ABSTRACT
This
study focused on the land capability classification, fertility mapping, and
pedodiversity assessment of soils developed over coastal plain sands in Abia
State, Nigeria. A reconnaissance soil survey covering 198,000 hectares across
10 Local Government Areas was conducted using the free survey method. The study
aimed to evaluate the land’s agricultural potential through the production of
land capability and soil fertility maps, and to assess the pedodiversity of the
region. Three soil mapping units COPSOL I (62,300 ha), COPSOL II (42,200 ha),
and COPSOL III (93,500 ha) were delineated based on variations in elevation and
landscape characteristics. These soils occur on gently sloping plains (0–2%
gradient) and are generally deep with sandy to coarse loamy surface textures and
coarse to medium loamy subsoils. Laboratory analyses revealed that the soils
are strongly to very strongly acidic (pH 5.05–5.35), and deficient in key
nutrients such as total nitrogen (0.07–0.10%) and exchangeable potassium
(0.07–0.10 cmol/kg). However, they exhibited medium to high levels of available
phosphorus (22.5–28.5 mg/kg) and organic matter (2.06–3.07%). These properties
were reflected in the fertility maps produced. The soils showed low base
saturation (35.0–58.7%) and were classified as Typic and Grossarenic Paleudults
(USDA), correlated with Haplic Acrisols (WRB). Land capability assessment
categorized the soils under Class IIen, indicating moderate limitations
primarily due to erosion risks and fertility constraints. Statistical analysis
using descriptive statistics and coefficient of variation indicated low
variability in soil properties, while pedodiversity analysis revealed high
homogeneity, with a Shannon entropy index of 1.00, richness of 3.00, evenness
of 1.00, and Simpson’s dominance index of 0. These results underscore the
uniformity of soil types across the area. The study provides essential soil
information for policymakers, land users, and agricultural planners, promoting
informed land use, efficient fertilizer application, and sustainable
agricultural practices. Recommendations include implementing soil erosion
control measures, liming, integrated nutrient management, and cultivation of
suitable crops such as oil palm and cassava. The land capability and fertility
maps produced serve as valuable tools for future land use planning and soil
management in the region.
TABLE
OF CONTENTS
CHAPTER
1
INTRODUCTION
1.1 Background of the Study
1.2 Objectives of the Study
CHAPTER
LITERATURE
REVIEW
2.1 Land Capability Classification (Lcc)
2.1.2
Modification of land capability
classification
2.1.2.1 Basis for grouping soils
in different capability classes
2.1.2.2 Advantages of land capability classification
2.1.2.3 Disadvantages of land capability classification
2.1.2.4
The structure of land capability classification.
2.2
Soil Fertility Mapping
2.2.1
Components of soil fertility
2.3 Pedodiversity
2.3.1 Measurement of pedodiversity
2.3.1.1 Shannon’s entropy or diversity index (H)
2.3.1.2 Maximum diversity
2.3.1.3 Evenness (E)
2.3.1.4 Simpson’s
dominance index (Gini index) (D)
2.3.1.5 Gini-Simpson’s
diversity index (G)
2.3.2 Importance
of pedodiversity
2.4 Coastal
Plain Sands
2.4.1
Properties of soils derived over
coastal plain sands.
2.5 Works on
Fertility Mapping Of Soils Derived Over Coastal Plain Sands
CHAPTER
3
MATERIALS
AND METHODS
3.1 Study Area
3.2 Field
Study
3.3 Laboratory Analysis
3.3.1: Physical
analyses
3.3.1.1 Particle size distribution
3.3.2 Chemical
analyses
3.3.2.1 Soil pH
3.3.2.2 Exchangeable acidity (H+ + Al3+)
3.3.2.3 Total exchangeable bases (TEB) (Ca+ Mg+ Na+K )
3.3.2.4 Percentage base saturation (BS)
3.3.2.5 The effective cation exchange capacity (ECEC)
3.3.2.6 Organic carbon
3.3.2.7 Total nitrogen
3.3.2.8 Available
phosphorus
3.3 Land
Evaluation Method
3.3.1: Land capability
classification (LCC)
3.3.2 Soil classification
3.4 Method
of Fertility Mapping
3.4.1
Interpretation of soil fertility data
3.5 Pedodiversity Analysis
3.5.1 Shannon’s
entropy or diversity index (H)
3.5.2 Maximum
Shannon diversity (Hmax)
3.5.3 Evenness
(E)
3.5.4 Simpson’s
dominance index (D):
3.5.5 Gini-
Simpson’s diversity index (G)
3.6 Statistical Analysis
CHAPTER 4
RESULTS
AND DISCUSSION
4.1 Description
of Mapping Units
4.2.1
Morphological properties of COPSOL I
4. 2 .2 Morphological
properties of COPSOL II
4.2.3 Morphological
properties of COPSOL III
4.3.1 Particle
size distribution of COPSOL 1
4.3.2 Particle size distribution of COPSOL II
4.3.3: Particle
size distribution of COPSOL 1II
4.4.1 Chemical
properties of COPSOL 1
4.4.2 Chemical
properties of COPSOL II
4.4.3: Chemical
properties of COPSOL III
4.5 Taxonomic
Classification Of The Soils
4.6 Land
Capability Studies
4.7. Fertility
Mapping Of The Soils
4.8 Pedodiversity
of Soils Derived From Sands in Abia State
CHAPTER
5
SUMMARY,
CONCLUSION AND RECOMMENDATIONS
5.1 Summary
5.2 Conclusion
5.3 Recommendations
References
Appendix I: Soil Profile Description
Appendix Ii:
Nutrient Ratings For Soil Data Interpretation
LIST
OF TABLES
Table 3.1: Land Capability Classification
System-General guidelines
Table 3.2: Interpretation of pedodiversity ratings
Table 4.1: Morphological properties of COPSOL I
Table 4.2: Morphological properties of COPSOL II
Table 4.3: Morphological properties of COPSOL III
Table 4.4: Particle-size distribution
of COPSOL I
Table 4.5: Particle-size distribution
of COPSOL II
Table 4.6: Particle-size Distribution
of COPSOL III
Table 4.7: Chemical Properties of COPSOL I
Table 4.8: Statistical Summary of the Chemical Properties of COPSOL I
Table 4.9: Chemical Properties of COPSOL II
Table 4.10: Statistical Summary of the Chemical Properties of COPSOL II
Table 4.11: Chemical Properties of COPSOL III
Table 4.12: Statistical Summary of the Chemical Properties of COPSOL III
Table 4.13:Taxonomic Classifications of the Soils
Table 4.14: Pedodiversity of soils derived from
sands in Abia State
LIST
OF FIGURES
Figure 3.1: Location
map of the study area
Figure 3.2: Geology Map of the Study Area
Figure 3.3: Location of Soil Profile Pits
Figure
3.4: Soil fertility sampling points
Figure
4.1: Soil mapping units of the area.
Figure 4.2: Soil acidity map of the study area
Figure 4.3: Available Phosphorus Map of Study Area.
LIST
OF PLATES
Plate 1: Profile
description at Umuohu (pedon 1) with Dr G.O Chukwu
Plate 2: Profile description at CKC Aba (pedon
5)
CHAPTER
1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Land capability classification is a broad grouping of
soils based on their limitations as a guide to assess land suitability for arable
crops, grazing and forestry (Dent and Young, 1981). There is need for the
provision of more infrastructural facilities like good roads, stadia, markets, hospitals,
schools, housing estates, airports and so on with creation of new states and
local government areas. However, demographic pressures as a result of increasing
urbanization and ecological problems especially gully erosions have contributed
immensely to the diminishing of agricultural lands. As a result of the
diminishing of agricultural lands, there is a pressing need to match land types
and land uses in the most rational ways so as to maximize sustainable
production and satisfy the diverse needs of society while also conserving the
fragile ecosystems.
Akamigbo (1999) opined that Nigeria should evolve a
land use policy for the 21st century using land capability
classification as a tool. Land use policy involves a body of laws whether
legislative, executive, administrative directives and specific commitments of
government to enhance rural life and reduce poverty through sustainability in
agriculture and maintenance of environmental harmony among others. It aids
judicious application of inputs to achieve sustainable soil management
decisions, to enhance agro - technology transfer and overall agricultural
development. Consequently, it is a sustainable land management strategy because the system of land capability classification requires
that every hectare of land be used in accordance with its capability and
limitations. Aderonke and Gbadegesin (2013) stated that poor knowledge
and appraisal of suitability of parcels of land for agricultural production are
the major problems of agricultural development in Nigeria.
Land capability maps
and soil fertility mapping help in explaining soil survey information to
enhance their usefulness to non pedologists such as policy makers, farmers,
town planners and other stakeholders in land resources management. Such maps
are called interpretive soil maps by Chukwu (2015a) and Chukwu and Okonkwo
(2015) because they facilitate dissemination of soil information to non- soil
scientists and could assist land users in site selection for land utilization
types and guide the use of appropriate quantities of inputs in order to
maximize output in relation to chosen soil management and land use options. This challenge stimulated Chukwu (2015b) to
start soil evangelization (SE). SE is defined as an agricultural transformation
project to impact on Nigerians a positive attitudinal change towards
sustainable soil resource management in other to enhance conservation of
ecosystem and increase food security. This can only be achieved with improved
soil resource literacy and passion for soil resources management. According to
Wasim-Iftikar et al (2010)
soil fertility maps help in rational nutrient management, discourages
indiscriminate blanket use of fertilizers by farmers and also reduces the need
for elaborate plot-by-plot soil test.
There
is a widespread inefficient soil management due to poor knowledge of soil data
interpretation (Chukwu et al., 2010).
This probably explained why the present
land use does not take into consideration on how land will be used despite the
fact that agricultural policy of Nigeria published in 1988 recognized the need
to allocate land based on its most suitable uses.
The
current system of blanket fertilizer use results in a colossal waste of scarce
fertilizer investment because the soil is not well prepared to take the
nutrients for root interception within its short lifespan of arable cropping
(National Council on Agriculture and Rural Development (NCARD, 2016).
Consequently, there is persistent food insecurity because agriculture has failed
to provide enough food, feed and raw materials for the populace, their
livestock and raw materials for industries. This food insecurity therefore is
as a result of absence of soil survey reports for most rural villages, towns
and Local Government Areas (LGAs) where production of these food and fibres take
place. Also, most national soil surveys scales are so coarse (at reconnaissance
level) making pedological information about rural communities virtually
non-existent.
Pedologists
are better positioned to strengthen the linkage between researchers and
farmers by translating soil survey reports into interpretive soil maps such as
soil fertility maps and land capability maps (Chukwu and Okonkwo, 2015). These
interpretive soil maps could be used as visual aids (communication channels) to
facilitate the transfer of land management information from a source (subject
matter specialist, extension agents, literate farmer) to a receiver (extension
agents or illiterate farmer). Available information has shown that the land
capability classification of the soils derieved from sands of Abia State is
non-existent. This information is necessary for land use planning.
Although Chukwu
et al (2012) and Chukwu and Okonkwo (2015) provided land capability maps
for Ikwuano Local Government Area (LGA) of Abia state, which is within the study
area but similar maps are not available for the other LGAs in Abia State, Nigeria
covered by the study .
1.2 OBJECTIVES OF THE STUDY
The
objectives of the study were to:
i.
conduct a soil survey
of the project area,
ii.
produce land
capability map of the project area,
iii.
delineate the area
into soil fertility classes and
iv.
ascertain
pedodiversity of the study area.
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