This 5th edition of "Principles of Plant Nutrition", first published in 1978, maintains the same format as in previous editions with the primary aim of the authors to consider major processes in soils and plants of relevance to plant nutrition. This new edition gives an up-to-date account of the scientific advances of the subject by reference to about 2000 publications. A feature of the book is its wide approach encompassing not only basic nutrition and physiology but also practical aspects of plant nutrition involving fertilizer usage and crop production of direct importance to human nutrition. Recognizing the international readership of the book, the authors as in previous editions have attempted to write in a clear concise style of English for the benefit of the many readers for whom English is not their mother tongue. The book should be of use to undergraduates and postgraduates, in agriculture, horticulture, forestry and ecology as well as those researching in plant nutrition.