The organic fertilizer fermentation process can improve the fertilizer efficiency of organic matter and has many other important meanings. Tongda Heavy Industry will teach you more about organic fertilizer fermentation!
The various stages of organic fertilizer fermentation temperature
Heating stage
After the organic fertilizer raw materials (such as livestock and poultry manure, crop straw, fungus residue, etc.) are mixed with the fermentation bacteria, the microorganisms begin to use the organic matter for metabolic activities, decompose the organic matter and release heat, so that the compost temperature gradually increases. This stage usually lasts several days to about a week, and the temperature can rise to 40-60℃.
High-temperature stage
When the temperature reaches a certain height (generally 50-70℃), it enters the high-temperature stage. High temperatures can kill harmful organisms such as pathogens, insect eggs, weed seeds, etc. in the raw materials. And accelerate the decomposition and transformation of organic matter16. The duration of this stage varies depending on the fermentation conditions and raw materials, usually 1-2 weeks.
Cooling stage
As the organic matter continues to decompose, the easily decomposable substances gradually decrease, the metabolic activity of microorganisms slows down, and the compost temperature begins to drop. At this stage, microorganisms continue to humify and produce a large number of metabolites that are beneficial to plant growth, such as humic acid, organic acid, amino acids, etc.
Maturity stage
When the compost temperature drops to a temperature close to the ambient temperature and remains stable, the compost is basically mature. The mature organic fertilizer has a loose texture, black color, no obvious odor, and has a high nutrient content and good soil improvement effect.
Organic fertilizer fermentation raw materials
Reasonable raw material ratio
1. Carbon-nitrogen ratio (C/N) is a key factor. A suitable carbon-nitrogen ratio can ensure that microorganisms have sufficient energy and nutrition during the fermentation process. It is generally believed that the ideal carbon-nitrogen ratio for organic fertilizer fermentation is between 25-35:1. If the carbon-nitrogen ratio is too high (such as too much raw materials with high carbon content such as straw), the microorganisms will grow slowly due to insufficient nitrogen, resulting in a prolonged fermentation process; conversely, if the carbon-nitrogen ratio is too low (such as too much raw materials with high nitrogen content such as livestock and poultry manure), a large amount of ammonia and other smelly gases will be produced, causing nitrogen loss and environmental pollution.
2. At the same time, the moisture content of the raw materials should also be considered. The moisture content of general raw materials should be controlled at 50% – 60%. If the moisture content is too high, the ventilation of the pile will be poor, leading to anaerobic fermentation and producing unpleasant odors; if the moisture content is too low, the activity of microorganisms will be inhibited, affecting the fermentation speed.
Raw material quality
Make sure that the raw materials do not contain toxic and harmful substances, such as excessive heavy metals (lead, cadmium, mercury, etc.) and excessive pesticide residues. Organic fertilizers produced using contaminated raw materials will cause harm to the soil and crops. For example, heavy metals will accumulate in the soil and enter the human body through the food chain, affecting human health.
Fertilizer fermentation condition control
Temperature control
1. In the early stage of fermentation, pay attention to the temperature rise of the pile. Generally speaking, the temperature will gradually rise within 1-3 days after the start of composting. When the temperature reaches 50-70℃ (high-temperature stage), this temperature can effectively kill pathogens, insect eggs, and weed seeds. However, if the temperature is too high (over 75℃), the activity of microorganisms will be reduced or even die, so proper ventilation and heat dissipation should be carried out to avoid excessive temperature.
2. In the cooling stage and the maturity stage, pay attention to temperature changes to ensure the smooth completion of the fermentation process. If the temperature drops and then rises suddenly, it may be that the ventilation inside the pile is uneven or new easily decomposable organic matter enters, which needs to be adjusted in time.
Ventilation conditions
Aerobic fermentation requires sufficient oxygen. During the composting process, oxygen supply can be ensured by turning the pile, ventilation pipes, etc. For large-scale fermentation, such as a roulette turner, a special ventilation system is required. For example, regular turning of the pile in the fermentation tank (generally every 1-3 days) can make the materials inside the pile fully contact with the air and ensure the aerobic respiration of microorganisms. If the ventilation is poor, it will lead to anaerobic fermentation, produce harmful gases such as hydrogen sulfide, slow down the fermentation speed, and reduce the quality of organic fertilizer.
pH adjustment
Most microorganisms grow in a neutral or slightly alkaline environment. During the fermentation process, the pH value will change. Generally, the pH value will decrease in the early stage of fermentation because microorganisms will produce organic acids when they decompose organic matter. When the pH value is lower than 5.5, it will inhibit the growth of microorganisms. The pH value can be adjusted by adding alkaline substances such as lime and wood ash to keep it between 6.5 and 8 to promote normal fermentation.
Fertilizer fermentation process monitoring
1. Observe the state of the pile
Regularly observe the color and texture of the fermented materials. The color of the normally fermented materials will gradually darken from light yellow to dark brown or black. The texture will change from loose to more compact, but not too hard. If the material collapses, expands excessively, or has white mold spots on the surface (except for some beneficial white actinomycetes), there may be problems in the fermentation process, such as excessive moisture or poor ventilation.
2. Detect odor changes
In the early stage of fermentation, due to the decomposition of organic matter by microorganisms, some light ammonia or rancid odors will be produced, but as the fermentation proceeds, the odor should gradually decrease. If a pungent odor (such as the rotten egg smell of hydrogen sulfide) appears during the fermentation process, anaerobic fermentation has likely occurred, and timely measures need to be taken, such as strengthening ventilation and adjusting the pile structure.
3. Detect nutrient changes
The nutrient content in organic fertilizers, such as nitrogen, phosphorus, potassium, and organic matter, can be regularly tested. Through testing, you can understand the fermentation process and judge whether the fermentation is sufficient. For example, fully fermented organic fertilizer has a relatively stable organic matter content, less loss of nutrients such as nitrogen, and some organic nitrogen will be converted into a form that is easier for plants to absorb.
Safety and environmental protection issues
1. Prevent fire
During the fermentation process, heat will be generated due to the activity of microorganisms, especially in the high-temperature stage. If there are flammable materials near the pile, or the pile is poorly ventilated and the local temperature is too high, it may cause a fire (generally, the fertilizer plant will not cause internal combustion if it is turned over once every three days). Therefore, the area around the fermentation site should be kept clean, avoid stacking flammable items, and have certain fire prevention measures.
2. Environmental protection measures
For the waste gas generated during the fermentation process, it is necessary to effectively treat it. For example, deodorization equipment or biological filtration methods are used to treat harmful gases such as ammonia and hydrogen sulfide to reduce pollution to the surrounding environment. For the leachate during the fermentation process, it is necessary to collect and treat it to prevent it from polluting the soil and water.