Assessment of potential impact of climate change on peanut yield in Senegal through a modelling approach

iii ACKNOWLEDGMENTS . v DEDICATION . vi LIST OF TABLES . xii LIST OF FIGURES . xiii LIST OF ABBREVIATIONS . xvi CHAPTER ONE . 1 GENERAL INTRODUCTION . 1 Study background . 1 Problem statement . 5 Objectives . 7 Hypotheses . 8 Thesis structure . 9 CHAPTER TWO . 10 LITERATURE REVIEW . 10 Importance of peanut in West Africa . 10 Effect of fertilizer application and drought stress on peanut . 14 Fertilizer application . 14 Drought stress . 15 Modelling crop growth and yield in West Africa . 16 Climate change impact analysis on crop over West Africa . 19 Digitized by UCC, Library viii Modelling heat stress on crop for climate change studies . 23 Impact of climate change on peanut yield and adaptation . 25 CHAPTER THREE . 28 MATERIALS AND METHODS . 28 Study area. 28 Description of the experimental procedure . 32 Effects of fertilization rate and water availability on peanut in Senegal . 34 Field measurements of crop parameters . 35 Phenological observations . 35 Leaf area index . 37 Biomass sampling . 37 Soil sampling and analysis . 38 Bulk density . 39 Soil moisture measurement in-situ. 39 Data analysis . 39 Model development . 40 Experimental data . 40 Soil properties . 40 Weather data . 41 Model description . 43 Model parameterizations . 48 Model calibration and evaluation. 52 Model calibration procedure . 53 Model evaluation . 56 Climate change impact analysis on peanut . 57 Digitized by UCC, Library ix Simulation setup. 59 Climate model input . 61 Observed data analysis . 61 Scenario data analysis . 62 Input data . 62 Harvest yield estimation . 66 CHAPTER FOUR . 68 RESULTS . 68 Soil analysis . 68 Effects of fertilization rate and water availability on peanut in Senegal . 70 Above ground Biomass (AGB) . 70 Leaf area index (LAI) . 73 Harvest yield . 75 Effect of water stress on peanut yield . 77 Final biomass yield . 77 Seed yield . 80 Effect of fertilizer application rate on peanut yield . 83 Final biomass yield . 83 Seed yield . 85 Evaluation of performance of SIMPLACE crop model for peanut in Senegal . 87 Model calibration and evaluation. 87 No heat stress and no drought stress . 87 With heat stress and without drought stress . 90 With combined heat stress and drought stress . 91 Evaluation of model performance . 94 Digitized by UCC, Library x Model performance for simulating above ground biomass and leaf area index . 94 Model performance for simulating seed yield . 96 Climate impact analysis and adaptation strategies to climate change on peanut in Senegal . 98 Climate data analysis . 98 Standard precipitation index (SPI) and temperature anomalies for observation . 98 Simulation of inter-annual variation of precipitation and temperature . 99 Climate change analysis . 102 Yield changes under projected climate change conditions . 105 Relative changes in biomass yield . 105 Biomass yield under dry season condition with irrigation . 105 Biomass yield under rainy season condition with irrigation . 107 Biomass yield under rainy season condition without irrigation. 109 Relative seed change yield . 111 Seed yield under the dry season . 111 Seed yield with irrigation in the rainy season . 113 Seed yield without irrigation under rainy season . 115 Seed yield without irrigation under rainy season condition according to the sowing date. 117 CHAPTER FIVE . 119 DISCUSSION . 119 Soils properties. 119 Effect of water stress on peanut development, growth and yield . 120 Modelling heat and drought stress on peanut . 124 Digitized by UCC, Library xi Climate change impact analysis . 128 Bias correction of precipitation and temperature . 128 Impact of climate change on peanut . 129 Biomass yield . 129 Seed yield .