When winter temperatures drop below 5℃, organic fertilizer fermentation often faces the dilemma of “slow temperature rise, short high-temperature period, and incomplete decomposition.” The material temperature fails to reach above 50℃, inhibiting the activity of aerobic microorganisms and extending the fermentation cycle from the usual 30 days to 60-70 days. However, with precise intervention in three dimensions—heating agents, microbial strain selection, and insulation measures—compost can be “heated up” even in sub-zero conditions.
Heating Agents: Quickly Igniting the “First Flame”
Heating agents are easily decomposed organic materials or additives that generate heat rapidly. Their core function is to provide explosive energy in the early stages of fermentation, helping the compost pile temperature break through the low-temperature bottleneck of 15-20℃.
Common heating agents: rice bran, wheat bran, corn flour, molasses or glucose, and a small amount of urea (to adjust the carbon-nitrogen ratio). Adding 10-15 kg of rice bran to each cubic meter of raw material can raise the core temperature of the compost pile by 8-12℃ within 48 hours.
High-efficiency chemical heating agent: Calcium peroxide or urea peroxide, which slowly releases oxygen and heat upon contact with water. Evenly sprinkled into the compost pile at a ratio of 0.3%-0.5%, it can provide continuous heating for 3-5 days, especially suitable for extremely cold regions (below -10℃).
Usage method: The heating agent must be thoroughly mixed with the raw materials; do not allow it to clump together. Maintain an initial moisture content of 55%-60%; excessive dryness will inhibit the heat-generating reaction.
Strain selection: Use cold-resistant compound bacteria. Ordinary ambient temperature fermentation bacteria (Bacillus subtilis, yeast) are almost dormant below 10℃. In winter, cold-resistant bacteria or low-temperature start-up inoculants must be used.
Recommended strains: Low-temperature composting inoculants contain cold-resistant strains of Pseudomonas, Bacillus licheniformis, and Trichoderma, which can still metabolize and generate heat in environments of 2-8℃. After inoculation, the compost pile can rise from ambient temperature to above 35℃ within 3-5 days.
Propagation Techniques: First, mix the inoculant with 5 times its weight of a warming agent (such as rice bran), add a small amount of warm water (around 25℃), and stir until it can be formed into a ball by hand. Pile it for 24 hours to “activate the inoculum” before adding it to the main pile. This operation can shorten the start-up time by 1-2 days.
Dosage: Liquid inoculant: 1-2 liters per ton of raw material; Solid powder: 0.5-1 kg per ton. Do not use simultaneously with bactericides or strong alkaline substances.
III. Insulation Measures: Locking in Every Bit of Heat
Even if the core generates heat, if the heat dissipates too quickly, the low-temperature environment will prevent the “cold outside, warm inside” temperature from spreading throughout the pile.
Pile Design: Increase the height of the windlass or trench pile to 1.5-2.0 meters, and the width to no less than 2 meters. Small piles dissipate heat too quickly; in winter, raw materials should be combined to form a larger pile.
Covering with an insulation layer: Cover the surface of the compost pile with 10-15 cm of dry grass, rice husks, or crushed straw, then add an outer layer of old agricultural film or waterproof insulation felt. This “quilt” can raise the pile temperature by 5-8℃. Note: The covering material must have ventilation holes (2-3 per square meter) to prevent anaerobic digestion.
Site selection and windbreaks: Place the fermentation tank in a sheltered, sunny location; build a 1.5-meter-high windbreak wall on the north side using corrugated steel sheets or bundles of corn stalks. Actual measurements show that windbreaks can reduce heat convection loss by more than 30%.
Forced ventilation regulation: Reduce the ventilation frequency to 1/3 of that at low temperatures (e.g., ventilate for 2 minutes every 4 hours) to avoid excessive cold air inflow.
Summary: The slow fermentation of organic fertilizer in winter is essentially due to an imbalance between heat generation and dissipation. Adding a heating agent solves the problem of insufficient heat production, selecting cold-resistant bacteria solves the problem of low biological activity, and implementing insulation measures solves the problem of excessive heat dissipation—these three factors work together to ensure that even when the outside temperature is -10°C, the compost pile can reach a high temperature period of over 55°C within 7 days. Mastering this method ensures that organic fertilizer plants have no off-season throughout the year.
Mastering winter fermentation unlocks year-round production capacity for any organic fertilizer manufacturing plant, transforming seasonal downtime into sustained revenue generation. Once thermophilic composting is complete, the matured material enters downstream processing through an animal manure processing machine for initial solid-liquid separation and impurity removal, followed by a half-wet material crusher machine that breaks fibrous clumps into uniform particles suitable for granulation. Within a comprehensive organic fertilizer granulator series, producers can select disc, drum, or extrusion systems tailored to their target pellet morphology and moisture profile, with a dedicated fertilizer drying and cooling machine ensuring moisture content is stabilized below 20% for extended shelf stability. When evaluating organic fertilizer equipment price, winter-capable facilities must factor in insulated fermentation infrastructure and cold-resistant inoculant procurement alongside core processing machinery. By integrating thermal management at the fermentation stage with robust downstream material handling, producers can maintain consistent output quality and volume regardless of ambient temperature—establishing a resilient, all-season operation that maximizes asset utilization and market responsiveness throughout the calendar year.