1;Preface;5 2;Contents;8 3;Contributors;17 4;Part I Introduction;22 4.1;What Are Soils?;23 4.1.1;1 Introduction;23 4.1.2;2 Soil Genesis;24 4.1.3;3 Biogeochemical Processes in Soils;28 4.1.4;4 Biotic Interactions Involving Soil Microorganisms;31 4.1.5;5 Integrative Considerations on Functions of Microorganisms in Specific Soil Compartments;33 4.1.6;6 Conclusion or Back to Biodiversity of Soil Microbes;35 4.1.7;References;36 4.2;Microbial Diversity in Soils;38 4.2.1;1 Introduction;38 4.2.2;2 Origin of Microbial Diversity;39 4.2.3;3 Types of Soil Microorganisms;41 4.2.4;4 Microbial Diversity and Biological Spheres;52 4.2.5;5 Microbial Diversity and Chemical Transformation;56 4.2.6;6 Microbial Diversity and Biotic Interactions;61 4.2.7;7 Conclusion;66 4.2.8;References;68 5;Part II Microorganisms and Soil Genesis;75 5.1;Role of Microorganisms inWear Down of Rocks and Minerals;76 5.1.1;1 RockWeathering or RockWear Down?;76 5.1.2;2 Carbon Dioxide and RockWear Down;80 5.1.3;3 Balance of Carbon Dioxide Sources and Sinks;85 5.1.4;4 RockWear Down as a Potential Carbon Dioxide Sink;87 5.1.5;5 The Fractal Dimension of Biological RockWear Down;88 5.1.6;6 Calcium Carbonate and SilicateWear Down, Dissolution and PrecipitationWith Special Reference to Biological Rock Degradation;91 5.1.7;7 Conclusions;96 5.1.8;References;97 5.2;Humification and Mineralization in Soils;102 5.2.1;1 Definitions and Introduction;102 5.2.2;2 Soil Organic Matter Resources;103 5.2.3;3 Mineralization and Humification Pathways;108 5.2.4;4 Conclusions;119 5.2.5;References;121 5.3;Importance of Microorganisms for Soil Aggregation;124 5.3.1;1 Introduction;124 5.3.2;2 Evidence of the Role of Soil Microorganisms;125 5.3.3;3 Microbial Metabolites Responsible for Soil Aggregation;127 5.3.4;4 Manipulation of Microbially Mediated Processes to Improve Soil Aggregation;130 5.3.5;5 Conclusion;132 5.3.6;References;132 6;Part III Microorganisms and Biogeochemical Processes in Soils;137 6.1;Microbial Energetics in Soils;138 6.1.1;1 Introduction;138 6.1.2;2 Soil, Energy and Microorganisms;139 6.1.3;3 Microbial Communities;142 6.1.4;4 Microbial Metabolism in Soil;144 6.1.5;5 Holistic Approaches to Evaluate Energetic Strategies of Soil Microbial Communities;148 6.1.6;6 Conclusions;151 6.1.7;References;151 6.2;Role of Microorganisms in Carbon Cycling in Soils;154 6.2.1;1 Introduction;154 6.2.2;2 Carbon Sources;155 6.2.3;3 Spatial Distribution and Protection of Carbon Sources;157 6.2.4;4 Spatial Distribution of Soil Microorganisms and Their Activities;158 6.2.5;5 Microorganisms and Enzymes Involved in C Cycling;162 6.2.6;6 Dynamics of Organic Matter Decomposition in Agroecosystems;163 6.2.7;7 Soil Organic Matter, Below-Ground Processes and Climate Change;166 6.2.8;References;168 6.3;Contribution of Bacteria to Initial Input and Cycling of Nitrogen in Soils;173 6.3.1;1 Introduction;173 6.3.2;2 Nitrogen Transformations in the Soil;174 6.3.3;3 Bacteria Involved in the Nitrogen Cycle;176 6.3.4;4 Nitrogen Fluxes;181 6.3.5;References;186 6.4;Influence of Microorganisms on Phosphorus Bioavailability in Soils;191 6.4.1;1 Introduction;191 6.4.2;2 Microbial Effects on Rhizodeposition;191 6.4.3;3 Mechanisms of Microbial Influence on Phosphorus Availability;193 6.4.4;4 Interactions Between Microorganisms and Higher Plants from Competition to Symbiosis;198 6.4.5;5 Phosphorus-Mobilizing Microorganisms as Biofertilizers;198 6.4.6;6 Conclusions;201 6.4.7;References;202 7;Part IV Biotic Interactions Involving Soil Microorganisms;206 7.1;Interactions Between Mycorrhizal Fungi and Bacteria to Improve Plant Nutrient Cycling and Soil Structure;207 7.1.1;1 Introduction;207 7.1.2;2 Beneficial Bacteria and Fungi in Agro- and Natural Ecosystems;208 7.1.3;3 Interactions Between Mycorrhizal Fungi and Symbiotic N2- Fixing Rhizobial Bacteria;209 7.1.4;4 Interactions Between Mycorrhizal Fungi and Phosphate- Solubilizing Bacteria;213 7.1.5;5 Interactions Between Mycorrhizal Fungi and Phytostimulators Azospirillum Bacte