Answer: Moisture control in organic fertilizer production must be integrated into every stage—from raw material pretreatment and fermentation to granulation and final product processing—with precise adjustments made according to the standards of each specific step. The optimal moisture range for standard production is 50%–60%. Moisture levels can be scientifically regulated through humidification, moisture control, and drying to prevent issues such as pile putrefaction during fermentation, granulation failure, and product caking.
First, moisture control during raw material pretreatment is essential. Raw materials like livestock manure, crop straw, and sludge vary significantly in initial moisture content; fresh manure often exceeds 70% moisture and requires preliminary dewatering. Methods include air-drying or mechanical squeezing and draining, combined with the addition of dry bulking agents—such as straw, sawdust, or spent mushroom substrate—to balance the wet and dry materials and rapidly bring moisture levels down to fermentation standards. If materials are too dry, an appropriate amount of clean water or mature liquid digestate can be sprayed to ensure material porosity and fermentation activity.
Second, dynamic moisture adjustment is required during the fermentation process. The high-temperature fermentation stage has strict moisture requirements; excessive moisture leads to oxygen deprivation and foul-smelling, rotting material, while insufficient moisture results in slow temperature rise and incomplete decomposition. Regular monitoring is necessary: if moisture is too high, frequent turning with a windrow compost turner accelerates evaporation and improves aeration; if moisture is too low, water is evenly added during the turning process to maintain the optimal fermentation moisture level of around 55%.
Finally, moisture is managed during granulation and final product processing. During granulation, material moisture must be controlled between 30% and 35%; levels that are too high cause sticking to machinery and screen clogging, while levels that are too low result in loose granules and poor pellet formation. Precise control is achieved by fine-tuning the ratio of dry to wet materials. After granulation, dryers and cooling equipment are used to further remove moisture, reducing the final product's moisture content to below 20% to meet factory standards, prevent caking and mold growth during storage, and ensure fertilizer quality and shelf life.
