High-quality organic granular fertilizer is not simply formed by compressing raw materials, but the result of a complete set of biological fermentation and physical forming processes. Every control link in production directly determines the decomposition degree, nutrient activity and application safety of the fertilizer. Understanding the core production processes can help growers judge the product quality more clearly.
The first step is raw material selection and pretreatment. Qualified organic granular fertilizer gives priority to raw materials with stable sources and no heavy metal or antibiotic residues, such as pure plant straw, edible fungus residue, and quarantined livestock manure. After entering the production line, the raw materials are crushed and purified, and their carbon-nitrogen ratio and moisture content are adjusted to create suitable conditions for subsequent fermentation, avoiding risks of excessive impurities and harmful substance residues from the source.
The second step is high-temperature aerobic composting fermentation, which is the core process determining the safety and effectiveness of the fertilizer. The raw materials enter the fermentation bin and undergo high-temperature decomposition through the action of beneficial microorganisms in a ventilated and oxygen-supplied environment, with the core temperature continuously maintained above 55–65℃. This process can not only completely kill insect eggs, harmful pathogens and weed seeds to achieve harmless treatment, but also decompose macromolecular organic matter into small molecules such as humic acid and amino acids that are easy to absorb, preventing secondary fermentation and root burning after incompletely decomposed fertilizer is applied to the soil. Regular factories control the decomposition degree throughout the process through turning and temperature control, with a fermentation cycle usually no less than 15 days.
The third step is precise granulation and low-temperature drying. The decomposed materials are screened and then enter the granulation process. Common processes include extrusion granulation and disc granulation, aiming to make loose organic fertilizer into regular granules. After granulation, low-temperature hot air drying is adopted, with the drying temperature strictly controlled below 60℃. It can not only reduce moisture to meet the national standard, ensure particle hardness and storage stability, but also retain the activity of beneficial microorganisms in the fertilizer to the greatest extent, avoiding high-temperature killing of functional flora.
The final step is multi-stage screening and finished product quality inspection. The dried granules are graded by a vibrating screen to remove powder and irregular granules, ensuring uniform finished granules and up-to-standard strength. Before delivery, multiple indicators such as organic matter content, total nutrients, moisture, pH value and heavy metal limits shall be tested. Products can only leave the factory after meeting the national organic fertilizer standards. It is the standardized control of the whole process that ultimately produces high-quality organic granular fertilizer with stable nutrients, safety, high efficiency and convenient application.
