How hot does your compost get? (pics)

[TomNJ]

This year I borrowed my neighbor's chipper/shredder and ran tons of leaves through it, pulverizing them to near powder. I then intimately mixed the shredded leaves by hand with an equal volume of fresh grass clippings and built the pile all at once, adding limestone, lawn fertilizer, and water every six inches. Finished pile is 4' x 4' x 3' (~50 cubic feet). I then stuck a digital meat thermometer in the center about 5" deep.

The temperature rose to 140F over four days, then began slowly cooling (133F after seven days). It is probably hotter in the center of the pile but I can't measure it that deep. When I pushed the thermometer another two inches deep it did go up a couple of degrees.

How hot does your pile get, and how do you measure it?

TomNJ

[heirloomdaddy]

that's a killer looking pile. I'm jealous. Mine is suffering due to lack of shredding...but still producing some compost. Slowly.

[Sherry_AK]

Ours usually gets to 150° and we measure with a compost thermometer. We also have some deep fryer thermometers (from WalMart in the BBQ section) which were inexpensive and work fairly well. They don't reach in as far as the compost thermometer, but probably a good bit further than your meat thermometer. We have lots of horse, chicken, sheep, etc., manure in our piles, so it heats pretty well.

Sherry

[mdvpc]

I use a nature mill composter-my wife wont let me have a pile. And I always do what she says. The composter cooks the "pile" up to 150 degrees.

[David Marek]

Nice bin.

If you turn the pile at least once or twice it will stay hot, decompose faster and gives the outside a chance to become part of the inside to kill off many weeds and disease organisms.

I had an aerobic (the bacteria breathe oxygen like us) "batch" pile get up to 165 after the second turning, but 150-155 for a week or two is about average followed by a slow two or three week cool down. At 170 or higher the good guys start to die off and nutrients begin to volatilize. I take the reading with a short meat thermometer from the center of the pile when I turn it.

[tjg911]

i've yet to get a hot pile here in 10 years but i don't have grass clipping i rely on green stuff from the garden and it's not shredded. at my other house i had a small lawn and bagged the grass clippings. my pile was about 5' X 4' X 3' and it got HOT! when i'd turn it steam would pour out and no lie you couldn't get near the pile! i made compost fast. here it takes time w/o grass clippings.

Many comments on compost threads suggest the heat in a compost pile is the mechanism which kills weed and grass seed in the pile. Many people also say their compost piles never seem to generate heat, but the seeds seem to be killed over time anyhow.

I wonder if the moisture content and the warm (not hot) temps inside a compost pile cause seed to germinate. Since no sunlight is available, the germinated seed simply dies.

Which is more important in a compost pile, generating enough heat to cook the seed or creating an environment which causes the seed to germinate?

Ted

[Mischka]

My vote is for generating heat sufficient enough to kill the germplasm within the seeds.

Weed seed kept at a temp above 140°F for an extended period of time will lose germination viability.

Originally Posted by Mischka

My vote is for generating heat sufficient enough to kill the germplasm within the seeds.

Weed seed kept at a temp above 140°F for an extended period of time will lose germination viability.

What is "an extended period"? A few hours or a few days?

Will the high heat not not degrade the bacterial colony that caused the high heat?

Will the high heat not degrade the nutritional value of the compost exposed to the heat for an extended period?

Ted

[acorn]

The highest my pile has ever got was a little over 160 here in AZ. Was early fall and I was turning every 2 days in order to speed up the process. Also was using black plastic sheet over the pile to keep moisture in. I use an 18" long probe that I connect to my Voltmeter. the meter has a setting for temp and uses a certain standard type probes. I got the long one from McMaster for another project but it works well for this also.

- Aaron

[mjc]

Originally Posted by tedln

What is "an extended period"? A few hours or a few days?

A few hours would get some to most. A few days will get most to all. About a week will get everything.

Originally Posted by tedln

Will the high heat not not degrade the bacterial colony that caused the high heat?

Actually, yes. But not completely wipe it out. But, without the addition of fresh material, it will die off anyway...and the bacteria responsible are common in all soils, so there is a ready supply to move in and 'be fruitful and multiply (or is that divide?).

Originally Posted by tedln

Will the high heat not degrade the nutritional value of the compost exposed to the heat for an extended period?

Ted

No. It actually transforms some of the nutrients into more 'useful' forms. Water will leach out far more nutrients.

[Too Tall Toms]

160 F compost??? Wow....the hottest my compost ever got was 120. It cooled down and when I added horse manure and other compostables, the highest it got was 80F

[Too Tall Toms]

Hey....since I added alpaca and rabbit manure to my compost over the weekend, the temp of my compost pile is at 130F! That's excellent! It started out at about 90F and it's been averaging about a 10F a day increase since Saturday.

[dustyrivergarden]

My first post on this form and it might as well be talking about compost. lol As a guy that has only been composting for a couple of years is there one major no no for the compost pile that rookies try to toss in. So far I have had great success but one never knows...

[Too Tall Toms]

Originally Posted by dustyrivergarden

My first post on this form and it might as well be talking about compost. lol As a guy that has only been composting for a couple of years is there one major no no for the compost pile that rookies try to toss in. So far I have had great success but one never knows...

Well I consider myself a rookie but I do know that you're not supposed to add cat or dog poop to your compost pile. You should avoid adding any poop that comes from a meat-eating creature.