Leaving the advice from manufacturers of the compost tumblers alone about making compost in their equipment in 14 days the link below from Pennsylvania State University and based on information from the Rodale Institute says you can make compost in 14 days.
The best way to see if this is accurate is to follow the directions and make some compost.

Here is a link that might be useful: Compost in 14 days

This is one of those debates that I've never gotten too excited about. Even if I could make mature compost in 14 days, I don't have enough time to allow for the continuous turnover.

There's housework, gardening and canning to do, not to mention what life throws at you in the meantime.

I suppose if you checked the pile every 14 days and sifted it, you might have a few handfuls of compost in the middle of the pile but is it worth the time?

I think 'mature compost' is the key words here and how important it is to the individual. For me personally the question is 'how much time do I want to spend on my compost'? It's going to happen no matter what but do I really want to devote myself to it? Ummmm....no.

Val
IALBTC

I am all in favor of debunking tumblers. I don't think you can get 14 compost in a tumbler. Daily turning is too much turning. The ground contact is very helpful. I don't think I could get two week compost in a tumblers. The drainage to the ground helps to achieve the ideal moisture ratio. Tumblers have bad drainage and would be counter productive two week compost. Take a fruit that you can ID in the hot bin, it is actually gone with in week. It will not look like a piece of fruit anymore. But, I also precook fruits by microwaving them. I just turn the top layer when I add new items, but I do this maybe a couple of times a day and add fresh woody browns and also starbucks coffee. The starbucks is critical to two week compost. It can be done, but not in a tumbler. One does not put fruits in a tumbler and turn it and then magically get compost in two weeks. You can get usable compost in two weeks, but not necessarily if you are starting a new batch. It takes time for a new batch to develop heat. If you have a big hot bin which you tend a bit daily, then turn completely once or twice in the two weeks, you will have no problem harvesting quite a bit of compost in two weeks.

I am all in favor of debunking tumblers. I don't think you can get 14 compost in a tumbler. Daily turning is too much turning. The ground contact is very helpful. I don't think I could get two week compost in a tumblers. The drainage to the ground helps to achieve the ideal moisture ratio. Tumblers have bad drainage and would be counter productive two week compost. Take a fruit that you can ID in the hot bin, it is actually gone with in week. It will not look like a piece of fruit anymore. But, I also precook fruits by microwaving them. I just turn the top layer when I add new items, but I do this maybe a couple of times a day and add fresh woody browns and also starbucks coffee. The starbucks is critical to two week compost. It can be done, but not in a tumbler. One does not put fruits in a tumbler and turn it and then magically get compost in two weeks. You can get usable compost in two weeks, but not necessarily if you are starting a new batch. It takes time for a new batch to develop heat. If you have a big hot bin which you tend a bit daily, then turn completely once or twice in the two weeks, you will have no problem harvesting quite a bit of compost in two weeks.

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>You can get usable compost in two weeks, but not necessarily if you are starting a new batch.Then it's more than two weeks. It still requires a prior investment of time and energy. In the end, total cost, time & energy, is more than two or three weeks.

I'm afraid I'm not sold on that qualification.

to sense
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WRT the How to Make Compost link provided by Kimmsr, I have to admit I have never made compost quite that way - 2./3 shredded leaves and 1/3 grass clippings plus some kitchen scraps; then turning every two days twice and then every three days after.

I suspect that it would cook rather quickly. Once, when the planets lined up, I got a fresh batch of 17 cu ft to cook down in two months with some frequent turning. As I recall it was a lot of grass clippings and reduced in volume significantly.

Maybe one of these days when I have two weeks and 34 cu ft of material handy I'll give it a try. 34 cu ft of shredded leaves and grass clippings wouldn't be that heavy to turn that frequently. It would be interesting to see how much of that 34 cu ft remains in the end.

In the meantime, I guess I'll just continue digesting kitchen scraps and yard waste in a slow, low energy manner and what ever I get, whenever I get it, will go into the garden.

Thanks for the link.
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pt03, In the lab I think they made 14 day compost, that was not totally finished, but so finely ground that it looked finished. That is the grain of sand the legend came from.
A lot of small scale lab work does not work in the large scale world.
I pick up wet chaff that was a day old & going though a heat.
With in 7 days I was spreading it around vegetables & watering it in. There was not unfinished or chunks parts of any organic matter, just soup.
But the bags that I left siting in the field untouched were 48" tall X 48" wide X 96" long. Left alone for months, it become 48" X 12" X 96", so why the shrinkage if it was finished in 7 days when I open one bag & not the other?
It must be because it was not finished in 7 days, but so finely ground that it turn to soup & melted into the soil.
This soup did not hurt the plants, it made them grow, but the volume chance says that the 7 day chaff was unfinished.

If anyone were to do a respiration test on their 14 day compost, it would fail. I'm willing to bet money on this.

Lloyd

Just a note leaves are very slow. One would have to compost only fast composting items, use coffee ground and woody browns. But, I like to harvest often because I like to have some always on hand. No matter how much I make it is never enough, and I don't always have finished compost on hand. Just coffee and woody browns together are very fast.

Some time ago, I flew across the Atlantic headed to FAO headquarters in Rome, sitting beside an expert in composting pig manure. He was off to set up a pig manure composting system in Thailand, where the wet matter was mixed with rice chaff, put in a semi-sealed, lengthy auger, which turned, mixed, and aerated the stuff, and three days later, out the other end came sterile, complete compost.

/ I want one too.

From what I've seen, Lloyd had the equipment to attempt an experiment. Those barrel tumblers you have look like the thing.

If a person can get some good, fresh grass clippings (freshly mowed grass get hot fast) from a source that is known not to have used herbicides, and has some preferably finely shredded leaves at the ready, then a compost drag race can be attempted. When I have been fertilizing and watering my grass, the clippings are practically flammable when they are freshly mowed.

The catch is that the compost would have to be turned as very particular moments. From what I have read, when the temperature exceeds something like 150, it needs to be turned to cool it off.

I have the feedstocks, but I would need to build a large tumbler. I'm not going to try to turn two cubic yards of compost by hand every other day. Well, maybe.

When the compost looks done, and is no longer heating up after turning, the testing can start. Clearly, the best test is the seed sprouting test. Start testing every other day until the seeds sprout equally well in the control pots and the compost mix pots.

People at the Rodale Institute, Cornell, and Michigan State University have all made good, finished compost in 14 days. It is a lot of work and it can be done.

I did mention you must tend it daily, at least mixing the top layer and two complete turnings during the two week period. You must have coffee grounds in large amounts. You must have woody browns. Shredded paper and leaves will slow it down. You must precook the fruits and vegetates use a blender food processor. But, doing all of this and get the temp up to at least 140, you can not fail to make compost in 14 days. So, try it, it will work, and it if doesn't I can dx why it did not work.

kimmsr, tropical_thought, I want to clarify a point. Do the both of you assert that a person can take this 14 day compost and immediately use it as a soil amendment? Do you claim to be able to sprout seeds in a mix of 14 day compost and soil?

I think a few people are using an extremely loose definition of finished compost.

Lloyd

P.S. I think one person is off their rocker.

I did make compost that way years ago when much younger and found it to be as good as anything made in a more conventional way. I understand there are those that believe compost needs to "cure" for somewhere between 6 months to 2 years before use and that is not necessary.
I never tried starting seeds in the 14 day compost I made so I cannot say whether that can be done.

I would not use it sprouting seeds. I would use it as a top dressing. I like to mix with bagged browns. I like to use it as amendment mix with native soil. I have already stated these points before, but I don't think you are reading carefully if you have to ask this again. The only thing I have not stated earlier is I don't use to sprout seeds. But, it is not that big a deal to make the compost finish in two weeks, but it is possible. That is my only point.

It is not impossible. But, you have to follow guidelines which I already also mentioned. You can not just throw a few fruits rinds in a bin and open it in two weeks and find finished compost.

This is a case of some people who as soon as they put any kind of ingredients together in a bin call it "compost", and others know that "mature compost" is something entirely different. I'm gonna believe some experts myself.

Lloyd

P.S. There are many more experts out there that say the same thing.

Here is a link that might be useful: More experts

I never said it would be mature compost, but it is usable compost. The best part is I get more compost that way. If I wait for it to "mature" I get less of it. I know it continues to mature once it is the ground and used. My soil really needs a lot of compost. If I don't apply it once a month the soil begins to harden up again.

If that is your criteria, skip the composting altogether. Just mix shredded leaves, fresh grass clippings and UCGs together and till it into your soil.

Lloyd

TT, I think your usable immature compost is much better then the raw compostables that you started with.The balance of your soil should not chance enough for you to see a chance in the plant growth, IMO. This is what my 7 day chaff probably did.
I have not use unfinished chaff/coffee waste compost in 4 years. But that one year I did,I had a great garden. I do have some compost that is 7 months old, the rest is 24 months old.

I don't have a vegetation shredder, and I like to compost. If I bypassed the bins it would not be fun anymore. I like to look in and see how it is decaying. I got a paper shredder recently, but adding the shredded brown paper bags is slowing me down. I can't get more then 100 degrees anymore. So, I am not making two week compost any more.

Two weeks ????
That is way too long for compost in my bins, I just toss the stuff into the bins , wait a week and toss it onto my beds , VIOLA... finished compost ;-)

I rest my case, the longer you wait the less you get.

14 day compost you say? I dont think a tumbler is the solution. You would need a 2 sided barrel with screen covering each end. Attach a large fan from an old air handler or one of those moon jump inflation fans to a duct feeding to one end of the barrel providing a constant oxygen supply to the mulch and introduce a hefty batch of frothing compost tea and I bet you could compost alot faster than 14 days. If you really want to get crazy scratch the first idea all together and use a tumbler with an oxygen tank pumping a continuous fresh supply of oxygen into your compost. This of course is impractical but very possible.

My post was just a joke, I do get fast compost, fast, is relative,I would guess that it takes me 4 months, I don't use compost except once per year, so , though it cooks fast and I keep it turned, it just waits to be used, this year I decided that since all of my beds were filled and already topped off, I would go ahead and plant in the compost bins, I got lots of Butternut, Cantaloupes and Watermelons.... Yeah Babyyyyy

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Isn't that a steam shovel, I see?

Hi TT,
If it wasn't for that excavator, I would be a "slow" composter, it is wayyyy too much work to move around that much compost ;-)

John, did you rent that excavator or do you own it? I have been confused for a while now, buy an excavator, or rent one from an equipment rental. I am on about 10 acres.

nick, I think John owns a construction company & the excavator also.

OK, here goes my two cents worth.
I tried an experiment this past January since my grow boxes were idle and I was curious. I took my compost I made in a tumbler using about 2/3 shredded leaves and 1/3 fresh grass. That was the basis but I added a small amount of horse manure and some fish imulsion. I turned this mixture regularly, reached a temp of 155 for close to a week, then it cooled slowly over the next week, and was left in the tumbler for about two more weeks. It looked great, was very crumbly, smelled good, seemed perfect to me.
My experiment was this. I started seeds (all the same seed was used) in 6 packs in my controlled environment grow boxes.
1 My compost 1oo% #2 Commercial compost. #3 6 year old cow manure #4 a pile of 6 to 8 year old shredded pine needles. #5 Compost from the town digester which was three years old. #6 Crushed pine bark about 6 to 8 years old.
I did not "Finish" my compost as Lloyd later informed me I should have, I merely put the compost in a 1.5 cu ft plastic bag and stored it there for future use.
My results really shocked me. My compost did the worst job of growing the plants out of all the different material I tried. The plants germinated ok, but never would grow Even the pure rotted pine needles did a better job of growing the seedlings. I'm convinced at this point Lloyd is absolutely correct, in that compost MUST be allowed to finish, and in the open air, not a plastic bag.

Wow. Actual data! :-D

Dang it!
Now I have to hate John as well as LLoyd! Why doesn't my wife buy ME an excavator/ tractor/ biga** tumblers for my birthday and Xmas?

oh and btw. I am on Lloyd's team for this one. I can't see finished compost happening in 14 days..... I cans ee a type of compost usable to amend my clay soil which I would plant in 6 months later maybe, but not finished compost.

I have 'repaired' most of the backyard flower gardens at our rented house over the last 3 years (and spent 2 years ripping out the 200' of ivy in those beds before that). In those beds I used a 1/2-2/3 sort of finished compost + other amendments and the results are fine. The partial compost has given the beds some body and have continued to rot down and helped the soil structure. I can now use my finished compost to dig into the flower beds each year. My soil is 1000% better then when we moved in and now my wife has happy spring-fall days sitting looking at her flowers.

But 'finished' in 14 days........ nopers.

Tropical, is your soil the usual 99.9% sand that seems to be all they have in SF? My wife's brother lives in the outer sunset and they keep asking me why they can't grow anything..

Get some clay from the east bay (check craigslist under FREE) and then you can put a bit of body into your sand! Then keep piling in the compost

You want to make sand better?

Look up Greening The Desert. They convert desert sand into a farm that can grow fungi in the middle of a dry dead desert.

How? pigeon manure! ;)

Thanks for the data ken.
I am not surprised that your seeds did not do good.
I do not use 7,14 or even 30 day compost most of the time.
But in my case it would not matter, because I would till it in, not grow seeds in it.
I have tilled in raw grass clippings & whole leaves & found no trace in 80-90 days.
I do not think anyone pushing the 14 day compost really believe it is finished.
This is just a way to make beginners think it is easy, so they will start composting.
Much the way new concepts in raised beds seem easier to beginners, because they do not have to double dig.
Do not misunderstand many full time, hardcore gardener use these concepts too. But they would use them if they were harder, but better for them. Not everyone is that committed to raising their on food.

Cornell Composting
Glossary of Composting Terms

'Curing - the last stage of composting that occurs after much of the readily metabolized material has been decomposed. Provides for additional stabilization and reduction of pathogens and allows further decomposition of cellulose and lignin.'

'Mature Compost - the stabilized and sanitized product of composting; it has undergone decomposition and is in the process of stabilization. It is characterized as containing readily available forms of plant nutrients; it is low in phytotoxic acids.'

University of Vermont
Office of Sustainability
"How long does it take a batch of compost to cure fully?"
"Typically, in a conventional "windrow composting" method, the process of mixing, pile building, active phase composting, curing and finishing could take 6 - 9 months."

Cornell Composting
Frequently Asked Questions
by Nancy Trautmann and Tom Richard
'Under optimum conditions, thermophilic composting with frequent mixing or turning can produce useable compost within a month or two. A worm bin requires three to six months to turn food scraps to compost, and an unmanaged leaf pile may take more than a year to break down.

In general, it is best to let compost "cure" for several months even after it appears finished. During this additional time, degradation occurs at a slower rate, resulting in a more chemically stable end product.'

I use hot composting in my mesh bins when ingredients permit, with core temps from 130F to 160F at times. It still takes three or four months until I feel the compost is ready for use.

My one book devoted to composting "Easy Compost" Brooklyn Botanic Garden, suggests at least a 30 day curing/cooling off/whatever you want to call it period.