Newly Registered
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Joined: Sat Mar 16, 2013 5:07 am
Location: Netherlands

Pile only 104 degrees F max. Size or outside temperature?

Hi everybody,

First post btw. I started composting 2-3 months ago. Read many articles and was fascinated by hot composting. So I decided to make my own hot heap.

Took mostly leaves and straw as browns and fresh green plant clippings, horse manure and kitchen waste as greens.
Couldn't get enough material to get a 1m3 pile (about 4x4x4 feet), but its more like 3x3x3 feet. Used a setup that would allow air coming from below, 1 side and above. Made a cone shaped pile.

I have turned the pile about 8 times in the past 2 months. Used enough water when rebuilding every time. The pile smells good, no anaerobic odor and its crawling with worms.

I even bought a compost thermometer :)

Now, here's the problem: My pile doesnt heat up that good. At first i reached about 25 degrees Celcius (77 degrees F). So I decided to add more horse manure and fresh grass clippings.

Since then I have only managed to get it at a 'lousy' 40 degrees Celsius (104 degrees F). It took about 10 days to reach this temperature, held for about 5 days, and then got back to 20 degrees Celsius.

Should I:
1. Add more greens still (added quite a lot already)
2. Should I what until the outside air temperature rises (it has been around zero degrees Celcius here for the past 2 months)
3. Should I build a bigger pile (once I get the materials)
4. Something else??

Thanks a lot in advance!

Cool Member
Posts: 87
Joined: Thu Mar 14, 2013 6:40 pm
Location: Cambridge UK

I'm still learning, but perhaps the compost pile will warm up in a few days time when the temp rises
Spend sixpence on the plant but a shilling on the hole - Anon

Greener Thumb
Posts: 728
Joined: Wed Sep 24, 2008 1:15 am
Location: Ventura County, CA, Sunset 23

A lousy 104 F(40 C)? Todays paper showed Amsterdam at 37 F or 3 C. 37 C (100 F) above ambient strikes me as pretty good.

Having said that, after 2 to 3 months I think you're going to get all you're going to get out of that batch. The high temperatures come early not late in the process. Eventually all batches cool down and you let them finish.

Re-assess your batch. Consider what went well and what didn't and let it finish. Start a new one and apply what you've learned so far in building your next one. After that one, repeat. Repeat that again and again and soon enough, hopefully, you'll start sharing your knowledge with the rest of us.

Good show

Greener Thumb
Posts: 955
Joined: Sun Apr 04, 2010 3:29 pm
Location: Central PA

the "answer" is extremely simple:

"heat" in the compost pile come from the decomposition of organic matter.
to make that as efficient as possible - hence generating max 'heat' - you need the exact ratio of browns to greens and mixed properly and with the right moisture. too much or too little of any of the above produces less than optimum results.

so, go Thee forth and set up a Chemistry lab; or do as I do, not as I say, just chuck it on the heap and wait. it'll all rot away, sooner or later.

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Super Green Thumb
Posts: 5478
Joined: Mon Mar 23, 2009 1:59 pm
Location: TN. 50 years of gardening experience.

I have 2 large 55 gallon barrels painted flat black in the yard. I dump my compost material in the barrels. I put organic material, soil, water, grass, leaves, food scraps and urine in the barrel. When 1 barrel is full I put on the lid. It sets in the sun and gets hot enough it is too hot to touch, the compost must be 130 degrees F. In the mean time I am filling the 2nd barrel with organic material. In 30 days the 1st barrel has composted down to what looks like potting soil. Every 30 days I get about 15 gallons of compost. I remove the lid several
times a day to give it fresh air and I stir it by hand a little bit but it is not easy to stir until the volume gets smaller.

Heat speeds up the compost process.

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