Soil Salinity and Its Effects on the Coastal Peri-Urban Vegetable
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RHEINISCHE FRIEDRICH-WILHELMS-UNIVERSITÄT BONN Faculty of Agriculture M A S T E R T H E S I S As part of the Master programme Agricultural Science and Resource Management in the Tropics and Subtropics Submitted in partial fulfilment of the requirements for the degree of „Master of Science“ Soil salinity and its effects on the coastal peri-urban vegetable production system of Maputo, Mozambique – exploration of the status quo and management recommendations – submitted by: Jakob Herrmann 2964974 submitted on: 09.05.2019 first examiner: apl. Prof. Dr. Nazim Gruda second examiner: PD Dr. Heide Hoffmann Declaration I hereby affirm that I have prepared the present paper self-dependently, and without the use of any other tools, than the ones indicated. All parts of the text, having been taken over verbatim or analogously from published or not published scripts, are indi- cated as such. The thesis hasn’t yet been submitted in the same or similar form, or in extracts within the context of another examination. Bonn, 09.05.2019 _______________________________ Jakob Herrmann Acknowledgements I wish to thank, first of all, the “Stiftung für Tropische Agrarforschung”. Without its finan- cial support the research stay in Maputo might not have been possible. Furthermore, I am indebted to Professor Famba, Professor Magaia, Professor Nuvunga, and Professor Chiconela from the agricultural faculty of the University Edu- ardo Mondlane, who provided scientific guidance and who have done everything pos- sible to support my research activities. I share the credit of my work with the team of the agricultural soil and water laboratory of the Eduardo Mondlane, first and foremost, Dr. Machava, Romano Guiamba and Jo- sé Matlombe. I am thankful for your mentorship and active support of my research en- deavor. The same holds true for the colleagues of the Department of Economic Activi- ties of the Municipality of Maputo and the Casa Agraria of KaMavota. I especially want to thank Matias Siueia Júnior and senhor Mania for their genuine interest, and support of all field research activities. Not to forget, Evelina Carlos Manhiça from the agricultur- al faculty of the University Eduardo Mondlane, for being a valuable research partner. I am highly indebted to all the interview partners who shared their time, knowledge and thoughts with me. Without you, this thesis would not have been possible. A very special thanks goes to all the farmers who regularly welcomed me at their fields, and occa- sionally even supplied me with fresh vegetables. Lastly, I would like to thank Professor Hoffmann and Professor Gruda for their scientific supervision of this thesis; as well as the UFISAMO research team for their support in organizational matters and occasional interchange of ideas. Dedication This thesis is dedicated to my family and friends. I am grateful for your consistent support. Table of Content List of Abbreviations and Technical Terms ..................................................................... i List of Tables ................................................................................................................. ii List of Figures ............................................................................................................... iii List of Annexes ............................................................................................................. iv Summary ....................................................................................................................... v 1 Introduction ................................................................................................................ 1 1.1 Thematic Contextualization .................................................................................. 1 1.2 Conceptual and Methodological Framework ........................................................ 3 1.3 Hypothesis, Objectives and Organization of the Thesis ........................................ 5 2 Review: Soil Salinity and Vegetable Production .......................................................... 7 2.1 Characteristics and Development of Salt-Affected Soils ....................................... 7 2.2 Soil Salinity Effects on Plant Growth and Crop Production ................................... 8 2.3 Agronomic Management of Soil Salinity ............................................................. 13 3 Study Location: Maputos’ Peri-Urban Vegetable Production System ........................ 21 3.1 Geographic Context ........................................................................................... 21 3.2 Socio-Political Context ....................................................................................... 22 3.3 Economic Context .............................................................................................. 25 3.4 Bio-Physical Context .......................................................................................... 27 3.5 Soil Salinity as an Impairing Factor .................................................................... 29 4 Methodology and Research Process ........................................................................ 32 4.1 Literature Review ............................................................................................... 32 4.2 Field Research Site ............................................................................................ 32 4.3 Interviewing and Field Observations .................................................................. 34 4.4 Participatory Soil and Water Survey ................................................................... 36 5 Results: Local Perception and Management of Soil Salinity within Maputos’ Peri- Urban Vegetable Production Areas ............................................................................. 39 5.1 General Farming Practices and their Underlying Rationales .............................. 39 5.2 Local Indicators for Soil Salinity and Economic Evaluation ................................. 46 5.3 Local Perception on Significance, Causes, and Spatio-Temporal Dynamics of Soil Salinity .............................................................................................................. 48 5.4 Local Strategies to Cope with Soil Salinity ......................................................... 51 5.5 Participatory Soil and Water Survey ................................................................... 56 6 Discussion of the Studies’ Results ............................................................................ 59 6.1 General Farming Practices and their Underlying Rationales .............................. 59 6.2 Local Indicators for Soil Salinity and Economic Evaluation ................................. 60 6.3 Local Perception on Significance, Causes, and Spatio-Temporal Dynamics of Soil Salinity .............................................................................................................. 61 6.4 Local Strategies to Cope with Soil Salinity ......................................................... 63 6.5 Participatory Soil and Water Survey ................................................................... 65 7 Discussion of Potential Management Approaches Adapted to the Local Context ..... 67 7.1 Regional Management Approaches ................................................................... 67 7.2 Agronomic Management Approaches ................................................................ 69 8 Conclusions and Outlook .......................................................................................... 72 References .................................................................................................................. 74 Annexes ...................................................................................................................... 91 List of Abbreviations and Technical Terms ABIODES Associação pela Agricultura Biológica, Biodiversidade e Desenvolvimento Sustentável (Association for Biological Agriculture, Biodiversity and Sustainable De- velopment) Casa Agraria Governmental Agricultural Extension Institution at the District Level CMM Conselho Municipal de Maputo (Municipality of Maputo) DAE Departamento de Actividades Económicas (Department of Economic Activities of the Municipality of Maputo) DASACM Direção da Agricultura e da Segurança Alimentar da Cidade de Maputo (National Government Directorate of Agriculture and Food Security in Maputo) DMPUA Direcção Municipal de Planeamento e Urbanização (Municipal Directorate of Planning and Urbanization) ECe Electrical Conductivity of the Saturated Soil Paste Extract ECw Electrical Conductivity of Irrigation Water ESP Exchangeable Sodium Percentage of a Soil Green Zone Peri-Urban Agricultural Production Area; from port. Zona Verde IIAM Instituto de Investigação Agrária de Moçambique (Institute of Agrarian Research of Mozambique) MASA Ministerio da Agricultura e Seguranca Alimentaria (Ministry of Agriculture and Food Security) SAR Sodium Adsorption Ratio of a Soil Solution UEM University Eduardo Mondlane, Maputo i List of Tables Table 1: Classification of salt-affected soils. ................................................................. 7 Table 2: List of salt tolerant under-utilized leafy vegetable crop species. .................... 19 Table 3: Member and land statistics of the farmers associations of KaMavota. .......... 34 Table 4: Local bio-physical soil salinity indicators and economic evaluation categories for soil salinity. ...........................................................................................................