Synthesis of soil, water and nutrient management research in the Volta Basin Edited by: Bationo A TSBF-CIAT, Nairobi,Kenya Tabo R. ICRISAT, Niamey, Niger Waswa B. TSBF-CIAT, Nairobi, Kenya Okeyo J. TSBF-CIAT, Nairobi,Kenya Kihara J. TSBF-CIAT, Nairobi,Kenya Fosu M. Savanna Agricultural Research Institute (SARI) Tamale, Ghana Kabore S. Institut de L’Environnement et de Recherches Agricoles (INERA), Burkina Faso Synthesis of soil, water and nutrient management research in the Volta Basin i ISBN 978-92-9059-220-04 Published by Ecomedia Ltd P.O Box 30677-00100 Nairobi, Kenya Tel. 020 7224280 Email: ecomedia @cgiar.org All Right researved © 2008 TSBF ii Synthesis of soil, water and nutrient management research in the Volta Basin Content Preface v Foreword vii Chapter 1 General Characteristics of the Volta Basin 1 Bationo A., Tabo R., Okeyo J., Kihara J., Maina F., Traore P. C. S. and Waswa B. Chapter 2 Soil Resources of Ghana 25 Asiamah R. D. Chapter 3 Agroforestry and soil fertility maintenance 43 Bayala J. and Ouedraogo S. J. Chapter 4 Soil Organic Matter and Nitrogen in Ghanaian Soils: A review 67 Fosu M. and Tetteh F. M. Chapter 5 Infl uence du mode de gestion de la fertilité des sols sur l’évolution de la matière organique et de l’azote dans les zones agro écologiques du Burkina Faso 83 Bonzi M., Lompo F., Kiba D. I. et Sedogo M. P. Chapter 6 Role of legumes in soil fertility maintenance in Ghana 99 Buah S. S. J. Chapter 7 Rôle des légumineuses sur la fertilité des sols et la productivité des systèmes de cultures 127 Bado B. V., Bationo A., Lompo F., Sedogo M. P., Cescas M. P., Sawadogo A. et Thio B. Chapter 8 Soil and water conservation in Ghana: practices, research and future direction 143 Agyare W. A., Antwi B. O. and Quansah C. Synthesis of soil, water and nutrient management research in the Volta Basin iii Chapter 9 Integrated Soil, Water and Nutrient Management for Sustainable Irrigated Rice Systems in Burkina Faso 159 Segda Z. and Sedogo M. P. Chapter 10 Review of Work on Soil Phosphorus in Ghana 189 Issaka, R. N., Buri, M. M., Tetteh, F. M. and Boadi, S. Chapter 11 Promotion de l’utilisation des phosphates locaux pour la recapitalisation de la fertilité des sols au Sahel : Etat des lieux des connaissances sur la valorisation agronomique des phosphates naturels du Burkina Faso 205 Bonzi M., Lompo F. et Sedogo M. P. Chapter 12 Cropping systems, land tenure and social diversity in Wenchi, Ghana: implications for soil fertility management 233 Adjei-Nsiah S. Chapter 13 Impact Socio-economique des Technologies de Conservation des eaux et des Sols au Burkina Faso 251 Ouedraogo S. Chapter 14 Livestock and soil fertility - Elevage et maintien de la fertilité des sols 269 Kabore S., Sawadogo M. and Traoré F. Chapter15 Economic Evaluation of Water and Nutrient Management Technologies In Ghana: a Literature Review 297 Abatania L. N. and Bediako J. A. Chapter 16 Cropping Systems: With particular emphasis on dry season vegetable production in Ghana. Kanton R. A. L. 313 Chapter17 Way forward and future perspectives 325 Tabo R., Bationo A., Hassane O., Fatondji D., Abdou A. and Koala S. iv Synthesis of soil, water and nutrient management research in the Volta Basin Preface The majority of the population in the Volta basin is resource poor smallholders who rely on rainfed agriculture for their livelihoods. However, the average rainfall of 1000 mm per year, which seems to be enough for crop production in the region, is quite variable, thereby making rainfed agriculture a risky enterprise. The distribution of rain over the growing season has also been noted to be another bottleneck in agricultural production. Especially the onset of the rainy season is very unreliable and the frequent periods of drought (10-20 days) within the season cause signifi cant crop damage. Furthermore, there has been a decrease in rainfall in most of the region since the 1960’s when compared to the 20th century average. Food security is under threat in the entire Volta basin due to the low water availability, increasing soil degradation and the dwindling farm sizes. Crop failure results quite often as a result of low and poorly distributed rainfall, increasing land degradation caused by inappropriate management practices like plowing and intensive hoeing causing surface crusting, soil compaction, decrease in soil organic matter and hard- pan formation. All these have contributed to the ineffi cient use of the precious and scarce water available. Water and nutrient use effi ciency is therefore the key to improving agricultural and livestock productivity in the Volta Basin. Improving water productivity will mean getting more value from every drop used for crops, fi sh, forests or livestock while maintaining or improving ecosystems services. More importantly past research have shown that only 10% of the rainwater is used by the crop, the majority of it being lost to evaporation In the past, international and national agricultural research systems have developed high-yielding cereal and legume varieties that respond to different rainfall regimes. However, although it is known that an integrated approach to water, crop and nutrient management is essential for increasing and stabilizing crop production and optimizing inputs use, there is a dearth of empirical studies on such interactions. Furthermore, majority of research has been conducted with little participation of farmers and rural communities who are the ultimate users and benefi ciaries of research results. This has largely limited the adoption of agricultural technologies by small scale farmers, especially women who constitute the majority of farming population. We now know that farmers and rural communities are searching for new ways to intensify and diversify their systems to meet their food security needs as well as generating income, and seize upcoming market opportunities. A win-win situation can occur when a systems research integrates germplasm, crop, nutrient, soil and water management, with explicit focus to empowering farmers and rural communities to take advantage of market opportunities to raise their incomes and invest in better management of their resources. New tools such Geographical Information Systems (GIS) and models can be very useful in facilitating the analysis of these integrated systems. The DSSAT-CENTURY (Decision Support for Agro technology Transfer) Synthesis of soil, water and nutrient management research in the Volta Basin v cropping systems models enables the analysis of how different soil, climatic and land management strategies affect the yield of a range of crops. On the other hand, participatory research approaches have been found very effective in enhancing the adoption of technologies, empowering rural communities and promoting equity. The project entitled “Enhancing rainwater and nutrient use effi ciency for improved crop productivity, farm income and rural livelihoods in the Volta basin” is funded by the Challenge Program on Water and Food (CPWF) and led by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). It is designed to address the major constraints that are encountered by small-scale resource-poor farmers in the Volta Basin, who rely on rain fed agriculture for their livelihoods. The overall research hypothesis is that using a systems approach that integrates water use effi ciency, soil and nutrient management, and improved germplasm together with market opportunity identifi cation and building rural communities capacity will result in signifi cant benefi ts to the rural poor and the environment. As one of the major outputs of the project, this book which contains 16 chapters covers a range of topics related to natural resource management in the Volta basin. The authors have made a good synthesis and review of the soil, water, crop and nutrient management research in the Volta basin. The biophysical and socio- economic characteristics of the Volta Basin are described extensively in chapter 1. Chapters 2 to 16 contain the syntheses of the research and development work that was conducted, over the years, by various research organizations in Burkina Faso and Ghana that are the participating countries in this project. From this information, constraints to agricultural productivity and opportunities for complementary research were identifi ed. The book provides excellent background information to guide future research activities in the Volta basin. As editors of this synthesis book, we would like to thank all the authors for their efforts in pulling together this vast amount of information on the research work on soil, water, nutrient and crop management in the region. We wish to express our sincere gratitude to the reviewers for their invaluable comments and suggestions which helped the authors to improve on their papers. We are most grateful to the Challenge Program on Water and Food (CPWF) for providing the necessary funds for this project and for the publication of the book. Andre Bationo, Ramadjita Tabo, Boaz Waswa, Jeremiah Okeyo, Job Kihara, Mathias Fosu and Seraphine Kabore vi Synthesis of soil, water and nutrient management research in the Volta Basin Foreword Throughout the world, water scarcity constitutes one of the most pressing issues that humanity faces today. Suffi cient water supply is critical for human health, agriculture and poverty reduction. However, this resource is in considerable shortage, both in terms of availability and quality and the most impoverished inhabitants of developing countries are the most vulnerable, with very limited coping strategies. The majority of the population living in the Volta Basin comprises resource poor smallholders who depend on rainfed agriculture for their livelihoods. However, the average rainfall of 1000 mm per year, which seems to be enough for crop production in the region, is quite variable over the cropping season, thereby making rainfed agriculture a risky enterprise. Furthermore rainfall amount has been decreasing in the most parts of the region since the 1960’s compared to the 20th Century average.