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Carbon/nitrogen ratio

Indicates whether the carbon to nitrogen ratio of the herbaceous plant is low, medium, or high.

Two definitions of C:N 'Carbon to Nitrogen' ratio are:
1) The ratio of the weight of organic carbon to the weight of total nitrogen (mineral + organic forms) in organic material;
2) The value obtained by dividing the percentage of organic carbon by the percentage of total nitrogen in organic material. When the percentage of organic carbon is not known, the C:N ratio was estimated using the crude fiber percentage (%CF) and either the crude protein percentage (%CP) or the nitrogen percentage (%N). This method is described below.

 

%CP/6.25 = %N
%CP – %N = % of non-N fraction in protein
% non-N fraction in protein x 0.667 = % C in protein; The value 0.667 is an estimate of the proportion of C in the non-N fraction in protein.
C:N ratio estimate = (%C in protein + %CF) / %N

 


We specify the organic material as either the above ground biomass of a herbaceous plant or the above ground herbaceous material of a woody plant. We determine the C:N ration at the plant growth stage when the C/N ratio is lowest; usually when the N content is highest.

 

Low ?23, Medium >23 and ?59, High >59

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