When should organic fertilizer compost be turned for the first time?
It is recommended to start turning organic fertilizer compost when the compost temperature reaches 50℃. 50℃ is the key threshold for aerobic composting to transition from the mesophilic stage to the hyperthermic stage. At this point, sufficient heat has accumulated inside the compost pile, and thermophilic microorganisms begin to multiply rapidly, making it the optimal time to start turning.
Why 50℃?
The composting heating process consists of three stages: the heat generation stage (room temperature to 50℃), the hyperthermic stage (above 50℃), and the maturation stage. When the compost temperature reaches 50℃, it means that the activity of mesophilic microorganisms has accumulated sufficient heat for the compost pile, and the pile has officially entered the hyperthermic fermentation period. Turning the compost for the first time at this time not only brings the insufficiently fermented material on the outer layer of the compost pile into the interior to participate in high-temperature decomposition, but also prevents excessively high local temperatures (above 65℃) from causing nitrogen loss, while simultaneously replenishing fresh oxygen to maintain an aerobic state.
Specific Operating Procedures for the First Turning of the Pile
Temperature Measurement Method: The temperature at a depth of 30 cm from the outer surface of the pile should be used as the reference. The temperature should be measured at least once a day.
Turning Requirements: During turning, the material should be rotated inside and out, and its position changed vertically to ensure thorough and uniform mixing. If the material is too dry, a small amount of moisture can be added simultaneously.
Equipment Selection: For large-scale production, it is recommended to use a compost turning machine (wheeled, tracked, or roller type) for mechanized turning, as it offers high efficiency and good uniformity.
Temperature Management After the First Turning
After the first turning, the turning frequency should be dynamically adjusted according to changes in pile temperature:
When the pile temperature is between 50℃ and 60℃, it is recommended to turn the pile once every 3 days;
When the pile temperature exceeds 60℃, the frequency should be increased to once every 2 days;
When the pile temperature exceeds 65℃, it is necessary to turn the pile immediately to cool it down, preventing high-temperature burning and excessive nitrogen loss.
When the pile temperature no longer rises with turning and gradually decreases to around 40℃ and approaches ambient temperature, it indicates that aerobic fermentation is basically complete. The entire high-temperature phase typically lasts 10–30 days.
Comprehensive Recommendations In production, adhere to the principle of daily temperature monitoring and turning the compost pile as soon as the temperature reaches the target level. Avoid mechanical operation based on fixed days—the rate of temperature increase varies greatly depending on the season and the raw materials. It is recommended to closely monitor the temperature starting 2–3 days after composting begins, and immediately perform the first turning of the pile once it reaches 50℃ to lay a solid foundation for subsequent efficient fermentation.
