Organic fertilizer is hailed as the "nutritionist of the soil." It does not occur naturally but is instead derived from various types of organic waste through scientific processing and transformation. From foul-smelling livestock and poultry manure and agricultural and forestry crop residues to urban kitchen waste and by-products from agricultural processing—these seemingly useless "wastes" can, through a standardized organic fertilizer production process, be transformed into high-quality fertilizers that nourish crops and improve soil structure, thereby realizing the circular utilization of resources.
The first step in organic fertilizer production is the screening and pre-treatment of raw materials, which serves as the foundation for ensuring fertilizer quality. According to agricultural industry standards, production materials are categorized into "applicable" and "assessable" classes. The applicable class includes materials such as crop stalks, livestock and poultry manure and urine, and rapeseed cake; the assessable class—such as kitchen waste and residues from traditional Chinese medicine—requires a safety assessment before use; meanwhile, prohibited materials, such as urban sewage sludge, are strictly excluded. Workers sort and clean the collected raw materials to remove impurities; large-sized materials, such as crop stalks, are then shredded to a size of less than 2 centimeters, while moisture levels are adjusted to between 55% and 65% to ensure the subsequent fermentation process proceeds smoothly.
Batching and mixing constitute the critical link connecting raw material preparation with fermentation. The core objective is to adjust the carbon-to-nitrogen ratio to the "golden range" of 25:1 to 30:1—for instance, by pairing nitrogen-rich livestock manure with carbon-abundant shredded crop stalks—followed by the addition of a compound microbial inoculant to provide the necessary "fuel" for microbial activity. A mixer is used to thoroughly blend the primary ingredients, auxiliary materials, and microbial inoculant, ensuring that every particle of material comes into contact with the microorganisms, thereby laying the groundwork for efficient fermentation.
Aerobic fermentation is the core operation in organic fertilizer production—the veritable "key to transformation." The mixed materials are either piled into windrows or loaded into fermentation tanks. Through periodic turning using a windrow compost turner, oxygen is replenished, allowing microorganisms to proliferate rapidly under optimal conditions and break down complex organic macromolecules. During fermentation, the temperature rises to between 55°C and 70°C and is maintained at this level for a specific duration; this serves the dual purpose of eradicating pathogenic bacteria, insect eggs, and weed seeds, while simultaneously accelerating the decomposition of organic matter. This process typically spans 15 to 25 days, during which temperature and moisture levels must be continuously monitored, and the frequency of turning adjusted as needed. Upon the completion of fermentation, the material enters a curing and maturation phase, during which it is left to rest in curing bins for 10 to 15 days. This allows organic matter to undergo further stabilization and humification, thereby eliminating the risk of secondary fermentation. Subsequently, the material undergoes crushing and screening to remove any coarse, uncomposted particles; the resulting compliant material can then be directly packaged as powdered organic fertilizer. Alternatively, if granular organic fertilizer is desired, the material must undergo additional processes—such as granulation, drying, and cooling—to render the fertilizer easier to store and apply.
From organic waste to high-quality organic fertilizer, every step of this journey is imbued with scientific ingenuity. This process not only resolves the issue of waste pollution but also facilitates the return of vital nutrients to the soil, thereby realizing an ecological cycle that transforms "waste into treasure." Today, this mature organic fertilizer production process is fueling the development of green agriculture, safeguarding both soil health and crop safety.
