1st Edition

Water Productivity in Rainfed Agriculture Redrawing the Rainbow of Water to Achieve Food Security in Rainfed Smallholder Systems

By Hodson Makurira Copyright 2010
    170 Pages
    by CRC Press

    170 Pages
    by CRC Press

    The challenge of water scarcity as a result of insufficient seasonal rainfall and dry spell occurrences during cropping seasons is compounded by inefficient agricultural practices by smallholder farmers where insignificant soil and water conservation efforts are applied. The hypothesis of this research is that many of the past research efforts have taken a fragmented approach to deal with the challenges facing subsistence farmers in rainfed systems.

    The research has been conducted in the semi-arid Makanya catchment of northern Tanzania and has successfully applied different analytical techniques to better understand soil and water interactions at field scale. It has been demonstrated that there is indeed scope to increase crop water productivity provided the local farmers adopt more efficient cultivation techniques. Substantial yield increases occur as a result of diverting runoff and these further improve when other techniques such as ripping, application of manure and cover cropping are introduced. This confirms that no single solution exists to solve the problem of low yields in rainfed farming systems.

    However, even with these promising results, the research has shown that there is room to further improve the efficiency of crop water use through improvement in research approaches and exploration of better techniques.

    Chapter 1: Introduction
    1.1. Background
    1.2. The SSI Programme
    1.3. This research
    Chapter 2: Rainfed agriculture in sub-Saharan Africa
    2.1. Water and food security
    2.2. Water productivity
    2.3. Water for food in sub-Saharan Africa
    2.4. Scope for improved crop productivity
    2.5. Research and information gaps
    2.6. Objectives and research questions
    2.6.1. Main objectives
    2.6.2. Key research questions
    Chapter 3: The study area
    3.1. Physiography
    3.2. Rainfall
    3.3. Demography
    3.4. Soils
    3.5. Current land use practices
    3.6. Water for food security and coping strategies
    3.7. Yields obtained
    3.8. Traditional farming preferences
    3.9. Discussion and conclusions
    Chapter 4: Research sites and observation techniques
    4.1. Site selection
    4.2. Background to the development of tested techniques
    4.2.1. Conservation tillage
    4.2.2. Seed selection
    4.2.3. Cover cropping and manure
    4.2.4. Rainwater harvesting
    4.3. Typical experimental setting
    4.4. Conceptual framework
    4.5. Parameters measured
    4.5.1. Rainfall
    4.5.2. Net in-field runoff contribution
    4.5.3. Soil evaporation
    4.5.4. Soil moisture measurements
    4.5.5. Biomass and leaf area measurements
    4.5.6. Yield observations
    4.6. Results
    4.6.1. Rainfall
    4.6.2. Runoff generation
    4.6.3. Net runoff contribution
    4.6.4. Soil moisture observations
    4.6.5. Soil evaporation
    4.6.6. Biomass measurements
    4.6.7. Obtained yields
    4.7. Discussion and conclusions
    Chapter 5: Water partitioning analysis using modelling techniques
    5.1. Introduction
    5.2. Water balance modelling
    5.2.1. Results
    5.2.2. Water balances
    5.2.3. Analysis and discussion of results
    5.2.4. Conclusions
    5.3. Application of the HYDRUS2D model to interpret sub-surface flow dynamics
    5.3.1. Background to the HYDRUS2D model
    5.3.2. Model setup and inputs
    5.3.3. Results
    5.3.4. Discussion and conclusions
    5.4. Application of geophysical methods and repeated soil moisture measurements to interpret sub-surface flow dynamics
    5.4.1. Introduction
    5.4.2. Direct soil moisture monitoring
    5.4.3. Indirect soil moisture monitoring (ERT)
    5.4.4. Data processing
    5.4.5. Results
    5.4.6. Discussion
    5.4.7. Conclusions
    Chapter 6: Productivity analysis
    6.1. Introduction
    6.2. Data collection
    6.3. Data analysis
    6.3.1. Grain yield
    6.3.2. Water productivity
    6.4. Discussion of results
    6.4.1. Water availability
    6.4.2. Yields and water productivity
    6.4.3. Additional benefits of "improved" techniques
    6.5. Conclusions
    Chapter 7: Synthesis of the research
    Chapter 8: Conclusions

    Biography

    Hodson Makurira obtained his BSc in Civil Engineering from the University of Zimbabwe and his MSc from the International Institute for Infrastructural, Hydraulic and Environmental Engineering (now UNESCO-IHE) in Delft, The Netherlands. He worked as a water resources engineer for the Ministry of Water Resources and Development and for the Zimbabwe National Water Authority. He is currently a lecturer at the University of Zimbabwe and involved in several educational and research development programmes. His subjects of expertise are improving livelihoods for semi-arid rainfed environment communities, mitigation of dry spells on crop productivity and water partitioning processes at field scale and the linking to crop productivity.