Book excerpt: A reference text focusing on basic organic chemistry and reactions of naturally occurring organic substances in soils. Covers pools of organic matter in soils, transformations, methods of extraction and fractionation. Section two deals primarily with the chemistry of known classes of organic compounds in soils including saccharides, lipids and constituents containing nitrogen, phosphorus and sulfur. Section three is concerned with basic organic chemistry of humic substances, followed by the importance of organic matter associations and interactions. Contains new chapters on NMR spectroscopy, analytical pyrolysis and on chemical structures.