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Home >> Our Services >> Plant Services >> Compost Facility

Composting is the management and manipulation of the natural biological process of organic decomposition. Microorganisms, primarily bacteria that consume oxygen, carbon and nitrogen as food and generate CO2, H2O and heat, carry out the composting process. A benefit of composting is that the heat generated in the process (exceeding 131F) kills undesirable pathogens including E coli and Salmonella. By mixing organic ingredients in the proper ratios (C/N ratio), and managing (turning or aerating) the piles, the natural process takes place over a shorter time period. The recipes used by WSU were originally developed to safely and efficiently manage the organic waste stream generated on campus. This blend also results in a compost product that turned out to be a good quality soil amendment that can be sold.

The qualities of the finished WSU compost are as follows:

• Organic, rich, dark brown color 
• Low salt content and slightly alkaline (does not harm plants - can be used to adjust Ph of soil)
• Slightly high carbon to nitrogen ratio (it is recommended that supplemental nitrogen be added when incorporating)
• Extremely low concentrations of persistent herbicides that will not harm plants
• Each batch of WSU compost is tested by a certified testing laboratory and on plants to assure product quality

   

  Standard Mixture: 
  The various feed stocks are mixed together. Temperatures are constantly monitored to until the optimum interior temperature is reached at which time the final product is screened to remove undesirable material then moved to curing piles. The standard mixture generally includes feed stocks in these proportions:

  Animal manure and bedding - 78% Coal ash - 10%  Processed compost - 10%  Food waste - 1% Green house soil and potting plant material - .5% Yard waste - .5% Shredded wood waste (added during wet seasons to increase porosity) - .5%

   
  Bedding Mixture:
  The bedding product was developed to process large amounts of dry high carbon material during summer months when wet manure (nitrogen source) is less available. This product heats to temperatures in excess of 165F effectively pasteurizing the bedding and reducing pathogens. Because the bedding is produced in the dry summer months, the ending moisture content is very low producing a clean, safe, and absorbent bedding material. Compost bedding is used extensively by WSU animal units because of reduced pathogen exposure and major cost savings compared with other bedding products. The feedstock for the bedding material includes: 
  
  • Used animal bedding (less than 10% manure content) - 90%
  • Processed bedding compost - 10%