The environmentally oriented specialties of microbiology are in the midst of a major paradigm shift from a focus on single or a few key microbial species to consideration of the entirety of the microbial community and its interactions. This fully revised and updated edition focuses on the importance of soil microbial communities to sustainability of terrestrial ecosystems and solutions to global problems. Basic principles are covered, and details of the finer points of processes and their implications have been updated. This is a one-of-a-kind reference for advanced students and professionals.