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Are partially decomposed leaves OK source of carbon?

Posted by indigo_tex 8,texas (My Page) on
Mon, Oct 7, 13 at 10:53

I am a new composter and have just emptied my first batch of wonderful compost. Very exciting!. Now I want to start a new batch, but I�ve used up most of my leaves and have no grass clippings. What I DO have are several bags of mostly decomposed leaves and twigs left over from my yard crew�s 2012 Spring clean up. My question is: since this material is already 3/4 decomposed, can I use it as my carbon source in my new compost pile until I have a new crop of leaves or should I just go ahead and spread it in my yard & flower beds?


Follow-Up Postings:

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RE: Are partially decomposed leaves OK source of carbon?

Either is ok but if you have ample space to finish composting them AND the soon to fall leaves as well,I would finish them.


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RE: Are partially decomposed leaves OK source of carbon?

Leaves have a Carbon to Nitrogen ratio of between 40:1 and 80:1 so they would be a good source of carbon in the compost pile. For many of us leaves are our primary carbon source.

Here is a link that might be useful: C:N ratio simplified


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RE: Are partially decomposed leaves OK source of carbon?

Thanks! I guess I'm not being clear about my question, which I admit may be a bit ignorant. Once leaves are already decomposed, are they still a good source of "fresh" carbon for the pile? In other words, does something get used or burned up in the decomposition process that the new pile will need for its own biologic processes to occur? I guess, in short, once it's decomposed, will it still act as fuel?


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RE: Are partially decomposed leaves OK source of carbon?

The amount of carbon that is available as fuel for microbes decreases as the leaves decompose. If they aren't "fully decomposed", there is still some C left in them, but not as much as if they were "fresh". For the average composter, there really isn't any good way to tell how much C remains available, or the residual C:N value of partially decomposed leaves. A very crude approximation would be to use the partially decomposed leaves in a ratio that is a multiple of how much decomposition you would guess (experience estimate) remains, relative to what you would use if they were fresh, e.g., if half remains, use 2X as much, if 25% remains use 4X as much, etc.


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RE: partially decomposed leaves as source of carbon

That was a fantastic answer, TXEB - just the information I was hoping for/needing. Thank you so much!


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RE: Are partially decomposed leaves OK source of carbon?

indigo - one thing to be aware of is the remaining carbon in partially decomposed leaves will be les of the fast-to-decompose stuff, and more of the slow-to-breakdown type of carbon. When we talk about materials being browns and C:N ratios, that's great for figuring out the final result, when the compost is fully finished. What that doesn't address is the rate at which decomposition occurs. Not all carbon in those browns is the same. There are some forms of predominantly carbon that decompose quickly, like - simple sugars and carbohydrates, and cellulose. Those are used up early in composting by the early mesophiles and thermophiles. When they're done what's left behind are the more challenging things like lignin, which is very slow to decompose and is mostly attacked by the fungal community. Looking at it practically, the more partially decomposed brown material you use the slower the overall process will proceed and most likely at lower early and peak temperatures. It's still good stuff, just don't expect the pile to behave the same once the easily and rapidly degraded carbon has been consumed. That's one of the reasons piles slow down after their early burst.


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RE: Are partially decomposed leaves OK source of carbon?

Yes, yes, that makes sense! I had already decided upon your first reply to back off on using my decomposed leaves. Now, I'm sure of it. So that leads me to another question: how does decomposed leaves compare with finished compost? I'm guessing they're still great to use but no where near the value of actual hand made compost.
Thoughts? More wisdom?


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RE: Are partially decomposed leaves OK source of carbon?

indigo - well, if you have patience (good things come to those who wait) there is leaf mold from the FAQ section for tis forum, and Fine Gardening's version. Some do it over about a year and half, others allow it to go three years.

I use to do this annually when I lived up north and had more leaves than I knew what to do with. Since moving to SE TX (nearly two decades ago), no leaves, no leaf mold. It is a wonderful thing. Once it's done, use it just as you would compost.


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RE: partially decomposed leaves OK source of carbon?

You wouldn't be close to Houston would you? That's where I am.


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RE: Are partially decomposed leaves OK source of carbon?

50 miles south , 12 miles inland


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RE: Are partially decomposed leaves OK source of carbon?

Well, it's great to know I have such an expert not too far away! What do you use, if I may ask, for Carbon since you don't have leaves. Just curious. Guess that 'ole Texas coastal plain probably has lots of grasses, if not much else. But probably you don't have those in your yard.


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RE: Are partially decomposed leaves OK source of carbon?

I use predominantly wood chips (mulch) - available free from our little city. I can have 10 yards per year, no cost, just pick 'em up. I use them in composting along with non-animal food waste.


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RE: Are partially decomposed leaves OK source of carbon?

Sounds perfect - like you said, no leaves, no raking, etc.

Have a great day and thanks again for all your expert help!


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RE: Are partially decomposed leaves OK source of carbon?

I've got oak and hickory leaves that can take a long time to break down by themselves. I store them in an open corral over the winter, and use them in the spring to mix with grass clippings. They get a bit of a head start that way but not much. Right now (actually for the past year) I'm attempting my first true leaf mold, 100% leaves allowed to decompose for about 2 years. They are starting to look like something, something wonderful.


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RE: Are partially decomposed leaves OK source of carbon?

Not that I want a ballel delivered to my house but what happens with fish bi-products along the coast? I'm sure large operations send thiers to commercial processors ,but I'm curious if individuals use it.


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