Anaerobic compost in the bunker

Anaerobic compost – compost with no oxygen – is by definition a bad process. Oxygen is one of the most important elements in the composting process. If the computer shows the temperature in the compost rising above 80oC, this tells you that enough oxygen is getting into it. All good, you might think. But despite the nice graph on the computer, lower temperatures could be lurking in various places in the tunnel (at a height of about 70-120 cm). Here I explain how to check and prevent this.

Check the appearance of the compost

Check for anaerobic compost by going into the tunnel and watching while it is being emptied. Always make sure the person operating the loader knows that you are going into the tunnel. Safety is paramount! If you watch as the compost is being removed, you will notice any anaerobic compost. Instead of dry-looking black-brown compost, you’ll see more watery yellowish-brown material.

Check the smell

If you can’t smell the compost or it smells sour, it is anaerobic.   If it smells of ammonia, that’s good! The best way to smell the compost is to go and stand in the vapour left behind by the loader as it leaves.

Measuring the temperature

Temperature is also a good indicator, so to measure is to know. A tunnel is generally measured with four sensors during the process. If possible. use a manual thermometer with a 1 m stem that measures the temperature at the tip. Then you can measure the temperature in different places and, importantly, at different heights. You’ll get to know the tunnel better and discover where any anaerobic patches are lurking.


There are various causes of anaerobic patches:

  • Not cleaning the spigot
    The spigot stays blocked so no water drains out and no air is blown into the compost.
  • Poor drainage in the underfloor pipes
    If water is blown out of the spigot as air is supplied to the system, drainage is poor. The water is not drained away and is blown back into the compost, causing the anaerobic conditions.
  • Watering too much during or just before filling the bunker
    It is difficult, if not impossible, to drain this water off during the process. The water blocks the inflow of oxygen. If you are filling with an overhead system, give the bottom layer less water. This reduces the risk of anaerobic compost in the bottom layer.
  • A lot of fine material in the straw or too much chicken manure
    This seals off the compost, so to speak.

There are countless other causes, but you can often think of them yourself as a composter. Detection is usually the problem. So keep looking, smelling and measuring in the bunker!

Bron: Mushroom Blog – Mark den Ouden

Anaerobic compost in the bunker-mushroom growth


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