OVERCOMING SOIL NUTRIENT CONSTRAINTS TO CROP PRODUCTION IN WEST AFRICA - IMPORTANCE OF FERTILIZERS AND PRIORITIES IN SOIL FERTILITY RESEARCH

The Alfisols, Oxisols, Ultisols and Inceptisols which dominate the soils of West Africa have sustained crop growth for a very long time. As a consequence, their fertility has become perilously low and the task of increasing or even maintaining the productive capacity of these soils has become perhaps the greatest challenge to agricultural scientists in this latter half of the 20th century. Water is useful not only for the growth of plants but also for the efficient use of costly inputs such as fertilizers. On the other hand, fertilizers increase the water-use efficiency. Such interactions must be closely studied so as to maximize the impact of inputs of agricultural production. The nutrients in the soil are always in a state of flux, with additions and substractions. Monitoring the dynamics of the nutrients would promote their efficient use by crops and prolong the productive life of the soils. Several models currently exist for the study of organic matter dynamics in soils. These models should be applied to the West African situation since it is vital to develop management practices that can promote efficient use of nutrients released during mineralisation of soil organic matter. Judicious fertilizer use in West Africa should be promoted as this practice will enhance agricultural production while protecting the fragile environment.