This book provides various aspects of Soil Organic Matter and Biological Activity written in a simple and lucid style to help the reader grasp the information quickly and easily. The book contains 14 chapters and each chapter present update material sufficient to meet the students expectations from a basic textbook.Knowledge of this soil fraction is required by a variety of scientists, ranging from ecologists to agriculturalists. Many have strong academic backgrounds in soil, biological, and ecological sciences; many are novices. Thus the topics con Atained herein were developed with a gradient of complexity. The planks of basic knowledge were first laid before the complete structure of our understanding of each subject was constructed.This book is offered as an instrument to assist the evaluation of current knowledge and provide a direction in implementation of soil organic matter studies in future land use, ecosystem management, and reclamation plans.