Cold Compost

[Nordo]

About 6 weeks ago I bought a trailer load of horse manure mixed with urine soaked sawdust (from a local stable).
I tipped the whole lot onto a plastic tarp, then covered the top with the same tarp. It was quite damp from the urine, and after a couple of weeks I uncovered it and watered it, then recovered it.

Today I uncovered it and turned it over with a shovel. I was a bit surprised that nothing appears to be composting. Most of it was still quite damp, but most importantly, when I pushed my hand into the middle, it was cold. I would have thought it would be warm, even hot in the middle of the pile.

What is going wrong?

We have been having nights down to about 10 deg C(48degF), with up to 26 deg C(73degF) during the day.

I've decided to leave the pile uncovered, but should I move it off the plastic tarp that it still sits on?

[a0c8c]

It being cold is definately why it's not composting quickly. You also gotta give it more time than 6 weeks. I'd build a compost bin, or buy one. Having more solid sides will help trap the heat in, while a tarp probably won't. I only have three solid sides, and I noticed the top of my pile which is uncovered hardly does anything, but everything inside does great.

[applestar]

You need good infiltration of air to compost aerobically. It seems to me that what you describe would be pretty compressed, even with the wood shavings. Being "urine" soaked, the wood shavings also may not provide sufficient ratio of BROWN. You said "damp" is that "damp" as in wrung out sponge or soaking wet and drippy? I'm imagining a pretty STRONG ammonia smell blasting you as you uncovered the tarp. If this was indeed the case, than definitely too green, too wet, and not enough air.

Why did you put the pile on the plastic tarp? That would also prevent excess moisture from soaking away into the ground. AND keep out the earthworms and other soil denizens that willingly help accelerate the composting process.

My recommendation is to make a brush pile directly on the ground next to the existing pile, then using manure fork/pitch fork/garden fork, move the lot onto the brush pile (the brush pile will create airspace under the pile). If what you have is too wet, it would be a good idea to alternate layers of dry straw, fluffing and mixing the ingredients together as you go. Aim for a pile that is at least 3 ft x 3 ft x 3 ft or 1 m^3, if possible -- actually it sounds like you have MUCH MORE than that -- either make one huge pile or make multiple piles -- and fashion a dimple in the middle of the top to collect rainwater. When the pile is completed, surround and cover the pile with more straw to mulch it and conserve moisture.

I wouldn't use the tarp. If you have overabundance of rain, one way would be to arrange the straw mulch like a haystack -- stack the flakes with stems in vertical orientation, then more flakes on top like a thatched roof. Another is to use just a small square tarp -- just enough to cover the top -- tied down with twine to stakes in the ground -- with the sides open.

The brush pile can be a pain when you go to turn the pile again, but it really does help provide air, and the extra woody carbon as it breaks down really helps to enrich your compost. Other people can/have described the microbial processes better in other thread on this forum. The older sticks in my pile snap and crumble in my fingers.

Good luck!

[Nordo]

Thanks Guys. Great information. I thought aeration probably was my main problem.

I placed the pile on the tarp so that I wouldn't lose too much of it in the grass, etc. But it obviously prevents aeration from beneath. Also worms, etc can't get into the pile.
I pulled the remaining half of the tarp over the top to help prevent drying out. The tarp didn't completely seal the pile, and air could easy enter at the sides.

The pile doesn't have any smell at all. When I first brought it home, it had the strong ammonia smell of the urine, but that seems to have gone. The manure and sawdust is damp throughout, but not wet.

I can build a layer of brush easily, and I will probably buy some hay for the brown layers, although I may be able to scrape up enough from when I cut my knee high grass about 4 weeks ago.

Thanks again for all the critical information.

[rot]

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Just how big is the pile.

In a bin the classic optimal size is a cubic yard or somewhat less than a cubic meter. In a simple pile, because there are no walls to insulate and protect plus keep things together closer, your pile may need to be bigger in volume.

Air is a good thing.

After six weeks, I'd expect peak temperatures to have passed. After you turn it you should see something as long you've got some moisture.

Bare ground better for worms. Worms will do an awful lot in doing the work for you. Protect from wind and sun.

Nice warm winter you got there. I'm envious.

Always good to look at the basics (good site):
https://www.compostinfo.com/
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[Nordo]

Using my trailer as a guide, I think the pile is a bit over a cubic yard, about 0.9 cubic metre.
Currently I still have it sitting on the plastic, but this coming weekend I will build a mattress of sticks and brush, and move the pile on to that, adding in layers of 6 week old grass clippings (brown and dry) and watering at the same time. Hopefully I'll have enough clippings left over to cover the whole pile once completed. If I run out, I may have to buy a bale of hay from a local produce outlet.

Does all this sound logical?

[stella1751]

Add some soil while you're at it. That's where the action is. Soil has the bacteria necessary to make it hot

[Nordo]

Ah thanks.
I didn't think of that.

[Nordo]

Just an update.
I re-built my compost a couple of weeks ago. First I moved the heap of horse manure and urine soaked sawdust off the plastic sheeting.
I starting building it in layers about 100mm (4") thick. The horse manure/sawdust was layered with dead leaves/grass and then soil which I dug out of my vege patch. I continued layering like this 'til I had used up all my manure.

This time I needed something to hold up the sides. On some sides I used concrete blocks laid on their sides. This allows the large holes in the blocks to aerate the heap. On other sides I used some old timber planks I had. I added spacers between the planks to make 50mm(2") gaps between the planks. We've had fairly hot windy weather recently, so after wetting the heap down, I covered the heap with the plastic sheeting.

Can anyone please comment on anything I may have done wrong or forgotten?


I've noticed that my soil is difficult to wet deeply, but I started another thread on this.

[rot]

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Turning that thing sounds like a lot of work. turning it with some frequency will get air and you can add a little water as you go along to the dry patches.

If you don't do anything else, just add water to keep it from drying out. The worms will move in. We've got a dry climate here but when the rains come, the worms move in big time to get above the saturated ground so keep it covered in the rain. In a few months, 6 max, you should have some good top dressing with oodles of worms to layer thickly about the ill draining soil.

The worms will go down into the ground and come back up working the compost into the ground and bring up some soil into the compost. It won't fix things quickly but a couple of applications will make a difference.

I know a lot of folks add soil to their piles but I don't. I don't believe it necessary. Build it and the microbes that aren't already there will come. So will the worms and the bugs to do the rest. If you see mushrooms, expect a good amount of reduction in volume.

I've heard of people using concrete blocks. I don't know if they lay them on the side like you did or if they simply leave gaps in the dry stacking. I believe they mention it in the following link.

https://www.compostinfo.com/

Warm winds? It's fire season here.

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[Nordo]

Hi
I'm in a sub-tropical area (100miles north of Brisbane). We are into spring at the moment, but it has been unseasonally hot and dry.
I'll keep adding water to stop it drying out, but, as you said, it's a big heap and turning it over would be a big chore.

I'll have a bit of a dig in it this weekend and see if it is warm inside. If I get energetic enough, I'll turn over at least the top half to mix and aerate.
Thanks.
Cheers:

[a0c8c]

I'm with the other school of thought. I only turn mine 2-3 times a year. I figure, the more I disturbe it, the slower it'll compost. You could potentially pull bacteria away from their food at the wrong time. I wouldn't even turn mine, if it weren't for the outsides drying out in Texas heat. Then again, I'm lazy

[rainbowgardener]

I don't turn my pile either, just turn it over 3 times a year, when I want to use the finished compost at the bottom (I.e. pile all the stuff on top to be the bottom of a new pile). If you have a big pile, it can help to drill holes in a few lengths of PVC pipe and stick them into the pile to help with aeration.

My pile which in previous years has been a little warmish, but never hot, has run hotter than ever this year, steaming. I think the two reasons for this are that I did a better job than in the past balancing out all the green stuff (in my case mainly kitchen scraps and weeds) with browns (fall leaves that I collected tons of last fall, so I had enough to last into this summer) AND that we had unprecedented amounts of rain, so the pile stayed dampened all the time. So that's the lessons for getting it to run hotter!

[Nordo]

From what I've learnt in this forum, getting the mix of greens and browns is important, and having the right moisture content is critical.

[rot]

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Hot compost takes work and cold compost takes time. That's your basic trade-off. Both need air and water. There are varied strategies between the two. The best method is the one that works for you and what you need it for.

For the fastest mostest compost I think an active hot composting operation is what you want. For just digesting stuff that would otherwise be discarded maybe the cold compost will do.

I have a couple of cold bins, wooden pallets pushed together to make a box, on two year cycles. I feed the bin on a regular basis for about a year and then for 6 months to a year I just water. After the 6 months to a year of just watering, I apply. They sit on pavers that are just laid on the ground. The worms come up between the pavers and do their thing and reproduce. When I apply the compost, I'm applying worms at the same time. The pavers also keep the burrowing critters out. To keep other critters at bay, I've started nailing window screen to the pallets.

My sort of hot bins are just plastic cylinders with a bunch of holes and open at either end. They sit on concrete and I turn them every couple of weeks. I'd prefer to turn once a week but I'm lazy and time is an issue too. There was one study that decided turning every 4 to 5 days was the fastest to finished compost. I've heard of folks say that's too much and others that will turn almost daily.

What works for you and how much you want to work it versus what you want out of it is the best. You need to consider your lifestyle for the labor part and the climate conditions plus how much space and other resources you want to devote to the bio-remediation process.

Good easy to understand info on dos & don'ts plus different bins and such in the link below.

https://www.compostinfo.com/

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[rot]

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By the way, thanks for the update.

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[Nordo]

Thanks for all the info. Interesting about cold composts. I thought if it was cold, then it wasn't working, at all.
Thanks for the link.
The heap is starting to have a nice smell to it now, so hopefully it is starting to compost. I did some watering over the weekend, but didn't get a chance to turn it or even dig a hole to check the temp.
Thanks again.