Nitrogen constitutes about 79 percent of the earth's atmosphere, yet, in an agricultural plant production system, it is still common for soils to be deficient of the nitrogen needed for maximum plant growth. But nitrogen fertilizers that are essential for the economically driven production of food and fiber are recognized as polluters of natural waters, and it has become increasingly apparent that manufactured and naturally occurring nitrogen resources must be better managed. This book addresses the problem by describing how the various factors such as types of soils and crops, irrigation methods, climate, and the nitrogen cycle itself affect levels of nitrogen in plant production systems. The book also provides a practical guide to the many advantages and disadvantages of using different fertilizers across such factors as environment, type of plant, and method of farming. This book will be part of the solution to nitrogen management and agricultural problems and will be of interest to workers in local, state, and federal agricultural extension services, consulting firms, environmental regulators, and students and researchers in soil chemistry. This book is intended for workers in