How is granular organic fertilizer processed?

Granular organic fertilizer offers balanced nutrients, ease of application, and convenience in storage and transport, making it a widely used fertilizer in modern ecological agriculture. The complete processing workflow consists of six main stages: raw material pre-treatment, aerobic fermentation, crushing and batching, granulation, drying and cooling, and screening and packaging. Huaqiang Heavy Industry’s organic fertilizer production lines are capable of reliably executing this entire process.

Raw materials typically consist of organic waste such as livestock and poultry manure, crop straw, biogas residue, and fungal substrate (spent mushroom compost). To ensure effective fermentation, materials like straw or sawdust are added to adjust the carbon-to-nitrogen (C/N) ratio, along with fermentation microbial agents, while maintaining a moisture content of approximately 55%. Once placed in fermentation tanks, the material is periodically turned and aerated by a compost turner. This sustains a high-temperature fermentation process (55–65°C), which eliminates pathogens and insect eggs, ensures thorough decomposition, and removes odors. Following fermentation, the material undergoes a maturation (aging) phase to further stabilize the organic matter.
The decomposed material then proceeds to the crushing and screening stage. A semi-wet material crusher breaks up clumps, while impurities such as stones and plastics are removed, resulting in a fine, uniform organic powder. Based on the product formula, nitrogen, phosphorus, potassium, and mineral additives are incorporated and thoroughly blended in a mixer to ensure consistent nutrient content across every batch.
Granulation is the core stage of the process. Common methods include disc granulation, rotary drum granulation, and flat-die extrusion granulation. Disc and rotary drum granulation (wet methods) produce rounded granules, ideal for products where appearance is a priority. Flat-die extrusion granulation offers high adaptability to various raw materials; it requires minimal water addition and produces dense, hard, and durable granules. This method is energy-efficient, and the resulting granules are well-suited for use as a base fertilizer in open fields and orchards. Since the freshly formed, moist granules are soft, they must be passed through a rotary dryer to reduce their moisture content to a level suitable for storage, thereby preventing mold growth and clumping.
Finally, the hot granules enter a cooler, where they are rapidly brought down to a lower temperature; this stabilizes the granular structure and further increases their hardness. After cooling, the material is fed into a screening machine for classification; granules that meet specifications are sent to the packaging stage, while fine powder and broken particles are returned to the granulation process for reprocessing, ensuring the recycling of raw materials. Some products may undergo an additional coating process to provide slow-release properties or prevent caking.
Finally, the qualified granules are automatically weighed, bagged, sealed, and placed into storage. This entire process transforms agricultural waste into high-quality organic fertilizer, which improves soil structure and enhances soil fertility—aligning with the development goals of sustainable, "green" agriculture. By strictly controlling the degree of decomposition, moisture content, and granulation parameters, the enterprise can consistently produce granular organic fertilizer of stable quality.