Back to: Environmental Biology 200 Level
Welcome to class!
Hello brilliant mind! I’m so happy you’re here again. Let me ask you a simple question: Have you ever wondered why some farmlands produce very healthy crops, while others struggle no matter how much they are watered? The secret is in the soil! Just like you need good food to stay strong, plants need healthy soil to grow well. Today, we are learning about Soil Composition and Nutrient Cycling — and by the end of this lesson, you will understand why soil is called the foundation of life on land.
Soil Composition And Nutrient Cycling
What is Soil?
Soil is the thin layer of natural material covering the earth’s surface, where plants grow. It is made up of broken-down rocks, water, air, organic matter (like decayed leaves and animals), and tiny living organisms. In Nigeria, farmers know that “good soil is wealth,” because fertile soil means better harvests of yam, cassava, or maize.
Components of Soil
Soil is like a balanced recipe — each ingredient matters. The key components include:
Mineral particles: Sand, silt, and clay make up the bulk of soil. The proportion of these particles determines if soil is sandy, loamy, or clayey.
Organic matter: This includes decomposed plants and animals. It improves soil fertility and helps the soil hold water.
Water: Needed for plant growth and nutrient movement.
Air: Found in spaces between soil particles; plant roots and soil organisms need air to survive.
Living organisms: Worms, ants, fungi, and bacteria that help break down organic matter and recycle nutrients.
A loamy soil — with the right balance of sand, silt, clay, and organic matter — is perfect for crops. That’s why many Nigerian farmers prefer it for planting maize, beans, and yam.
Soil Formation
Soil forms from the weathering of rocks over hundreds of years. In areas like Jos Plateau, weathered granite forms the rich soils used for vegetable farming. The climate, plants, animals, and even human activities all affect the type of soil found in a place.
Nutrient Cycling
Nutrient cycling is how essential elements like nitrogen, phosphorus, and potassium move between the soil, plants, animals, and back to the soil. For example, when a plant grows, it takes nutrients from the soil. When animals eat the plant, they absorb these nutrients. When animals or plants die, decomposers break them down, returning nutrients to the soil. This cycle ensures soil stays fertile.
Human Impact on Soil and Nutrient Cycling
Human activities can either help or damage soil health. For example:
Over-farming without adding fertilisers can make soil poor.
Burning bushes and deforestation reduce organic matter and kill soil organisms.
Adding compost, manure, or cover crops improves soil nutrient cycling.
Nigerian Example
In the north, farmers rotate crops (like millet and groundnut) to maintain soil fertility. In the south, cocoa farmers add organic matter such as palm fronds and compost to keep soil productive.
Summary
- Soil is made up of minerals, organic matter, water, air, and living organisms.
- Soil composition affects plant growth and farming success.
- Nutrient cycling keeps soil fertile by recycling key elements.
- Human activities can either protect or destroy soil quality.
Evaluation
- List the five main components of soil.
- Explain why loamy soil is better for farming than sandy soil.
- Describe the role of decomposers in nutrient cycling.
- Mention two human activities that improve soil fertility.
You’ve done brilliantly today! Always remember: healthy soil means healthy life. Each time you see a thriving farm, know that the secret is in the care given to the soil. Keep shining, and let’s get ready for another exciting class with Afrilearn!