Influencing Factors and Control of Organic Fertilizer Fermentation

1. Turn the heap
Oxygen supply by turning the heap is one of the basic conditions for aerobic fermentation production. The main functions of turning the heap are: (1) to provide oxygen to accelerate the fermentation process of microorganisms; (2) to adjust the temperature of the heap; (3) to dry the heap.
If the number of turnings is small, the ventilation volume is not enough to provide sufficient oxygen for the microorganisms, which will affect the rise of fermentation temperature; if the number of turnings is too large, the heat of the compost may be lost and the degree of harmlessness of fermentation will be affected. Usually turn the heap 2-3 times during fermentation depending on the situation.
2. The content of organic matter
The content of organic matter affects the temperature of the stack and the ventilation and oxygen supply. If the organic matter content is too low, the heat generated by decomposition is not enough to promote and maintain the proliferation of thermophilic bacteria during fermentation, and it is difficult for the compost to reach the high temperature stage, which affects the hygienic and harmless effect of fermentation. Moreover, due to the low content of organic matter, the fertilizer efficiency and use value of fermented products will be affected.
If the organic matter content is too high, a large amount of oxygen supply is required, which will cause practical difficulties in supplying oxygen to the turning heap, and may cause some anaerobic conditions due to insufficient oxygen supply. The suitable organic content is 20-80%
3.C/N ratio
Best 25: 1
In the fermentation process, organic C is mainly used as the energy material of microorganisms. Most of the organic C is oxidized and decomposed into CO2 and volatilized in the process of microbial metabolism, and part of the C constitutes the cellular material of the microorganism itself. Nitrogen is mainly consumed during protoplasm synthesis
Among them, the most suitable C/N ratio is between 4 and 30 in terms of nutrient requirements of microorganisms. When the C/N ratio of organic matter is about 10, the decomposition rate of organic matter by microorganisms is the highest.
The fermentation time was relatively prolonged with the increase of C/N ratio. When the C/N ratio of the raw material is 20, 30 to 50, and 78, the corresponding required fermentation times are respectively 9 to 12 days, 10 to 19 days, and 21 days, but when the C/N ratio is greater than 80 : 1, fermentation is difficult to carry out.
The C/N ratio of each fermentation raw material is usually: sawdust 300~1000, straw 70~100, raw material 50~80, human manure 6~10, cow manure 8~26, pig manure 7~15, chicken manure 5~10 , sewage sludge 8~15.
The C/N ratio after composting will be significantly lower than that before composting, usually at 10~20:1. The decomposing and fermentation of this C/N ratio is better for agricultural fertilizer utilization.
4. Moisture
Whether the moisture is suitable or not directly affects the fermentation speed and the degree of rot. For sludge fermentation, the appropriate moisture content of the stack is 55-65%. In actual operation, the simple and convenient measurement method is as follows: the material can be formed into a group by holding the material tightly with the hand, and there are water marks, but it is appropriate that the water does not drip out. The most suitable moisture for raw material fermentation is 55%.
5. Granularity
The oxygen required for fermentation is supplied through the pores of the fermentation feedstock particles. The porosity and pore size depend on the particle size and structural strength, such as paper, animals and plants, fiber fabrics, etc., the density will increase when exposed to water pressure, and the pores between particles will be greatly reduced, which is not conducive to ventilation and oxygen supply. The straight size of the particles is generally 12-60mm.
6. pH
Microorganisms can thrive in a wide pH range, with a suitable pH of 6-8.5. pH adjustment is usually not required during fermentation.