Preface. Contributors.Chapter 1. The Chemical Structure of Humic Substances: Recent Advances (Cesareo Saiz-Jimenez). Chapter 2. Humus in World Soils (Francis Andreux). Chaptr 3. Organic Matter Dynamics in Forest Soils of Temperate and Tropical Ecosystems (Wolfgang Zech et al.). Chapter 4. Dissolved Humus in Soil Waters (Adam Zsolnay). Chapter 5. Humus and Soil Conservation (Alessandro Piccolo). Chapter 6. Microorganisms and Humus in Soils (Heribert Insam). Chapter 7. Humus and Enzyme Activity (Paolo Nanniperi, P. Sequi, P. Fusi). Chapter 8. Organisms and Humus in Soils (Lijbert Brussaard, N.J. Juma). Chapter 9. Biological Activity of Humus (Serenella Nardi, G. Concheri, G. Dell'Agnola). Chapter 10. Organic Forms of N in Soil (Kenneth R. Kelley, F.J. Stevenson). Chapter 11. Dynamics of Organic Phosphorus in Soils under Natural and Agricultural Ecosystems (Jacob Magid, H. Tiessen. L.M. Condron). Chapter 12. Soil Organic Sulphur and its Turnover (Fang-Jie Zhao, J. Wu, S.P. McGrath). Chapter 13. Organic Matter Reactions Involving Micronutrients in Soils and their Effect on Plants (Yona Chen). Chapter 14. Humic-like Substances in Organic Amendments and Effects on Native Humic Substances (Nicola Senesi, T.M. Miano, G. Brunetti). Chapter 15. Interactions of Humic Substances and Soil Clays (Juan Cornejo, M.C. Hermosin). Chapter 16. Soil Organic Matter as a Factor Influencing the Fate of Organic Chemicals in the Soil Environment (Josef Kozak). Subject Index.