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help with heating up my compost bin  RSS feed

 
Gail Saito
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Location: Medford, OR
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My compost bin is loosing temperature. Started out at 70 degrees, which I know is not hot enough, and is currently at 58. Any help/advice would be appreciated.

(I live in San Diego, CA)
 
Miles Flansburg
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Gail could you please tell us the steps you have taken so far? What kind of bin, what ingrediants, etc. That would help a lot.
 
Ken Peavey
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For hot compost you must have the right recipe

-Volume
At least a cubic yard: 3' high, 3' wide, 3' deep.
The mass and volume of the heap will serve to insulate itself. A heap that is too small allows warmth to escape.

-Moisture
A dry pile won't heat. The bacteria need sufficient moisture to live and work. It is the activity of the microbes that create the heat. The rule of thumb: as moist as a wrung out sponge.

-Mixture of Greens and Browns
This is all about offering the right diet. A heap that is too cool or cooling down could probably do with some added green material: grass clippings, manure, coffee grounds, even urine would give it a boost. Also, this added material needs to be mixed into the pile rather than added in one spot.

-Oxygen
If the size, moisture, and mix are right, turn the pile to introduce oxygen. Those little guys have to breathe.
 
Gail Saito
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Location: Medford, OR
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Thank you. I purchased a bin through Costco and I am guessing my problem is that it is too small...not quite 2 ft...height, width and depth. I have more browns than greens and it is adequately damp. Must be the size of the unit. I should have investigated size before purchasing!
 
John Polk
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Most bins will get warmer than the same volume would in a stand-alone pile.

Some points to remember for bins/tumblers:
* Do not over pack. Your microbes NEED oxygen to survive.
* Ideal C:N ratio is +/- 30:1
* A scoop of good topsoil will add beneficial microbes to the mix - pre-inoculating it.
* Finely chopped will decompose quicker than coarse - greater surface area for the same mass size.

As each ingredient has a different C:N ratio, it is nearly impossible to get a 'perfect' balance. A rule of thumb measurement is to put one shovel of 'greens' to one shovel of 'browns'.

If it begins to smell rotten, or moldy you probably have too much 'green'.
If it won't heat up, you probably have too much 'brown'.

You cannot hurt it, so just play around with it 'till it works. You'll get a feel for it. It gets easier each time.

 
Gail Saito
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Location: Medford, OR
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John...thank you so much for the tips. Please clarify one thing for me. If it is a 30 to 1 ratio, then I don't understand your reference to one shovel of green and one shovel of brown.
 
John Polk
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The 1:1 ratio of 'brown' to 'greens' is based on the fact that almost anything you would put into a compost pile has more carbon than nitrogen. Some things are 6:1 (greens), and other things might be 200:1 (browns). So with equal proportions of greens/browns, you should be in the ball park.

"Proper" composting is a 'fine art', but it is not an exact science. There are C:N tables on the net (I can't find a bookmark right now), but they give ranges for different items. These ranges for a common item may be 6-20:1, or 200-300:1. So you would need a gram scale and a scientific lab to get exact numbers for each item. With a 1:1 ratio of browns:greens, you should be close to 'ideal'.

As I said in the previous post, if it smells, add more carbon - if it won't heat up, add more nitrogen.

The bottom line is that it will all turn to compost at some time. A 'perfect' pile will just do it quicker.
Some people won't put it in their garden until it is done, while others like to incorporate it earlier.
And others just turn the raw materials into the soil, and let 'it' happen there.
Those I know who like to incorporate it before it is 'finished' claim that it will help feed the microbes in their soil.
(And that is the basic reason for adding compost.)

With compost, you can't do it wrong. Some is just 'righter' than others, depending on views.

 
Gail Saito
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Location: Medford, OR
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Finally I get it! I never really understood that all organic matter contains both carbon and nitrogen. Thank you, thank you, thank you!
 
Julia Winter
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When my compost pile won't heat up, the problem is often not enough moisture. The classic description of the right amount of moisture is "wet as a wrung out sponge." In a plastic bin, you might also be missing oxygen. I would try to fluff it up and mix it up (I'd probably use a long handled hand fork, or maybe a pitch fork) and while I'm doing that, evaluate for moisture.
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