Much has been learned about the proper and judicious use of fertilizers. Fertilizer application by farmers has grown from an art to a science. As food producers have strived to increase crop yields by overcoming nutrient deficiencies the use of fertil izers has increased dramatically. This has created a large chemical industry capable of supplying the needed plant food elements. A more complete understanding of soil chemistry and plant nutrition has led to greater fertilizer use with improved fertilization methods and crop cultural practices. Improved fertilizer technology has led to the production of more efficient forms of fertilizer. The modem fertilizer industry and with it fertilization practices began in the humid countries of the world. The use of fertilizers in arid and semiarid regions was later in development, although agriculture had its beginning in semiarid and arid regions. The development offertilizer use is parallel to industrial development in various areas of the world.

Forward. A call for integrated soil fertility management in Africa. Introduction. ISFM and the African farmer. Part I. The principles of ISFM: ISFM as a strategic goal, Fertilizer management within ISFM, Agro-minerals in ISFM, Organic resource management, ISFM, soil biota and soil health. Part II. ISFM practices: ISFM products and fields practices, ISFM practice in drylands, ISFM practice in savannas and woodlands, ISFM practice in the humid forest zone, Conservation Agriculture. Part III. The process of implementing ISFM: soil fertility diagnosis, soil fertility management advice, Dissemination of ISFM technologies, Designing an ISFM adoption project, ISFM at farm and landscape scales. Part IV. The social dimensions of ISFM: The role of ISFM in gender empowerment, ISFM and household nutrition, Capacity building in ISFM, ISFM in the policy arena, Marketing support for ISFM, Advancing ISFM in Africa. Appendices: Mineral nutrient contents of some common organic resources.

Interest in African irrigation investment is growing. However, irrigation is not a monolithic concept, and the opportunities and risks can vary substantially by approach. To help provide an understanding of the variation, this paper builds on previous work to provide a detailed typology of irrigation systems as currently used in Ghana.

Problems of irrigated regions; Soil as a medium for plant growth; Soil and water relations; The salt problem; Evaluating land for irrigation; Source and quality of irrigation water; Measuring irrigation water; Planning A farm for irrigation; Irrigation practice Dainage; Reclamation and management of saline and alkali soils; Control of the physical properties of soil; Control of the biological properties of soil; Maintaining organic matter in soil; Minerals and plant growth; Fertilizer elements and fertilizer materials; Using fertilizers; Soil management for general field crops; Soil management for fruit, vegetable and specialty crops; Farm planning.

Precision farming involves soil fertility and crop growth monitoring, electronic equipment, remote sensing, global information and positioning systems, computer models, decision support systems, variable-rate technology, and accurate recordkeeping. This book on precision techniques provides valuable information on instrumentation and methodology. I

World Bank Technical Paper No. 408. This report is a critical review of the technical, economic, and institutional constraints on improving soil fertility in Sub-Saharan Africa, and the actions recommended to address them. Action plans prepared for Ghana, Kenya, Malawi, and Mali examine the demand for and supply of mineral fertilizers, the exploitation of local mineral resources, the prevention of soil erosion and increasing soil-water retention, and soil fertility management using organic technologies and management practices.