The fermentation of organic fertilizer is a biodegradation process closely related to temperature, with temperature changes directly affecting fermentation efficiency and product quality. Below is a detailed explanation from the perspectives of fermentation stages, temperature control points, regulation methods, and environmental adaptability:

I. Fermentation Stages and Temperature Changes

Organic fertilizer fermentation typically progresses through four stages, each characterized by distinct temperature profiles and microbial activities:

1. Heating Phase (Initial Stage)
   • Temperature Change: Gradual rise from ambient temperature to 40-45°C.
   • Microbial Activity: Mesophilic microorganisms (e.g., bacteria, fungi, actinomycetes) dominate, decomposing simple organic matter like sugars and starches while releasing heat.
   • Key Point: Maintain a loose pile structure to promote oxygen circulation and prevent local anaerobic conditions.
2. Thermophilic Phase (Core Stage)
   • Temperature Change: Elevation to 50-70°C, with an optimal range of 55-60°C.
   • Microbial Activity: Thermophilic microorganisms (e.g., Bacillus spp., actinomycetes) become predominant, breaking down complex organic matter such as cellulose and lignin.
   • Key Points:
     • Sustain temperatures above 50°C for at least 5 days to eliminate pathogens, insect eggs, and weed seeds (sanitization).
     • If temperatures exceed 70°C, microbial activity declines; prompt pile turning is necessary to cool.
3. Cooling Phase (Transitional Stage)
   • Temperature Change: Gradual reduction to below 50°C.
   • Microbial Activity: Mesophilic microorganisms resume activity, decomposing residual refractory organic matter (e.g., hemicellulose, proteins).
   • Key Point: Humus content begins to stabilize, with reduced oxygen demand.
4. Maturation Phase (Completion Stage)
   • Temperature Change: Stabilization at ambient temperature, signaling fermentation completion.
   • Material Characteristics: Dark brown to black, odorless, with humus content exceeding 30% and a stable pH of 6.5-8.5.

II. Temperature Control Points

1. Optimal Temperature Range
   • Thermophilic Phase: 55-60°C (maximizes microbial activity and sanitization efficacy).
   • Minimum Requirement: If only maturation (not sanitization) is desired, temperatures above 15°C suffice, though fermentation slows.
2. Impact of Temperature Anomalies
   • Excessive Heat (>70°C): Causes carbonization of organic matter, nutrient loss, and microbial death.
   • Insufficient Heat (<15°C): Slows or halts fermentation; insulation measures (e.g., indoor fermentation) may be required.

III. Temperature Regulation Methods

1. Pile Turning and Aeration
   • Thermophilic Phase: Turn the pile to replenish oxygen if temperatures drop below 50°C; turn immediately if exceeding 65°C.
   • Cooling Phase: Reduce turning frequency to prevent excessive heat loss.
2. Temperature Monitoring
   • Tools: Use a thermometer with a probe length ≥30 cm, inserted ≥30 cm into the pile core.
   • Frequency: Monitor 1-2 times daily during the thermophilic phase; every 2-3 days otherwise.

IV. Environmental Adaptability

1. Seasonal and Regional Considerations
   • Southern Regions: Higher ambient temperatures facilitate fermentation.
   • Northern Cold Regions: Insulation measures (e.g., indoor fermentation, covering) are essential in winter.
2. Feedstock Ratio Adjustment
   • Carbon-to-Nitrogen Ratio (C/N): Optimize to 25-30:1 by adding straw or mushroom residue.
   • Moisture Content: Maintain at 50-60% to prevent anaerobic conditions or microbial inhibition.

V. Summary

Effective temperature management in organic fertilizer fermentation balances efficiency and quality:

• The thermophilic phase is critical for sanitization and complex organic matter decomposition, requiring strict control at 55-60°C.
• Pile turning and aeration are core regulatory tools, adjusted flexibly based on temperature fluctuations.
• Environmental adaptability necessitates tailored insulation or cooling measures depending on regional climates.

By scientifically controlling temperature, efficient, safe, and high-quality organic fertilizer with optimal maturation and nutrient stability can be produced.