Effective Microorganisms Uses

I’d like to get into the uses of effective microorganisms.

(If you don’t know what EM is, you can start here.)

YouTube video

We already know that microorganisms perform many critical tasks in the world – in our bodies, in the soil, on plants, in waterways, and practically everywhere else.

As a reminder, in the garden, microorganisms:

  • Improve soil health in many ways
  • Help plants take in nutrients
  • Help protect plants from pests and environmental stressors

When I think of EM, I just think of it as a mixture of microbes that are particularly good at these tasks.

Saccharomyces cerevisiae, a yeast that’s one of the microbes in EM.

Interestingly, Dr. Higa says that microorganisms can be divided into 3 categories: positive microbes involved in regeneration, negative microbes involved in decomposition, and opportunistic microbes that can go either way depending on their environment.

He says EM is made up of positive microbes that, when we put them into any environment, will actually influence the opportunistic microbes to be more regenerative overall.

That hasn’t been proven but is mentioned so often in EM literature that I wanted to share it. Whether this impact would be due to how EM microbes modify the chemistry of the surrounding environment or something else, I’m not sure, but it’s an interesting idea.

Certainly, we know the behaviors of people impact the behavior of those around them, so perhaps this can happen on the microbial level.

Mostly, I just think of EM as a source of beneficial microbes that do all of the things good microbes do.

And since EM is made in a lab under controlled conditions, you know you’re getting a consistently good product. If you were to buy compost tea, that wouldn’t necessarily be the case.

Since EM microbes are mostly facultative anaerobic (they don’t need oxygen), the product can be stored for months and even years while still retaining its beneficial properties. That’s not the case with aerated compost tea, which should be used within 24 hours of brewing.

The other benefit of the facultative anaerobic microbes is that EM works anywhere that anaerobic conditions might occur.

Here are some specific effective microorganisms uses…


Compost treated with EM can be finished faster (I’ve read as high as 30% faster).

Because of this, and because EM microbes are fermenters, less nutrition is lost to volatilization (the conversion of elements like nitrogen and sulfur to gas), so the final compost is more nutritious.

On top of that, anaerobic conditions within a compost pile encourage anaerobic microorganisms, which produce potentially-toxic compost. While that should be taken care of by building and maintaining the pile properly in the first place, EM is good insurance.

The only application rates I’ve come across for applying EM to compost are 2 Tbsp per 10 pounds of organic material from one source and 5 liters per ton from another. Both of those work out about the same. I don’t know exactly how much the various compost materials weigh but I do know that finished compost is often around 1500 pounds per cubic yard, so 3 liters of EM makes sense for that.

This can be applied undiluted or mixed with some water.

Also, I always spray the pile whenever I’m spraying the garden – with the same recipe I use for the whole garden, which is coming up in another lesson.


EM microbes do many of the good things that microbes do in the soil but they’re especially noted for breaking down organic matter as well as toxins.

Spraying EM on your mulch layer will speed up the break down of that mulch and get more of its nutrients into the soil.

And spraying EM on worn-out, compacted soil can help bring it back towards balance.

That aid, although I often talk about EM (and compost tea) as being a way to get microbes into the garden when you don’t have any compost around, using EM doesn’t mean you don’t need organic matter.

Indeed, their benefit on the soil will be much greater when they have some organic matter to break down. The organic matter can be leaves, grass clippings, coffee grounds or whatever else you can get your hands on.


In some studies, EM has a positive impact on yield, fruit size, fruit damage, brix, and storage life.

This is probably due to the microbes doing what they do: feeding the plants and protecting them from diseases.

EM can help plants beat diseases and insects. It’s not a pesticide – it simply creates health in the plant and helps to outcompete microbial predators on the leaf surface.

The rice weevil is a serious pest for stored grains, including wheat and maize as well as rice. EM-fermented plant extracts have been used to discourage this and other plant pests.

EM may have some nutritional benefit of its own – apparently, it’s high in antioxidants – but it’s best to apply it along with organic liquid fertilizers to really give the microbes something to work with to feed the plants.


Soaking seeds in EM can substantially improve seed germination.

But you do need to go light with seeds because too much EM could inhibit germination.

Use just a 1:1000 ratio, a scant 1/4 teaspoon per quart of water.

(Seaweed and sea minerals help with germination, too, so if you have them, mix either or both of them in at 1 teaspoon each per cup of water.)


EM is very helpful for improving animal health.

EM can be used with chickens to improve health and reduce odors.

For pets and farm animals, EM is fed to them as a probiotic. You add it to their drinking water and/or spray it over their food.

For dogs, it’s 1/2-1 tsp per day for small dogs and up to 2 tsp for large dogs.

For cats, it’s 1/2 – 1 tsp per day.

You can also spray it directly on animals to help control pests and diseases and odors. You can spray their homes and their waste for the same benefits. For livestock, you can spray the whole barn.