This book is a specialized monograph on soil physical conditions and root-system relations. It attempts to explain the importance of physical properties of soil by showing how they affect root growth and functions; and on the other hand, how roots themselves change their environment. Emphasis is placed on the interactive effects of soil physical factors. An attempt has been made to analyze the possibilities of the root system's modification by both soil and plant management.The book is addressed to research workers and advanced students in soil and plant sciences and may also be of interest to agronomists and related specialists.