The world-wide shortage of plant production menacing the survival of many people demands for more and better research, particularly on how to increase food and where it is most needed. Major problems of international concern for the scientific community are the availability in soil media of macro and micro nutrients and the efficiency of nutrient uptake by plant roots, the interactions between nutrients and other factors, the distribution of nutrients in different plant species, biochemical functions of nutrient elements, and their contribution to plant growth, yield and product quality. Feasibility and profit are also permanent concerns about plant nutrition in crop management, to which new require­ ments are now imposed by the need to decrease pollution hazards, a problem of prime importance to preserve the environment of the future. is A deeper insight into basic knowledge further required as well as into practical problems in the domains of agriculture, horticulture, and forestry. Such has been the concern of the International Association for the Optimization of Plant Nutrition (IAOPN) since 1964, promoting International Colloquia every four years as an opportunity for scientists concerned with plant nutrition to report new findings and to exchange ideas, experiences, and techniques. The Eighth International Colloquium for the Optimization of Plant Nutrition was hosted by Portugal and held in Lisbon from 31 August to 8 September 1992, with 280 delegates from 34 countries.