Bacillus bacteria are representative bacteria in the high temperature stage of composting, they can form a very thick spore wall to resist adverse environments such as high temperature, radiation and chemical corrosion. Actinomycetes can break down some cellulose, dissolve lignin, and can tolerate higher temperatures and pH than fungi. The ability of actinomycetes to degrade cellulose and lignin is not as strong as that of fungi, but they are the dominant flora to decompose lignocellulose in the high temperature period of composting. Under harsh conditions, actinomycetes survive in the form of spores. Nocardia, Streptomyces, Thermoactinomycetes and Micromonospora are all thermophilic actinomycetes that are dominant in composting, not only in the high temperature stage of the composting process, but also in the cooling stage and The aging stage works, and complex organic compounds such as cellulose, hemicellulose, lignin and some proteins begin to be gradually oxidized and decomposed. During the high temperature period, as the temperature rises, the microbial populations that work are also gradually changing. Thermophilic fungi and actinomycetes are active in the environment around 50 °C. The nematodes and bacteria continue to be active. When the temperature is higher than 70°C, most of the thermophiles dormancy or die. The organic matter is decomposed under the action of enzymes, and the degradation rate slows down. Therefore, the best temperature for the high temperature period of composting should be within 55~60℃. The microorganisms in this range are rich in species and quantity and have the best activity, which can ensure a high rate of organic matter degradation, and can kill parasites, Pathogenic microorganisms and harmful bacteria to achieve harmless composting.
3. Cooling period
In the later stage of composting, the easily degradable nutrients are basically completely consumed, the activity of thermophilic microorganisms decreases, and the heat release decreases. When the temperature gradually decreased to below 50 °C, the number of mesophilic microorganisms such as yeast, actinomycetes and nitrifying bacteria increased, which further decomposed the refractory organic matter. During the period, the content of humus and fulvic acid increased and tended to be stabilized, the oxygen demand decreased, and the water content decreased.
4. Mature period
When the compost temperature gradually drops to the same as the ambient temperature, the compost enters the mature stage. The organic matter has been largely decomposed and tended to be stable, and the content of nutrients in humus and fertilizer, especially N fertilizer, has increased significantly.