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Incomplete decomposition in bio-organic fertilizer production lines leads to issues such as excessive insect egg counts in the final product, crop “burning” (phytotoxicity), and low viable microbial counts. The root causes lie in four areas: an unbalanced carbon-to-nitrogen (C/N) ratio, insufficient moisture or oxygen supply, inadequate turning, and an insufficient fermentation cycle. These issues can be thoroughly resolved through systematic adjustments to the process and bio-organic fertilizer equipment.

First, precisely adjust the raw material C/N ratio to establish a solid foundation for fermentation. Fresh livestock and poultry manure have high nitrogen content, while straw, sawdust, and peat provide abundant carbon sources; the mixture should be controlled at a C/N ratio of 25:1 to 30:1. When using pure manure, add straw or spent mushroom substrate to dilute nitrogen levels and prevent the pile from acidifying or emitting foul odors; introduce decomposing microbial inoculants to boost microbial activity and accelerate the initial temperature rise. If salt content is excessive, mix in soil or weathered coal to neutralize it, inhibit harmful bacteria, and ensure smooth aerobic fermentation.

Second, strictly control the moisture content and aeration conditions of the pile. Maintain moisture at 50%–60% after mixing; the material should form a clump when squeezed by hand but crumble upon impact with the ground. Excessive moisture clogs material pores, creating anaerobic conditions and causing localized blackening and odors; insufficient moisture causes microorganisms to go dormant due to dehydration, slowing the temperature rise. For trough fermentation, embed aeration pipes and supply low-pressure air regularly; for windrow fermentation, leave ventilation channels to prevent oxygen depletion within the pile. During the rainy season, install rain shelters to prevent rainwater from raising the pile’s moisture content.

Third, standardize the turning frequency to ensure uniform decomposition. Use crawler-type or wheel-type turners for regular turning: once every 3–5 days during the heating phase and once every 7 days during the cooling phase. During turning, thoroughly break up compacted clumps and swap materials—moving cooler outer material to the core and hotter inner material to the outside—to balance the pile’s temperature and destroy insect eggs and weed seeds. For trough fermentation, control the pile height between 1.6 and 2.2 meters; excessive height leads to oxygen deficiency at the bottom, while insufficient height results in poor heat retention, making it difficult to reach the required decomposition temperature of over 55°C. Fourth, control the fermentation cycle and monitor temperatures. Effective decomposition is achieved only when the compost pile maintains a high temperature of 55–65°C for seven consecutive days; continuous temperature monitoring is required, with timely turning and moisture adjustment if temperatures fall short. Material must not proceed to the subsequent crushing stage until high-temperature decomposition is complete; pre-discharge spot checks must confirm the material is dark brown, free of foul odors, and loose in texture.

Supporting management measures include: ensuring proper leachate drainage at the bottom of fermentation bays to prevent water accumulation and anaerobic conditions; regularly inspecting and maintaining the turning machine’s blades to ensure effective material breakdown; and adopting a batch-feeding and zone-based fermentation approach—keeping fresh and mature materials separate—to prevent uncomposted raw material from contaminating the finished product and to eliminate decomposition quality issues at the source.