Soil degradation and nutrient depletion have become serious threats to agricultural productivity in Africa. Soils cannot supply the quantities of nutrients required and yield levels decline rapidly once cropping commences. This book addresses these issues and includes papers from an international symposium held at Cotonou, Benin, October 9-12, 2000, organized by the International Institute of Tropical Agriculture, Ibadan, Nigeria and the Department of Land Management of the Katholieke Universiteit Leuven, Belgium. In five main parts it marks the end of a first phase of collaborative research on "Balanced Nutrient Management Systems for the Moist Savanna and Humid Forest Zones of Africa" and concludes with recommendations, providing essential reading for crop and soil scientists.

Table of Contents:
Part I: General Introduction 1: Forty years of soil fertility work in sub-Saharan Africa, R Dudal 2: Soil fertility replenishment takes off in East and Southern Africa, P A Sanchez and B A Jama Part II: Variability in biophysical and socio-economic factors and its consequences for selection of representative areas for nutrient balance experiments; possibilities and techniques for extrapolation 3: A systems approach to target balanced nutrient management in soil scapes, J Deckers 4: In for a penny, in for a pound: Strategic site-selection as a key element for on-farm research that aims to trigger sustainable agricultural intensification in West Africa, M E A Schreurs, A Maatman and C Danbégnon 5: Agricultural transformation and fertilizer use in the cereal-based systems of the northern Guinea savanna, Nigeria, V M Manyong, K O Makinde and A G O Oguingbile 6: Partial macro nutrient balances of mucuna/maize rotations in the Forest Savannah Transitional Zone of Ghana, J Anthofer and J Kroschel Part III: Soil processes determining nutrient dynamics, in particular nitrogen and phosphorus; modelling nutrient fluxes in tropical farming systems 7: Process research and soil fertility in Africa: who cares? R Merckx 8: Fertilizer equivalency values of organic materials of differing quality, H K Murwira, P Mutuo, N Nhamo, A E Marandu, R Rabeson, M Mwale and C A Palm 9: Plant N uptake from plant and animal organic residues, measured using the soil pre-labelling 15N isotope dilution approach, R Hood 10: Contribution or organic residues to soil phosphorus availability in the highlands of Western Kenya, G Nziguheba, R Merckx and C A Palm 11: Resource acquisition of mixed species fallows - competition or complementarity? G Cadisch, S Gathumbi, J K Ndufa and K E Giller Part IV: Interactions between organic and inorganic nutrient sources; functions of soil organic matter 12: Targeting management of organic resources and mineral fertilizers: Can we match scientists' fantasies with farmers' realities? K E Giller 13: Direct interactions between N fertilizer and organic matter: evidence from trials with N labelled fertilizer, B Vanlauwe, J Diels, K Aihou, E N O Iwuafor, O Lyasse, N Sanginga and R Merckx 14: On-farm evaluation of the contribution of sole and mixed applications of organic matter and urea to maize grain production in the savanna, E N O Iwuafor, K Aihou, J S Jaryum, B Vanlauwe, J Diels, N Sanginga, O Lyasse, J Deckers and R Merckx 15: Yields trends and soil nitrogen and organic matter content during twenty years of continuous maize cultivation, J Gigou and S K Bredoumy Part V: Improved utilisation of rock phosphate; capitalisation of soil phosphorus 16: Meeting the phosphorus needs of the soils and crops of West Africa: The role of indigenous phosphate rocks, U Mokwunye and A Bationo 17: Options for increasing P availability from low reactive rock phosphate, O Lyasse, B K Tossah, B Vanlauwe, J Diels, N Sanginga and R Merckx 18: Phosphorus (P) uptake from sparingly available soil-P by cowpea (Vigna unguiculata) genotypes, G Haar, T S Gahoonia, and N E Nielsen 19: Improving rock-P solubility and uptake and yields of lowland rice grown on acidic soil amended with legume green manure, E A Somado, R F Kuehne, M Bvecker, K L Sahrawat, and P L G. Viek Part VI: Decision support systems to improve fertilizer use efficiency at farm level; on-farm testing of technologies improving the soil nutrient balance 20: Decision making on integrated nutrient management through the eyes of the scientist, the land user and the policy maker, E M A Smaling, J J Stoorvogel and A de Jager 21: Legumes, when and where an option? (No panacea for poor tropical West African soils and expensive fertilizers), H Breman and H van Reuler 22: Options for soil organic carbon maintenance under intensive cropping in the West-African Savanna, J Diels, K Aihou, E N O Iwuafor, R Merckx, O Lyasse, N Sanginga, B Vanlauwe and J Deckers 23: On-farm research and operational strategies in soil fertility management, P L Woomer, E J Mukhwana and J K Lynam Part VII: Recommendations 24: Recommendations