Soil ecology is the study of the interactions among soil organisms, and between biotic and abiotic aspects of the soil environment. It is particularly concerned with the cycling of nutrients, formation and stabilization of the pore structure, the spread and vitality of pathogens, and the biodiversity of this rich biological community. This book emphasizes the interrelations among plants, animals, and microbes, by establishing the fundamental physical and chemical properties of the soil habitat and then functionally chracterising the major components of the soil biota and some of their most important interactions. The fundamental principles underpinning soil ecology are established and this then enables an integrated approach to explore and understand the processes of soil understand them processes of soil nutrient cycling and the ecology of extreme soil conditions such as soil-water stress. This book is designed to meet the increasing challenges faced by today’s environmental scientists, ecologists, agriculturalists, and biotechnologists.