slow compost

10 years ago

Well, I didn't want to hijack another post which I was starting to do. I have a compost pile I started last fall with shredded leaves and veggie scraps in a 3-1 ratio. It heated up and I added to it in the early spring. Now its just sitting there and is almost compost but the leaves are still visible even though they are tiny since they were shredded. My grass is full of weeds and I don't like to put clippings in an almost finished pile this late in the summer when they have all emerged. So I was wondering what the best "green" would be to heat up my pile and get it fully decomposed. What about coffee grinds? That would be easy to mix in. Do you think that would get the leaves to finish composting or would something else be better (beside grass clippings)?

Comments (9)

Kimmsr
10 years ago
Does that material need a source of Nitrogen or is the material too dry or too wet?
TXEB
10 years ago
In thermophilic composting it is perfectly normal for piles to through their high temperature phase then slow down and cool off. It's part of the process. It happens because in a properly constructed pile all the easily degradable carbon material (sugars and simple carbohydrates, celluloses, etc.) have been consumed and what remains are essentially lignins. That cool down phase is called "curing", an depending upon what was used to build the pile and how the pile is managed it can last from a few weeks to months. It sound to me like this is the stage you're in.

That said, compost piles can also cool prematurely for any of several reasons. First is, as you suggest, that the microbes used all the available nitrogen and are now nitrogen starved while readily available carbon remains to be digested. In that case adding a bit more low C:N material, like used coffee grounds or a bit of blood meal as a N boost, or some would advocate peeing on it (urea) may speed it up again. Another is the pile dried up and needs moisture. Another is lack of oxygen, possibly caused by too much moisture and compacting, which can be resolved by turning it (I suspect you did this already).

Not being able to see your pile or know it's history I can't begin to judge what's going on in your situation, but recognize that the curing stage is a normal part of the process.

This post was edited by TXEB on Sat, Jun 22, 13 at 10:29
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The OP asked how to store the shredded leaves to use in the spring & whether or not to add nitrogen to them. Don't bother adding anything to them. Bagging up won't prevent them from composting. Composting won't hurt them either. I've had good results putting them in heavy duty black plastic bags out of the way. It's nice that slugs & weed seeds aren't in the bags when you open in spring. The 1st year I bothered with poking holes & turning the bags, but they weren't heavy duty & ripped a bit by spring. The mostly maple leaves weren't shredded either, so took 2 years to be ready to use as leaf mold & slugs made their way into the holes. Since then I don't poke holes or turn unless the bags are in the way of other projects. I've also stored in a chicken wire ring with stakes in the ground & eventually used it as a potato planting bin. Anything that keeps them from blowing around the garden for use in the spring should work. My preferred veg. garden mulch is dried grass clippings (no herbicides or fertilizers). Straw works as well and bleaches to an even color in the sunshine. I gather them all year when I can get them free & store in the garden until use. This year I had one of those compressed bales that refused to open up, so I pulled apart sections an inch thick for blocks of mulch over soaker hoses for the tomatoes. Hope that helps!
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TXEB
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Added - a link to the Cornell Composting page about the physics of composting, which does a decent job explaining the typical temperature profile over time in thermophilic composting.

Here is a link that might be useful: Compost Physics

This post was edited by TXEB on Sat, Jun 22, 13 at 7:52
bibbus 7b
Original Author
10 years ago
Yes, I did faithfully turn the compost and it has been kept at a moisture level to resemble a squeezed sponge. So my pile does meet most of the criteria of finished compost except for the one requirement that the materials not be recognizable. It looks like a pile of tiny leaf pieces mixed in with dirt. My camera is not good enough to take a closeup or I would post it.

Another question is what is the best way to store finished compost? I would like to start another pile in this space. Could I put the compost in a trash can outside or does it need contact with the ground? I need this for a new vegetable bed but am not able to put it into the bed just yet.
Lloyd
10 years ago
This is compost that has gone through the thermophilic stage and is just entering the curing stage. It still has some residual heat but isn't hot. It still has a moderate requirement for air so storage in a closed container is not recommended.

This on the other hand is completely matured compost and can be stored in almost anything.

Ground contact is not a factor in any kind of composting.

Lloyd

This post was edited by pt03 on Sat, Jun 22, 13 at 18:48
TXEB
10 years ago
Great pics Lloyd.
Kimmsr
10 years ago
Perhaps this tutorial will be of some help.

Here is a link that might be useful: Composting Tutorial
redbudd
10 years ago
Hi Lloyd,

Thank you for posting the pictures.

I had been to the first stage. But had never been to the second one. Did you screen it or shred it?
robertz6
10 years ago
I assume the 3 to 1 ratio is based on volume, and not on weight. It helps to make clear which is being used. I used weight when I first started trying to get hot temps with my tumbler (it came with a compost thermometer).

I find the best 'green' to get a pile back to hotter temps is grass rather than used coffee grounds. The grounds often have a lot of moisture, and therefor are heavy and tend to compress the pile. Grass is easier to mix, and does not compress. Both materials have about the same C:N ratio; aprox 19:1.

Of course adding greens to an existing pile does not guarantee that the pile will heat up again in the same manner.

If you wish to use problematic materials such as fish and fresh manure, I find the optimal time to add this stuff is to add into the core (center) during the first temp spike. Beginners might be wise to avoid adding these materials into the original pile, and wait until they see the core will reach 130F or above.