Organic fertilizers mainly kill harmful microorganisms such as plant pathogenic bacteria, insect eggs, weed seeds, etc. in the warming stage and high temperature stage of composting. However, the main role of microorganisms in this process is metabolism and reproduction, and only a small amount is produced. Metabolites, and these metabolites are unstable and not easily absorbed by plants. In the later cooling period, microorganisms will humify organic matter and produce a large number of metabolites that are beneficial to plant growth and absorption. This process takes 45-60 days.
The compost after this process can achieve three goals:
One. It is harmless, the biological or chemical harmful substances in the organic waste are treated in a harmless or safe manner;
Second, it is humusification. The process of humusification of soil organic matter is to decompose. The simple decomposition products produced under the action of microorganisms produce new organic compounds-humus. This is the process of humification, a form of accumulation of nutrients;
Third, it is the production of microbial metabolites. During the metabolism of microorganisms, a variety of metabolites, such as amino acids, nucleotides, polysaccharides, lipids, vitamins, antibiotics, and protein substances, are produced.
The fermentation process of organic compost is the process of the metabolism and reproduction of various microorganisms. The metabolic process of microorganisms is the process of decomposition of organic matter. The decomposition of organic matter will inevitably generate energy to increase the temperature. The death, replacement and material form transformation of various organisms and microorganisms in the composting process are all carried out at the same time. Whether it is from the perspective of thermodynamics, biology or material transformation, the composting fermentation process is not a short time of several days or ten days. What can be done is why composting still takes 45-60 days even if the various temperature, humidity, moisture, microorganisms and other conditions are well controlled.
Generally, the fermentation process of organic fertilizer compost is heating stage → high temperature stage → cooling stage → maturity and heat preservation stage
1. Fever stage
In the initial stage of compost production, the microorganisms in the compost are mainly medium-temperature and aerobic species, and the most common are non-spore bacteria, spore bacteria and molds. They start the fermentation process of composting, decompose easily decomposable organic matter under aerobic conditions and generate a lot of heat, and continuously increase the compost temperature from about 20°C to 40°C, which is called the fever stage.
2. High temperature stage
As the temperature increases, the thermophilic microorganisms gradually replace the mesophilic species and play a leading role. The temperature continues to rise, generally reaching above 50°C within a few days, entering the high temperature stage.
In the high temperature stage, thermoactinomycetes and thermogenic fungi become the main species. They strongly decompose the complex organic matter in the compost, accumulate heat, and the compost temperature rises to 60-80°C.
3. Cooling stage
When the high temperature stage lasts for a certain period of time, most of the cellulose, hemicellulose, and pectin substances have been decomposed, leaving complex components that are difficult to decompose and newly formed humus, the activity of microorganisms weakens, and the temperature gradually drops. When the temperature drops below 40°C, mesophilic microorganisms become the dominant species again.
4. The stage of decomposing and maintaining fertilizer
After the compost is decomposed, the volume shrinks, and the temperature of the compost drops to slightly higher than the temperature. At this time, the compost should be compacted to cause an anaerobic state and weaken the mineralization of organic matter to facilitate the preservation of fertilizer.
The mineralization of compost organic matter can provide crops and microorganisms with quick-acting nutrients, provide energy for microbial activities, and prepare basic raw materials for the humification of compost organic matter.
Reference indicators for organic fertilizer fermentation process:
1. Looseness
The biological fermentation method starts to loosen up on the fourth day of fermentation and is in the form of broken pieces.
2. Odor
The bio-fermentation method started to reduce the odor from the second day, basically disappeared on the fourth day, completely disappeared on the fifth day, and exuded the fragrance of soil on the seventh day.
3. Temperature
The biological fermentation method reached the high temperature stage on the 2nd day, and began to fall back on the 7th day. Maintain the high temperature stage for a long time, and the fermentation will be completely decomposed.
4. PH value
The pH value of the biological fermentation method reaches 6.5.
5. Moisture content
The initial moisture content of the fermentation raw materials is 55%, and the moisture content of the biological fermentation method can be reduced to 30%.
6. Ammonium nitrogen (NH4+-N)
At the beginning of the fermentation, the content of ammonium nitrogen increased rapidly and reached the highest amount on the 4th day. This was caused by ammoniation and mineralization of organic nitrogen. Subsequently, the ammonium nitrogen in the organic fertilizer was lost and converted due to volatilization. It becomes nitrate nitrogen and gradually decreases. When the ammonium nitrogen is less than 400mg/kg, it reaches the maturity mark. The content of ammonium nitrogen in biological fermentation method can be reduced to about 215mg/kg.
7. Carbon to nitrogen ratio
When the C/N C/N ratio of compost reaches below 20, it reaches the maturity index.
Disclaimer: Part of the data in this article is for reference only.
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Post time: Dec-29-2021