In the organic fertilizer production process, fermentation and composting are the core steps determining product quality, directly affecting the degree of harmlessness, fertilizer efficiency, and soil friendliness of the organic fertilizer. Skipping or simplifying this step prevents the removal of harmful substances from the raw materials, hindering fertilizer effectiveness and potentially polluting the soil and burning crop roots. Therefore, fermentation and composting are considered the "soul process" of organic fertilizer production.
The core principle of fermentation and composting is to utilize the metabolic action of microorganisms to decompose large-molecule organic matter in raw materials such as livestock and poultry manure, straw, and kitchen waste into small-molecule nutrients. Simultaneously, it kills insect eggs, pathogens, and weed seeds in the raw materials, degrades odors, and achieves the harmlessness and resource utilization of the raw materials. Currently, the most widely used technology in the industry is aerobic fermentation, which artificially controls temperature, humidity, and oxygen content to provide a suitable environment for microbial reproduction and accelerate the composting process.
The fermentation and composting process mainly consists of three stages, with a standardized and interconnected process. The first stage is the heating period, where pre-treated raw materials (moisture content adjusted to 55%-65%, carbon-nitrogen ratio controlled at 25:1-30:1) are piled up. Microorganisms multiply rapidly, and the pile temperature gradually rises, typically reaching above 55℃ in 3-5 days, initially killing some pathogens and insect eggs. The second stage is the high-temperature period, crucial for composting. Regular turning with a compost turning machine is necessary to ensure ventilation and oxygen supply, maintaining the temperature at 55-65℃ for 7-15 days to completely kill harmful organisms and decompose recalcitrant organic matter. The third stage is the cooling and composting period, where the pile temperature gradually drops to room temperature. Microbial activity weakens, organic matter further transforms into humus, the pile becomes loose and black, and odors are largely eliminated.
Controlling these key points of fermentation and composting directly determines the quality of the composting process. First, temperature control is crucial. During high-temperature periods, the temperature must be consistently maintained above 55℃ for a sufficient duration; otherwise, it will be difficult to meet the harmlessness standard. Second, ventilation management is essential. Regular turning or forced ventilation is necessary to prevent anaerobic fermentation and the generation of foul odors and harmful substances. Third, humidity control is vital. Maintaining a suitable moisture content throughout the process is crucial; excessive moisture promotes anaerobic digestion, while insufficient moisture inhibits microbial activity. Fourth, the degree of decomposition must be assessed. Qualified decomposed material is odorless, dark brown, loose to the touch, has a stable organic matter content, and meets national standards for the detection rate of insect eggs and pathogens.
High-quality fermentation and decomposition are the core difference between organic fertilizer and raw manure. Fully decomposed organic fertilizer not only eliminates the harmfulness of raw materials but also improves soil permeability, replenishes organic matter, and alleviates soil compaction. Simultaneously, it slowly releases nutrients, preventing root and seedling burn and providing a gentle and lasting boost to crop growth. Controlling the fermentation and decomposition process in organic fertilizer production is essential to producing safe, efficient, and environmentally friendly high-quality organic fertilizer, truly realizing the resource utilization of waste and contributing to the development of green agriculture.
