Compost stuck at 85-90 degrees

16 years ago

I'm completely stumped.

For the past few years I have not been able to get my compost hotter than 85-92 degrees. I have 3x3x4 black covered bins that I start in late March 3/4 full with an aprox. 50/50 mix, (by volume), of oak leaves and various greens such as kitchen scrap and coffee grounds saved and frozen throughout winter, a few shovels of composted horse manure, a few shovels of soil, and of course wet down to damp sponge feel as I build. I mix every week or so and continue to add greens through the spring, and of course keep it all moist. At the end of fall I only have half composted material that has never gotten past toasty warm. It will take another year to finish. The end result is good, but it has never gotten hot enough to kill weed seeds, or finish the process in one growing season.

This year I bought a compost thermometer to see if I could heat things up by adding more strong greens. I used the same materials, but this time I wet it with dilute fish emulsion and, (I hate to admit), threw in a few handfuls of compost starter. I watched and waited. The temp went up to 85, hovered for a couple of days then dropped. I turned and added a handful of kelp meal, a couple of handfuls of corn mean, more greens, more grounds, and watered with fish emulsion mixed with a little molasses. The temp went up to 92 then fell a couple of days later. Good smell, nice brown decaying of leaves, lots of worms and other crawlies, but no high heat.

I'd like to give this one more try before I give it up and just appreciate my reliable two year compost. Any help would be greatly appreciated. I wonder if I need more N in the pile, but how can that be with the fish emulsion, the manure, and the 50/50 mix? What am I missing or doing wrong?

Thanks, Fernhillhall

Featured Answer

Kimmsr

16 years ago

There is some research that says it is not the heat of a compost pile that kills the "weed" seeds but how long they are in the compost where they can germinate and die because they cannot access the sunlight they need to grow.
The volume of your pile may also be a limiting factor.
There is no real need for compost to reach those high temperatures some talk about, many of us cold compost and our compost never gets warmer that maybe 100 degrees and it is fine.

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Comments (7)

Kimmsr
16 years ago
That might be too wet for the aerobic bacteria to function well. Compost needs only be as wet as a well wrung out sponge, not a wet sponge.
anney
16 years ago
fernhillhall

In your shoes I'd add a bit of blood meal, maybe a teaspoon per gallon of browns and greens, to increase the nitrogen content. That should speed up the composting-heating process. And yes, see if you can keep the mixture a little drier if it's wetter than a wrung-out sponge! You can always add some dry shredded newspapers.
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namfon
16 years ago
I would make one more suggestion, if you have the space to make the pile 1 foot wider on each side ( 2 feet wider total )and you dig down another foot and start your 'greens' layer down there you might get enough volume to get it up over 120F especially if you are turning regularly.

Good Luck
computergardener
16 years ago
I have found over the years, my piles get the hottest if I spread the layers of green and brown in only 2-4" layers before starting the next layer. It seems the more thin layers the hotter my pile gets. Also, I have over the years started to use less and less water and it seems my piles break down better.

Finally, glad to hear you pick up a thermometer. I think it helps quite a bit. A few years ago I tracked the life cycle of my pile and the results were interesting. The pile went from 80ish to 120-130 within 7 days of building. Then slowly decreased to 80-95 within another seven days. Stayed in that range for about a month and then settle around 60-75.

When you build your next pile, track the temp in Excel daily or at least every 2-3 days and see the results. It really helped me learn how to get more out of my piles.

Best of Luck...
jonas302
16 years ago
Previously composted horse manure will not add heat like fresh if you could get your hands on some fresher manure The stuff that is steaming when you get it and your pile would heat
bigger would be better and maybe drier would be better
Also no soil is necessary it just makes it heavier to turn
HU-374719067
3 years ago
My suggestion is to run everything through a chipper to add more surface area. I always do this and reach high temperatures quickly. Also the compost is produced in as little as 4 months.