Fermentation is a crucial step in the production of organic fertilizer, primarily due to the following reasons:

1. Elimination of Pathogens and Parasite Eggs

• Mechanism: Raw organic waste materials, such as livestock manure and crop straws, may harbor numerous pathogens, parasite eggs, and weed seeds. Direct application of these unprocessed materials to soil poses risks to crop growth and the soil environment. The elevated temperatures (typically between 50-70°C) generated during fermentation effectively sterilize these harmful microorganisms and parasite eggs, mitigating the spread of diseases and pests.
• Outcome: Post-fermentation, the pathogen count in organic fertilizer is significantly reduced, and parasite eggs are inactivated, thereby enhancing the safety of the fertilizer and safeguarding crop health.

2. Decomposition of Organic Matter and Enhancement of Nutrient Availability

• Mechanism: Large organic molecules (e.g., cellulose, proteins) present in organic waste are challenging for plants to absorb directly. During fermentation, microorganisms secrete extracellular enzymes that break down these large molecules into smaller organic compounds (e.g., amino acids, sugars), which are subsequently mineralized into inorganic nutrients (e.g., nitrogen, phosphorus, potassium).
• Outcome: Fermented organic fertilizer exhibits a marked increase in readily available nutrients (e.g., ammonium nitrogen, nitrate nitrogen, available phosphorus,速效 potassium) and a degree of humification of organic matter, rendering it more accessible to plants and improving fertilizer utilization efficiency.

3. Reduction of Odor and Harmful Gas Emissions

• Mechanism: Unfermented organic waste emits foul-smelling gases (e.g., ammonia, hydrogen sulfide) during storage, posing environmental and health risks. Fermentation processes facilitate nitrification and denitrification, converting nitrogen-containing organics into nitrogen gas, while organic sulfur is oxidized to sulfate, thereby diminishing odor production.
• Outcome: Fermented organic fertilizer emits significantly less odor, reducing environmental pollution and improving working conditions for handlers.

4. Improvement of Fertilizer Stability and Maturity

• Mechanism: Fermentation enables microorganisms to metabolize unstable components (e.g., labile sugars, proteins) in organic waste into stable compounds (e.g., humic substances). Humic substances are complex, stable organic macromolecules that enhance soil structure and water retention capacity.
• Outcome: Post-fermentation, organic fertilizer attains greater maturity, preventing secondary fermentation upon soil application and avoiding adverse effects such as root burning. Additionally, humic substances combine with soil minerals to form stable soil aggregates, fostering soil microbial activity and fertility.

5. Optimization of Fertilizer Physical Properties for Ease of Application

• Mechanism: Fermentation alters the physical structure of organic waste, rendering it more porous, reduced in volume, and lighter in weight.
• Outcome: Fermented organic fertilizer is uniform in texture, facilitating transportation, storage, and application. Its improved porosity and water retention also promote root growth and development.