How to monitor compost windrow?
Step-by-Step Monitoring Process
- Monitor the Temperature
- Detect Any Odors & monitor moisture content
- Visually Inspect the Pile
Windrow temperature monitoring is also a compliance mechanism with one or more regulatory agencies. These agencies typically require you to document that your pile has reached temperatures sufficient to inactivate or eliminate pathogens. This is known as the Process to Further Reduce Pathogens (PFRP).
In general, temperature correlates with microbial activity in the pile. During the thermophilic (high temperature) composting phase, the pile should reach temperatures between 55°C to 71°C (131°F to 160°F) . These levels are required to meet regulatory standards.
Your compost monitoring sheets serve as essential tools to:
- Record data accurately
- Understand challenges that may arise
- Remediate issues when needed
- Track pile activity for regulatory review
How to monitor compost windrow temperature?
It’s important to measure the temperature from the core of the windrow. For instance, if you have a 4-meter-wide windrow, the measuring probe should be 2 meters long.
Note that the temperature curve is not constant over time. Typically, the temperature rises initially, remains elevated for weeks or months, and then gradually drops to ambient levels.
Therefore, Periskop smart probes or compost thermometers with up to 2 meter spike lengths are ideal for commercial composting.
Benefits of compost temperature monitoring
Monitoring temperature provides valuable insights, such as:
- Is the decomposition progressing effectively?
- Why isn’t the pile heating up?
- Are the probes working as expected?
- When should I turn the compost?
Example: A pile temperature of 40°C to 50°C (104°F) to (122°F) indicates good carbon-nitrogen balance and active microbial life.
Troubleshooting temperature Issues
If the Compost Pile is Too Hot
- Turn the pile more often to release trapped heat
- Add more browns (carbon rich material)
If the compost pile is too cold
- Add water to improve microbial activity
- Aerate the pile for better oxygen supply
Heat is generated by microbial activity during decomposition.
What the Ideal temperature range for composting?
The optimal range for organic matter decomposition is 32°C to 60°C (90°F to 140°F).
- Below 32°C (90°F): Decomposition slows.
- Above 60°C (140°F): Microbes begin to die off.
Temperature tells a lot more about compost…
Temperature can be an indirect indicator of moisture content in a compost windrow. Low temperatures may suggest limited microbial activity, potentially due to insufficient moisture, which is essential for microbial reproduction and enzyme function.
Conversely, high temperatures can indicate active microbial decomposition. However, prolonged high temperatures may lead to excessive moisture loss through evaporation, ultimately reducing microbial activity and causing a sudden drop in temperature in the windrow.
How to check the moisture content of a compost pile?
- Visual and physical checks
- Dripping moisture: If water drips when squeezed, moisture content is 70% too high.
- Moisture glistening: If it glistens between your knuckles, you’re likely around 65%.
- Squeeze (Ball) Test: If it holds shape without falling apart, moisture is between 50 to 65%.
- Odor as a moisture Indicator
Strong or unpleasant odors may indicate:
- Excess moisture
- Poor aeration/oxygen
These issues can be fixed by turning the pile, adjusting moisture, or improving aeration.
What is the ideal moisture content in the compost windrow?
The recommended moisture content is 60-65%.
When to turn the compost pile?
After the initial decomposition phase (around 3 days), the temperature begins to cool.
Turn the pile at this point to:
- Reactivate microbial activity
- Supply oxygen through aeration
If the pile hits 60°C (140°F), turn it to avoid overheating. High temperatures can:
- Kill beneficial microbes
- Cause spontaneous combustion
- Lead to regulatory violations
At what temperature can a compost pile catch fire?
If the temperature exceeds 70°C (158°F), it can trigger spontaneous combustion.
This poses a risk, can produce smoke, and may lead to legal or compliance issues at the composting facility.
