I must admit to feeling pretty apprehensive when I saw the subject of this email (same as the title of this post) from one of our readers! I had visions of beer being poured directly into a worm bin (which might sound like fun to some, but certainly wouldn’t be great for the worms!)
As it turns out, it is a query about brewery wastes – one of those tricky materials that – while certainly offering plenty of “food” potential – warrants a very cautious approach.

I had read somewhere that worms like beer , so I took a trip to the closest micro-brewery and after a couple of taster sets , decided my red worms might like a couple of pounds of spent malt . I mixed it in
with the other compost and 5 pounds of red worms , much to my surprise they didn’t seem to like the excessive heat the malt was throwing off (still fermenting?) and seem to have all perished! Please advise your readers to “not try this at home” as the “brewery worms” seen on TV , don’t seem like home brewers!!!
I have now resorted to having to lie to my wife as to the current condition of OUR worms ! Do you have any advise on what I should tell my wife ?

Warmest Regards
Haven

Hi Haven,
Hopefully your wife isn’t one of our regular readers! I couldn’t resist adding this as one of our “Reader Questions” posts since it is a topic that deserves some attention!

I myself have not used brewery waste in a worm composting system for quite a few years now, but when I DID experiment with it, I had a VERY challenging time getting it to work well as a “food” material. Like many others, I’d read that it was supposed to be a fantastic material for vermicomposting. Edwards and Bohlen (1996), in fact, offer this glowing review on page 247 of “Biology and Ecology of Earthworms”:

“[Brewery waste] needs no modification in terms of moisture content to grow earthworms. Worms can process it very quickly and grow and multiply rapidly in it.”

This is not even close to what I experienced with this material. I found that it had the tendency to become very foul very quickly, and as such, was not well received by the worms even in relatively modest quantities and/or when mixed with other materials.

Looking back now, with quite a bit more experience under my belt, I can certainly see why this may have been the case. It is something akin to adding material straight from a bokashi bucket into a worm bin – something you can get away with in moderation (and when using a larger, well-ventilated system), but a bit trickier with smaller enclosed bins. In both cases, you are dealing with a material that is very anaerobic and which has undergone some fermentation. Well, we all know what fermentation can produce – alcohol! Not exactly something you want to be adding to your worm composting ecosystem!

I’m guessing there must be different kinds of brewery wastes. I just can’t see how else Dr. Edwards (mentioned above – who was involved in the original research being referred to in the book) could have reached that conclusion otherwise! In my experience (and clearly, the experience of others) this material definitely DOES require some “modification” prior to use!

What I would likely recommend now is some sort of “pre-composting” (or at least “aging”) period before attempting to use the material in a vermicomposting system. Some may recall how long it took for Red Worms to colonize that “bad” bokashi waste I dumped out in my yard this summer (see “Bokashi Gone Bad” and “Bad Bokashi Update“). Clearly, even when excess moisture is allowed to drain, and the material is allowed to sit exposed to the elements, it can take quite some time for aerobic decomposition processes to become re-established.

If one had a compost tumbler and lots of dry absorbent material (such as coco coir), plus some mature compost, I suspect you could speed up the process considerably! In terms of knowing when the material is “ready”, my recommendation is simply to go with a good ol’ smell test (this applies to any material you are planning to add to a worm composting system for that matter). Some stink should be fine (and again, in larger open systems you can get away with a LOT more than in a small enclosed bin), but if the material still smells really foul when you dig into it, it likely isn’t yet ready to be used as worm food.

Unfortunately, my talents as a marriage counselor aren’t exactly on par with my vermicomposting know-how, so I’m not really sure what to recommend you tell your wife, Haven! (haha)
If I was in your shoes, I’d likely use the quote from Edwards and Bohlen (highly reputable worm experts) as a starting place from which to build my case! You didn’t even put the worms in pure brewery wastes, as they seem to be suggesting! It was a perfectly honest mistake the way I see it.

Smoothing things over with a new batch of worms probably wouldn’t hurt either!
8)

REFERENCES

Edwards, C.A. and P.J. Bohlen. 1996. The biology and ecology of earthworms (3rd Edition). Chapman & Hall, London, 426pp.