Ambient air temperatures do kind of influence the bacterial activity in compost but more is the ratio of Carbon to Nitrogen, the amount of moisture, and the amount of air in the mix. Bacterial activity is what causes the heat generation in compost and if they are happy and at work they will generate heat.
I have had very active compost piles with ambient air temperatures much lower then what you have had.

OAT is a huge factor in tumbler operations.

Lloyd

Lloyd, by OAT, I assume that you mean Outside Ambient Temperature.

I've been taking some concrete surface temperatures below the tumbler with an IR thermometer to have a measure of the average temperature below the tumbler. That temperature has not varied terrifically over time. The other extreme temperature, which I've not bothered to measure, is the temperature in outer space. That's affected by the cloud cover, or lack thereof. It's Cold out there year-round!

I've also been taking tumbler surface temperatures of the East sides of both bin chambers in a repeated location with that IR thermometer. The outside tumbler surface temperature has always been higher than the concrete temperature until very recently. Clearly the tumbler contents insulate the much higher core temperatures from the compost surface temperature.

Eventually I hope to find just a few easy temperature measurements which I can take daily or even less frequently to monitor the tumbler operation and to control it with tumbling, added water, and added nitrogen fertilizer, if necessary, to get the compost where I'm trying to get it: hot and fast. Yes, actually I am a Rocket Scientist! I'm trying hard to avoid adding any organic matter after the batch is initially filled, to avoid restarting the 14 day compost clock.

So far, I'm learning and collecting some temperature data and doing some Excel scatter plots. But I'm no where close to doing 14 day compost with my existing equipment and compost inputs in my North Alabama winter environment!

Jim Marconnet

Sorry, Outside Air Temperature.

If the skin of the tumbler is higher than the OAT then the tumbler is losing heat to the air. If one loses more heat than can be generated, a tumbler will eventually cool to ambient. A tumbler is way different than a pile because there is no insulation effect from the ground.

Lloyd

Thanks for the inputs. It looks like my tumbler is cooling quickly to ambient. Like in a day or two. Not a week or so like I was expecting.

And so far it looks like there IS "some ambient temperature below which the tumbler contents simply won't heat up regardless how much nitrogen fertilizer I add. " And I seem to currently be below that average temperature, whatever it is!

So I guess I wait impatiently or patiently for a warmup.

Jim

Also important is total mass. The smaller the mass, the more rapidly it will cool. I.E. larger masses cool more slowly.

Heat moves from high to low, so the heat generated by the bacteria digesting the material you are composting is going to move to the air around the tumbler. Since the tumbler is much more exposed to much more air that heat loss can be significant. Volume, mass, can help inhibit heat loss since some of the mass would act as insulation, slowing heat loss to the atmosphere, ambiant air.
Water is a very good heat sink, much better then air, so the more water, moisture, in the mix (which also excludes air the bacteria need) to quicker heat is lost, but no necessarily to the air.
The larger the surface area exposed to the atmosphere the more heat you will lose, faster. However tumbler manufacturers appear to indicate you can still make compost in their tumblers in the winter.

I gotten a suggestion to add sugared Coke and some beer to my tumbler to encourage the little tiny beasties! I certainly can try that, since nothing else is working for me right now out there in the cold. Coke I have. While I'm waiting for my son to find some really cheap beer, I've been reading more online about composting.

One thing I read about is proper moisture. You know, the barely moist sponge thing. Ug! I've noticed lately that when I first crank my tumbler, some water comes out from the several places where water normally comes out if I add a lot of water to the tumbler. Soooooo I'm wondering if as the compost shrunk to about 1/2 it's original volume, whether perhaps the water which was in there stayed there, and it got too wet. That could eliminate air spaces needed for aeration, and it could make heat conduction from the core out to the tumbler exterior too fast, allowing any generated heated to escape too fast to maintain the hot temperatures that I'm trying for.

Anyway, now I'm considering how to dry it out some without adding anything like shredded newspaper - AFAIK, that would restart the 14 day composting clock, something to avoid at all costs!

Jim

Yes, I'm devising a way to dry out my tumbler.

But I'm also thinking of adding thin weatherstripping to the doors and possibly adding Saran Quick Covers (like cute little shower caps!) to seal off the screened vents to reduce airflow thru the tumbler and thereby keep more of the heat inside.

Anyone done similar and/or had results to share?

Oops, when looking for a link to share, I found out that Saran no longer makes or sells the Quick Covers. I guess they were too handy a product and/or did not wear out fast enough. I'll have to hoard the package that I have on hand!

Jim

If sufficient moisture was in the mix at the start it would be used by the bacteria as they digest the solid material and would not increase in quantity. Moisture leaking out of a tumbler is one really good indication the material in that tumbler is too wet to compost properly.
Several studies I have seen indicate that adding sources of sugars, sodas or beers, really do little and often the added moisture is more detrimental then beneficial.

I purchased a tumbler eight years ago, trying for the 14 day compost. It took me a few years to understand that hot composting is but one stage (and the shortest) in the composting process. 'Hot' composting is the 'sexy' part because one can see the results, steam, shrinkage, and high core temp. But the other stage (mesophilic) is just as important in the finished compost product.

Now I shoot for 130-145F hot stage, followed by a several month mesophilic stage where bacteria growth falls and fungi growth rises. My bins are either 4' diameter and 2-3 feet high; or 4'deep by 8'long by 2' high.

If you do a external (to GW) Search 'stages of composting', you will find a number of short articles along these lines. This is in comparison to composting advertising products giving you compost within a short time.

Cornell recommends a long curing time, one year in one of their publications. My book, "Easy Compost" recommends a 30 day min. aging period. My average compost time, with a hot start, is about 4-6 months.

Yep! Searching on Stages of Composting brought up a lot of new articles that I had not seen specifically before. Thanks!

What I've been trying to do this fall/winter is to find/use a technique with my two-sided tumbler to hot-compost the leaves that I have on hand quickly so I can process several batch loads over the winter in order to have a substantial amount of at least partially-processed compost for my flower and vegetable beds (Alabama Red CLAY!) starting in the early spring. Hopefully in time to start out with raising Sugar Snap Peas. And to have some fun along the way, and perhaps even to meet some fun and knowledgeable gardeners and composters and Worm folks along the way. Finding such folks locally would be a plus!

And to stay out of smell, pests, vermin, and other problems with my HomeOwner's Association, not to mention my nearby neighbors, or my allergic wife!

I've realized in my reading, doing, and taking measurements, that there are a lot of variables, a lot of wishful thinking and advertising for expensive equipment and supplies, a lot of opinions, and no one single best meeting place or useful information storage bin for Mantis ComposT-Twin owner/operators, or even for tumbler operators in general. It all depends!

So now my ComposT-Twin sits full of shredded leaves and stuff, cold, wet, and either right where one would expect it to be after this much time and effort and additions, or perhaps not. And I don't know which is correct, or where to go from here....

You cannot believe everything that you find on the internet - Abraham Lincoln

I think that I may have a plan. I really want to start a new batch of compost, but my tumbler is basically full on both sides, ignoring the partial settling, and is sitting at about the average ambient temperature, which I've read must be 50 degrees F or above for hot composting to occur. To wait or to start a new batch now? Both!

It occurred to me that I can use my Toro blower/vacuum/metal impeller shredder to suck out the compost from one side, chopping it up some in the process, into a wheelbarrow or similar. Then suck out the compost in the other side, and dump it into the empty first side. Then suck up the compost from the wheelbarrow into the first side, at least till it's really full. The second side is then empty, perhaps with some amount of compost in it for providing initial bacteria and such, available for starting a brand new batch!

This will definitely be some work. And it will give the Toro catch bag a definite wet earthy smell! But it should chop up some of the roots that I found still intact in the left side of the tumbler. I can then crank and monitor the temperatures on both sides at once.

I can have my cake and eat it too! Figuratively, that is!

Jim

I got delayed a bit on my latest plan. Rainy weather, and now my Mom is coming in from out of town. Both tumbler sides are warming up just a few degrees F a day. I suppose that tells me that I'd need to add a lot more Nitrogen if I want them to heat up fast at my current ambient temperature? I bought a 50 Lb. bag of Urea, but I was waiting to open it till I started the next batch.

I'm not tumbling it lately, but I would need to do so if I added the urea, to mix it up and in. Clearly tumbling lowers the core temperature lately.

Suggestions, anyone?

Jim

Jim, at the risk of the pot calling the kettle black, I think you are overworking this. Composting is a matter of getting three basic things (C:N ratio, moisture and air) in the correct range and then letting time handle the rest.

An analogy of my impression of what you are doing is lighting some barbecue briquettes and then continuously throwing lighter fluid on just to see the flames. I'm not sure it is productive in the big scheme of things.

Having said that, I've done my share of fiddling and manipulating so I'm being kind of hypocritical here.

Lloyd

Thanks, Lloyd, I'll bet that you made several or many people Smile!

I did some searching, now that I know some suitable search terms, and your name came up a lot! I noticed that over the past 5 years or so, you were always here helping people out. You never ever had any needs or questions yourself, except asking for more info in order to help others. Thanks for all that help and thereby recorded for posterity info, links, and experiences.

Thanks!
Jim

I don't know how big the tumbler is, but my gut feeling is that 14 lb of 29% N fertilizer is a *lot* of N. Just saying.

From the Mantis web page "The Mantis ComposT-Twin dual-chamber composter holds almost 25 cubic feet of raw material" that's 10 bushels in each chamber!"

14 lbs X .29 is 4.06 lbs total Nitrogen that I added using just the lawn fertilizer.

Compost density - Who knows? Assume it's 30% water, and the organic matter weighs almost nothing. The tumbler is now about half full, now that it settled about 50%. Water weighs 62.42 pounds/cubic foot. 62.42 X .3 X 25 X .5 is 234 lbs of compost, before the N was added. That means that I added 1.735% Nitrogen by weight. Or a 57.6:1 C:N ratio, ignoring any N from the Starbucks Coffee grounds I added much earlier.

So from this simple math, my addition of the fertilizer does not seem to me to be out of line at all. In fact, had I done this calculation earlier, I ought to have added twice the fertilizer than I added!

Thanks for indirectly suggesting that I do this simple math as a double-check on my "ongoing experiment".

Jim

Since the core temperature was only rising slowly, perhaps a degree F or two a day, today I added 4 lbs total of Urea. I've yet to do the math on that, but mentally I'm not out of line with this addition, since it's about twice as strong as the lawn fertilizer.

Here is a link that might be useful: Mantis ComposT-Twin page

A few days ago I shoveled the left half of my composT-Twin into the right side and started a brand new batch in the left side. 1/3 Starbucks UCG, and 2/3 shredded newspaper and corrugated cardboard. In two days, I have no warming so far in either side, despite ambient temperatures up into the low 60s. I'm beginning to think that I need warmer ambient temperatures than this to start things warming up, regardless of the mix and whether I added N or not.

I'm still collecting the temperature data daily, now on 30-day old compost, and a brand new batch, both now subjected to the same ambient temperature and turning or no turning. The data should be interesting!

Jim

If your aim is to grow snap peas?? One year, I dug a trench where I was going to grow my peas. Over the winter, I filled the trench with kitchen waste then covered it with soil. Early in the spring, I planted peas in it. I have NEVER had such a crop!! Plants grew enormously and they were covered with sweet, lovely snap peas. I'm trying this again this winter where my bean trellis is and if lazyness doesn't get me, I'll do the pea row again.

Thanks dottyinduncan for sharing your experience and encouragement. Hopefully my compost past the hot-stage to be worked into the bed soon will perform similarly well.

Today on the third day of the new batch of compost, I recorded 95 degrees F temperatures. While the 30-day old batch is still at ambient temperature. So I'm guessing that my current ambient temperature in/around 60 degrees F is not too cold for the high-temperature phase to begin on a brand new batch. And that the 30-day old compost is probably completely past the hot-phase, despite my adding lawn fertilizer and even urea to try to get it hot again.

Now I see where my packages of Sugar Snap peas say to plant them from January to March in my zone. I'll need to get going with the compost on hand to meet that schedule!

Jim

What do we suppose is becoming of all that ammoniac N fert?

My composting in the the two sides of tumbler continues, slowly. But now the weather threatens to get much colder, so things may come to a halt. Who knows!

Jim