I realized that I'll need a lot of loads processed thru this tumbler to do my desired flower and garden beds to any significant depth of compost. All I got to do was a sprinking over the first bed, where I had hoped to add and till in several inches of compost. I learned a lot fast!

I'm now trying to get 'er going to see how fast I can reasonably get a batch of leaves, coffee grounds, and some lawn fertilizer hot-composted thru a reasonable cool-down period. And then perhaps to "finish" the batch in a trash can composter, or simply in the vegetable bed that I hope to plant Sugar Snap peas in early next spring.

I've been cranking the tumbler about 5 rotations a day, and taking some temperature measurements using an IR thermometer to gauge progress. Anyone aware of any "serious" compost tumbler operators and/or groups?

Jim Marconnet

Multi-tumbler

Medium sized tumbler

45 gallon drum tumbler

The first drum on the multi finally rusted through this fall so it is down to two drums. I have replacements but I've been too busy to get them up and running on the frame.

I like the tumblers for what I use them for (kitchen waste) but the bulk of my yard trimming composting is done in windrows.

Lloyd

I appreciate the feedback received so far.

The one main thing I'm coming out of this with so far is a strategy for when to turn the tumbler. The seemingly best (and why it works) strategy that I've read about so far is:

"Monitor Temperature

If you are using a hot composting method:
Turn if the pile is less than 100�F
Turn if the pile is more than 150�F

Why? Because the Thermophilic bacteria prefer temperatures in the 105-140�F range, and these microbes are the fastest at converting raw materials to compost.

If the compost pile exceeds 155�F, or so, it may be too hot for the bacteria population to thrive. At higher temperatures the heat may actually kill off part of the bacteria population. If this happens, the temperatures will fall off, and then the populations will slowly rebuild."

I was (and still am using) an IR thermometer to take daily temperature measurements of the tumbler surroundings, the bin exterior, and the top surface of the bin contents.

Yesterday I dug out a multimeter I own with a thermocouple. Stuck the thermocouple to a stick, and have taken some middle of the tumbler contents temperature measurements. Those readings are harder to get, but it makes sense to do it because the center is clearly the hottest place.

Starting today, I plan to only crank the tumbler using those 100 to 150 degree control set points. That should get and keep the center of the tumbler on average hotter. But getting all the tumbler contents done at the same time will still require some cranking to move the materials around and hopefully mixed into the center. We'll see what the eventual temperature data tells me. Hopefully not all this data recording will be needed in the long-term for FAST composting with minimal effort expended. By correlating external and middle of the tumbler measurements, I may well be able to just shoot the IR temperature of the outside of the bin and thereby know when to crank it.

Jim

I used my tumbler for two years. Then I switched to composting with mesh bins; first a round 4 foot diameter size, now 4'x8'x2' high bins. The tumbler was just too much work for the return in terms of time and effort.

Jim

But your temperature idea, dangit Jim. It makes so much sense.
Now my brain is generating plans for wiring in a temp sensor for the middle of the mega drum. Hooked to a simple (!) logic circuit that tells a motor to turn for a couple of minutes "If the temp is below 100 or above 150" and then wait for a couple hours before caring about the temp again.

I am cursed with the combo of lazy body and imaginative brain.

I think just hanging the whole shebang from a tree or frame would do. And then rig a belt to go to a dryer motor or something.

Dag nabbit. Like I needed another project...
(but hey, this puppy should digest like crazy)

8-)
Rick

Anyone have a convenient list of what to use and to not use materials-wise for 14 day tumbler hot compost?

The 14 day compost articles I've found so far seem to stop at C:N ratio and ignore how fast different materials can decompose. I guess they just want to sell expensive tumblers.

Jim

Old discussion here.

Leaves are one of the best if not the best material for composting. Lots of various micro-nutrients, I've posted links to analysis and could probably dig them up again if anyone wants the data.

Lloyd

:-(

Lloyd

Thanks for the link to that thread with the great photos and description of your process. Given that you measure temperatures, do you turn your tumbler every day, or use some other system to decide when to turn it? Do you add more nitrogen while in process if the temperature does not go as high as you want, or as long as you want?

And do you consider the mostly completed compost to be mostly completed and therefore ready to be moved somewhere else to finish, based on temperature, looking less like shredded leaves and more like compost, the 14 day calendar, the smell, what?

Thanks!
Jim Marconnet

If I remember and if I'm around (not at work). Sometimes it will get tumbled twice a day, sometimes I miss a day or three.

"Do you add more nitrogen while in process if the temperature does not go as high as you want, or as long as you want?"

I have added more clippings but normally I don't. I've been pretty good at getting a decent mix right off the get go (except when I tried using wheat straw as the exclusive C, that was a disaster and I hang my head in shame). After three to five(ish) days I often top up the tumbler with appropriately mixed materials due to settling.

I empty the tumblers primarily based on temperatures. Once I can no longer sustain around 105 or more, I empty them and start a new batch. The contents go into the curing bin for further curing (hence the name of the bin). This can be weeks to months depending on season and if I don't have a use for the material.

Keep in mind these are all guidelines and not carved in stone. I've emptied a tumbler at 120F just because I had some really nice grass clippings and no empty tumbler. I always have shredded leaves available.

Lloyd

Thanks, also for your specific answers to my questions. From reading about and from you, I now understand the scope of your operation and can see how you are using appropriate technology for different purposes. IE using your massive motor-driven tumblers for hot-composting kitchen scraps where vermin would otherwise be a problem. Windrows for mass quantities of benign materials. Makes sense to me.

My interests and needs are much more limited and specific due to my subdivision location in North Alabama, rather than a wheat farm in Canada.

Thanks again!
Jim Marconnet