A comparison of two methods for routine characterization of humus in pedological studies

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Abstract
Humus fraction analyses were conducted for six soil samples in applying the Nagoya and UBC methods, and the results were compared with one another. Permanganometry used in the Nagoya method sometimes produced significant errors in the estimation of total organic carbon. With the exception of one sample (Podzol Bhf), the Nagoya method always enabled to recover substantially more humic acid (HA) and fulvic acid (FA) than the UBC method, but the two methods yielded similar information with respect to HA/FA (Ch/Cr) ratios. Methodological differences in assessing optical properties were too great to allow effective comparison between the results obtained by the two methods. Each method provided useful information on humus fraction properties not available from the other. In particular the separation of two HA fractions, and features of their optical absorption spectra (Nagoya method) and the separation of two FA components (UBC method) indicated major qualitative differences in the humus composition of the samples examined. The desirability of combining the best features of each method in a new procedure is indicated.