Aiming to provide comprehensive coverage on the subject, Tan (agronomy, U. of Georgia, Athens) begins with the basic concepts of humus and humic matter, including the controversy regarding humic matter as a real or false compound, followed by discussion of the nature and distribution of humic matter in a variety of environments; the extraction, isolation, and fractionation of humic substances; the genesis of humic matter; the chemical composition of humic matter; the characterization of humic substances by molecular weight and spectroscopic analysis; electrochemical properties of humic matter; the agronomic importance of humic matter; and the environmental and industrial importance of humic matter. Suitable as a textbook or as a reference.