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| soil-life - 12/1/2011 05:36
OM. Lab procedure.
Your close.
call Midwest or A and L labs, visit with their chemist and they will tell you their procedure.
I am sure someone working, or recently familiar with the lab procedures will chime in.
%OM = 100 - %ash...where ash is the residue remaining after igition at 500C for say a 8-12 hr oven cycle....that is roughly the AOAC procedure which should be available at your library. The exact procedure we use for forages/feeds is weighing before then after ashing. In theory, C,H, N and O liberated in the oven...other elemets remining. A soil lab should do the same and report as OM%. I do know that if we are not cognizant of how a pasture soil sample is taken SOM can easily be biased upward by 1% or more....root/thatch contamination etc.
Anyway, SOM could also be back calculated from direct C determination with a N, C, and O analyazer (Leco, Elementar etc). On our litter alalysis, the results come back as actual C in lbs/ac...which tells me they ran samples through an Elementar (or =) to get both N and C.....HIGHLY accurate piece of equip because C and N are measured in gaseuos form in an enclosed system with no losses.
FWIW....in each ton of HQ broiler litter we get 500-600 lbs of 'as-is' C. Based on a nominal 2 T litter/ac rate and considering an ~40:1 C:N ratio in rye, I figure we get a free rye cover crop (~3000 lb/ac above ground biomass) worth of organic material with each litter application. Hope that makes sense? Coming out of the drought litter made a huge difference in poor thin pasture soils this fall....a visual line where and where not the truck could run the last 2 yrs. Didn'd expect to see this until about the 4th yr of application. | |
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- A good study, Manure, crop residue & Building soil O.M. - soil-life : 11/30/2011 22:37
- Re: A good study, Manure, crop residue & Building soil O.M. - behog : 11/30/2011 22:51
- Re: A good study, Manure, crop residue & Building soil O.M. - tntfarm : 11/30/2011 23:43
- RE: A good study, Manure, crop residue & Building soil O.M. - IDAGCON : 12/1/2011 01:07
- Re: A good study, Manure, crop residue & Building soil O.M. - Hamstn : 12/1/2011 08:09
- RE: A good study, Manure, crop residue & Building soil O.M. - IDAGCON : 12/1/2011 10:56
- Re: A good study, Manure, crop residue & Building soil O.M. - mafrif : 12/1/2011 17:20
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A good study, Manure, crop residue & Building soil O.M.
