Here is a question from Heather:
I have notice that the shredded bedding in my worm bin looks like it
has been burning (almost charred black and that brownish tinge). I
tried to wet it more, but then my worms seemed to disappear, so i
don’t know if I overwatered. Is it possible that my worm bin could be
heating up to the point where the paper is catching fire?
Thanks for helping me out. Love the newsletters too. very helpful.
That is indeed an intriguing question (and your subject header certainly made me smile). I’ll be honest, my initial reaction was “no way – not possible!”, but I decided that rather than assuming the role of a closed-minded ‘Negative Nelly’ (haha), I would look into it further.
I have certainly heard of spontaneous combustion occurring in straw storage areas, and even in largescale compost heaps, but my assumption with home vermicomposting systems is that they are too small, and too wet! That being said, I decided to read up a little on the process to see what I could learn.
I found a lot of really interesting info on this page: Fire – Compost and Organic Matter.
The temperatures required for the spontaneous combustion of organic matter are apparently as low as 150-200 C (212-392 F). What’s really interesting, is that while the heating is initiated by microbes, once it gets up past 70-80 C (158-176 F) – i.e. once the microbes are killed off – heat-releasing chemical reactions take over, continuing to drive the temperatures upwards.
Large volumes of material seems to be one important requirement (just as it is with hot composting), since a certain ‘critical mass’ is required in order to overcome the various cooling mechanisms at work (air flow, evaporative cooling).
It seems that my notion about the material needing to be quite dry isn’t necessarily true. According to the article, moisture contents as high as 45% still fall within the acceptable range for initiating the process. Given the fact that moisture can quickly evaporate from a pile during hot composting, and that large compost heaps often sit outside in the sun, I can now see how this could easily happen.
Getting back to the idea of this happening in a worm bin…
While I am still not sure that you could ever initiate a full-blown ‘fire’ in a worm composting system (it would have to be a huge system, and most of your worms would likely be killed off long before it happened), the aerobic decomposition process is in a sense akin to a slow biological ‘burning’. Paper that has been partially composted for example, often looks almost burnt. I suspect that the colonization of certain organisms can also make it look like there has been some charring of the material. For example, I’ve written previously about the way in which coffee grounds seem to develop a burnt look, even when decomposing in relatively small quantities – something I suspect is caused by the presence of certain fungi.
As for your worms disappearing once you added water, I’m not really sure what might be going on there! Hopefully they have shown up again since the time of your writing.
Anyway, I’m not sure if this has helped to answer your question at all, Heather – but thanks again for bringing up the interesting topic. It was cool to learn a little more about spontaneous combustion.
Written by Bentley on September 25th, 2009 with 3 comments.
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Here is a question from Francisco:
I am learning about worm bins and have been trying to start one just
by catching them in the backyard. Your blog is great and I have spent
so many hours reading the old posts.
I am not sure if the worms I catch are even good for composting.
Unlike what some people have done, I don’t just go outside after it
rains to try to find them. I have been putting wet cardboards in
shady/wet areas of my yard that have a lot of old dead leafs. I would
move the leafs and lay down the cardboards. To my surprise, I am
catching a couple of them every time I left up the cardboard. The
worms are fairly red, very thin and about 1/2 to 3/4 of an inch long.
Since they are coming up to eat the cardboard, is it safe to assume
they are composting worms?
Any help would be greatly appreciated.
Keep up the good work on the blog, I know I will definitely be
Thanks for the email – that is a really great question, and this is certainly a topic in general that quite a few people have inquired about. Unfortunately, there seems to be a very common misconception that any old type of worm can be used for worm composting – which as you obviously know, is not the case. To compound this issue, the first worms people usually think of are the ones that come out after a heavy rain and/or those ones encountered when digging around in the garden. More often than not, these are exclusively soil-based worms – NOT those species adapted for life in rich organic matter (such as that found in a compost heap or worm bin)!
There are three basic groupings of earthworms – 1) ‘Anecic‘, 2) ‘Endogeic‘, and 3) ‘Epigeic‘. The anecic worms, such as the large ‘Canadian Nightcrawlers’ (aka ‘Dew Worms’ – Lumbricus terrestris) build deep burrows, typically extending down to the mineral soil layers. They live a relatively solitary life (coming up the the surface for feeding, mating, and to escape from flooded burrows), and generally thrive at cooler temperatures than those worms in the other two groups.
Endogeic worms are basically the intermediates between the other two groups. They are still soil worms, but are typically located closer to the soil surface. Unlike the anecic worms, they often create horizontal (rather than vertical) burrows.
The last group, the epigeic earthworms, are of course the ones we are most interested in from a composting stand-point. This group generally lives at or above the soil surface – typically associated with concentrations of rich organic matter (eg. leaf litter, manure etc). They also tend to be much more tolerant of crowded conditions and wider fluctuations in temperature. Because they live in these potentially harsh/challenging environments, epigeic worms also tend to grow and reproduce much more quickly than the other groups of worms (helping to ensure the success of future generations).
You are certainly on the right track with your approach, Francisco. If there ARE any epigeic species of worms located on or near your property, there is a decent chance you will be able to attract them to an area where you have added organic matter on the soil surface. Whether or not you will attract the best species and/or enough worms to make your efforts worthwhile, is another matter altogether.
I know that if I did the same thing in my own yard, I would end up with lots of Red Worms (Eisenia fetida) concentrated in the organic-material-rich-zones. As an illustration, I recently left a few (freshly harvested) zucchinis on my lawn for a day or two. When I went to collect them, I discovered a handful of small Red Worms underneath each of them! I can only imagine how quickly I could populate a heap of aged manure if I dumped it on my lawn!
If one of your neighbors happens to be composting with worms, or if they have found their way into the area via some other means, you may be in luck! More than likely though, you will end up with a mix of epigeic and endogeic species that just happen to be living close by.
The fact that you’ve found some small reddish worms could be a good sign, but the only way you will know for sure if they will work is to put them to the test in a worm bin. As for them coming up under your cardboard – this is pretty common for most types of earthworms. Leave just about anything to sit out on your lawn for long enough, and you’ll likely end up with quite a few worms congregating underneath.
Hope this helps!
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Written by Bentley on September 25th, 2009 with 5 comments.
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