Should I lime my compost?

Dick and Jill Miller

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Sep 7, 1993, 12:18:48 PM9/7/93

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Hi Jim: jim.m...@gcbb.granite.mn.org (Jim Mcnelly)

In a posting to rec.gardens you said:
>There are few if any minerals I recommend adding to the composting
>process, especially avoid adding lime as it disturbs the natural pH
>shift and has actually been shown to retard composting and
>unnecessarily volatilize N.

I have been adding lime to my compost whose main carbon component is oak
leaves. Does the above mean I should stop this practice. (I use whole
leaves as I do not have time, money or space for a machine to chop them.)

Thanks for any advice.

--Jill

Steve Daukas

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Sep 7, 1993, 1:37:54 PM9/7/93

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Dick and Jill Miller (dmi...@theory.lcs.mit.edu) wrote:
: Hi Jim: jim.m...@gcbb.granite.mn.org (Jim Mcnelly)

: In a posting to rec.gardens you said:
: >There are few if any minerals I recommend adding to the composting
: >process, especially avoid adding lime as it disturbs the natural pH
: >shift and has actually been shown to retard composting and
: >unnecessarily volatilize N.

: I have been adding lime to my compost whose main carbon component is oak
: leaves. Does the above mean I should stop this practice. (I use whole
: leaves as I do not have time, money or space for a machine to chop them.)

: Thanks for any advice.

Lime has been used for a least a hundred years to aid decomposition of
all sorts (including humans). I can see where using too much is bad,
but judicious use shouldn't stop the process...

Karen Kolling

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Sep 7, 1993, 3:14:53 PM9/7/93

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In article <26ic98$u...@GRAPEVINE.LCS.MIT.EDU> dmi...@theory.lcs.mit.edu (Dick and Jill Miller) writes:
>Hi Jim: jim.m...@gcbb.granite.mn.org (Jim Mcnelly)
>
>In a posting to rec.gardens you said:
>>There are few if any minerals I recommend adding to the composting
>>process, especially avoid adding lime as it disturbs the natural pH
>>shift and has actually been shown to retard composting and
>>unnecessarily volatilize N.
>
>I have been adding lime to my compost whose main carbon component is oak
>leaves. Does the above mean I should stop this practice. (I use whole
>leaves as I do not have time, money or space for a machine to chop them.)

I have a soil test kit collecting dust in my kitchen, so I don't yet
know the state of my garden soil, but I was encouraged to read in a
new Sunset large-size paperback called Organic Gardening that oak
leaf compost and steer manure are opposites in the acid/alkaline universe,
so I've inadvertently been doing the right thing by adding both to
my garden. It does warn against salts in steer manure, however.

The Sunset book, by the way, has numerous pictures of
our Bug Friends and our Bug Baddies for id purposes.
--
Karen Kolling kol...@adobe.com or kol...@netcom.com

^._.^ ^._.^ ^._.^ ^._.^ ^._.^ ^._.^ ^._.^ ^._.^ ^._.^ ^._.^

Jim Mcnelly

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Sep 7, 1993, 2:36:00 PM9/7/93

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Dick and Jill Miller to All - Tuesday, September 7th:
Discussing: Should I lime my compost?

DAJM>Hi Jim: jim.m...@gcbb.granite.mn.org (Jim McNelly)

DAJM>In a posting to rec.gardens you said:
>>There are few if any minerals I recommend adding to the composting
>>process, especially avoid adding lime as it disturbs the natural pH
>>shift and has actually been shown to retard composting and
>>unnecessarily volatilize N.

DAJM>I have been adding lime to my compost whose main carbon component is oak

>leaves. Does the above mean I should stop this practice. (I use whole
>leaves as I do not have time, money or space for a machine to chop them.)

Hi Dick and Jill,

That's right. After years of trying to find a beneficial use for lime in
the composting process, and not finding any data to back up the
practice, I have concluded that adding lime is an "Old GI's tale" that
should be put out to pasture.

To the best of my knowledge, the practice of adding lime was introduced
into the composting vocabulary by GI's returning from World War II. It
was widely used as a means of deodorizing "night soil" from privies. For
that purpose, it serves a valid purpose. The sudden pH shift kills off a
whole generation of bacteria and even sterilizes the slurry over a pH of
10. Lime itself has deodorizing properties as Arm and Hammer baking soda
has demonstrated.

Common misunderstanding has led many to think of all organic matter
piles to be akin to raw festering feces with the idea that lime is a
standard deodorizing practice. For leaves that have a sweet musty aroma,
lime is an unnecessary masking agent. A well mixed composting pile that
is not in standing water and has natural ventilation does not develop
offensive odors. It is true that lime can be used as a last resort
method of deodorizing a festering globule that has gone ballistic on the
putrefaction scale, but that is no reason to add it as a preventative
measure.

As far as accelerating the decomposition process, there is little
evidence that calcium carbonate, CACO3 has significant properties that
oxidize or otherwise cause a softening of plant tissue. Hydrated lime
CASO4H20, can oxidize plants, but its extreme reactivity is not
recommended or considered beneficial. In a sense, it is like adding acid
or some other sort of chemical reactant instead of allowing nature's
agents of decomposition to biologically decompose matter.

There are valid reasons to add lime to a soil if it is too acid. Perhaps
if you have an acidic compost, you may wish to add lime to bring the pH
up. But neither of these practices call for adding lime to the early
stage of the composting process.

The primary inhibitor in leaf decomposition is actually surface tension
on the cell wall. The leaf simply sheds water. The recommended
techniques for softening leaves to enable them to turn to leaf mould
over the winter are primarily a matter of watering properly. In my leaf
stockpiles, I water, layer by layer, and water again. I even cheat a
little by adding a bit of soil wetting agent such as basic H or other
degradable detergents.

Adding a sprinkling of old compost in with the leaves is a great way to
help leaves soften. The compost not only inoculates the mass with
beneficial organisms, it holds water right on the surface of the leaf,
forcing it to take on water. If you live in a cold climate, letting
leaves lie on the ground, once again well moistened, so that they go
through the freeze-thaw cycle is also beneficial. Ice crystals can
penetrate cell walls and make pathways for bacterial penetration the
next spring. Leaving leaves in self-insulated large dry piles is a sure
way to pickle them in a silage that does not decompose.

Running leaves through a shredder or mower will also scratch the leaf
surface and expose more area to take on water. But I agree that if
properly managed, that step is not really necessary. Effective
composting need not require significant work or wear and tear on
equipment. I believe in letting the microbes and earthworms do the work.

So that is the line on lime. I have it listed in my "ten myths of
composting" as an unnecessary but often recommended practice.

Jim Mr Compost~~~ McNelly

Granite Cities BBS 612-654-8372-HST 654-0678 v.32bis

e-mail jim.m...@granite.mn.org
---
* September 8th - Religion without heart is enslavement.

Bob Klebba

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Sep 9, 1993, 6:06:16 PM9/9/93

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In article <26ic98$u...@GRAPEVINE.LCS.MIT.EDU> Dick and Jill Miller,

dmi...@theory.lcs.mit.edu writes:
>In a posting to rec.gardens you said:
>>There are few if any minerals I recommend adding to the composting
>>process, especially avoid adding lime as it disturbs the natural pH
>>shift and has actually been shown to retard composting and
>>unnecessarily volatilize N.
>
>I have been adding lime to my compost whose main carbon component is oak
>leaves. Does the above mean I should stop this practice. (I use whole
>leaves as I do not have time, money or space for a machine to chop them.)

I have read that compost pretty much seeks its own pH. It will start to
go acidic and as it ripens, it will go more neutral. South central
Wisconsin has very high soil pH, so there is no need to lime anything.
Therefore I tell people here never to bother with lime. Elsewhere I
would say lime only if it makes you feel better. I don't think it
changes the decomposition process much.

Bob Klebba
Madison, Wisconsin, USDA zone 4
Inet: nicmad!klebba%astroa...@spool.cs.wisc.edu
"Feed the soil, not the plant"