In Smallholder Farming Systems of Zimbabwe Brenda T. Manenji
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Understanding the current role of legumes and their significance for Biological Nitrogen Fixation (BNF) in smallholder farming systems of Zimbabwe Brenda T. Manenji MSc Thesis Plant Production Systems October, 2011 1 2 Understanding the current role of legumes and their significance in Biological Nitrogen Fixation (BNF) in smallholder farming systems of Zimbabwe Brenda Tsungai Manenji MSc Thesis Plant Production Systems PPS 80424 October 2011 Supervisor: Linus Franke (Wageningen University) Examiner: Ken E. Giller (Wageningen University) 3 4 Preface This research was my major Master thesis and the report is a part of N2 Africa project “Putting nitrogen fixation to work for smallholder farmers in Africa.” The project was funded by N2 Africa (Bill and Melinda Gates Foundation). This report was written for Plant Production Systems chair group of Wageningen University, the Netherlands. The field work for this study was carried out in Zimbabwe, in collaboration with TSBF- CIAT- Zimbabwe, in Mudzi and Murehwa districts from February-May 2011. 5 Acknowledgements I would like to thank everyone who contributed through one way or another for this work to be a success. Field work would not have been successful without the help of TSBF-CIAT, and the extension officers. Many thanks go to SPRL for the analysis of my soil and plant samples, and to Mazvita Murwira in particular for the cooperation when things seemed challenging. I greatly acknowledge my supervisor Franke Linus for the insightful advice he gave me. I am indebted to him for his academic input. Many thanks also to Ken Giller for the constructive ideas and reading materials. My sincere thanks go to people at the Plant Production Systems Group, Wageningen University for the support in my work. I would not have made it without the love and support from my family and friends. Thanks so much mum for the prayers and to Charity for being a pillar all the way. Finally I would like to thank God for seeing me through. 6 Table of Contents Preface................................................................................................................................... 5 Acknowledgements ................................................................................................................ 6 Table of Contents ................................................................................................................... 7 List of tables ........................................................................................................................... 9 List of Figures....................................................................................................................... 10 Abstract ................................................................................................................................ 11 1. Introduction ...................................................................................................................... 13 1.1 Background ................................................................................................................ 13 2. Methodology ..................................................................................................................... 17 2.1 Study sites .................................................................................................................. 17 2.2 Farm and plot characterization (Objective 1) ............................................................... 18 2.2.1 Development of farm typology .............................................................................. 18 2.2.2 Development of field typology ............................................................................... 19 2.2.3 Soil sample analysis ............................................................................................. 19 2.3 Quantifying legume productivity trends (Objective 2) .................................................. 20 2.3.1 Yield and farm area measurements. ..................................................................... 20 2.3.2 Legume-Total nitrogen analysis ............................................................................ 20 2.4 Agronomic practices (Objective 3) .............................................................................. 21 2.4.1 Nutrient management ........................................................................................... 21 2.5 Identification of opportunities for legume expansion (Objective 4) ............................... 21 2.6 Data collection sheets ................................................................................................. 21 2.7 Statistical analysis ...................................................................................................... 22 3. Results ............................................................................................................................. 23 3.1 Study sites .................................................................................................................. 23 3.2 Wealth classes and farm characterisation ................................................................... 23 7 3.3.1 Comparison of productivity between Mudzi and Murehwa .................................... 26 3.3.2 Maize and legume productivity in Mudzi ............................................................... 27 3.3.3 Maize and legume productivity in Murehwa .......................................................... 28 3.3 Agronomic practices ................................................................................................... 31 3.3.1 Soil fertility management ...................................................................................... 32 3.3.2 Crop allocation ..................................................................................................... 35 3.3.3 Use of legume residues ........................................................................................ 36 3.3.4 Cropping patterns ................................................................................................. 37 3.3.5 Sources of legume seed ....................................................................................... 38 3.3.6 Constraints faced in legume production ................................................................ 38 3.4 Legumes marketing .................................................................................................... 39 3.5.1 Soil status in Mudzi .............................................................................................. 41 3.5.2 Soil fertility status in Murehwa .............................................................................. 41 3.6 Soil structure ............................................................................................................... 44 3.7 Legume N analysis ..................................................................................................... 45 3.8 Nitrogen budget .......................................................................................................... 46 4. Discussion ........................................................................................................................ 51 4.1 Field and farm characterisation ................................................................................... 51 4.2 Productivity trends of legumes relative to maize ......................................................... 52 4.3 Agronomic practices adopted by different farmers ...................................................... 53 4.4 Opportunities to ensure expansion of legume production ............................................ 57 5. Conclusion ....................................................................................................................... 59 6. References ....................................................................................................................... 61 8 List of tables Table 1. Wealth indicators and the characteristics of the different groups .............................................. 18 Table 2: Characteristics of the different plot types for Mudzi and Murehwa ............................................. 19 Table 3: Distribution of farms in the different RGs in Mudzi and Murehwa ............................................. 24 Table 4: Annual organic and inorganic fertilizers (kg ha-1 yr-1) applied to maize in different plot types by farmers in different resource groups .............................................................................................. 25 Table 5: Areas and yields of maize and different legumes in the study areas ........................................ 26 Table 6: Number of farmers in the different resource groups growing legumes ..................................... 31 Table 7: Labour allocation between cereals and legumes by farmers in different resource groups ................................................................................................................................................................. 32 Table 8: Quantities of organic and inorganic N and P (Kg ha-1 yr-1) applied to maize in the different plot types by farmers in different RGs in (A) Mudzi and (B) Murehwa ...................................... 34 Table 9: Different ways of using groundnut, Bambara nut and cowpea residues (% farmers) ............ 37 Table 10: Sources of ground nut seed (% farmers) .................................................................................... 38 Table 11: Constraints