I. Core Conclusions on Shelf Life

The shelf life of organic fertilizers varies significantly based on type and storage conditions:

1. Conventional Organic Fertilizer (Non-Microbial Type)

• Shelf Life: No strict expiration date; can be stored for 10+ years under proper conditions.
• Key Conditions: Requires dry, cool, and sealed environments to prevent nutrient loss (e.g., nitrogen volatilization) or moisture-induced deterioration.
• Note: Prolonged storage may lead to minor nutrient degradation, but fertility remains. Early use is recommended to avoid space occupation.

2. Microbial Organic Fertilizer (Containing Active Bacteria)

• Shelf Life: Typically 1–2 years, with some products labeled 18 months.
• Critical Factor: Active bacteria survival time is limited; expired products lose efficacy as bacterial populations decline sharply.
• Usage Advice: Use within the production year; apply promptly after opening to maximize bacterial activity.

3. Compost and Decomposed Manure

• Compost: Fully decomposed compost maintains stable fertility and can be used continuously for 2–4 years (e.g., in vineyards or vegetable gardens).
• Decomposed Manure: Recommended 3-year application cycle, with 22.5 tons per hectare for optimal soil health.

II. Key Factors Influencing Shelf Life

1. Storage Conditions

• Ideal Environment:
  • Dry: Avoid moisture to prevent caking or nutrient loss.
  • Cool: High temperatures accelerate nitrogen volatilization and bacterial death.
  • Sealed: Prevent oxygen/moisture ingress to reduce oxidation and bacterial inactivation.
• Poor Conditions:
  • Heat/Sunlight: Accelerates nutrient decomposition (e.g., nitrogen loss) and bacterial mortality.
  • Humidity: Causes caking, mold, or spoilage, reducing fertility.
  • Air Exposure: Microbial fertilizers lose active bacteria gradually.

2. Fertilizer Type

• Conventional Organic Fertilizer (e.g., compost, decomposed manure): Composed of stable organic matter and nutrients; no active bacteria, hence long shelf life.
• Microbial Organic Fertilizer (e.g., bio-fertilizers): Relies on active bacteria for efficacy; bacterial survival dictates shelf life.

3. Processing Methods

• High-Temperature Composting: Kills pathogens but may reduce microbial activity.
• Additives: Preservatives/stabilizers extend conventional fertilizer storage.
• Packaging: Microbial fertilizers require light-proof, oxygen-barrier packaging to sustain bacterial viability.

III. Usage Recommendations

1. Conventional Organic Fertilizer

• Store in dry, cool, sealed containers.
• Though no strict expiration, use within 2–3 years for optimal nutrient retention.

2. Microbial Organic Fertilizer

• Prioritize products from the current production year; apply immediately after opening.
• Avoid expired products, as bacterial populations decline significantly, reducing efficacy.

3. Compost and Decomposed Manure

• Use fully decomposed compost to avoid root burn or pathogen introduction.
• Replenish every 2–3 years based on crop needs and soil conditions.

4. Long-Term Storage

• Regularly inspect for caking, mold, or odors; discard compromised fertilizers.
• Store away from chemical fertilizers or alkaline substances (e.g., wood ash) to prevent chemical reactions.

IV. Special Cases and Data Support

1. Microbial Organic Fertilizer Bacterial Survival

• Research shows a 50%–70% decline in viable bacteria after 18 months of storage.

2. Compost Field Application

• Vineyards using finished compost for 3–4 years, at 100–250 tons per hectare, show improved soil structure and yield.

3. Decomposed Manure Application Cycle

• In corn cultivation, a 3-year cycle with 22.5 tons per hectare of decomposed manure increases annual yield by 10%.

V. Summary

Organic fertilizer shelf life depends on type and storage:

• Conventional Organic Fertilizer: Stable under proper storage (>10 years), but use within 2–3 years for best results.
• Microbial Organic Fertilizer: Strict 1–2 year shelf life; discard expired products.
• Compost/Decomposed Manure: Stable post-decomposition; use continuously for 2–4 years, replenishing every 3 years.

Final Advice: Choose storage methods based on fertilizer type, prioritize microbial products for timely use, and monitor soil conditions for replenishment.