Anaerobic Compost and Alcohol.

by Haydn
(Perth – Western Australia)

I’ve read that anaerobic compost could contain up to 30 ppm alcohol and that 1 ppm will kill plants. It would therefore be great to know the answers to the following questions:

a. How do I know when or if I’m producing alcohol in the compost?
b. Is the compost OK to use when it becomes aerobic again?
c. Is the potential production of alcohol dependent on the ingredients used?

Pls keep your Compost Junkie notifications coming Dave…..I love em!

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Mar 07, 2012
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Your Nose Isn’t Just for Smelling Roses
by: Dave

Hi Haydn,

Do you recall where you read that re the 30ppm of alcohol in aerobic compost? I don’t disagree, I’d actually like to read it out of curiosity.

My thoughts on your questions…

a. As the title of this post reads, your nose isn’t just for smelling roses; it’s also a great means of determining the quality of your compost. My best guess is this…the only way you’re going to get a build up of alcohol in your compost is if your pile goes anaerobic and stays anaerobic for an extended period of time. If that’s the case, you’ll know as soon as you go to turn it, because it will stink.

So as a means of monitoring, make sure you really get your sniffer in that pile when you’re turning it. If you can smell any offensive odors you’re most likely fostering anaerobic conditions. I’m sure there are labs that will test this for you, but I don’t know if that’s necessary, especially in a backyard gardener scenario.

The key is prevention. As the saying goes, “an ounce of prevention is worth a pound of cure.” That is, make sure you build your pile right in the first place. Stick to the basics (proper ingredients, aeration, and moisture) and you shouldn’t have to worry about this.

b. As far as I know, all compost (even those we consider to be completely aerobic at all times) will have teeny tiny pockets of anaerobic areas throughout. These are like microcosms of minimal oxygen.

Is it okay to use these composts when they become aerobic again? I would be hesitant to use this compost on my edible crops and/or prized garden plants.

When in doubt, do a test on a small area in your garden. Or throw some of this compost on your lawn and see if you have a kill zone. Or better yet, put some seeds into it and see if they germinate and thrive. All of these simple tests will help answer your question. I’ll discuss some other tests we can do with compost in an upcoming article.

c. I’m no expert in the field of alcoholic compost, but wouldn’t you agree that the ingredients would have at least some effect on the production of alcohol if the compost wasn’t managed properly? For instance, if I had a pile of wet manure and I didn’t manage it properly (adequate turning, addition of bulking materials, carbon sources, etc.) it would go anaerobic and start producing alcohols a lot more quickly than a pile of wood chips that was improperly managed, right?

Nonetheless, alcohol production in compost probably hinges on a lot of factors, all of which contribute to inadequate oxygen levels.

I hope this helps.

Your Soil and Health Scout,
d

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Mar 08, 2012
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Anaerobic Compost and Alcohol.
by: Haydn G

HI Dave,

As usual, a very comprehensive and helpful reply, thank you yet again.

It all made sense with your words “extended period of time”. I guess a very short period of anaerobic composting or, as you say, “teeny pockets of anaerobic areas” will ultimately make no difference by the time the compost has cured. I would assume then that any small volume of alcohol would be broken down or eliminated in the pile by the time it becomes aerobic again.

I fully agree with your comments re testing the final product. I have produced some pretty bad compost and grown some pretty sad plants as a result but I guess these are the ones you learn the most from.

With regard to my initial comment of alcohol production reaching 30 ppm, this figure is quoted by Dr Elaine Ingham in her compost DVD “True Fertility Compost & Compost Tea Workshops, (Ref Disk 3). I found this set of 5 DVD’s fascinating.

Thanks again Dave and Happy Composting.
Haydn

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