[permaculture] Soil Carbon Sequestration

Paul Cereghino paul.cereghino at comcast.net
Wed Jul 4 13:48:28 EDT 2007

Young, Anthony. 1997.  Agroforestry for Soil Management.  CAB 
International: New York, NW.  ISBN 0851991890

I seem to recall he has some diagrams of carbon cycle rates.  Young also 
wrote primarily about tropical systems.  My recollection (basic 
biogeography... text is at work) is that in tropical systems temperature 
prevents accumulation of organic matter in soil, and the majority of the 
carbon pool is in a litter layer and standing biomass, which is why 
tillage based annual agriculture is so destructive in the tropics.  In 
temperate systems you see accumulation of stable organic humus, 
particularly under anoxic soils where soil metabolism is very slow 
(truely organic soils occuring only in wetlands).  So you would have a 
spatial pattern of carbon accumulation based on climate which drives 
both primary production and decomposition, soil hydrology that can 
increase primary production and decrease decomp. (with wetlands 
accumulating carbon), and management regime where tillage accelerates 
soil organic decomp by providing oxygen.  In my climate, biomass 
accumulates as wood both above and below ground, with a massive carbon 
legacy in the form of heaps of sodden large woody debris.

The Rodale study compared continuous corn to a corn/soybean rotation:
"It is likely that the increased carbon storage in the [manure-based] 
system is partially due to the return of steer manure to the field. 
Compared with senescent-crop residues, a larger proportion of 
manure-derived carbon is retained in soil, probably because manure is 
already partly decomposed and contains a larger proportion of chemically 
recalcitrant organic compounds (8,9). On the other hand these studies 
did not find significant effects of types of plant species on long-term 
carbon equilibrium (1,8,9)."

I would suggest that the alt. ag. methods resulted in a recovery of soil 
organic matter, but that regeneration to forest would have provided a 
greater rate.  This 15 year experiment was completed in Pennsylvannia, 
USA, temperate cold winter, warm moist summer, and given the climate 
controls of all factors affecting carbon cycling I would be wary of 
extrapolating to other systems.  Additionally they did not calculate the 
whole system carbon balance including fuel costs in transporting food to 
cows and back to fields, tillage, transport and end use of product.  
Finally the tables reflecting the data patterns are not provided, but 
you can buy a glossy version for only $14.95.  I get annoyed by advocacy 
spin that reinterprets "science" to easily solve our little carbon 
problem, but I can see the allure.

Paul Cereghino

lbsaltzman at aol.com wrote:

>Also checkout http://www.yeomansplow.com.au/index.htm?and read Yoeman's numbers on carbon sequestration with keyline design. It is covered in detail in the book Priority One available on the website.
>-----Original Message-----
>From: Charles de Matas <cdematas at hotmail.com>
>To: permaculture at lists.ibiblio.org
>Sent: Wed, 4 Jul 2007 8:47 am
>Subject: [permaculture] Soil Carbon Sequestration
>Okay - I'll try to find the book and give you a better idea of what he 
>actually wrote. I think the book is "Agroforestry for Soil Management".  I 
>was quoting from memory which is always risky.
>    It would be nice if soil carbon sequestration could help in the problem 
>of climate change.  I think that scientists have recognized that no single 
>tactic will be enough.  They have listed about a dozen or so modalities 
>(more efficient appliances, hybrid cars, solar and other renewable energies, 
>energy efficient buildings, sequestration, etc.) where each one will take up 
>a 'slice' of the carbon needed to be removed to offset burning of fossil 
>fuels.  Maybe soil carbon sequestration can help with a small slice, but I 
>haven't seen enough to convince me that it will be a major factor in 
>controlling CO2.
>Could you get a better reference on that book. The conclusions are contrary 
>to a
>number of studies and articles I have seen. I am curious to read how he got 
>his conclusions.
>Do a google search on carbon sequestration in the soil and you be amazed at 
>number of studies and the amount of mainstream research being done. Here are
>just a few references on carbon sequestration in the soil from that search:
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