Re: [compost_tea] Re: C:N

From: L Blair <rlbct_at_clear.net.nz>
Date: Wed, 22 Dec 2004 08:41:38 +1300

The first reference below (ranchmondo) ends with
"... put in about 30 times more carbonaceous material (estimate wt.)
than nitrogenous material (guess at dry wt.). "

Well that doesn't make sense to me.  Just look at the ratios quoted higher
up the page
"sawdust  150-200     leaves from oak, maple  40-60
peatmoss  50     sun-dried grass clippings  20
straw  50-150     hay from legumes  15
raw garbage  25     fresh grass clippings  15
cow manure  30     fresh garden debris  20"

If I was using sawdust ( say 175 and and so carbonaceous) and legume hay (15
and nitrogenous) to
make compost and used the 30:1 suggested ratio by weight, I would have
(175 x 30) + 15 = 5265 parts Carbon, and (1 x 30) + 1 = 31 parts Nitrogen.
Dividing by 31,
I get C:N of 175:1 to start composting with.

To get 30:1, I would need to solve ((175 x X) + 15) / (X + 1) = 30
where X is the quantity of sawdust to put with the hay
X = 15/145 = approx 0.1  (actually 1.034)
So, in this case, I would need 0.1 parts sawdust to one part legume hay, not
the 30 suggested.

Obviously the proportions of input materials to add to the heap will vary
according to what the materials are.

Lynton
>
>  <http://www.ranchomondo.com/compost/cnratio.htm>
> http://www.ranchomondo.com/compost/cnratio.htm
>
>
>




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Received on Tue Dec 21 2004 - 18:52:44 EST

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