Compost heats up because of the activity of the bacteria that are digesting the material. The temperaturesd will stay up as long as there is something for them to digest, there is a nutrient source (Nitrogen), there is enough moisture (but not too much), and there is enough air to keep them functioning.
If very little of the input is recognizable asw it was originally and the product smells like good rich earth it is finished. You will not "tie" up Nitrogen with unfinished compost.

Ken1, you sound like one of the "serious compost tumbler operators" that I've been looking for! You are actively monitoring and attempting to control the batch in your tumbler to do it hot and to get it done.

One thing I've noticed in my several attempts so far at a hot batch of compost in my Mantis ComposT-Twin is that as the materials in the tumbler reduce in volume, they get wetter and wetter, as indicated by the substantial amounds of the dark water that drips out of the tumbler into the catch buckets that I have below mine. I suppose I could add some shredded newspaper, dried grass clippings, or something like that to absorb the extra water. But it seems to me that if I add paper or grass clippings, that I'm basically starting the load back at the beginning in terms of having materials in there that are back at the beginning of the composting process.

What I'm trying in this batch is to add only water or lawn fertilizer, if necessary, to keep the batch hot. And I'm only turning my tumbler if the center temperature is below 100 degrees F or above 150 degrees F.

Jim

"WOULD IT BE A GOOD IDEA TO ADD FRESH GRASS CLIPPINGS WEEKLY TO KEEP THE TEMPERATURES UP LONGER?"

I wouldn't, after a heat cycle I put the material into a curing bin for finishing and start a new batch.

"How can you be sure your compost is finished?"

There are respiration tests that can be done but for a home composter it probably is not worth the cost. Try the bag test and a seed germination test.

You are not likely to tie up nitrogen based on the description of your procedure/materials. Nitrogen deficiency usually happens with high carbon materials being incorporated (mixed) into the soil.

This is an old thread but it has some good information.

Here is a thread that talks about using unfinished compost and some of those issues.

Lloyd

Compost is considered finished when:

1) Ingredients not recognizable any more
2) Dark brown color, almost black
3) Earthy smell only

Compost is not considered done when the hot stage is completed. I sometimes use it at that point, but only because I'm in a rush to start the next batch.

There have been a number of threads on whether compost needs to be 'cured' or not. Those who write papers and books on the subject use 'cure' differently than some people in the Compost forum. They say 'mature', 'cure' or 'stabilize' for the period of mesophilic breakdown. Experts say there are either two, three, or four stages of the composting process. Cornell says a one year period is best for curing; my book "Easy Compost" says at least thirty days.

Without agreement on the basics; some will try to sell you on making compost in 14 or 30 days. My outdoor mesh bins, make a decent compost in three to six months, with a hot stage in the beginning.

I basically have the same question as Ken1 but I have an outside bin. Just as Ken1 my compost ingredients are leaves (oak leaves double shredded) and grass clippings. The Bin is 4'x4'x4'. It is turned once a week for three weeks. It is no longer heating up. The grass clippings seem to be unrecognizable but the oak leaves are still recognizeable. I am trying to have finished compost by mid Feb. As Ken1 asks, can you add grass clippings (or maybe a fetilizer high in nitrogen) to heat up the pile again and speed up the decomposition of the leaves.

Any idea on the ratio of leaves to grass? Volume wise, 50/50, 75/25? Also what kind of heat did you get temperature wise, 120-140 or 140+ and how long did it sustain the highest heat?

I suspect with a bin that large it should have sustained a temperature of 130+ for at least three to four weeks if all the conditions were in the optimal range. If it didn't, then one of the parameters was out and it could very well be the C:N ratio.

Lloyd

Thanks for all the input, the compost does meet all the criteria for "finished compost" as far as color, smell and the components are for the most part are just crumbles.
I bag the finished compost and twist tie in the bags which are 1.5 to 2 cu ft, will this "finish" the compost OK?
In the past I have just used my compost more as a mulch, but plan to till in a large amount of it this year which led to my question.
James, I think if you read the posts Lloyd linked in his reply to me it will help you a lot. I do turn mine daily when I'm here, which is four out of seven days a week.
It sounds like you may be adding too much water, but as you can see by my question, I consider myself a novice in the midst of all this knowledge.
Thanks again
Ken

Loyd -

When I started my first bin, the internet searches I came up with said 75/25 leaves to grass. But I don't think that is the right ratio for my leaves. In my newest bin (3'x 3'x 3') I am now trying 50/50. But it is very hard to determine whether I am getting 50/50. Leaves are very finely shredder and grass has not been shredded because it clogs the shredder. So today I tried measuring the leaves vs grass before the leaves were shredded. Maybe that will work.

Unfortunately I have not yet purchased a compost thermometer. I am using a tomato stake with a metal core and plastic on the outside to determine if the pile is still hot. There were to many brands of thermometers and I just gave up trying to figure out what was a good brand to buy. Any suggestions.

75/25 would be a decent mix if the leaves were whole. Using shredded leaves (especially finely shredded) a person can up the N and 50/50 by volume would be a good starting point. The N in grass can also vary with the season, so there may be some adjusting required.

There can also be issues with using very finely shredded leaves in that it may inhibit air infiltration into the pile. Some coarseness is good to increase the porosity of the pile.

As far as heat goes, for the first few years I just used a steel bar as my temperature probe. I left it in the pile and just pulled it out to take the temperature. If I could brand cattle with it it was too hot. If it was too hot to touch at all, probably over 150F, if I could grasp it for a few seconds I guessed around 130-150 depending on how long I could hold it. When I could easily hold the bar it was under 110. Of course this wasn't exact but it was fun to show people. I now use a 20 inch Reotemp to monitor the temperatures.

Lloyd

The most simple formula I found to reach 160F (now I try for 140F)is:

1 pound of dry, finely shredded leaves to 1.5 pounds fresh grass clippings.

'Dry' in this case means as they fall off the tree, and for the next few weeks, without any additional water such as rainfall.

You could substitute Starbucks used coffee grounds for grass (they give you the expresso grounds which have more water than the other grounds you can find in the dumpster).

I used a digital bathroom scale to weight trash cans of shredded leaves and shredded grass. The coffee grounds I weighted in a Rubbermaid container. The following year I had an good idea of what the ingredients weighted, and just went by eye, or went by trash can volume.

On the issue of adding versus not adding material, I have no steadfast rule. I try to mix up a large enough pile to retain heat on the first day. A four foot diameter pile two feet high is a nice size for piles containing mainly leaves as the 'brown'. Since I was informed one could not have ten small compost piles (there was not actually any limit on the number of piles in the regulations), I switched to a rectangular size for my two piles. Four or five feet by eight or nine feet long, two feet high.

If material is added after the pile is first constructed, it is usually fresh-cut grass, which breaks down quicker than most ingredients. If fruit/veggie wastes, or fish parts become available, they are added to the core (hot center part), IF THE CORE TEMP. IS 130F OR HIGHER.

The most overlooked factor often seems to be particle size of the ingredients. Smaller is better, at least until you get down to fine sawdust size, which may cut off air if the pile is too large. Browns consisting of sawdust, shredded leaves and large wood chips would not compost at the same rate.

The perfect compost is half bagged browned bought from a store like home depot. Half starbucks coffee, but then you add all your table scraps and leaves and clipping also. It does not matter how much of the other things you ad as long as the bagged browns and coffee stay at equal portions. And you want enough of the coffee and bagged browns to create a medium and that surrounds the things you are breaking down. Also you need the bin to be at least half full to get the hottest results. Low volume will not get very hot or maybe not hot at all. Lawn clipping are ok, if you have them, but have to be mixed up or they just get matted together and don't work very well. Leaves that are mixed up, will breakdown fast. Once it is broken down, I use it as soon as possible, but I mix it with native soil when I am planting. If you allow it to just sit there, it will decrease in volume. I have never had a problem with it burning anything. But, straight coffee grounds will burn the plants. I can get compost every two weeks if I want it, but if I get lazy about adding the coffee and browns it takes longer. It could take a month or even a few months if I am not adding the coffee before I can take some compost from the bin. I put the unfinished compost back, so some sorting is involved.

Tropical: what do you mean by "bagged browns"? The only browns I can think of that are sold at Home Depot would be some sort of wood mulch. That would work fine, I'm just curious exactly what you're using.

I've used pine wood chips that are sold in square bales as horse bedding, because I found broken bags in the dumpster. :-] I'm too cheap to pay for browns.