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Worm Castings vs Vermicompost – Whats The Diff?

I tend to use the terms ‘worm castings’ and ‘vermicompost’ interchangeably here on the site, when technically speaking they are not quite the same thing.

Worm castings are literally little worm turds (for lack of a better word – haha) – that is to say, material that has gone in one end of the worm and out the other. If you have 100% pure worm castings (virtually impossible to achieve) you should have a material that looks a lot like coffee grounds.

Vermicompost is really a more accurate term when it comes to the material produced in most worm composting systems. It is basically a mixture of worm castings, partially composted wastes, and any resistant materials that won’t readily break down. Really high quality vermicompost should have a high percentage of worm castings in it, but the chances of having every last bit of material in your system pass through a worm at least once is pretty slim.

I’ve talked previously about the awesome vermicompost produced by Worm Power. Although I referred to it as ‘worm castings’, it isn’t 100% pure castings, but there is definitely a very high percentage. If I remember correctly, they actually let the material pass through the flow-through system twice in order to ensure that it is as close to pure castings as possible!

The problem is that there are no standards in place to dictate what percentage of worm castings has to be present in order for a product to be “100% pure” – nor are there really any ways to accurately measure the castings percentage. It really just comes down to the look and feel of the material, the reputation of the company producing it, and of course its ability to boost plant growth.

Anyway – definitely not trying to split hairs here – just thought some of you might be curious about the technical difference between these two terms!

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Written by Bentley on April 23rd, 2008 with 2 comments.
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Get your own gravatar by visiting Shawn (worm power guy)
#1. April 24th, 2008, at 11:24 PM.

Bentley – great article. It is definitely a topic worth discussing (as it comes up all the time). From a product liability standpoint – it’s very difficult to call anything 100% nowadays without some level of worry or misrepresentation (as it should). In my mind, premium vermicompost should contain a large percentage of castings – combined with the undigested portions of the composted (quality controlled compost) material that the worms thrived in (i.e. from the same system). The goal should be to produce a material that contains beneficial biological, chemical and structural properties (the building blocks of great soil). Some level of diversity in the finished material (such as that in vermicompost) would be required to meet these three (3) criteria. Also – regarding the lack of standards, you hit the nail on the head. This plagues the industry from hitting that credibility mark. What needs to continue is real scientific testing (like that happening at Cornell University and others) to determine what mechanisms or combination of mechanisms make vermicompost / worm casting material work as great as they do.

Get your own gravatar by visiting Bentley
#2. April 25th, 2008, at 3:11 AM.

Heya, Shawn! Thanks for popping by a sharing your thoughts. Great info!
You are definitely right about the need for more scientific testing as well. Hopefully, as the use of vermicompost becomes more popular, we’ll see an increase in the number of researchers taking an interest in it.

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