1. The Soil Ecosystem: Physical and Chemical Boundaries -- 2. The Soil Ecosystem: Biological Participants -- 3. Energy Transformations and Metabolic Activities of Soil Microbes -- 4. Process Control in Soil -- 5. Soil Enzymes as Indicators of Ecosystem Status -- 6. Microbial Interactions in Soil and Community Development and Resilience -- 7. The Rhizosphere/Mycorrhizosphere -- 8. Introduction to the Biogeochemical Cycles -- 9. The Carbon Cycle -- 10. The Nitrogen Cycle: Soil-Based Processes -- 11. Nitrogen Fixation: The Gateway to Soil Nitrogen Cycling -- 12. Symbiotic Nitrogen Fixation -- 13. Denitrification -- 14. The Sulfur and Related Biogeochemical Cycles.