Basic Science and Technology - Junior Secondary 3 - Environmental hazard I - Soil erosion

TERM: 1^ST TERM

WEEK: 4

CLASS: Junior Secondary School 3

AGE: 14 years

DURATION: 40 minutes each for 2 periods

DATE:

SUBJECT: Basic Science

TOPIC: Environmental hazard I - soil erosion

SPECIFIC OBJECTIVES: At the end of the lesson, the learners should be able to

1. ) Define soil erosion
2. ) Mention and explain the types of soil erosion
3. ) Outline the causes, effects and control of soil erosion

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, story-telling, videos from source

INSTRUCTIONAL MATERIALS: Recommended Basic Science textbooks for Junior Secondary School 3

INSTRUCTIONAL PROCEDURES: PERIOD 1-2:

NOTE

ENVIRONMENTAL HAZARD I- SOIL EROSION

Soil erosion is the process by which the top layer of the soil, which contains the most nutrients, is worn away or removed by natural forces such as wind, water, and ice, or by human activity. It leads to the loss of fertile soil, reducing agricultural productivity and causing environmental degradation.

Types of Soil Erosion

There are three main types of soil erosion:

• Water Erosion: This is the most common form of soil erosion. It occurs when rainwater or surface runoff washes away the topsoil. There are different forms of water erosion, such as:
• Sheet Erosion: A thin layer of soil is removed evenly across the land surface by rainwater.
• Rill Erosion: Water concentrates in small channels or rills, causing deeper erosion.
• Gully Erosion: When rills become larger and develop into deep channels or gullies that are difficult to repair.
• Wind Erosion: This type occurs in dry, arid, or semi-arid regions where loose, dry soil particles are lifted and carried away by strong winds. Wind erosion is particularly common in desert regions or areas with sparse vegetation.
• Human-Induced Erosion: Activities such as deforestation, overgrazing, and urbanization can accelerate soil erosion. For instance, plowing fields without proper management can make the soil more vulnerable to erosion by water or wind.

Causes, Effects, and Control of Soil Erosion

Causes of Soil Erosion:

• Water: Heavy rainfall, improper drainage, and farming on sloped land can lead to water erosion.
• Wind: Drought, deforestation, overgrazing, and the removal of vegetation increase the susceptibility of soil to wind erosion.
• Human Activity: Poor agricultural practices, deforestation, urbanization, and construction lead to the loss of soil integrity and increase erosion risk.
• Poor Soil Management: Over-cultivation, improper irrigation, and lack of crop rotation can degrade soil structure, leading to increased erosion.

Effects of Soil Erosion:

• Loss of Fertile Soil: Erosion removes the nutrient-rich topsoil that is essential for healthy plant growth, leading to reduced agricultural productivity.
• Water Pollution: Eroded soil can carry pollutants into rivers, lakes, and oceans, causing water quality issues.
• Desertification: In areas with continuous erosion, the land can become barren and desert-like, unable to support plant life.
• Increased Flooding: Erosion can lead to the formation of gullies and poor water drainage, resulting in floods and damaging infrastructure.

Control of Soil Erosion:

• Vegetation Cover: Planting cover crops, grass, and trees helps bind the soil particles together, reducing wind and water erosion.
• Terracing and Contour Farming: In areas with slopes, creating terraces and farming along the contours of the land can help slow water flow and prevent soil movement.
• Mulching: Using mulch or organic matter on the soil surface reduces the impact of raindrops, helping to prevent surface erosion.
• Windbreaks: Planting rows of trees or shrubs as windbreaks can reduce the impact of wind erosion.
• Proper Irrigation Practices: Implementing proper irrigation techniques, such as drip irrigation, can minimize the risk of water erosion caused by over-irrigation.
• Reforestation and Afforestation: Planting trees and restoring forests can help prevent soil erosion in deforested areas

EVALUATION:

1. What is soil erosion, and how does it affect the environment?
2. Explain the different types of soil erosion and provide examples of each.
3. What are the main causes of soil erosion, and how do human activities contribute to it?
4. Describe the effects of soil erosion on agriculture and water resources.
5. What are some effective methods to control and prevent soil erosion? Discuss at least three measures.

CLASSWORK: As in evaluation

CONCLUSION: The teacher marks their books and commends them positively