Chemistry of soil organic matter / Kyoichi Kumada. Kumada, Kyoichi, 1921- Soils Humic acid content. S592.8 .K86 1987 547 19 KUC Includes bibliographical references and index. Tokyo : Japan Scientific Societies Press ; Amsterdam ; Elsevier, 1987. 1987. 1987 Text xi, 241 p. : eng Developments in soil science ; 17