[Terrapreta] More Studies Needed on N2O Soil Emissions

[Shengar at aol.com]

Hi All,
 
Could the Soil science folks here  help me in my search for  corroborating 
Nitrous Oxide N2O soil emission work?
 


On the holography Forum there has  been concern about quantifying the over 
all equations of Terra Preta's impact on  soil N2O emissions.The lack of more 
studies and hard data will make it  difficult to prove  TP's extra GHG credit 
for the reported  reductions in soil emissions .  I mean with N2O being 296  
times stronger than CO2 as a GHG, and 40% reductions reported, benefits add  up 
quick for equivalent Carbon credits,
that are no laughing matter  :-)
Cheers ,
Erich
 
 
_http://forums.hypography.com/earth-science/3451-terra-preta-34.html _ 
(http://forums.hypography.com/earth-science/3451-terra-preta-34.html) 
 
 
 
Re: Terra Preta - 02-02-2007, 02:27 AM  

  
____________________________________


 
 
Quote:
Originally Posted by RBlack  
(http://forums.hypography.com/earth-science/3451-terra-preta-34.html#post156938)  
... about gaseous losses. One paper I read  by Lehmann (don't know which one 
but will try and find out), mentiond that  TP soils reduce outgassing but I 
don't remember if N2O was  mentioned.

Again, sorry for not being able to give you links yet, which is also why  I'm 
sending annoyingly separate replies. There  is huge 23Mb Powerpoint from 
Marco A. Rondón, Juan A. Ramirez & Johannes  Lehmann from a USDA Symposium on C 
sequestration. Baltimore, March 24, 2005. You  could google it; I could mail the 
relevant slides; or you could just take the  headlines:

"Net fluxes of methane and nitrous oxide decrease with  additions of charcoal 
to soils
Even small amounts of charcoal added to soils  can offset net emissions of 
CH4 and N2O"

N20 emissions reduced by 40% in  test trenches of beans + charcoal.
CH4 emissions reduced by 100 mg per sq m  per crop cycle in field conditions 
+ charcoal, in one case going negative  (absorption).

If these could be verified, I guess they would be  creditable under Kyoto, 
unlike the far more effective sequestration of  char.







Re: Terra Preta: when is  pollution not pollution? - 02-05-2007, 02:45 AM  

  
____________________________________


 
 
Quote:
Originally Posted by Michaelangelica  
(http://forums.hypography.com/earth-science/3451-terra-preta-post157300.html#post157300)  
What is the significance of "significant  reductions in . . . N2O emissions 
from  soil"

Nitrous oxide is a global warming gas whose effect is 296 times stronger  
than CO2 (methane is 23 times stronger). See global warming potentials (GWP) in  
Intergovernmental Panel on Climate Change, _Climate Change 2001: The 
Scientific Basis_ (http://www.ipcc.ch/pub/wg1TARtechsum.pdf)  (Cambridge,  UK: 
Cambridge University Press, 2001)

Fortunately we emit relatively  little N2O compared with the carbon gases, 
but one of the sources is  agricultural soil, I guess by decay of nitrogen 
compounds such as fertiliser.  Its strength makes it about as important as methane 
from that source. So if as  Rondon et al say charcoal reduces emissions by 
40%, excellent! Another feather  in TP's hat.

Rondon et al calculated the N2O + CH4 reduction to be  relatively minor 
compared to the carbon sequestration in effect on overall GWP,  but they didn't 
look at whether it recurs annually after a single charcoal  addition in the first 
year. If it does, this could be a major hidden benefit.  Could even be worth 
a govt paying farmers to spread charcoal in order to meet  its climate 
commitments. Assuming of course you have a govt prepared to commit  to anything. 




Erich J. Knight 
Shenandoah Gardens
E-mail: _shengar at aol.com_ (mailto:shengar at aol.com) 
(540)  289-9750





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