ABSTRACT
A field study was undertaken to characterize, classify and evaluate the suitability of some wetland soils of Akwa Ibom State for wetland rice, cassava and maize production. The study area covered Ekpene Ukpa, Ikot Ebo, Oto Akan and Etinan in Etinan Local Government Area (LGA); Esin Ufot, Esuk Oron in Oron LGA; Ibaka, Akai Ati, Ebughu, NungAtai Eta in Mbo LGA; Ekeya, EsukInwang, Okobedi, EbighiAnwa in Okobo LGA; Ikot Mbonde in Uyo LGA A free method of soil survey was adopted. Soil profile description followed the FAO Guidelines on soil profile description. Soil samples collected were analyzed in the laboratory using standard procedures. The soils were classified based on USDA Soil Taxnomy and World Reference Base. Qualitative and quantative methods of land evaluation were used. Results showed that three soil mapping units: Floop plain (FP), Inland depression (ID) and Coastal swamp (CS) were delineated. Results showed that the soils were generally poorly drained to moderately and well drained with reddish brown(5YR 3/3) to dark grey (7.5YR 6/2) and dark brown (7.5YR 3/2), brown (10YR 6/4) to yellowish brown (7.5YR 5/8). The Flood plain has moderate to strong coarse to sub-angular blocky structure,with moderate sticky to plastic constistency and mostly loamy. The soils have mean pH of 5.80, 0.21. cmol/kg K and 9.90 mg/kg P and a base saturation of 76 %..Soils of Inland depression and Coastal swamp are generally sandy, with weak structure and non-sticky to non plastic consistency. They have mean pH of 6.40 and 6.00 with mean exchangeable K of 0.12 cmol/kg respectively. The mean available P were 21.2mg/kg for (ID) and 3.60 mg/kg for CS with organic matter contents of 1.60 to 2.8o % for ID and 0.88 to 4.26 % fot CS. The base saturation of in ID and CS were 27.7 and 12.8 %, respectively. The soils were classified as Arenic Paleaquults, Arenic Endoaquepts in the USDA Soil Taxonomy and correlated with Gleyic Acrisols, Gleyic Cambisols and Gleyic Fluvisols in the WRB system. Soils of the Flood plain are currently not suitable (N1) for cassava, but marginally suitable (S3) for maize and wetland rice. Soils of the Inland depression are not suitable (N1) for cassava but marginally suitable (S3) for wetland rice and maize. Soils of the Coastal swamp are marginally suitable (S3) for wetland rise, cassava and maize, respectively. It is recommended that the soils are not recommended for commercial prduction of wetland rice, cassava and maize because of the inherent limitations. However, with adeguate drainage, optimal use of mineral fertilizers and liming the soils can be used for commercial production of the evaluated crops.
TABLE OF CONTENTS
Title
page i
Declaration
ii
Certification
iii
Dedication iv
Acknowledgement
v
Table
of content vi
List of
Tables x
List of
Figures xi
List of
Plates xii
Abstract xiii
CHAPTER
1: INTRODUCTION
1.1 Background of
the Study 1
1.2 Statement of the Problem 4
1.3 Significance of the Study 4
1.4 Justification of the Study 5
1.5 Objectives of the Study 5
CHAPTER 2: LITERATURE
REVIEW
2.1 Wetland
Soils 6
2.2 Importance
of Wetland Soils 10
2.3 Types
of Wetlands 11
2.3.1 Man-made
wetlands 11
2.3.2 Natural
wetlands 11
2.4 Values
of Wetlands 11
2.4.1 Economic
value 12
2.4.2 Ecological
value 12
2.5 Functions
of Wetland 13
2.5.1 Values
of wetland 13
2.5.2 Life-support
functions 14
2.5.3 Hydrology 14
2.5.4 Biogeochemistry 15
2.5.5
Carbon sequestration 15
2.6 Evaluation
of Wetland 16
2.7 Distribution of Wetland Soils
in Nigeria 16
2.7.1 Flood
plain (FP) 17
2.7.2
Coastal
swamp (CS) 18
2.7.3 Inland depression (ID) 19
2.8 Properties of Wetland Soils
(Floodplain, Inland Depression and
Coastal Swamp) in Nigeria 19
2.8.1 Flood
plain (FP) 20
2.8.2 Inland depression (ID) 25
2.8.3 Coastal plain (CP) 29
2.9 Classification of Wetland
Soils in Nigeria 33
2.10 General Uses of Wetland Soils
in Nigeria 35
2.11 Management-Related Problems of
Wetland Soils 37
2.11.1
Acidity 37
2.11.2
Poor
drainage 38
2.11.3
Salinity 38
2.11.4
Low
nutrient status 39
2.12 Land Evaluation 39
2.13 Land
Suitability Classification 41
2.14 Crop Growth Requirements 42
CHAPTER 3: MATERIALS
AND METHODS
3.1 Research Location 46
3.1.1 Climate 49
3.1.2 Geology and landforms 49
3.1.3
Vegetation and land use 50
3.2 Field Work 51
3.2.1 Study area 51
3.3 Laboratory Analysis
53
3.3.1 Soil analysis 53
3.3.2 Physical analysis 53
3.3.2.1 Particle size distribution 53
3.3.2.2 Soil moisture content 54
3.3.2.3 Bulk density (pb) 54
3.3.2.4 Total porosity (Pt) 54
3.3.2.5 Saturated hydraulic conductivity (Ksat)
55
3.3.3
Chemical Analysis 56
3.3.3.1 Soil pH determination 56
3.3.3.2 Total nitrogen 56
3.3.3.3
Available phosphorus 56
3.3.3.4
Exchangeable acidity 57
3.3.3.5
Total exchangeable bases (Ca,
Mg, K and Na) 57
3.3.3.6
Effective cation exchange
capacity 57
3.3.3.7
Base saturation 57
3.3.3.8 Percent Base saturation 58
3.4 Soil Classification 58
3.4.1 Land suitability evaluation
(LSE) 58
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Morphological Properties of
Soils of the Study Area 60
4.1.1 Floodplain (FP) 60
4.1.2 Inland depression (ID) 60
4.1.3 Coastal swamp (CS) 61
4.2 Physical Properties of Soils
of the Study Area 65
4.2.1 Soil Texture 65
4.2.2 Bulk density 70
4.2.3 Saturated hydraulic conductivity
(Ksat) 70
4.3 The Chemical Properties of
Soils of the Study Area 73
4.3.1 Soil pH 73
4.3.2 Electrical conductivity (EC) 78
4.3.3 Exchangeable sodium percentage
(ESP) 80
4.3.4 Organic matter 82
4.3.5 Total N 82
4.3.6 Available P 84
4.3.7 Exchangeable bases 86
4.3.8 Exchangeable H and Al 90
4.3.9 Effective cation exchange
capacity (ECEC) 92
4.3.10 Base saturation 94
4.4 Soil Classification 99
4.4.1 Floodplain 101
4.4.2 Coastal swamp soils 101
4.4.3 Inland depression 103
4.5 Land Suitability Evaluation 104
4.5.1 Wetland rice cultivation 110
4.5.2 Maize cultivation 113
4.5.3 Cassava cultivation 116
CHAPTER 5: CONCLUSION
AND RECOMMENDATIONS
5.1 Conclusion 119
5.2 Recommendations 119
REFERENCES 121
APPENDICES 142
APPENDIX 1 142
APPENDIX 2
157
LIST
OF TABLES
3.1:
Soil mapping units and profile pit
locations 52
4.1: Morphological
properties of Flood Plain 62
4.2: Morphological properties of Inland
Depression 63
4.3: Morphological properties of Coastal Swamp 64
4.4: Some physical properties of mapping units
(Flood plain) 66
4.5: Some physical properties of mapping units
(Inland Depression) 67
4.6: Some physical properties of mapping units
(Coastal swamp) 68
4.7: Mean Physical properties of particle size
distribution and bulk density
of the study area 69
4.8: Chemical properties of Flood Plain 74
4.9: Chemical properties of Inland Depression 75
4.10: Chemical properties of Costal Swamp 76
4.11:
Mean chemical properties of soils of
the study area 96
4.12: Taxonomic classification of Pedons in the
study area 99
4.13: Land characteristics/qualities of the study
area 106
4.14: Factor rating of land-use requirements for
wetland rice 107
4.15: Factor rating of land- use requirements for
maize 108
4.16: Factor rating of land use requirements for
Cassava 109
4.17: Suitability class scores of soils of the
study area for wetland rice cultivation 111
4.18: Suitability aggregate scores and suitability
classes of soil types for rice cultivation,
indicating limiting characteristics 112
4.19: Suitability class scores of soils of the
study area for maize cultivation 114
4.20: Suitability aggregate scores and suitability
classes of soil types for
maize cultivation, indicating
limiting characteristics 115
4.21: Suitability class scores of soils of the
study area for cassava cultivation 117
4.22: Suitability aggregate scores and suitability
classes of soil types for cassava
cultivation, indicating limiting characteristics 118
LIST
OF FIGURES
3.1: Map of Nigeria showing Akwa Ibom State 47
3.2:
Map of AkwaIbom State showing
samplings locations 48
4.1: Distribution of bulk density in the study
area 72
4.2: Distribution of saturated hydraulic
conductivity in the study area 77
4.3: Distribution of soil pH in the study area 79
4.4: Distribution of electrical conductivity in
the study area 81
4.5: Distribution of soil organic matter and
total N in the study area 83
4.6 Distribution of available P in the study
area 85
4.7 Distribution of exchangeable Ca and Mg in
the study area 87
4.8 Distribution of exchangeable Na and K in
the study area 89
4.9 Distribution of exchangeable H and Al in
the study area 91
4.10 Distribution of ECEC in the study area 93
4.11 Distribution of base saturation in the
study area 95
4.12 A soil map map showing the taxonomic
classification in the study areas 100
LIST OF PLATES
1: Collection of Auger Sample 157
2: Horizon description of profile pit 1 158
3: Grid measurement 159
4: Horizon description of profile pit 2 160
5: Horizon description of profile pit 3 161
6: Horizon description of profile pit 4 162
7: Horizon description of profile pit 5 163
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
In
Akwa Ibom State, farmers have traditionally utilized both uplands and wetlands
for cultivation. Wetland soils in Akwa
Ibom State are commonly found in alluvial flood plans, inland depression. Flood
plains are the major land forms built by alluvial deposits in the low-lying
areas where streams and rivers over flow (Akpan et al., 2017).When the river floors, its bed is raised through the
accumulation of alluvium deposited by the water. A layer of sediment is thus formed during
each flood, gradually buildings up fertile flood plain for crop production.
Wetland
can be defined as “land that has the water table at, near, or above the land’s
surface or which is saturated for a long period of time to promote wetland or
aquatic processes (Brady and Weil, 2002).
Wetland is an area of land that has hydric soil properties, hydrophytic
vegetation and various kinds of biological activity that are adapted to the wet
environment. Wetland is typically
flooded for part of the year, and formed a transition zone between aquatic and
terrestrial systems (Brady and Weil, 2002).
Wetland can also be regarded as a land subject to excessive wet
conditions to the extent of influencing
possible land uses (Andriesse, 1986). This is because wetlands are
characterized by the presence of wetland hydrology, hydrophytic vegetation, and
hydric soils and are complex ecosystems that are poorly understood relative to
terrestrial and aquatic system. Wetlands are frequently transitional landscapes
between terrestrial and aquatic systems and therefore possess characteristics
of both.
Wetlands
are among the most productive and economically valuable ecosystems in the
world. They provide critical ecosystem goods and services, including carbon
storage, biodiversity, conservation, fish production, fuel production, water
purification, flood and shoreline surge protection and erosion control, and
recreation.Wetlands are considered to be marshes, peatlands, floodplains,
mangrove, and lacustrine wetlands-submerged permanently or periodically under
flowing or still fresh, salty, or brackish water.
Rice
(Oryza sativa) is an important
component of food consumption pattern in Nigeria (Anuebunwa, 2006).It is
important for its carbohydrate content and has higher available carbohydrate
than maize and wheat. It contains higher lysine and other sulphur containing
amino acids. Due to its high energy value and ease of preparation, it has replaced
major staples such as cassava, sorghum and millets on the average within a
period of 2000 - 2007 rice is the 4th most important crop in terms of calories
consumed in Nigeria following sorghum, millet and cassava (Angelucci, 2013).
They stated that per capita rice consumption in Nigeria has nearly doubled
between 1980s and 2006. The emerging issue has created high demand for rice,
hence high levels of importation (Dashelet
al., 1993). The Nigerian economy relies heavily on the importation of food to
supplement domestic food production. Rice is the most important staple food
imported in the country. According to Akande (2000)., the quantity and value of
annual import stood at 1,000,000 metric tones and 3000 million naira,
respectively More than 90 % of rice
farmers in Nigeria are small holders and resource-poor. Consequently, they apply
a low input strategy to get a low output. This accounts for Nigeria’s rice
productivity among the lowest within neighboring countries, with an average
yield of 1.51 tonnes/ha (Cadoni and Angelucci, 2013). Nevertheless, Nigeria is
the largest rice producing country in West Africa, but ironically, the largest
importer of rice in the world. According to Nkang et al. (2006), efforts to raise domestic rice production to ensure
that Nigeria is self-sufficient in rice production have failed because rice
import represented a good proportion of total food imports.
Nigeria is currently the largest
producer of cassava in the world with an annual output of over 34 million
tonnes of tuberous roots. Cassava production has been increasing for the past
20 or more years in area cultivated and in yield per hectare. On average, the
harvested land area was over 80 percent higher during 1990–1993 than during
1974–1977 The growth in cassava production has been primarily due to rapid
population growth, large internal market demand, complemented by the
availability of high yielding improved varieties of cassava, a relatively well
developed market access infrastructure, the existence of improved processing
technology and a well-organized internal market structure (Federal Ministry of Agriculture and Natural
Resources, 2020). Cassava
is produced largely by small-scale farmers using rudimentary implements. The
average land-holding is less than two hectares and for most farmers, land and
family labour remain the essential inputs. Land is held on a communal basis,
inherited or rented; cases of outright purchase of land are rare. Capital is a
major limitation in agriculture; only few farmers have access to rural credit. Almost
all cassava farmers in the southeastern, southwestern and middle belt are poor,
and grow cassava with maize, as an intercropp in their farming systems (Anuebunwa,
2006).
The farmers are generally aware of the benefit of inorganic fertilizer, but they
cannot afford to buy and use adequate quantities because of its scarcity and
high cost.
In 2018, Africa produced
around 75 million tons of maize, accounting for 7.5 percent of global maize
production. Maize accounts for approximately 24 percent of farmland in Africa,
with an average yield of around 2 tons/hectare/year. Nigeria is the largest
African producer, with over 33 million tons, followed by South Africa, Egypt,
and Ethiopia. According to the data collected from the United States Department
of Agriculture (USDA 2018), Nigeria now produces ten times more Maize per year
than it did when it gained independence in 1960.Nigeria’s production increased
from 10.1 million tons in 2014 to 10.6 million tons in 2015 and 11.6 million
tons in 2016. In 2017, the figure was 10.4 mm, but it increased to 11.0 mm in
2018, a figure that has been maintained in 2019.
1.2 STATEMENT OF THE PROBLEM
Variations
in soil properties are common. However, their utilization for crop cultivation
in unsustainable manner is among the factors causing wide disparity in crop yields
(FAO, 1998). Poor knowledge of soil resources is a major reason why many
farmers in Sub-Saharan Africa, which includes Nigeria, suffer from
chronologically low crop yields (Sanginga, 2009; Gibert, 2009). About 26 % of the land mass of Akwa Ibom
Statew is under wetland (Peter et al.,
1989). There is a dearth of information on their characteristics,
potentialities and limitations for crop production. Therefore, lack of adequate
knowledge of the wetland soils remains a major challenge to their utilization
and management for sustainable crop production. in Akwa Ibom State.
1.3 SIGNIFIANCE OF THE STUDY
Rice
productions activities in South-Eastern Nigeria are commonly carried out on
wetlands, (Chukwu, 2007; Ogbodo and Chukwu, 2012).. Maize and cassava
production are also carried out in wetlands.The soils are found on nearly
level, level and gently undulating flood
plains, inland valleys and
lowlands with slope ranges of 0.2 % which could be deep, poorly to very poorly
drained (Nwite et al., 2013).
According to Okusami (2003), a contributory factor to low crop yields is the
very low ratio of used to unused available hydromorphic lands (wetlands) and
lack of adequate knowledge to mamage them to give higher crop yields.
Increasing food production both to meet Nigeria’s food requirements and to help
the world overcome food crisis is one of the major issues facing Nigeria today.
This cannot be achieved without an adequate knowledge of the soil resource base
on which agriculture depends.
1.4 JUSTIFICATION OF THE STUDY
The
present drift towards wetlands for crop production (Peter et al., 1989) is a consequence ofdeclinining availability of
uplands for crop production due to population pressure, and increasing rural
development activities About 26 % of the
land mass of Akwa Ibom Statew is under wetland (Peter et al., 1989). Thus, there is need to expand arable cropping into
these vast and hitherto little exploited wetland soils. It, therefore becomes a
matter of necessity to carry out a detailed stuty to understand the types of
wetland available, their properties and distribution, as well as, their
potentialities and limitations for arable crop production. This is a
pre-requisite for their sustainable management to achieve higher crop yields
and enhance the soill resources base and improve the livelihood of farm
families.
1.5 OBJECTIVES
The
main objective of this dissertation was to characterize, classify and evaluate
wetland for sustainable crop production in soils of AkwaIbom State.
The
specific objectives of the study were to:
- delineate
and characterize the wetland soils of Akwa Ibom State ;
- classify
the soils using the USDA Soil classification system and correlate with
the World Legend /World Reference
Base (WRB), and
- evaluate
the suitability of the soils for sustainable production of selected crops
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