Project – Influence of land use on hydraulic response of vertisol clay of tropical soil.

CHAPTER ONE

INTRODUCTION

• Background to The Study

Vertisols, commonly known as vertisol clays, are expansive soils predominantly found in tropical regions. These soils are characterized by their heavy clay content, high swelling and shrinkage behavior, and unique water retention properties. Land use plays a crucial role in determining the hydraulic response of these soils, particularly in the context of their permeability, water retention capacity, and drainage characteristics. According to recent studies, land use practices, such as agriculture, deforestation, and urbanization, significantly influence the soil’s hydraulic behavior by altering soil structure, porosity, and infiltration rates (Singh et al., 2018). Understanding these influences is key to predicting and managing water movement in vertisols, especially given the impacts of climate change on tropical regions.

In agricultural land uses, the hydraulic properties of vertisol clay can be significantly modified by tillage practices and crop rotations. Tillage, especially intensive or conventional plowing, is known to disrupt the natural soil structure, leading to increased soil compaction and decreased porosity. This compaction reduces the infiltration rate and increases surface runoff, which can exacerbate water erosion and hinder effective water retention (Ayuba et al., 2020). However, conservation tillage and crop rotation practices have been shown to improve the infiltration capacity and water retention of vertisols. Studies by De Oliveira et al. (2017) demonstrate that conservation practices, such as reduced tillage and mulching, help preserve soil structure, allowing for more efficient water infiltration and improving soil hydraulic conductivity.

Forested areas, by contrast, tend to maintain better soil structure and porosity, leading to more favorable hydraulic conditions. The influence of forest land use on the hydraulic response of vertisol clay is attributed to the natural organic matter inputs, which improve soil aggregation and increase pore space for water movement (Mbagwu et al., 2016). Forest soils also tend to have higher levels of soil organic carbon, which enhances the soil’s water-holding capacity. The role of vegetation cover in mitigating runoff and promoting deeper percolation has been well documented in tropical regions, as highlighted by work from Perera et al. (2021), which shows that forested vertisols exhibit better water retention and lower surface runoff compared to agricultural lands.

Urbanization represents a land use change that typically results in the degradation of the hydraulic properties of vertisol clay. The conversion of natural land cover to built-up areas involves sealing the soil surface with impermeable materials such as concrete and asphalt, which leads to reduced infiltration and increased surface runoff (Mishra et al., 2019). This alteration of the hydrological cycle is particularly significant in tropical regions, where intense rainfall events can lead to rapid runoff, flooding, and soil erosion. Urbanization also alters the natural water table and groundwater recharge, which can further degrade the water availability in vertisol regions. Research by Ali et al. (2020) highlights that urban development often results in a shift in the soil’s water balance, with increased runoff and decreased soil moisture retention.

The combined effects of land use changes, such as deforestation, urbanization, and intensive agricultural practices, have profound implications for the water balance in vertisol regions. In their comprehensive study, Singh et al. (2019) found that land use changes can lead to significant modifications in the hydraulic properties of vertisols, affecting their ability to store and transmit water. Changes in land cover often result in reduced water retention in the soil, with a higher risk of flooding during the wet season and drought during the dry season. This variability in soil water behavior under different land uses underscores the need for adaptive land management strategies that maintain soil structure and enhance the resilience of vertisol soils to changing climatic conditions.

The influence of land use on the hydraulic response of vertisol clays in tropical soils is multifaceted, with significant implications for water management in these regions. Agricultural practices, urbanization, and forest cover all have the potential to modify the hydraulic properties of vertisols, affecting water infiltration, retention, and runoff. Research has demonstrated that sustainable land management practices, such as conservation tillage, reforestation, and urban planning that incorporates green infrastructure, can help mitigate negative impacts on the hydraulic response of these soils. Future research should focus on further quantifying these relationships and developing land-use strategies that can enhance the resilience of vertisol clay to the challenges posed by climate change.

• Statement of the Problem

Vertisols, characterized by their expansive clay content and high swelling and shrinking properties, are widely distributed in the tropical regions of Adamawa State, Nigeria. These soils play a crucial role in local agriculture, hydrology, and water management. However, their hydraulic properties—specifically their permeability, water retention, and drainage capabilities—are highly sensitive to land use changes. In Adamawa State, rapid agricultural intensification, urban expansion, and deforestation have led to significant alterations in the land cover, which are expected to have profound implications for the hydraulic response of vertisol soils. Yet, the specific influence of these land use changes on the water dynamics of vertisols in this region remains poorly understood, creating a critical gap in the knowledge necessary for sustainable land management and effective water resource planning.

One of the primary concerns is how agricultural practices, particularly intensive cultivation and irrigation, affect the water infiltration capacity and retention of vertisols in Adamawa State. Agricultural activities often involve tillage, crop rotation, and the use of fertilizers, all of which can modify soil structure and influence water movement. In vertisols, tillage can lead to soil compaction, reducing pore spaces and infiltration rates, while at the same time altering surface runoff patterns. This is particularly problematic in tropical regions like Adamawa, where heavy seasonal rains can lead to flooding and erosion. The limited research on the interaction between agricultural land use and the hydraulic response of vertisols in this specific region makes it difficult to develop appropriate soil management practices and predict the soil’s behavior under changing climate conditions.

Urbanization in Adamawa State, though at a relatively early stage compared to more developed regions, is beginning to influence land use patterns. The conversion of natural or agricultural land to urban areas, with the construction of roads, buildings, and other impermeable surfaces, disrupts the natural water infiltration process. The replacement of vegetative cover with impervious surfaces reduces the ability of vertisol soils to absorb water, increasing surface runoff and the risk of localized flooding during heavy rains. The change in soil structure due to urban development, coupled with alterations in groundwater recharge, further complicates the water balance in the region. There is a growing need to assess how urbanization is affecting the hydraulic properties of vertisols in Adamawa and the potential consequences for local water management and flood control.

Forestation and land conservation practices also play a significant role in the hydraulic behavior of vertisol soils. The natural vegetation cover in the region helps maintain soil structure by promoting organic matter accumulation, which in turn enhances soil aggregation and water retention. However, deforestation for agricultural expansion and urbanization has led to the degradation of these soils, reducing their ability to retain moisture and increasing the susceptibility to erosion and runoff. The dynamics of land use changes, particularly the balance between forested and non-forested areas, need to be better understood in terms of their impacts on soil moisture dynamics, permeability, and overall water balance in Adamawa’s vertisol regions.

The lack of comprehensive studies on the hydraulic response of vertisol clays to land use changes in Adamawa State exacerbates the challenges of managing water resources in the region. The region’s climatic variability—characterized by distinct wet and dry seasons—means that land use changes can have differential impacts on water availability and distribution. A major concern is how these land use shifts may affect agricultural productivity, water availability for local communities, and the potential for flooding or drought. Without empirical data and region-specific models, it is difficult to develop adaptive management strategies for mitigating the adverse effects of land use on vertisol hydrology, especially under the pressure of climate change.

In light of the rapid changes in land use in Adamawa State and their likely impact on the hydraulic behavior of vertisols, there is an urgent need for targeted research. Studies that explore the relationship between land use patterns and the hydraulic response of vertisol soils in this region are crucial for developing effective land management policies. Such research will provide the necessary scientific foundation for soil conservation, agricultural planning, and sustainable urban development, ensuring that the region’s water resources are managed efficiently and equitably. Without this knowledge, the potential risks of soil degradation, water scarcity, and flooding will remain poorly understood, hindering the long-term sustainability of the region’s natural resources.

1.3. Aim and Objectives of the Study

The aim of the study is to examine the influence of land use on hydraulic response of vertisol clay of tropical soil. The specific objectives of the study are:

1. To analyze the impact of different land use practices on the hydraulic conductivity of vertisol clay.
2. To investigate how land use affects the water retention capacity of vertisol clay in tropical soil.
3. To assess the changes in soil structure and porosity due to different land use practices in vertisol clay.
4. To determine the relationship between land use and soil erosion potential in vertisol clay of tropical soil.

1.4. Research Questions

The research questions are buttressed below:

1. How does different land use practices impact the hydraulic conductivity of vertisol clay?
2. In what ways does land use affect the water retention capacity of vertisol clay in tropical soil?
3. What are the changes in soil structure and porosity due to different land use practices in vertisol clay?
4. What is the relationship between land use and soil erosion potential in vertisol clay of tropical soil?

1.5. Significance of the Study

This study is significant in understanding the complex relationship between land use patterns and the hydraulic properties of Vertisol clay in tropical regions, specifically focusing on the Dangote Sugar Refinery in Numan, Adamawa State. Vertisols, or clay soils, are known for their high swelling and shrinking characteristics, which make them highly sensitive to changes in land use and hydrological cycles. The study aims to explore how various land use practices—such as agricultural activities, industrial operations, and infrastructural development—impact the soil’s water retention, permeability, and overall hydraulic response. This research is particularly crucial in regions like Numan, where large-scale agricultural and industrial activities intersect with local water resource management.

Understanding the hydraulic response of Vertisol clay under different land use conditions can significantly enhance soil management practices in the region. In tropical climates, where rainfall is intense and seasonal, the ability of soils to absorb, retain, and transmit water affects agricultural productivity and infrastructure longevity. By examining how different land uses at the Dangote Sugar Refinery site alter these hydraulic properties, the study will contribute valuable data to optimize land management and mitigate issues like erosion, soil compaction, and waterlogging. This has implications not only for improving agricultural yields but also for managing industrial effluents and wastewater, which may affect both soil and water quality.

In the context of the Dangote Sugar Refinery, the research holds particular relevance for sustainable industrial practices. Large-scale industries can drastically alter local ecosystems, and understanding the impact of such developments on surrounding soils and hydrology can help inform better practices. For example, changes in surface cover, irrigation practices, or the introduction of impermeable surfaces can reduce water infiltration and exacerbate runoff, leading to soil degradation. By studying these effects within the unique context of the Dangote Sugar Refinery, the research can provide insights that are directly applicable to future industrial developments, helping to balance economic growth with environmental sustainability.

Moreover, the study will contribute to the broader field of land use and hydrology in tropical regions. As urbanization and industrialization continue to expand in Africa and other developing regions, understanding the hydraulic behavior of soils like Vertisols will become increasingly important. With climate change amplifying the frequency and intensity of extreme weather events such as heavy rains and droughts, the ability of soils to manage water will be critical. This study’s findings can serve as a baseline for future research in similar environments and can help local governments, farmers, and industry leaders make informed decisions regarding land use and water management strategies.

The findings of this research are also significant for policy development and land use planning in Adamawa State and other parts of Nigeria. By providing detailed information on the effects of various land use practices on the hydraulic properties of Vertisol soils, the study can assist policymakers in creating guidelines for land management that are suited to the local environmental conditions. Such guidelines could influence zoning laws, land conservation practices, and agricultural extension services, promoting land use that minimizes environmental degradation while maximizing economic benefits. Additionally, these insights can help in the development of more effective soil conservation strategies to mitigate soil erosion, enhance water retention, and improve crop yields in the region.

Finally, the study’s significance extends to the wider scientific community by providing new data on the hydraulic properties of Vertisols in tropical regions, a subject that is still underexplored compared to other soil types. The research will contribute to the growing body of knowledge on soil-water relationships in the tropics, particularly in areas affected by both natural and human-induced changes. By addressing the knowledge gap in this field, the study will help scientists and researchers develop more accurate models of soil behavior in response to land use changes. This will, in turn, enhance predictive capabilities for land use planning, disaster risk management, and sustainable agricultural practices in tropical regions.

1.6. Scope of the Study

The study examines influence of land use on hydraulic response of vertisol clay of tropical soil. A Case Study Of Dangote Sugar Refinery Numan Adamawa State.

 

1.7. Operational Definition of Terms

1. Influence: In this context,influence refers to the capacity of one factor or condition (e.g., land use) to have an effect or impact on another factor (e.g., the hydraulic properties of soil). It describes how changes in one aspect of the environment can alter the behavior or characteristics of another, such as how land use practices might affect the soil’s ability to manage water.
2. Land Use: Land userefers to the way in which land is utilized or managed by humans. It includes various activities such as agriculture, industry, residential development, forestry, and conservation. The specific land use in question can significantly impact the physical and chemical properties of the land, including its soil, water retention capabilities, and overall environmental health.
3. Hydraulic Response: Hydraulic responserefers to how soil or another material reacts to changes in water, such as the movement, absorption, storage, or drainage of water within it. In soils, this includes processes like infiltration, permeability, water retention, and drainage capacity. A soil’s hydraulic response is crucial in determining how effectively it can manage rainfall and irrigation, especially in regions with variable or extreme weather patterns.
4. Vertisol Clay: Vertisol clayrefers to a specific type of soil found predominantly in tropical and subtropical regions. Vertisols are characterized by their high content of expansive clay minerals, particularly smectite, which causes the soil to swell when wet and shrink when dry. This results in the formation of deep cracks during dry periods and a tendency to become very sticky when wet. These soils can present both challenges and opportunities for agriculture and land management, depending on their moisture conditions.
5. Tropical Soil: Tropical soilrefers to soils found in tropical climates, which are typically warm and have high rainfall for much of the year. These soils can vary widely depending on local vegetation, moisture levels, and the degree of weathering. Common tropical soils include oxisols, alfisols, and vertisols, among others. They are often rich in nutrients but can also be prone to erosion and nutrient depletion due to the high rates of organic matter decomposition and leaching that occur in tropical environments.

Project – Influence of land use on hydraulic response of vertisol clay of tropical soil. A Case Study Of Dangote Sugar Refinery Numan Adamawa State.