I've recently had the opportunity to get a quantity of sawdust (about 10 cubic yards) on the cheap. My plan was to take delivery, mix urea into it and wait until next winter when I would have a nice pile of compost. That's how it worked with a smaller quantity during 2014 and that went great so I was very much looking forward to this.
Sadly, when I arrived to the location where the sawdust had been delivered (I'm not there permanently during winter), I noticed that it's very very fine. It's like sand for children's sandboxes. From what I've read online I believe this could present a problem as the material would get too compressed, forming a crust, not being permeable to water / gases etc.
How can I compost such fine sawdust? One idea would be to mix it with a load of coarser material (such as mulched prunings etc) but I don't have anything that would be available in a suitable quantity. Is the situation hopeless? I could give up on composting and still use it for garden paths but there's just too much of it and I would very much prefer composting.
Photo 1: regular sawdust proven to work well
Photo 2: newly acquired sawdust suspected of being too fine
The only thing I can think of that I can get in large quantities is wheat straw. Maybe a layer of straw - a layer of sawdust - sprinkle with urea - repeat. This would improve things somewhat I guess... Unsure whether it would be enough.
Are you using this in a composting toilet, or just weeing on the large pile to add some nitrogen? From my experience of using the Humanure Handbook system the second batch of sawdust looks PERFECT... fine material is more absorbent, absorbs odours more effectively and breaks down really quickly once it has been used in a loo bucket.
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I too believe it would be perfect for a composting toilet but this location includes a "modern" family house with all the facilities and I don't believe the girls would be happy with switching to an alternative toilet.
So the sawdust will be just sitting there in a shady corner, spread to a depth of maybe 8 inches or so. To aid the composting process my plan is to add some bagged urea and the village cats will contribute as well if last year's experience is valid. In fact I could totally pack this into bags and sell it as kitty litter. But then I'd have no compost for sure. Anyway -- the worry is that maybe the material would get too compacted. Any thoughts on that?
I'm dealing with a similar problem, only my sawdust is spent cat litter. If you come across any low effort ways of breaking this stuff down, I'd love to know. I added the urine saturated sawdust to some of my compost piles last year and overwhelmed them. I had two containers that were just rotting apples + sawdust and the dust seems a bit more broken down in those. I hope it starts to degrade more quickly once spring kicks in here. I'd like to experiment with pine eating mushrooms, but that's probably not very realistic. If your dust is hardwood, that may be worth looking into for you.
It needs a little more turning to keep aerated than coarse material, but will compost just fine. I go and break up the surface with a tine fork and make a big depression in the middle of the pile of a rain is coming to help soak in more moisture.
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