Co-composting solid swine manure with pine sawdust as organic substrate.

Area of Science:

• Environmental Science
• Soil Science
• Waste Management

Background:

• Composting is a vital process for recycling organic waste into valuable soil amendments.
• Pine sawdust is a common organic material, but often requires co-composting with nutrient-rich materials like manure to achieve optimal decomposition.
• Understanding the impact of varying swine manure proportions is crucial for efficient compost production.

Purpose of the Study:

• To investigate the physicochemical property changes during the co-composting of pine sawdust and swine manure.
• To determine the ideal swine manure percentage for producing high-quality organic compost substrates.
• To evaluate the influence of different manure ratios on nutrient dynamics and organic matter decomposition.

Main Methods:

• Co-composting experiments were conducted in laboratory-scale vessels (100.5 L) using pine sawdust with 20%, 30%, and 40% swine manure.
• Tea leaves and herb residues were used as conditioners, with initial moisture content maintained at 60%.
• Active aeration was applied, and physicochemical properties (temperature, pH, EC, moisture, organic matter, N, P) were monitored over 29 days.

Main Results:

• Nitrogen (N) and Phosphorus (P) decomposition were most significant during the initial mesophilic phase.
• Organic carbon decomposition predominantly occurred during the thermophilic phase.
• The treatment with 30% swine manure, exhibiting an initial C/N ratio of approximately 40, showed the most desirable composting characteristics.

Conclusions:

• The optimal swine manure proportion for co-composting pine sawdust is around 30%, balancing nutrient supply and organic matter decomposition.
• Effective composting requires careful management of the C/N ratio, with an initial ratio of ~40 being favorable.
• This study provides valuable insights for optimizing the production of high-quality compost from agricultural byproducts.