Re: Climate Changes - soil OM (mea culpa)
Bob MacGregor (RDMACGREGOR@gov.pe.ca)
Wed, 17 Dec 1997 10:53:49 -0400
Perhaps understandably, the comment that generated the most interest
from my earlier post about climate change was the one about using soil
organic matter as a carbon sink. Unfortunately, it appears that this is the
one that I was furthest off on (see note, below, from my contact at the
local research station; Dr. John MacLeod). Evidently my memory is
especially faulty beyond 5 or 6 years. Nevertheless, even though I had
the ratios wrong by an order of magnitude, I think soil organic matter is a
great way to lock up some atmospheric C.
BOB
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>>
Bob: I remember rather vaguely discussing the relationship between C
from organic matter and C content of forest but I don't remember the
source. The following is an attempt to calculate the relationship.
To estimate of organic matter in an acre of soil was based on simple
calculations that an acre furrow slice ( 6") weighs 2,000,000 pounds
hence 1% of that would be 20,000 pounds organic matter of about
10,000 pounds of organic C.
Since most plant material contains from 40 - 50 % C in the dry matter this
would relate back to 20,000 pounds of dry wood. I believe wood yields
would be about 10 times that.
If so it would take a change in soil OM of 1 % on 10 acres to equal
200,000 lbs (100 tons) of dry wood. You might be able to get better
estimates of actual biomass in rain forest. I expect the 1-10 ratio would
be closer than the 1 - 1 but it is still substantial.
John
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