Composting In Schools


Estimating Carbon Content

Tom Richard

If you know the nitrogen content for an ingredient, but not the carbon content or the C/N ratio, you can estimate the % C based on the volatile solids content if that value is known or can be measured. Volatile Solids (VS) are the components (largely carbon, oxygen, and nitrogen) which burn off an already dry sample in a laboratory furnace at 500-600°C, leaving only the ash (largely calcium, magnesium, phosporus, potassium, and other mineral elements that do not oxidize). For most biological materials the carbon content is between 45 to 60 percent of the volatile solids fraction. Assuming 55 percent (Adams et al., 1951), the formula is:

% Carbon = (% VS) / 1.8
where % VS = 100 - % Ash

References

Adams, R. C., F. S. MacLean, J. K. Dixon, F. M. Bennett, G. I. Martin, and R. C. Lough. 1951. The utilization of organic wastes in N.Z.: Second interim report of the inter-departmental committee. New Zealand Engineering (November 15, 1951):396-424. Return to citation in text.


Cornell
Composting

Science &
Engineering

Composting
in Schools

Resources

Cornell Waste Management Institute © 1996
Cornell University
Ithaca, NY 14853-5601
607-255-1187
 
cwmi@cornell.edu