Fresh pig manure is rich in nutrients such as nitrogen, phosphorus, and potassium, but it is also a major source of agricultural non-point source pollution. By scientifically processing it into granular organic fertilizer, the pollution problem can be solved, and high-quality fertilizer can be produced, achieving resource recycling. The production of organic fertilizer involves four key stages: pretreatment, fermentation and maturation, granulation, and finished product inspection, each step containing crucial details.
Pretreatment is the basic stage, focusing on impurity removal and optimization. Fresh pig manure has a water content of 70%-80% and is mixed with impurities such as straw and stones. First, screening equipment is used to remove stones, plastics, and other foreign objects. Then, auxiliary materials such as rice husks and sawdust are added to adjust the carbon-nitrogen ratio to 25:1-30:1, while simultaneously reducing the water content to about 60%, creating suitable conditions for subsequent fermentation. Too high a water content can lead to anaerobic fermentation and foul odors, while too low a water content will affect microbial activity and reduce the efficiency of maturation.
Fermentation and maturation is the core step, aiming to kill pathogens and degrade harmful substances. The pretreated pig manure is piled into fermentation piles 2-3 meters wide and 1-1.5 meters high, inoculated with microbial agents such as straw composting agents, and regularly turned to provide oxygen. During fermentation, the pile temperature needs to be maintained above 55℃ for 5-7 days to effectively kill harmful organisms such as E. coli and roundworm eggs. After 20-30 days of maturation, the pig manure transforms into a loose, dark brown substance, with a significantly increased organic matter content and a substantial reduction in harmful substances.
Granulation is a key process in organic fertilizer production that makes the product easier to store and apply. The matured material is first finely ground to over 80 mesh using crushing equipment, and then sent to a granulator. Through the disc granulation process, the material is made into granules with a diameter of 2-4 millimeters, and then sent to a dryer to reduce the water content of the granules to below 15%, preventing mildew during storage. The dried granules have a high temperature and need to be cooled in a cooler machine to bring the granule temperature close to room temperature, preventing secondary fermentation due to high temperature during subsequent storage, and simultaneously improving the hardness and stability of the granules. Finally, unqualified particles are removed through screening, resulting in uniform and regular granular organic fertilizer.
Product inspection is the last step in quality assurance. The organic matter content, total nitrogen, phosphorus, and potassium content, moisture content, and pH value of the granules are tested to ensure compliance with the national standard for organic fertilizers. The qualified granular organic fertilizer is not only convenient for transportation and mechanized application, but also releases nutrients slowly, improving fertilizer utilization, reducing soil compaction, and contributing to the development of green agriculture. The "transformation" of fresh pig manure is a vivid example of circular agriculture, providing a feasible path for the resource utilization of agricultural waste.
