It is becoming more relevant to explore soil biological processes in terms of their contribution to soil fertility. For instance, some agricultural chemicals may either overshadow or enhance biological contributions to soil fertility. The challenge is to select land management practices that improve the capacity of biological processes to contribute to soil physical and chemical fertility while increasing the sustainability of farming systems for particular soils and climates. This book presents a comprehensive scientific overview of the components and processes that underpin the biological characteristics of soil fertility. It demonstrates the interdependence of soil biological fertility with physical and chemical characteristics of soil. The book highlights the enormous diversity of life in soil and the resulting effects that management of land can have on the contribution of this diverse community to soil fertility in an agricultural context. It includes case studies of sustainable farming systems in relation to soil biological fertility and gives a global perspective on sustainability of soil management in relation to international agreements and environmental issue.