In pig manure organic fertilizer production, turning is the core operation in the fermentation and composting process. Its frequency directly affects the material's composting efficiency, product quality, and environmental compliance. A scientific turning frequency balances oxygen supply, temperature regulation, and microbial activity, and is key to realizing the resource utilization of pig manure in the organic fertilizer production process.
Pig manure, as a high-nitrogen raw material, typically has a moisture content of 70%-80% and a carbon-to-nitrogen ratio of approximately 15-20:1. It needs to be adjusted to 25-30:1 by mixing it with auxiliary materials such as straw. In the early stages of fermentation (the first 3-5 days), microorganisms rapidly multiply and decompose organic matter, requiring high-frequency turning using a compost turning machine: 1-2 times per day is advisable. Turning at this time replenishes oxygen in a timely manner, preventing the production of harmful gases such as methane and hydrogen sulfide during anaerobic fermentation. It also dissipates heat from the pile, preventing local temperatures from exceeding 65℃ and scorching beneficial microorganisms. During this stage, turning and turning the material are necessary to stabilize the temperature of the compost pile at 55-65℃, ensuring proper treatment (killing insect eggs and pathogens).
In the middle stage of fermentation (6-15 days), the decomposition rate of organic matter slows down, and the temperature remains at 50-60℃. The turning frequency can be adjusted to once every 2-3 days. At this time, the focus of turning is to break up the compacted layer of material, promoting uniform decomposition throughout the pile and preventing localized undercooking. If the pile temperature drops below 50℃ or an off-odor is detected, the turning frequency should be increased to reactivate microbial activity.
In the later stage of fermentation (16-25 days), the material gradually matures, and the temperature drops below 40℃. The turning frequency can be reduced to once every 3-5 days. At this stage, the main purpose of turning is to regulate the moisture content of the pile. As organic matter decomposes and moisture evaporates, turning is needed to gradually reduce the moisture content to below 25%, laying the foundation for subsequent drying.
The frequency of turning over the compost needs to be flexibly adapted to production conditions: open-air composting requires adjustment based on rainfall and temperature, and timely turning over is necessary after rain to prevent water accumulation; mechanical fermentation tanks can dynamically adjust the turning over frequency through an automated control system combined with data from oxygen content and temperature sensors. Excessive turning over will lead to heat loss and increased energy consumption, while insufficient turning will result in incomplete decomposition and low fertilizer efficiency. Only by accurately controlling the material state can high-quality pig manure organic fertilizer be produced.
