Vermitea Bacterial Quantification and Comparison to Commercial Products

In the previous post we covered vermicompost bacterial quantification, colony forming units, and how quantitative sequencing works. This post will hopefully be less technical and compare how vermitea stacks up to other commercial liquid amendments.

Vermitea Bacterial Quantification

Along with a vermicompost sample, Nicky at Permaculture Gardens had 2 vermitea samples sequenced. These samples were essentially replicate samples from the same brew. I believe one sample was taken just before the brewing was finished and another was taken just after the brew finished.

The first sample was estimated to have 460 million bacterial cell per ml (2.3 billion / 5 16S genes per cell) of tea while the second was estimated to have 340 million per ml. These numbers are pretty close despite some variability in sampling (due to my poor instructions). The composition of the microbial community itself was the same and I think it shows that this method is reproducible.

Vermitea compared to liquid commercial products

So how does vermitea compare to other products? Compared to vermicompost, 0.5 billion cells in one gram of tea is much less than the 16 billion in one gram of vermicompost, but what about other liquid amendments?

TerraGrow Liquid® from Arbico Organics

If we look at commercial bacterial amendments such as TerraGrow® Liquid ($260 per gallon) they have 5 different Bacillus species from 100-400 million cells per ml each for a total of 1 billion cells per ml .

It looks like our vermitea sample is about half as concentrated as the combined lab grown product. However, vermitea is as concentrated as any individual species they list. I assume the individual organisms in something like TerraGrow are grown individually and then concentrated into the final product.

Arbico also advises to dilute it 1 oz per 10 or more gallons (1:128 dilution factor) which comes out to 8 million cells per ml. You could dilute this vermitea about 1:60 and get about the same application rate in terms of bacterial cells.

For what it's worth, the organisms they list are likely decent plant growth promoting organisms. If you read their species descriptions on their website you'll see mention of mineral solubilization a few times which I've previously discussed as a specialty of bacillus organisms. Interestingly, they don't seem to mention anything about phytohormone production which they also seem to excel at.

Inocucor Garden Solution® from Arbico Organics

This liquid inoculant ( $32/gallon ) from the same company contains Bacillus Subtilis at 100 million cells per mil and Saccharomyces cerevisiae (yeast) at about 500 million cells per ml. Again vermitea is right in this concentration range.

While this product is much cheaper, I wouldn't recommend it. I'm not exactly sure how bakers yeast is going to improve soil or plant health and than the nutrients they provide after dying. Nonetheless, props to Arbico for being transparent about what's in their products and they aren't claiming any benefits from the yeast.

Other products / EM1 / Lactic acid bacteria

Many of the online commercial amendments I looked through didn't list quantities of their microorganisms at all. Bacillus species seem to be the most commonly listed. This likely because they are the easiest isolate and to grow in pure culture.

EM-1 and Lactobacillus

It's my belief that products like EM-1 are a total scam as they are only lactobacillus species (yogurt making acid generating organisms). Let's look at this example.

The description of the product states:

"The host of beneficial microbes, including photosynthesizing bacteria, multiple strains of lactic acid bacteria, yeasts and more help break down organic matter in the soil, turning it into food for plants and releasing essential minerals like nitrogen."

First off nitrogen is not a mineral... but they make it sound like it's this amazing mix of different organisms all working in harmony. EM itself stands for Effective Microorganisms(!). But lets look at the actual label -

That's curious, why do they only list Lactobacillus casei? Probably because that's all that's actually in there. Again, this is not a plant growth promoting organism, but you could probably make some great yogurt with it. Unfortunately, these types of products cast a bad light on all biological inoculants.

I do think there are uses for bokashi composting and fermenting foodwaste is fine, but you're not growing plant growth promoting organisms. I have some old bokashi data I'll talk about soon in another post.

To be honest I'm not 100% sure the organisms in vermitea are plant growth promoting, but at least there is literature suggesting that they could be. For most of these commercial biological amendments, I think this is the standard they are using as well.

Conclusions

In closing, vermitea has about half a billion cells per ml which lines up great with other liquid inoculants on the market.

Also, don't buy yogurt organisms to inoculate your soil (please don't sue me).

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