In the organic fertilizer production process, the fermentation stage of the organic fertilizer production line is the core process connecting raw material pretreatment and deep processing. It is also a key node in realizing the harmless and resource-based treatment of organic waste such as livestock and poultry manure and straw, directly determining the nutrient content, degree of decomposition, and application effect of the finished fertilizer. However, due to factors such as raw material characteristics and process control, various problems can easily occur during the fermentation process, becoming a key bottleneck restricting production efficiency.
Temperature runaway is the most common problem during fermentation. Normal fermentation requires maintaining a high temperature period of 55-65℃ for at least 7 days to kill pathogens and weed seeds. If the moisture content of the raw materials is too high or aeration is insufficient, the fermentation temperature will remain below 50℃, resulting in "low-temperature fermentation." This not only fails to achieve harmless treatment but also causes incomplete decomposition of the raw materials, posing a risk of secondary fermentation in the finished fertilizer. Conversely, if the carbon-nitrogen ratio is unbalanced or ventilation is excessive, the temperature may soar above 75℃, destroying the activity of beneficial microorganisms, causing nutrient loss, and reducing fertilizer efficiency.
Improper humidity control also affects the fermentation effect. The ideal moisture content for fermentation raw materials is 55%-60%. A good indicator is that the material should clump together when squeezed but crumble easily when released. If the moisture content is below 50%, microbial metabolic activity is limited, slowing the fermentation process. If it exceeds 65%, the material easily forms an anaerobic environment, producing foul-smelling gases such as hydrogen sulfide, polluting the environment and leading to fermentation failure. Some production lines lack precise humidity monitoring equipment and rely solely on experience to add water, often resulting in humidity imbalances.
Insufficient or uneven ventilation can cause anaerobic fermentation problems. Aerobic microorganisms are the core force driving the composting of raw materials and require a continuous supply of oxygen. Infrequent turning, an unreasonable fermentation tank structure, or excessively thick material accumulation can lead to oxygen deficiency within the material, decreased aerobic microbial activity, and excessive proliferation of anaerobic microorganisms. This results in the fermented material turning black, becoming sticky, and developing a strong odor, severely affecting the quality of the finished fertilizer.
An imbalance in the material ratio is also crucial. The carbon-to-nitrogen ratio (C/N) is a key parameter for fermentation, with an optimal range of 25:1-30:1. Excessive nitrogen sources (such as livestock and poultry manure) will lead to the volatilization of large amounts of ammonia nitrogen, causing nutrient loss and air pollution. Excessive carbon sources (such as straw) will result in a high carbon-to-nitrogen ratio, prolonging the fermentation cycle or even halting it. Some small and medium-sized enterprises lack professional testing methods and rely entirely on experience for raw material ratios, making it difficult to guarantee fermentation stability.
Furthermore, problems such as incomplete eradication of pathogens and inactivated weed seeds may occur during fermentation. Direct application to farmland could lead to the spread of pests and diseases, affecting crop growth. These problems are related to inadequate raw material pretreatment and imprecise control of process parameters, as well as factors such as equipment performance and operational procedures.
Therefore, in the production of organic fertilizer, it is necessary to strengthen raw material screening and pretreatment, optimize fermentation process parameters, and improve equipment configuration and operation management to effectively solve various problems in the fermentation process and ensure the quality of the finished fertilizer.
