Soil - Class 3 Notes & Olympiad Questions

Soil

a) Soil is a natural abiotic resource that plants live in.
b) It's made up of small pieces of rocks, minerals, and other things like clay and humus.
c) Humus is a dark, organic material that forms in soil when plant and animal matter decay or break down over time. It is made up of things like leaves, twigs, dead plants, and animal waste.
d) Soil is really important for plants because it provides them with the things they need to grow, like water, nutrients, and minerals.
e) Soil is formed when big rocks are broken down into tiny pieces by things like wind, rain, and the sun's heat.

Layers of Soil

Soil is made up of different layers and each layer has its own job to do to help plants grow. These are:

1. Topsoil

a) The top layer is called topsoil.
b) It's full of nutrients that plants need to grow big and strong.

2. Subsoil

a) The next layer is called subsoil. It's made up of things like small rocks, minerals, and clay.
b) Subsoil helps hold water, so the plants can use it when they need to.

3. Bedrock

a) The bottom layer is called bedrock.
b) Bedrock is hard and made of solid rock and acts as a foundation for the soil layers above it.

Types of Soil

Soil is the top layer of the Earth's surface, and it comes in different types depending on its composition and characteristics. Three common types of soil are:

1. Sandy Soil

a) Sandy soil is made of small, fine grains of sand.
b) It feels rough and doesn't hold water very well because the particles are large and have lots of space between them.
c) It's easy to dig in sandy soil, and it drains quickly.
d) It doesn't retain nutrients well, so plants may need extra fertilizers to grow in sandy soil.

2. Clayey Soil

a) Clay soil is sticky and smooth.
b) The particles in clay soil are very small and tightly packed together, so it holds water well.
c) However, because it doesn't have many spaces, air doesn't move through it easily.

3. Loamy Soil

a) Loamy soil is considered the best type of soil for plants.
b) It's a mixture of sand, silt, and clay.
c) Loamy soil has medium-sized particles that are not too large or too small.
d) This type of soil has a good balance of water-holding capacity and drainage.
e) It's fertile and contains plenty of nutrients that plants need to grow.