EM (Effective Microorganisms) & Vermicomposting

Worm Composting...

“Dear Kenny, I need your advice on the following:

  1. I have been keeping a few (unsealed) gunny sacks of dry vermicast for some months now. It doesn’t give bad odour. Is the stuff still good? Will spraying with 1:40 EM-water solution help reactivate/refresh the worm cast?
  2. Can vermicast combine with EM-treated animal dung and become fast acting manure?

I’d be grateful for your kind attention. Many thanks.” ~ Baharuddin Ghazali.

Hi Baharuddin,

Thanks for your question about EM!

I have written about this topic a while back before and it is great to re-visit the topic.

This question brings up two topics: The use of EM with worm cast and the storage of wormcast.

Before we talk about the storage of wormcast I think it will be worth distinguishing the difference between wormcast and vermicompost, because the way the two is stored is different.

Wormcast is the excrement of worms after they digest any material. Vermicompost is the mixture of degraded matter, non-degraded matter and wormcast.

Vermicompost is less stable due to the partially decomposed organic materials and will continue to breakdown during storage.

If during this stage, there is little or no oxygen in the container it is stored in, then it is really easy for it to go anaerobic (no oxygen) and anaerobic microorganisms will start to thrive creating plant toxic products.

It will also start to produce a foul smell allowing you to know it has gone bad. To store vermicompost, you will need to dry it down so that it is damp but not wet. This way it will allow enough air penetration if it is stored in a non-airtight container.

Wormcast is much easier to handle and store because it is already a stable material.

There is not further breakdown need. Therefore it can be stored in an airtight container with no problems of smell and lost of efficacy. The wormcast is best dried to a moisture level where it is almost dry to touch and sticks easily together as you squeeze it, but crumbles away when you let go. It can be stored like this for three years or even more!

It seems like what you have is wormcast and so your storage time of a few months is definitely not a problem!

Now onto EM, let me first introduce this to the other readers so that they know what it is. EM stands for Effective Microorganisms. They are a combination of different types of microbes such as bacteria, yeast and fungi.

This special combination was discovered by a Japanese Scientist called Teruo Higa back in the 1980’s.

Dr Higa was researching micro-organisms on the growth of plants and found the microbes he was using didn’t make much of a difference to plant growth.

However during his research days he miraculously found a small patch of grass outside his laboratory to grow extremely well compared to all the other grass around it. He came to realize that this patch of area also happens to be the place where he throws away his microbes.

From this he realized that these micro-organism on its own were very ordinary and readily available. What was unusual though is that once they are combined together they form a special symbiotic relationship which helps and support each other in growth.

Each species of micro-organism will produce by-products or waste products which may be the food source for the other others, hence helping and boosting each other up.

It is almost like us giving away a toaster we don’t need to a neighbour who doesn’t have a one, and at the same time the neighbour gives you the extra blender he is about to throw away because you don’t have one!

Different microbes can provide for what the other is lacking, hence diversity is important.

He researched more on the mix of these microbes and finalized on a mixture formula of three types of microbes:

– Lactic acid bacteria

– Photosynthetic bacteria

– Yeast

This collective mixture is known as ‘EM’ or ‘Effective Micro-organisms’. These microbes are easily found in nature and are very safe (so safe in fact that Dr. Higa has drunk this in front of farmers to prove how safe it is!).

The most important one here is the photosynthetic bacteria, while the lactic acid bacteria and yeasts exist to support it.

The use of EM was originally targeted for the farming industry.

Dr Higa believes that through the use of chemical pesticides and fertilizers and poor farming practices in agriculture, it has resulted in poor soil due to the plunge of beneficial/good microbes.

Not only has this lead to poor soil, it has encouraged the growth of bad microbes due to lowered soil immunity, resulting in soil and crop diseases.

As the use of EM became more wide spread, its uses has also diversified. Many have used it for its odour suppressing capabilities in removing odours in silage tanks and anaerobic composts, but a popular use in households is for making ‘Bokashi’.

I will talk about bokashi and the feeding of bokashi to worms in more detail in the next newsletter.

So back to your question, can EM help revitalize your wormcast/vermicompost?

Well that depends what you mean by revitalize. Will it provide benefits to the soil when you use it?

Probably Yes!

But will it be able to increase the microbes originally in your wormcast?


The EM liquid which is available for purchase in a bottle actually comes in a dormant state and the liquid does not contain much of a food source. Now most EM vendors will tell you to ‘activate’ the EM before using it by giving it a food source such as molasses, and give it a few days to ‘waken up’.

The micro-organisms in EM and the micro-organisms in wormcast are different.

Therefore whatever you have in wormcast, however abundant or non-abundant it is, will not increase just because you sprayed some other microbes onto it. The only way for the microbes to ‘revitalize’ or increase in growth is to give it a new food source, otherwise it will lay dormant and relatively inactive until it does.

Activated EM will contain some food source through the molasses to rejuvenate some of the microbes in the wormcast, however this will take a few days and the food source will only be suitable for some of the microbes only.

So it will probably be better off putting the cast straight into soil where the environment is better suited for the diverse set of microbes in the wormcast.

There are benefits for spraying EM onto the wormcast though. By doing this you will have added the EM microbes onto the wormcast and essentially diversify even more of the microbes it originally contained. You would have added the extra benefits of what EM can provide by the addition of the Lactic acid bacteria, photosynthetic bacteria and yeasts.

Since Dr Higa has discovered a diverse set of good micro-organisms is beneficial for the soil, you will have helped increased this diversity.

So adding EM is a good plus. However compared to spraying EM onto the cast, the method can probably be improved by spraying the EM directly onto the soil instead, and then use wormcast separately.

This way the microbes will immediately start getting to work in the soil and none will be wasted.

EM treated manure and worm cast can definitely be used together, although it may not necessarily increase its efficacy on soil or make it act faster.

Do be careful not to go for an overkill and do too much.

If you are already using manure, you may consider saving your wormcast for a later date or for something else such as your house plants.

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