Lime & Acidity In A Worm Bin

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“Thanks to your continued information. Please I want to know why my worms are dying, I have poured lime into the containers to dilute acidity if there was any as was previously suggested to know avail.

Secondly, the bins also contain reddish organisms in their millions I think and have all along lived with the worms peacefully, can they now be the cause or there is some thing else. Thank you again.” ~  Mosesele Sehlapelo

Hi Mosesele,

It seems quite a worrying problem you have there, but it isn’t something uncommon.

The reddish organisms that you mentioned should be red mites, which should be removed if they are causing problems in your worm bin. However my first concern is your pouring of lime into your system.

It is correct that agricultural lime (calcium carbonate/CaCO3) should be used to raise the pH i.e. make the system less acidic. But lime should only be an option to help mediate the system’s acidity in small quantities and not to be used as a one-off silver bullet saving solution.

Although having red mite infestation in your wormery system shows that your bin is acidic, you may need a pH meter to test just how acidic your bin is, and adjust using lime accordingly.

The easiest option is to keep a healthy worm bin where the system rises slowly and steadily towards an acidic state, which can then be  gently brought back to a neutral pH using lime. For you, the following need to be beared in mind to keep this worm bin healthy:

  • pH of the system and organic material
  • The carbon/nitrogen ratio of organic material you are putting in
  • Water content of the system

I cannot say for sure where the problem lies, which are causing the high acidity and mites in your bin, but it may be likely that you are adding too much high acidic material. It is also likely that your bin may be too wet to the point where it is more favourable to mites then the worms.

Not only does too much water attract mites, it also dissolves more carbon dioxide creating carbonic acid which is of course acidic.

Now onto the mite problem. Mites will appear as small dots which move around on the surface of your organic material.  There are different types of mites; white, brown and red. The white and brown tends to feed only on decaying material which helps the composting process and should not be something of concern.

However during infestations, Mite populations at high levels can also cause worms to stay deep in the beds and not come to the surface for feeding, resulting in poor growth and reproduction.

Red mites should be something to be aware of though. It is parasitic and can attach itself onto the worm to suck its blood and body fluids. They are known to also be able to pierce and feed on worm cocoons. Usually in small quantities these can be neglected, but in large amounts, this can cause a havoc in your system, and you will need to remove them!

Method 1 — Uncover the worm beds and expose them to sunlight for several hours. Reduce the amount of water and feed. Mites will not like this environment, and they may leave the worm beds.

Method 2 — Place pieces of watermelon, potato slices or bread on top of the worm beds. Mites are attracted to these materials and will accumulate on them. Within a day, you will be surprised to see the material almost 100% covered with the mites! The peels and bread can then be removed and dropped in water, buried or burned.

Method 3 — Place moistened newspapers or burlap bags on top of the beds, and remove the bags as mites accumulate on them. Repeat this procedure until mite populations are substantially reduced.

The following are other methods which I have come across. Although I have not tried these methods personally, it may be a good option if the above methods do not work for you.

Method 4 — Water heavily, but do not flood, the worm beds. Mites will move to the surface, and worms will stay below the surface. Use a hand-held propane torch to scorch the top of the bed and kill the mites. This procedure may be repeated several times, at three day intervals, if needed.

Method 5 — Use a light dusting of sulphur to kill the mites. After soaking the worm bed with water and causing the mites to surface, apply a rate of 1/16 ounce of sulphur per square foot of bed surface. Sulphur should not harm the worms, but in time, it may increase the acidity of the bed and reduce earthworm populations.

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