What are the stages of bio organic fertilizer production?

Bio-organic fertilizer production is a systematic project that relies on microbial action to transform organic waste into high-quality agricultural inputs. A standardized bio-organic fertilizer production line is primarily divided into four stages: raw material pretreatment, microbial fermentation, post-processing, and finished product testing. Each stage is closely linked and collectively determines the fertilizer's safety, effectiveness, and usability.

Raw material pretreatment is the foundation of production. Priority should be given to raw materials with high composting potential, such as livestock and poultry manure and crop straw. Impurities such as stones and plastics should be removed manually or mechanically to avoid affecting product purity. The straw should then be pulverized to 2-5 mm to increase the contact area with microorganisms. The raw materials are then blended at a carbon-to-nitrogen ratio of 25-30:1, with urea added as needed to adjust nitrogen content. Moisture content should be controlled at 55%-60%. Finally, the mixture is piled up and heated to approximately 50°C to initially kill insect eggs and pathogens, creating a suitable environment for subsequent microbial reproduction.

Microbial fermentation is the key step in nutrient conversion, consisting of two steps: high-temperature fermentation and composting. First, functional microbial agents such as Bacillus subtilis and yeast are inoculated into the pretreated raw materials. Fermentation is then carried out using windrows or troughs, with the temperature controlled at 55-65℃ and maintained for 10-15 days. This stage rapidly decomposes large organic molecules such as cellulose and protein. Afterward, a maturation stage is initiated at 40-50℃, lasting 20-30 days. During this stage, microorganisms convert the decomposition products into nutrients easily absorbed by crops, such as amino acids and humic acid. During this period, a compost turning machine is used to regularly turn and aerate the compost pile to ensure aerobic respiration for the microorganisms and prevent the generation of foul odors.

Post-processing determines the product's user experience and involves multiple meticulous steps. The fermented material undergoes initial drying to reduce moisture content to below 20% to prevent clumping. It is then sieved using a vibrating screen to remove incompletely decomposed residue. Depending on the needs of different crops, phosphorus, potassium, and trace elements such as zinc and boron are added and mixed thoroughly. The mixture is then granulated using extrusion or disc granulation to produce 2-4 mm granules. Immediately after granulation, the granules are dried with hot air at ≤60℃ to further reduce moisture content to below 12%, preventing high temperatures from damaging the viable bacteria. Finally, the granules are cooled to 25-30℃ to prevent mold growth during storage.

Finished product testing is the final line of defense for quality control. Strict testing is required for indicators such as organic matter content (≥40%), effective viable bacteria count (≥200 million/gram), pH value (5.5-8.5), and heavy metal content to ensure compliance with the national standard for "Bio-organic Fertilizer." Only products that pass this testing are packaged and shipped, ultimately achieving the agricultural sustainable development goals of improving soil structure, enhancing crop quality, and reducing environmental pollution.