For small-scale farms, the resourceful utilization of manure is a pivotal strategy to mitigate environmental pollution, reduce operational costs, and generate supplementary income. Through scientific processing and technological conversion, manure can be transformed into high-value products such as organic fertilizers, energy, and feed, forming a closed-loop ecological chain of "farming-processing-utilization." Below is a detailed plan and implementation guide for resource utilization:

1. Organic Fertilizer Production: Soil Enrichment and Agricultural Value Addition

A. Aerobic Composting Technology

• Process Flow:
  • Raw Material Mixing: Combine manure with auxiliary materials (straw, wood chips, rice husks) in a 3:1 ratio, adjusting moisture content to 55%-65% and carbon-to-nitrogen (C/N) ratio to 25-30:1.
  • Composting: Form windrows (1.5-2 meters high, 2-3 meters wide) and aerate regularly (every 3-5 days) to ensure oxygen supply.
  • Maturity Criteria: Maintain temperatures at 55-65°C for over 15 days until the compost turns dark brown, odorless, and achieves ≤30% moisture content.
• Product Upgrades:
  • Introduce functional microbial agents (e.g., phosphate-solubilizing bacteria, Bacillus subtilis) to produce specialized fertilizers, increasing market value by 30%-50%.
  • Pelletize for easier transportation and application, commanding premium prices.

B. Vermicomposting (Biological Processing)

• Technical Essentials:
  • Use Eisenia fetida worms, mixing manure with auxiliary materials in a 1:1 ratio at 20-25°C and 60%-70% humidity.
  • Stocking density: 10,000-20,000 worms/m², with a 60-day conversion cycle.
• Product Value:
  • Worms: High in crude protein (60%-70%), suitable for aquaculture or pet food.
  • Worm Castings: Organic matter ≥45%, valued at RMB 400-600/ton, ideal for premium horticulture.
• Benefits:
  • 1 ton of manure yields 150-200 kg worms and 300-400 kg castings, totaling over RMB 2,000 in revenue.

2. Biogas Engineering: Energy Conversion and Clean Production

A. Biogas Fermentation Systems

• Design Considerations:
  • Digester Types: Recommend water-pressure biogas digesters (10-30 m³) or FRP tanks for cost efficiency.
  • Feedstock Ratio: Mix manure with water (1:1) and inoculate with 10%-20% effluent for accelerated gas production.
  • Operating Conditions: 25-35°C, pH 6.8-7.5, and 20-30 days retention time.
• Product Utilization:
  • Biogas: For cooking, heating, or power generation (1 m³ biogas = 1.5-2 kWh electricity), reducing fuel costs by over 50%.
  • Digestate: Use as base fertilizer or foliar spray, cutting chemical fertilizer use by 30%-50%.
• Case Study:
  • A pig farm in Hunan processes 360 tons of manure annually via a 20 m³ digester, producing 2,000 m³ biogas to meet the energy needs of 10 households.

B. Biogas Upgrading to Bio-CNG

• Technical Pathway:
  • Purify biogas via membrane separation or water scrubbing to achieve ≥95% methane concentration, suitable for vehicle fuel or grid injection.
  • Price: 3-5 times higher than raw biogas.
• Applicable Scenarios:
  • Large-scale farms (≥100 m³/day biogas) or regional biogas supply projects.

3. Insect Protein Conversion: High-Value Feed Production

A. Black Soldier Fly Farming

• Technical Workflow:
  • Larval Inoculation: Mix manure with wheat bran (3:1) and inoculate with 3-day-old larvae at 2,000 larvae/kg.
  • Rearing Management: Maintain 25-30°C, 60%-70% humidity, harvesting at 8-10 days (larval weight ≥0.2 g).
  • Separation: Screen larvae from frass; dry or sell fresh larvae, and compost frass.
• Economic Returns:
  • 1 ton of manure yields 150-200 kg larvae and 300-400 kg frass.
• Market Applications:
  • Larvae as premium aquaculture feed; frass for organic vegetable cultivation.

B. Housefly Farming

• Technical Essentials:
  • Rear maggots on manure, yielding 100-150 g maggots/kg manure (50%-60% crude protein).
  • Extract chitin from defatted maggots for pharmaceutical or food additive use.

4. Eco-Circular Models: Integrated Farming and Industry Synergy

A. Pig-Biogas-Fruit (Vegetable) Model

• Mechanism:
  • Manure → Biogas digesters → Digestate → Orchards/fields → Fruits/vegetables → Market sales.
  • Drip irrigation with digestate reduces nutrient loss and enhances crop quality.

B. Chicken-Insect-Forest Model

• Mechanism:
  • Chicken manure → Black soldier fly farming → Larvae fed to chickens → Frass for fast-growing trees (e.g., eucalyptus).
  • Creates a "livestock-insect-plant", reducing feed costs by 20%-30%.

5. Branding Strategies

• Certifications:
  • Apply for organic or green food certifications to command 20%-50% price premiums.
• Sales Channels:
  • E-commerce platforms, agro-input dealers, or direct cooperative supplies.

Conclusion

Small-scale farms must adhere to the principles of "reduction, harmlessness, and resourcefulness" in manure utilization, aligning with their scale, technical capacity, and market demands. Key strategies include:

1. Technological Upgrading: Adopt advanced processes like aerobic composting and insect farming to enhance product value.
2. Model Innovation: Develop integrated eco-circular systems to reduce costs.
3. Policy Leverage: Maximize subsidies and carbon trading revenues.
4. Branding: Build premium products via certifications and e-commerce channels.

By systematically implementing resource utilization, small-scale farms can transform manure from a pollutant into a profit center, achieving dual wins in environmental and economic benefits.