Many investigators have studied the organic matter in soils, in the attempt to determine its nature and composition, the rate and character of the decomposition which it undergoes, the products of decomposition, and especially the value of various kinds of organic materials which may be applied to soils, as indicated by decomposition studies.
Smith, F. B. and Brown, P. E.
"Methods for determining Carbon dioxide production in soils,"
Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 12
, Article 1.
Available at: https://lib.dr.iastate.edu/researchbulletin/vol12/iss147/1