Global Warming Potentials And Degradation Rate Assessment Of Soils Of Selected Flood Plains In Imo State

MICHAEL AKANINYENE | 274 pages (49698 words) | Dissertations
Soil Science | Co Authors: OKON



This study investigated the Global Warming Potentials (GWPs), degradation rate and erodibility status of soils of selected floodplains in Imo State. A target soil survey technique was adopted and the experimental design was a 5x3 factorial experiment laid out in a randomized complete block design. The factors were floodplain and soil depth. Five floodplains were selected. They were Obiakpu, Mmahu, Amuzu, Umuneke and Orsu obodo.  Five minipedons were dug randomly in each floodplain and soils were sampled at depths of 0-20 cm, 20-40 cm and 40-60 cm. A total of 75 soil samples were collected from the study area and taken to the laboratory for analyses. Climate data of average monthly temperature and average monthly precipitation of the study area for a period of 30 years (1987 to 2016) were also analysed. Results showed that the area had a preponderance of sand fraction which ranged from 694 g/kg to 856 g/kg while clay content ranged from 105 g/kg to 191 g/kg. The textural classes of the soils of the study area ranged from sandy loam to loamy sand. Bulk density was moderate to high and ranged from 1.48 g/cm3 to 1.60 g/cm3. Total porosity ranged from 39.80 % to 44.13 %. The hydraulic conductivity values were moderate to slow. The results of the field capacity, permanent wilting point, saturation capacity and available water capacity were generally low. The soils also had moderate permeability. Results of the soil chemical properties showed that the soil pH were strongly acidic. Organic carbon ranged from 0.29 to 19.87 g/kg with the least in Orsu obodo and the highest in Obiakpu, total nitrogen ranged from 0.22 to 1.84 g/kg, available phosphorus ranged from 2.62 to 11.88 mg/kg.  The basic cations were also low in the study area. The TEB ranged from 3.62 to 11.87 Cmol/kg. The TEA ranged from 1.09 to 2.33 Cmol/kg. The ECEC ranged from 5.71 to 12.91 Cmol/kg. Obiakpu and Mmahu were more stable and less prone to erosion than the other locations. Assessment of physical degradation rate of the study area showed that 80 % of the soils of the study area were moderately degraded while 20 % were none or slightly degraded. For the chemical degradation, Obiakpu and Mmahu were none to slightly degraded while the other floodplains had varying degrees of degradation. Regression of average temperature and rainfall with time revealed that in Imo State, the mean annual temperature is increasing by 0.02oC while the annual rainfall totals is reducing by 13.50 mm annually indicating global warming and desert encroachment. Results of GHG emissions showed that CO2 flux was higher than CH4 flux in the study area and ranged from 29,365.47 kg/ha/yr to 40,337.37 kg/ha/yr, and the CH4 flux ranged from 1097.35 kg/ha/yr to 1440.62 kg/ha/yr while the net flux of CO2 and CH4 ranged from 30462.82 to 41777.99 kg/ha/yr. The GWP values followed similar pattern. GWP for CO2 ranged from 96745.33 to 655352.23kg/ha/yr, GWP for CH4 ranged from 11805.53 to 144473.81kg/ha/y. It was therefore recommended that more trees and crops should be grown in the study area to sequester carbon, and flood control measures should also be heightened.


Cover Page

 Title Page                                                                                                                               i

Declaration                                                                                                                              ii

Dedication                                                                                                                              iii

Certification                                                                                                                            iv

Acknowledgement                                                                                                                  v

Table of Contents                                                                                                                   vi

List of Tables                                                                                                                          xiii

List of Figures                                                                                                                         xiv

Abstract                                                                                                                                  xv

CHAPTER 1:              INTRODUCTION                                                                             1


CHAPTER 2:              LITERATURE REVIEW                                                                  4

2.1       Flooding in Nigeria                                                                                                     4

2.2       Causes of Flooding                                                                                                     5

2.3       Types of Flood                                                                                                            6

2.4       Climate Change and Global Warming                                                                        8

2.4.1    Definition of climate change                                                                                      8

2.4.2    Causes of increase in global surface temperatures and changing climatic patterns    9

2.5       Soil Ecosystem Green House Gaseous Exchange                                                      11

2.6       Flooding and Green House Gas Emissions                                                                13

2.7       Drivers of Green House Gas Emissions from soils                                                     13

2.7.1    Temperature                                                                                                                15

2.7.2    Humidity                                                                                                                     16

2.7.3    Nutrients                                                                                                                     17

2.7.3a  Soil physical fertility                                                                                                   18

2.7.3b  Soil chemical fertility                                                                                                  18

2.7.3c  Soil biological fertility                                                                                    19

2.7.4    Vegetation                                                                                                                  20

2.7.5    Land use and land cover                                                                                             21

2.8       Atmospheric Temperature, Soil Temperature and Greenhouse Gas Emissions          22

2.9       Methodologies to Quantify GHG Emissions from Soils                                            23

2.9.1    Chamber systems                                                                                                        25

2.9.1a  Closed chambers                                                                                                         25

2.9.1b  Open chambers                                                                                                           26

2.9.2    Micrometeorological methods                                                                        26

2.9.3    Remote sensing                                                                                                           27

2.9.4    Modeling of soil green house gas emissions                                                               27

2.10     Effects of Climate Change on Crop Yield                                                                 28

2.10.1  Effects of increased atmospheric CO2 on crop production                                        29

2.10.2  Effects of temperature alterations on crop production                                               30

2.10.3  Effects of precipitation regime changes on crop production                                      31

2.11     Importance of Mitigating the Emission of Green House Gases From Soils               32

2.12     United Nations’ Plan to Combat Climate Change                                                     34

2.13     Great Green Wall Accelerator Initiative                                                                     34       

CHAPTER 3               MATERIALS AND METHODS                                                     38

3.1       Description of Study Area                                                                                          38

3.1.1    Location of study area                                                                                                            38

3.1.2    Climate of study area                                                                                                  38

3.1.3    Geology and geomorphology of the study area                                                         39

3.1.4    Relief of the study area                                                                                              39

3.1.5    Drainage of the study area                                                                                          44

3.1.6    Socio-economic activities in the study area                                                                47

3.1.7    Vegetation of the study area                                                                                      47

3.2       Pre-Field Studies                                                                                                        48

3.3       Field Studies                                                                                                               49

3.4       Climatic Parameters                                                                                                    49

3.5 Laboratory Analyses                                                                                                         50

3.5.1    Soil meteorological properties                                                                         50

            Net Ecosystem Exchange                                                                                           50

            Global Warming Potential (GWP)                                                                              50

3.5.2    Soil physical properties                                                                                               51

            Particle size distribution                                                                                              51

            Silt/clay ratio                                                                                                               51

            Soil bulk density                                                                                                         51

            Total porosity                                                                                                              52

            Saturated hydraulic conductivity                                                                               52

            Soil permeability                                                                                                         52

Soil erodibility                                                                                                53

3.5.3 Soil chemical properties                                                                                                 54

            Soil pH                                                                                                                        54

            Soil organic carbon                                                                                                     54

            Soil organic matter                                                                                                      54

            Total organic carbon stock                                                                                          54

            Total nitrogen                                                                                                              55

            Available phosphorus                                                                                                  55

            Exchangeable acidity                                                                                                  56

            Percentage aluminium saturation                                                                                56

            Electrical conductivity                                                                                                56

Exchangeable bases                                                                                                    56

Effective cation exchange capacity                                                                            56

Percentage base saturation                                                                                          57

3.6       Soil Elemental Ratios                                                                                                  57

Exchangeable sodium percentage                                                                               57

3.7       Soil Degradation Assessment                                                                                     57

            Land degradation assessment by direct approach                                                      57

            Land degradation assessment by indirect approach                                                   58

3.8    Experimental Design, Data Presentation and Analyses                                                 60

            Experimental design and data presentation                                                                60

            Data analyses                                                                                                              60

            Spatial analyses                                                                                                           60

CHAPTER 4               RESULTS AND DISCUSSIONS                                                     62

4.1       Physical Properties of the Soils of the Study Area                                                     62

            Particle size distribution of the soils of the study area                                               62

            Silt/clay ratio                                                                                                               64

            Total porosity                                                                                                              65

            Bulk density                                                                                                                66

4.2       Moisture Properties of the Soils of the Study Area                                                    67

            Saturated hydraulic conductivity                                                                               67

            Field capacity                                                                                                              67

            Permanent wilting point                                                                                              69

            Available water capacity                                                                                             69

            Saturation capacity                                                                                                     70

4.3       Permeability Classes of the Soils of the Study Area                                                  70

4.4       Soil Chemical Properties                                                                                             72

            Soil organic carbon                                                                                                     72

            Total nitrogen                                                                                                              72

            Available phosphorus                                                                                                  74

            Soil pH                                                                                                                        75

            Electrical conductivity                                                                                                75

            Exchangeable basic cations                                                                                         75

            Exchangeable aluminium                                                                                            78

            Exchangeable hydrogen                                                                                              78

            Total exchangeable acidity                                                                                         79

            Effective Cation Exchange Capacity                                                                         80

            Base saturation                                                                                                            81

4.5       Soil Organic Carbon Stock and Soil Microbial Carbon Contents in the Study Area 82

            Soil organic carbon stock                                                                                            82

            Soil microbial carbon                                                                                                  82

4.6       Elemental Ratios of the Soils of the Study Area as Soil Fertility Indexes                 84

            Carbon: Nitrogen ratio                                                                                                84

            Calcium: Magnesium ratio                                                                                          84

            Potassium: Magnesium ratio                                                                                       86

            Nitrogen: Potassium ratio                                                                                           86

            Exchangeable Sodium Percentage (ESP)                                                                   87

4.7       Erodibility of the Soils of the Study Area                                                                  88

            Dispersion ratio                                                                                                           88

            Clay dispersion ratio                                                                                                   90

            Clay Flocculation Index                                                                                             90

            Aggregated Silt Plus Clay                                                                                          91

4.8       Land Degradation Assessment                                                                                   91

4.8.1    Land degradation assessment by direct approach                                                      91

            Physical degradation                                                                                                   93

            Chemical degradation                                                                                                 93

            Biological degradation                                                                                                94

4.8.2    Land degradation assessment using land degradation index values                          94

4.9       Results of the Climatic Parameters of the Study Area                                               99

            Maximum temperature                                                                                                99

            Minimum temperature                                                                                     99

            Temperature range                                                                                                      100

            Annual rainfall                                                                                                            100

4.10     Trend Analysis of Climate Parameters in the Study Area                                          106

4.11     Relationship between Climatic Variables with Time                                                  108

4.12     Estimation of Change in Mean Annual Temperature                                                 109

4.13     Estimation of Change in Mean Annual Rainfall                                                         109

4.14     Relationship between Air Temperature and Soil Temperature at Different Depths   110

4.15     Green House Gas (GHG) Fluxes in the Study Area                                                  114

            CO2 flux                                                                                                                      114

            CH4 flux                                                                                                                      114

            Net green house gas fluxes                                                                                         114

4.16     Global Warming Potentials (GWPs) of the Soils of the Study Area                          117

            Global warming potentials for CO2                                                                             117

            Global warming potentials for CH4                                                                             117

            Net global warming potentials in the study area                                                        118

4.17     Correlation Results of Erodibility Indices with Selected Soil Properties                   121

            Correlation of Dispersion Ratio with other soil properties                                         121

            Correlation of Clay Dispersion Ratio (CDR) with other soil properties                     121

            Correlation of Aggregated Silt and Clay (ASC) with other soil properties               123

            Correlation of Clay Flocculation Index (CFI) with other soil properties                   124

4.18     Correlation between Green House Gases and Global Warming Potentials with Soil Physical and Chemical Properties                                                                                        125

4.18a   Correlation of Green House Gases with other soil Properties                                    125

            CO2 fluxes with other soil properties                                                                          125

            CH4 fluxes with other soil properties                                                                          125

            Net Green House Gas fluxes of CO2 and CH4 with selected soil properties             127

4.18b   Correlation of soil Global Warming Potentials with selected soil properties             127

Global Warming Potential for CO2                                                                             127

Global Warming Potential for CH4                                                                              129

Net Global Warming Potentials for CO2 and CH4                                                       130

4.19     Multiple Linear Regression Models of GHGs with Selected Soil Properties             131

4.20     Multiple Linear Regression Models of GWPs with Selected Soil Properties 134

4.21     Principal Component Analysis                                                                                    137

4.22     Spatial Structure of Green House Gas fluxes and Global Warming Potentials from the Soils of the Study Area                                                                                                    141

4.22a   Spatial structure of Green House Gas fluxes                                                              141

            Spatial structure of soil CO2 fluxes in the study area                                                 141

            Spatial structure of soil CH4 fluxes from the soils of the study area                          141

4.22b   Spatial structure of Global Warming Potentials of the soils of the study area           144

            Spatial structure of Global Warming Potentials for soil CO2 fluxes in the study area144

            Spatial structure of Global Warming Potentials for soil CH4 fluxes in the study area144

4.23     Krigged Maps of Green House Gas fluxes in the Study Area                                   146

            Krigged Map of soil CH4 fluxes in the study area                                                     146

            Krigged Map of soil CO2 fluxes in the study area                                                     146

4.24     Krigged Maps of Global Warming Potentials in the Study Area                               149

            Krigged map of soil GWPCO2 in the study area                                                        149

            Krigged map of soil GWPCH4 in the study area                                                        149


5.1       Summary                                                                                                                     152

5.2       Conclusion                                                                                                                  155

5.3       Recommendations                                                                                                      156

REFERRENCES                                                                                                                    158

APPENDICES                                                                                                                       179


3.1       Permeability classes of soils                                                                                        53

3.2       Indicators and criteria for degradation of soils                                                          59

4.1       Physical properties of the soils of the study area                                                        63

4.2       Moisture properties of the soils of the study area                                                       68

4.3       Permeability classes of the soils of the study area                                                      71

4.4       Chemical properties of the soils of the study area                                                      73

4.5       Soil organic carbon stock and soil microbial carbon of the soils of the study area    83

4.6       Elemental ratios of the soils of the study area                                                            85

4.7       Erodibility Indices of the soils of the study area                                                        89

4.8a     Land Degradation ratings using direct approach                                                        93

4.8b     Land degradation indices of the soils of the study area                                             95

4.9       Mean monthly climate data of the study area (1987 to 2016)                                    101

4.10     Mean Decadal Variation of climatic variables of the study area                                102

4.11     Trend analyses of the climatic parameters in the study area                                       107

4.12     Relationship between Climatic Variables with Time                                                  108

4.13     Air temperature and soil temperature at different depths                                          111

4.14     Multiple Linear Regression of Air Temperature with Soil Temperature                     112

4.15     Green House Gas Fluxes in the Study Area                                                               116

4.16     Global Warming Potentials of the soils of the study area                                          119

4.17     Correlation between erodibility indices and other soil properties                              122

4.18a   Correlation between Green House Gases with selected soil properties                      126

4.18b   Correlation between Global Warming Potentials with selected soil properties          128

4.19     Multiple Linear Regression of Green house gases (GHGs) with selected soil properties in the Study Area                                                                                                                                    133

4.20     Multiple Linear Regression of Global Warming Potentials (GWPs) with selected soil properties in the Study Area                                                                                                      136

4.21     Rotated Principal Component Analysis (PCA) results                                               139


2.1       Key drivers of GHG emissions from soil                                                                   14

2.2       Overview of methodologies for measuring of green house gas emissions from soils25

3.1       Map of Imo State showing study areas                                                                      41

3.2       Geologic Map of the study area                                                                                 42

3.3       Relief Map of the study area                                                                                      43

3.4       Map showing the five major sub basins in Imo State                                                 45

3.5       Drainage Map of the study area                                                                                 46

4.1       Maximum temperature against months                                                                       103

4.2       Minimum temperature against months                                                                        104

4.3       Diurnal temperature range against months                                                                 105

4.4       Green house gas emissions from the soils of  the study area                                      120

4.5       Global warming potentials of the soils of the study area                                           120

4.6       Semivariogram for CO2                                                                                              143

4.7       Semivariogram for CH4                                                                                              143

4.8       Semivariogram for GWPCO2                                                                                     145

4.9       Semivariogram for GWPCH4                                                                                     145

4.10     Krigged Map of Soil CH4 flux in the study area                                                        147

4.11     Kriggeed Map of Soil CO2 flux in the study area                                                      148

4.12     Krigged Map of Global Warming Potentials of CO2 in the study area                      150

4.13     Krigged Map showing the distribution of Global Warming Potentials of CH4 in the study area                                                                                                                                          151     




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MICHAEL, A (2023). Global Warming Potentials And Degradation Rate Assessment Of Soils Of Selected Flood Plains In Imo State. Retrieved May 24, 2024, from

MLA 8th

AKANINYENE, MICHAEL. "Global Warming Potentials And Degradation Rate Assessment Of Soils Of Selected Flood Plains In Imo State", 10 Aug. 2023, Accessed 24 May. 2024.


AKANINYENE, MICHAEL. "Global Warming Potentials And Degradation Rate Assessment Of Soils Of Selected Flood Plains In Imo State".,, 10 Aug. 2023. Web. 24 May. 2024. < >.


AKANINYENE, MICHAEL. "Global Warming Potentials And Degradation Rate Assessment Of Soils Of Selected Flood Plains In Imo State" (2023). Accessed 24 May. 2024.

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