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Nigeria's free digital learning hub. Videos, lecture notes, practice questions and leaderboards aligned with CCMAS, NBTE, NCCE, WAEC, NECO, IJMB and JAMB curricula.
Environmental Health Science · 300 Level
This is the complete lecture note for EVM 302 Environmental protection, prepared for Environmental Health Science students at 300 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Series 1 Course code: EVM302 Course title: Environmental Protection Course credit load: 3 Units List of Series: Series 1: Soil Erosion and Environmental Protection Series 2: Land Reclamation and Rehabilitation Strategies Series 3: Bioremediation and Ecological Restoration Series 4: Quantitative Techniques in Environmental Analysis Series 5: Forecasting and Statistical Applications in Environmental Management Series 1: Soil Erosion and Environmental Protection Series Outline Part 1 (1.1): Causes of Soil Erosion Sub-Part 1.1.1: Natural factors (rainfall, wind, slope, soil type) Sub-Part 1.1.2: Human activities (deforestation, overgrazing, poor farming practices) Part 2 (1.2): Techniques for Preventing Soil Erosion Sub-Part 1.2.1: Soil cover and mulching Sub-Part 1.2.2: Contour farming and terracing Sub-Part 1.2.3: Crop rotation and intercropping Part 3 (1.3): Methods for Controlling Soil Erosion Sub-Part 1.3.1: Mechanical measures (bunds, check dams, terraces) Sub-Part 1.3.2: Biological measures (grasses, shrubs, cover crops) Part 4 (1.4): Role of Sustainable Farming Systems in Soil Protection Sub-Part 1.4.1: Conservation agriculture Sub-Part 1.4.2: Agroforestry practices Sub-Part 1.4.3: Integrated soil fertility management Part 5 (1.5): Tree Planting and Vegetative Measures for Soil Conservation Sub-Part 1.5.1: Afforestation and reforestation programmes
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Sub-Part 1.5.2: Shelterbelts and windbreaks Sub-Part 1.5.3: Indigenous and exotic species for soil stabilisation Introduction Soil erosion is one of the most pressing environmental challenges, undermining agricultural productivity, destabilising ecosystems, and contributing to land degradation. It occurs when the protective layer of soil is displaced by natural forces or human activities, leaving the land vulnerable to further damage. Understanding its causes and solutions is essential for protecting the environment and ensuring sustainable land use. The aim of this Series is to enable you to identify the causes of soil erosion and to apply effective prevention and control techniques, with particular attention to sustainable farming systems and vegetative measures that conserve soil resources. We shall commence this Series by examining the natural and human causes of soil erosion. Next, we will explore techniques for preventing erosion, followed by methods for controlling erosion through mechanical and biological approaches. Afterwards, we will consider the role of sustainable farming systems in soil protection. Finally, we will wrap up by discussing tree planting and vegetative measures as practical strategies for soil conservation. Series Learning Outcomes Upon completing this Series, you should be able to: SLO 1.1 define the natural and human causes of soil erosion, SLO 1.2 explain techniques for preventing soil erosion, SLO 1.3 demonstrate methods for controlling soil erosion using mechanical and biological measures, SLO 1.4 analyse the role of sustainable farming systems in soil protection, SLO 1.5 evaluate tree planting and vegetative measures as strategies for soil conservation. 1.1 Causes Of Soil Erosion 1.1.1 Natural factors Soil erosion is often driven by natural factors, which are environmental forces that displace soil particles from their original location. Rainfall refers to the impact of raindrops on bare soil, which loosens particles and makes them more susceptible to being washed away. Wind is another factor, especially in arid and semi-arid regions, where strong gusts lift and transport fine soil particles over long distances. Slope describes the gradient of land; the steeper the slope, the faster water flows, carrying soil along with it. Soil type also plays a role, as sandy soils are more prone to erosion compared to clay soils that bind particles more tightly.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS When rainfall intensity exceeds the soil’s ability to absorb water, erosion is accelerated. Similarly, wind erosion is more severe in areas with sparse vegetation cover. Fill in the blank: Soil erosion caused by strong gusts of wind in arid regions is known as __________. Diagram showing natural factors of soil erosion (rainfall, wind, slope, soil type) Figure 1.1 Natural factors influencing soil erosion 1.1.2 Human activities Human activities are a major contributor to soil erosion. Deforestation is the removal of trees and vegetation, which exposes soil to rainfall and wind. Without roots to hold the soil together, erosion becomes more severe. Overgrazing occurs when livestock feed excessively on vegetation, leaving the soil bare and vulnerable. Poor farming practices, such as continuous monocropping, improper ploughing, and lack of crop rotation, degrade soil structure and reduce its ability to resist erosion. In many regions, construction and mining also disturb the soil surface, accelerating erosion. These activities often strip away the protective vegetation cover and alter the natural drainage systems. Fill in the blank: The removal of vegetation cover due to excessive feeding by livestock is referred to as __________. Pilot questions 1.1
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 1. Which of the following is a natural factor contributing to soil erosion? 2. Soil erosion caused by steep gradients is primarily linked to: 3. The removal of trees and vegetation that exposes soil to erosion is called: 4. Which soil type is most prone to erosion due to weak particle binding? 5. Overgrazing contributes to soil erosion because it: 1.2 Techniques For Preventing Soil Erosion 1.2.1 Soil cover and mulching One of the simplest ways to prevent erosion is by maintaining soil cover, which refers to keeping vegetation or organic material on the soil surface. Mulching involves spreading plant residues, straw, or synthetic materials over the soil to protect it from raindrop impact and evaporation. This reduces erosion by shielding soil particles and improving moisture retention. Fill in the blank: Covering soil with plant residues to reduce erosion is known as __________. Image showing mulched farmland with crop residues
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Plate 1.2 Mulching as a soil erosion prevention technique 1.2.2 Contour farming and terracing Contour farming is the practice of ploughing along the natural contours of the land rather than up and down slopes. This slows water flow and reduces soil loss. Terracing involves creating step-like structures on steep slopes, which break the slope length and reduce runoff velocity. Both techniques are widely used in hilly regions to conserve soil and water. Fill in the blank: Ploughing along the natural curves of the land is called __________. 1.2.3 Crop rotation and intercropping Crop rotation is the practice of growing different crops sequentially on the same land to maintain soil fertility and reduce erosion. Intercropping involves planting two or more crops together, which provides continuous cover and reduces the risk of soil exposure. These practices improve soil structure, enhance biodiversity, and minimise erosion risks. Fill in the blank: Planting two or more crops together to reduce soil exposure is called __________. Pilot questions 1.2 1. What is the practice of covering soil with plant residues to reduce erosion called? 2. Which farming technique involves ploughing along the natural curves of the land? 3. What is the main purpose of terracing on steep slopes? 4. Growing different crops sequentially on the same land is known as: 5. Planting two or more crops together to provide continuous soil cover is called: 1.3 Methods For Controlling Soil Erosion 1.3.1 Mechanical measures Mechanical measures are physical structures designed to slow down water flow and reduce soil displacement. Examples include bunds, which are small embankments built across slopes to trap water and soil; check dams, which are barriers constructed across gullies to reduce water velocity; and terraces, which are step-like platforms created on steep slopes to break the slope length and minimise runoff. These measures are particularly effective in areas with heavy rainfall or steep terrain. Fill in the blank: Small embankments built across slopes to trap water and soil are called __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram showing bunds, check dams, and terraces as mechanical soil erosion control measures Figure 1.3 Mechanical measures for soil erosion control 1.3.2 Biological measures Biological measures involve using vegetation to stabilise soil and reduce erosion. Planting grasses, shrubs, and cover crops helps bind soil particles together, reduce runoff, and protect against wind erosion. These measures are cost-effective and environmentally friendly, as they improve soil fertility while preventing erosion. Fill in the blank: Planting vegetation such as grasses and shrubs to stabilise soil is an example of __________ measures.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Pilot questions 1.3 1. What type of soil erosion control involves building bunds and terraces? 2. Which structure is built across gullies to reduce water velocity? 3. What is the main purpose of terraces on steep slopes? 4. Planting grasses and shrubs to stabilise soil is an example of: 5. Which erosion control method improves soil fertility while preventing erosion? 1.4 Role Of Sustainable Farming Systems In Soil Protection 1.4.1 Conservation agriculture Conservation agriculture is a farming approach that minimises soil disturbance, maintains permanent soil cover, and
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