Book excerpt: Today's approach to crop production considers not only the effects of fertilizer applications on crop yield and quality but also includes awareness of the potential of fertilizer nutrients to adversely affect the environment. Managing crop nutrients deliberately and carefully takes on special significance in Hawaii, where imported nutrient inputs are costly and the environment--particularly the underground aquifer and coastal waters--is vulnerable to pollution. This book contains a distillation of decades of CTAHR research on soils, fertilizers, and crop nutrient needs, written for the lay reader and intended to provide a solid base of knowledge for the serious agriculturist. While the text makes reference to Hawaii's crops and soil conditions, its basic information is transferrable to similar tropical and subtropical locations throughout the world.