If compost is hot, should I turn it?

[grrlgeek]

Hi Everyone,

Perhaps some more experienced composters can advise me on this...

We pretty much gave up on the drum composter, and out of that frustration discovered that we did, in fact, have an out of the way spot on the side of the house that is exactly the right size for a real compost heap.

So far the results are encouraging but I'm a little worried about the temperature which as of today, hit 155F with the compost thermometer buried to the hilt. This reading repeats all over the pile, with it going as low as 152F about 4-6 inches down from the top.

We built it on Saturday last (4 days ago). It's 4'x4'x3' tall today. It was almost 4' tall when built. The location gets about 4 hours of morning sun then it is shaded the rest of the day. It's uncovered, but I am questioning the wisdom of that (flies).

We layered a repeating mix of ingredients and watered it along the way - lots of spoiled hay chopped up by the lawnmower (I don't know what kind), horse manure that's about 2-3 months from its departure from the horse, shredded cardboard and paper, straw, a lot of coffee grounds (I have discovered a local Starbuxx with virturally no limit on how many spent grounds I can acquire on a daily basis), kitchen scraps, lawnmower-chopped shrub trimmings, some dried maple leaves, not much grass since I saved that for mulch and I don't have much to begin with, some unfinishing compost same from the drum, and a sprinkling of local dirt.

For the airy layer on the bottom we used unchopped hay - just pulled apart the flakes - and some unchopped deaddried rosemary bramble, and some fresh bramble-style shrub trimmings. The top layer is a blanket of straw.

Moisture seems about that of the proverbial "wrung out sponge," but I didn't dig deep - just down about 4 inches or so.

If it gets to 160F I've read I should turn it to reduce the temperature - would you agree?

If it stays in the 140-159 band, should I turn it anyway - would that make things better/faster - or should I wait to turn it until the temp drops below "somenumber" ?

Did I do this right? Or did I put in too many greens?

All advice and admonitions welcome!

[rainbowgardener]

I don't know much about this kind of composting where you build a big pile all at once or about using manure in composting.

But as I was reading the list, I was thinking it sounded like a whole lot of intense greens:

- lots of spoiled hay chopped up by the lawnmower (I don't know what kind), horse manure that's about 2-3 months from its departure from the horse, shredded cardboard and paper, straw, a lot of coffee grounds (I have discovered a local Starbuxx with virturally no limit on how many spent grounds I can acquire on a daily basis), kitchen scraps, lawnmower-chopped shrub trimmings, some dried maple leaves, not much grass since I saved that for mulch and I don't have much to begin with, some unfinishing compost same from the drum, and a sprinkling of local dirt.

Green - spoiled hay, horse manure, coffee grounds, kitchen scraps, shrub trimmings, grass clippings

Brown - cardboard and paper, straw

Now obviously it depends on how much of what and the proportions, which you didn't give us any idea of. But especially with intense greens in there like coffee grounds and manure and grass/hay, you would want the browns to be more by volume than the greens.

[grrlgeek]

rainbowgardener,

Thanks for replying! I appreciate your insight and even if it's not your specialty. I've read so many of your posts that I'm sure, even flying blind, you're gonna be way better at this than me.

This is my first time making a pile all at once. Even as a kid, we just kept adding to one end of a long-ish mound and my mom would harvest the old stuff from the other end.

Around where I live there is a lot of horse property but most of my city lot is xeriscape, so without the cast-offs from the local ranches it would take years to accumulate and diversify materials that would net me more than a few buckets worth of compost. I found when I answered craigslist posts for "free manure" that they are usually hoping you show up with a tractor trailer and a backhoe. So I took as much as I could stomach, and the guy also gave me a two bales of horse hay from last year that he said had sat out and got wet over the winter. I figured since it was so old and dry, that would count as a brown, or at least a very low quality green. I bought the straw for mulch, but it keeps sprouting, so I demoted it to compost inputs.

Now obviously it depends on how much of what and the proportions, which you didn't give us any idea of. But especially with intense greens in there like coffee grounds and manure and grass/hay, you would want the browns to be more by volume than the greens.

I tried to have more browns than greens when making the layers: We used...

• about half a bale of hay, and almost a full bale of straw
  
  cardboard (brown shipping boxes) had been run through an office shredder and filled a 30 gallon trash can stuffed and stomped down to almost bursting.
  
  Coffee grounds filled a large laundry hamper.
  
  Half of a 5-gallon bucket of kitchen scraps and maybe half a lawnmower catch bag of grass clippings
  
  at least triple the scraps/grass volume in shredded office paper, newspaper, and assorted junk mail.
  
  I filled 3 lawnmower catch bags with a blend of leaves (from 2012) and dead rosemary bramble (oh!) and pine needles too, I counted all those as brown. The bramble was old growth, and quite dead, would that not be a brown? I counted it as such anyway.
  
  an 18-gallon tote filled with 2-3 month old manure.

I worried I might have overdone it on the greens, but aside from a non-offensive, barnyard-and-wet-straw kind of smell, I wasn't noticing any ammonia notes. The flies are another more pressing concern so I put a tarp on it today.

Anyway, it's still hot today - but not as hot. Readings all over the pile were between 145-152, down 4-5 degrees from yesterday. Now I am suspecting that yesterday was critical mass, or it may even have slowed because it got too hot? I'm going to water it a little bit today and keep monitoring the temp.

Still confused on where the temperature tipping points (high as well as low) should be to turn it. Or if I should turn it on a schedule, regardless of temp.

Thanks for your input!

[imafan26]

Lucky you, you got the pile up to temp that's how it is supposed to work! Once the pile gets up to temp (55-65 degrees Celcius (130-140 degrees Farenheit) and let it cook until the pile starts to cool off below 130 degrees and start to turn it. During the thermophillic stage it kills most of the weed seeds and bacteria. This can take weeks or months depending on the size of the pile, moisture content, C/N ratio, aeration, and particle size.

The more frequently you turn and aerate the pile, the faster it will break down. As long as you have the right moisture content it should not smell bad.

https://compost.css.cornell.edu/physics.html

I put too much greens in my pile and not enough browns, all I got was a slimy mess and the weeds kept growing in the pile. I also discovered that it helps to build the pile all in one day. Building it slowly, I eventually get compost but it is harder to get the the C/N ratio right and it ended up cold composting which takes a whole lot longer to do.

[grrlgeek]

imafan26,

Thanks for the encouragement as well as the link to that great Cornell article. I got a kick out of the link the article provided to a page of formulas for calculating the perfect mix of ingredients. A few too many symbols and letters to do math with this far beyond my college days though!

I am so pleased with the way this pile is going as compared to the drum that we tried first. This really is the best way to make compost.... for us anyway.... and especially right now when I need so much to get started filling these new beds. Temps were still 145-150F today, and it makes me hopeful that I will get some compost out of it to put in a bed in late November, and then I can make another big batch to cook during the winter.

Happy days~

Greetings,
Devon

[imafan26]

The formulas are for the researchers. Whatever you did to get the pile up to temp works. Compost should just happen.

Once the pile starts to cool, you should turn it as often as you can. The more it is turned the faster it makes compost.

One method recommends turning the compost everyday for the fastest result. But unless you really need the exercise, most people would consider turning the pile every 4-7 days a lot. With the let it rot method turning is done infrequently and it takes a year or more to finish.

The compost pile is probably the most efficient way to make compost. The barel composters are easy to turn but don't hold much, are hard to get up to temperature and you get very little compost in return.

I don't have a lot of browns so now I concentrate on worm composting and I am considering creating a keyhole garden sometime in the future. The compost bin is built into the garden, no turning required and it is water efficient. I just have to find the space for it.

In the meantime, since I have mostly green waste, I am worm composting, trench composting, tilling in residues, and using cover crops instead. When I do trim the few trees I have, it goes to green waste recycling. Besides palms are difficult to compost because they are hard to shred and can take up to two years to decompose. Just try putting a coconut husk in your pile and you will find out just how long that takes.

Composting is done at the garden where I volunteer. There we do vermicomposting, composting using commercial bin systems (cold composting) and there is a large composting area for composting all of the green waste produced on site. We did have a barrel composter but it never got hot enough and it was difficult to balance the browns and greens.

[rainbowgardener]

I pretty much agree with every thing imafan said, especially that an actual compost pile is the best way.

I would question this a little: ". With the let it rot method turning is done infrequently and it takes a year or more to finish."

Basically I do let it rot, cold composting. I only compost what comes from my garden and kitchen, so I never have a whole bunch at one time, and I just keep adding as stuff comes along, and turn rarely. I don't have much intense greens (manure, grass clippings), so it mostly doesn't heat up a whole lot. Sometimes if I skim duckweed off the pond and add it, the pile heats up pretty well for awhile.

But re it takes a year or more to finish, depends on the definition of finish. If you had a whole big pile and you wanted the whole pile finished, that might be so. I just keep adding stuff on top. I don't turn it, except every two-three months, I turn the pile over. That is I take all the stuff off the top down to the level where the earthworms are and move it to be the bottom of a new pile. What's left at the bottom is finished or nearly finished. Stirring it up and exposing it to the air, it finishes up quickly. So I can get more compost out of my pile within a couple months. Two months later I can get more, but what I will be harvesting at that point is the stuff that got moved from the previous pile, so it is certainly more than two months old. Since I have a small garden, I pretty much always have the compost I need.

[imafan26]

Yes, that is kinda what I meant. If the pile is turned and aerated more often (every couple of days) and the stuff on the outside is turned in more frequently, it will reheat the pile as the more undecomposed matter provides more food for the composting organisms. Usually if you are hot composting though, once the pile gets up to temperature you do not add anything more to that pile. The whole pile should finish about the same time that way. Very frequent turning in a hot pile shortens the finishing time. It also helped to use the lower C:N ratio materials. Food wastes and twigs decompose faster than hardwood chips, and coconut husks. We also covered the pile at the garden with burlap or cardboard mostly to retain moisture and heat and one of the piles has an air shaft to help aerate it.

With cold composting, people do tend to keep adding to the top and just sift out the compost from the bottom of the pile. It is a simple method, but it does not kill weed seeds, parasites or disease so you will need to make sure only clean material goes into the pile. It makes compost but will take a longer time to finish. Even a cold composted pile benefits if it is turned more frequently and the source material is chipped into small pieces.

https://extension.oregonstate.edu/lincol ... _ratio.pdf

https://deepgreenpermaculture.com/diy-in ... n-18-days/

[toxcrusadr]

I too would recommend not fretting too much about the temp.

If it's hotter than really necessary and you have some browns, turn it right then and incorporate some more browns. It will cool a bit and maybe you'll get a bit better compost (and a bit more).

But you'll still get good compost here if you do nothing or turn it when you feel like it. I've made piles overloaded with grass clippings that got up to 180F, and guess what, it turned into compost!

[imafan26]

Although I have never heard of it happening with a home pile. Mainly because home piles don't usually get that hot, compost can spontaneously combust if it gets too hot. There have been a few fires at the composting facility which is located in one of the hottest spots on the island.

The fire department said the piles were too high, and not turned frequently enough and not enough water to cool them off.

I don't think it is necessary to add more browns. Wouldn't that be like adding more fuel? I would think just turning frequently and keeping the moisture balanced would be enough. Every time the pile is turned, the undecomposed matter (fuel) is turned in. The pile's temperature will spike again but it should not reach the same peak and over time as the fuel is spent, the turning will bring the temp down faster.

[rainbowgardener]

I don't think it is necessary to add more browns. Wouldn't that be like adding more fuel?

Not really. The greens are the fuel. Adding browns helps slow it down.

[imafan26]

I see your point. Browns take longer to breakdown and it would slow the process. Greens are full of nitrogen and moisture and nitrogen is needed by the bacteria to do the work of breaking down the browns.

[toxcrusadr]

It's not unheard of for a residential pile to spontaneously combust, but 9 out of 10 incidents are at large commercial or municipal piles. However, it's reason #47 not to put the compost pile right up against the house.

[ElizabethB]

Sounds like you have a great compost pile going. Greens really get a pile cooking. Add more brown. Manure can be brown or a green. If it is well aged, very dry manure it will work as a brown. It is not well aged it is a green. A little early for mulched leaves. If you are concerned - toss. No harm done. Your core temperature is not at a point of concern of spontaneous combustion. With such great cooking I would toss just to get the rest of the pile cooking.

I quit fussing over my compost. I toss it when I feel like it and add water when we have a really dry spell. It either cooks or it does not. Regardless of what I do I usually have a couple of cubic yards of nice compost spring and fall.

[evtubbergh]

Sounds like you have a great compost pile going. Greens really get a pile cooking. Add more brown. Manure can be brown or a green. If it is well aged, very dry manure it will work as a brown. It is not well aged it is a green. A little early for mulched leaves. If you are concerned - toss. No harm done. Your core temperature is not at a point of concern of spontaneous combustion. With such great cooking I would toss just to get the rest of the pile cooking.

I quit fussing over my compost. I toss it when I feel like it and add water when we have a really dry spell. It either cooks or it does not. Regardless of what I do I usually have a couple of cubic yards of nice compost spring and fall.

+1 We just toss it in and let it rot. We toss it a bit when we're out there and w water it when dry. Otherwise we don't over think it. It turns out great. I agree with everything up there so I won't repeat.

[estorms]

There are no compost police. If you keep it outside in a pile, it's really hard to get it wrong. I put what I have on when I have it. In the fall, I layer it up with leaves. Every little bit you compost stays out of a landfill and enriches your garden.

[grrlgeek]

I thought I'd dredge up this topic that I started last fall to give an update and thank everyone again for their input.

I tend to like to know how everything works, and then how to be as efficient as possible doing it within the rules of the game. It's hard for me to sit on my hands and wait a year for a pile of compost, even though I do know full well that it will rot, and it will be good stuff when that happens. And your reassurances helped a lot!

But at the same time, as a mere fledgling in this adventure, nearly every (always excellent) piece of advice about how to obtain success begins with, you guessed it, compost! And the stuff they sell around here looks more like bark mulch, which is nice if you like mulch, but I need compost and I need lots of it. So, I know I may sound a bit impatient... and I dream of the day when I can harvest last year's compost that's been waiting patiently for me to use it.

For now, I'm trying to put in the perfect ratio, spend some extra time taking its temperature, fluffing, watering, and bang, mountains of black gold in a couple month's time. Not that we got to use it in the fall as I had hoped, but it was very close to ready and I could well have set up the new bed if it hadn't gotten too cold outside to build it (I'm a wuss in the cold) and a dozen other excuses too. LOL

The one thing I'd do differently though, is that I went ahead and turned it when it was still super hot (140+) because it had been days longer than the science says is the best time to turn it. The next pile, I'm going to let bubble until it gets into the 120 degree range, then charge the middle with some fresh hi-test greens to get it cooking again after turning. After that first turn, it only went back to 140 for about a day, then hovered in the low 130's and dropped quickly after that. It's dark and rich-looking though!

Here's the new bottomless pit I have to fill, not to mention the myriad other uses I have for compost. There will never be enough!!!

(That's the one-year design. Our plan for next year is to build a retaining wall around it and double the height, and ultimately, remove the wood. It's 100.25 sf, 6" deep on one side, 10" deep on the downslope.)

keyhole.jpg (22.04 KiB) Viewed 1214 times

Thanks again for all your very helpful replies!

Devon

[rainbowgardener]

Cool bed! I like how it has the inlet for walking in, being able to reach stuff.

I agree, never enough compost. You wouldn't really want to fill the whole bed just with compost anyway. Compost is better mixed with topsoil and other amendments. "Mel's mix" that square foot gardeners use is 1/3 compost, 1/3 peat moss (you could use coconut coir) and 1/3 mineral ingredients for drainage.

Once the bed is filled, as far as continued feeding through the season, I make some of my compost in to compost tea or compost infusion (not brewed and bubbled) to stretch it more.

Thanks very much for coming back and updating this... we often never hear any results of stories.

[estorms]

Your compost probably would have cooled down in a couple of days anyway. I try to turn mine once a month if possible, but I have a lot of grass clippings and leaves. I am willing to wait for it. This spring I will use the finished compost and anything that is still not decomposed can be the beginning of my new piles.

[RickRS]

I'm doing my first compost piles, as well.

Couple of things; Those piles of horse manure from stables are not very high in nitrogen (greens). I found this out when the master gardener advising the community garden I'm involve with had us start a pile with brown leaves and manure from a stable. It wouldn't heat up. I confirm this with the person involved in Florida's Sarasota community garden. They handle 30 tons of raw material annually for the numerous gardens in their area and run the Florida Online Composting Center website ( https://sarasota.ifas.ufl.edu/compost-info/ ) They found they needed to treat stable waste as high carbon (browns) and ramp up the nitrogen to balance. And their advice to get that pile going? Load it up with coffee grounds!

Second, USDA Organic standards for composting requires you to get the compost above 130F and then turn a minimum of five times in 2 weeks while maintaining temperature above 130. I'm recalling this from memory, so I may have it a little distorted, but they expect hot composting to require frequent turning. This mainly to breakdown potential pathogens in the manures (I think).

I'm thinking turning 4-5 days while it's hot may work well. I've turned my leaf and coffee pile at home (five foot diameter pile that 3 1/2 feet high) four times. The first 7 days after it got to 130F and stayed there at 130F all that time. After turning, which allow me to see the center was getting very dry and allowed rewetting, the temperature started at about 100-110F and then climbed to 140F and stablized for 5 days. Day 6 and 7 temperature edged down to 136, and I turned the pile again. Shot back to 140 in two days, so I turned on day 6. After a couple of days pile was back up to 140F and then climbed to 151F! That was 5 days ago, and I want to turn this monster tomorrow, if I can.

The center has been getting progressively richer in color and texture. With frequent turning, you'll get a good idea of the moisture content of the pile and bring more oxygen into the mix to keep the bacteria happy and growing. Sounds like a no-brainer if you have a big pile and got hot composting going to turn that thing often.

[estorms]

That sounds like the best way to get the best compost in the shortest amount of time. I have four piles 4X4X4 feet . I am just too lazy to turn that often.

[tomc]

I suppose it is possible to build and fill a pallet compost bin and have it catch afire. That said, after fourty years of trying, I never did manage to kindle one.

I have found that a bank of two or three bins will fill easier and make a progression easier. By filling each one in turn. the oldest will have been filled, heated and cooled and collapsed and can be shoveled out to use in the garden. The brushy-bits that are too noticable can go into the new pile that is currently being filled for another go at rotting.

Please notice there is darned little in the way of turning being described in my outline. Cause I don't do that. I'm old and broken down myself, and keeping me turning is enough for me...