Books:
Soil fauna: Key to soil organic matter dynamics and modelling: KEYSOM handbook of methods
Juan J. Jiménez & Juliane Filser
Mycorrhizal Fungi in South America
Marcela C. pagano & mÓnica a lugo
Soil Fauna Assemblages: Global to Local Scales
Uffe N. Nielsen
Earth Matters: How Soil Underlies Civilization
Richard Bardgett
Soil Ecology and Ecosystem Services
Edited by Diana H. Wall, Richard D. Bardgett, Valerie Behan-Pelletier, Jeffrey E. Herrick, Hefin Jones, Karl Ritz, Johan Six, Donald R. Strong and Wim H. van der Putten
Fundamentals of Soil Ecology
David Coleman, Mac Callaham, D. Crossley Jr.
Also, see a related blog post in the GSBI blog.