ABSTRACT

In a study at KNUST weather station,


the crop co-efficient values at initial, development, mid-season, and late


season stages of ABONTEM MAIZE (hybrid variety) were determined as 0.42, 0.98,


1.05, and 0.32, respectively. These locally determined values of ABONTEM hybrid


maize compared favourably with those recommended by FAO. The corresponding FAO


values are 0.4, 0.80, 1.15, and 0.70. The FAO values are average values and


recommended for a wide range of locations, but those determined by this study


are location specific. Another reason may be the use of specific variety of


hybrid maize in this experiment. However, locally determined values are


preferred to standard values (FAO values) in estimating location specific crop


evapotranspiration. The crop water productivity for the ABONTEM maize was found


to be 3.42 kgm^-3 as compared to some reported values of 1.1-2.7 kgm^-3.

Contents

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CHAPTER. 8

INTRODUCTION.. 8

1.1 INTRODUCTION.. 8

1.2 JUSTIFICATION OF STUDY. 9

1.3 OBJECTIVE OF STUDY. 10

1.3.1 MAIN OBJECTIVE. 10

1.3.1.1 SPECIFIC OBJECTIVES. 10

CHAPTER 2. 11

LITERATUR E REVIEW... 11

2.1 INTRODUCTION.. 11

2.2 CONCEPT OF CROP COEFFICIENT. 12

2.3 EVAPOTRANSPIRATION CONCEPT. 13

2.4 REFERENCE EVAPOTRANSPIRATION (ET_o). 14

2.5 METHODS OF DETERMINING EVAPOTRANSPIRATION.. 15

2.5.1 PENMAN-MONTEITH EQUATION.. 15

2.5.2 BLANEY-CRIDDLE. 17

3.5.3 HARGREAVES EQUATION.. 18

2.5.4 FIELD PLOT METHOD OR WATER BALANCE METHOD.. 18

2.5.5 CLASS A PAN METHOD.. 19

2.5.6 IVANOV EQUATION.. 20

2.5.7 THORNTHWAITE'S FORMULA: 20

2.5.8 LYSIMETER. 21

2.6 CROP WATER PRODUCTIVITY. 22

CHAPTER 3. 24

MATERIALS AND METHOD.. 24

3.1 LOCATION OF EXPERIMENT. 24

3.2 MATERIALS. 24

3.2.1 MAIZE VARIETY. 24

3.2.2 MICRO-LYSIMETER. 24

3.3 METHODS. 25

3.3.1 DATA GATHERING.. 26

CHAPTER 4. 27

RESULTS AND DISCUSSION.. 27

4.1 RESULTS. 27

4.1.1 CLIMATIC DATA.. 27

4.1.2 CROP COEFFICIENT. 27

4.1.3 CONSUMPTIVE WATER USE AND REFERENCE


EVAPOTRANSPIRATION.. 29

4.1.4 CROP WATER PRODUCTIVITY. 31

4.2 DISCUSSION.. 31

CHAPTER 5. 32

CONCLUSION AND RECOMMENDATION.. 32

5.1 CONCLUSION.. 32

5.2 RECOMMENDATION.. 32

REFERENCES. 33