ESTIMATING YIELDS AND YIELD GAPS: Experiences from East Africa - PowerPoint PPT Presentation

ESTIMATING YIELDS AND YIELD GAPS: Experiences from East Africa Godfrey Taulya, Lydia Wairegi, Piet van Asten International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

PRESENTATION OUTLINE 1. General approach 2. Yield estimation in banana/plantain systems 3. On-farm monitoring study vs. one-time farm visit survey 4. Non-destructive bunch weight estimation 5. Yield-determining factors and yield gaps International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

GENERAL APPROACH 1. What is happening in farmer fields ? 2. Study single factors in controlled environments 3. Field validation and testing for interactions 4. Modeling to understand interactions and extrapolate 5. Proposing technologies for on-farm testing International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

Understanding existing spatial variability at regional scale 0° Uganda L. Edward Kenya L. Victoria Rwanda L. Kivu Burundi Tanzania DRCongo L. Tanganyika 5°S 0 125 250 km 30°E 35°E International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

Understanding existing spatial variability diagnostics at farm scale Michael Okumu, Severine Delstanche International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

YIELDS IN BANANA/PLANTAIN SYSTEMS  Integrative index for impacts of: • constraints • cultural practices  Yield  bunch weight • Harvests are year-round • Temporal variations in fresh bunch weight International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

YIELD DATA COLLECTION BY FARMERS  One-time farm visits during surveys  patchy data o Mature bunches may be weighed o Immature bunches: visual ‘ guestimates ’ + extrapolation  Farm monitoring studies  comprehensive data o Challenge: Synchronizing farm visit with harvest operations  Yield data collection by farmers in monitoring studies o Extra demands on the farmer (time and labour) o Literacy/numeracy skills; accuracy and consistency in data o Restricting studies to literate farmers can bias datasets • Greater resource endowment, higher standard of management are correlated with higher literacy levels International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

ESTIMATION OF FRESH BUNCH WEIGHT  General allometric function for estimation of fresh bunch weight (FBW, kg) at harvest was established through linear regression: Where:  H is number of hands per bunch  F is number of fingers on second-last hand  V is the pseudostem volume at 1-m above ground (cm 3 )  k is linear regression intercept while a, b and c are coefficients Where:  G 0 is girth at base of pseudostem (cm)  G 1 is girth at 100 cm above ground level (cm) International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

APPLICATION OF ALLOMETRIC FUNCTION Across regions in Uganda Across cultivars in Uganda International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

LIMITING FACTORS AND YIELD GAPS  Each farm was visited once in 4 to 6 weeks  Input data for the allometric function were collected on flowered plants  Agronomic management/crop environment, pest damage data were also collected  Boundary line analysis  identify the limiting factor/s and to quantify the yield gap due to each factor International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

LIMITING FACTORS AND YIELD GAPS International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

LIMITING FACTORS AND YIELD GAPS International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

CONCLUSIONS  Evaluation of yield-determining factors during plant growth, and  Non-destructive estimation of bunch weights based on allometry permit:  Identification of limiting factors  Quantification of yield-gap International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org