The process begins with the collection of horse stable waste, including urine, feces, and bedding that can be sawdust, wood shavings, or straw. This material generally has the correct carbon to nitrogen ratio for thermophilic composting. The moisture content of the material is adjusted to 60%. Then it is mixed and fluffed to improve porosity and placed in a 10 cubic yard concrete cell.
The air we breathe is 21% oxygen. If we were to hold our breath, we would quickly consume the oxygen in our system. The same thing is true of a compost pile. If we do not add air, the oxygen level drops to anaerobic conditions within minutes. The most common commercial method of composting is turned windrow. As there is no method of turning alone that can overcome the oxygen consumption rate and prevent anaerobic biology to prevail, at Fern Hill Compost, we use covered aerobic static pile composting in order to maintain oxygen levels in the feed stock. With aerobic composting, the main by-products are CO2, water, and heat.
Advantages of this method include:
• Pile temperature and moisture content control
• Pathogens and weed seeds elimination
• Vaccine, antibiotic and pesticide degradation
• Composting process cycle time decrease
• Superior quality compost production.
Our equipment includes a system to deliver air to a plenum underneath each composting cell and to the feed stock it contains. Controlled by pile temperature, timers, and delivery valves, the proper oxygen level is maintained 24/7 throughout the 30 day stage 1 composting process.
Temperatures are recorded from multiple sample points within the pile to assure uniformity and that pasteurizing conditions are attained. Typical temperatures will run as high as 160 degrees F, remain above 131F for a minimum of three days, and then drop into the 100F – 110F range. These temperatures are sufficient to kill pathogens and weed seeds, but not the beneficial microbes we count on to perform the decomposition of the organic material.
Each composting cell has a water addition system to adjust moisture level in the feed stock, as well as a leachate collection system in the floor to allow any liquid that drains out of the pile to be returned to the cell, rather than leaching to the environment.
Every 7-10 days during the active stage of composting, the material is removed, remixed, and placed in another cell, where thermophilic temperatures are once again maintained.
After stage 1, the material is removed, and processed through a hammer mill in order to grind the cellulosic and lignin components and moved to a curing pad for stage 2 composting. This increases the surface area and hastens the fungal breakdown of these components. The material is stored for a minimum of two months in order to properly cure. In-house testing is done to assure a stable and mature product prior to packaging.