What is soil
Soil is formed by erosion that is breaking up of rocks , by the action of sun, wind and rain. It forms at the surface of land and is the “skin of the earth.” Soil is capable of supporting plant life and is vital to life on earth.
Soil contains a lot of different things; a few essential ingredients are listed below:
Sediment – Every soil contains some mixture of sediments. The three main sediments are sand, silt, and clay. The type of sediments determines a soil’s type. Ideal soils (for farming) are a mixture of the three.
Organic Matter – Soil contains a lot of partially decomposed organisms which is called organic matter. Microbes in the soil break it down to make important nutrients. Most organic matter comes from plants. This is also called Humus and is dark brown or black in color.
Minerals – There are tons of different minerals in the soil. They’re used by plants for growth. When plants die, their minerals return to the Earth.
Types of soil and properties
A look at the previous lessons on earth and universe :
Grade 2 Science (NSO) : Earth and universe
Weather and The Sky: Earth and Sky fundamentals
The motion around the sun along its orbit is called a revolution . The amount of time it takes for a single trip around the sun is called a period of revolution. The period for the Earth to revolve around the sun is 365.24 days or one year. The .24 days is why every four years February has 29 days.
There are 4 seasons in an year .In Autumn and Spring the northern and southern hemispheres are tilted equally toward the sun.In Summer the Earth is on the other side of the sun and the northern hemisphere is tilted toward the sun and gets better sun rays. In winter the northern hemisphere is tilted away from the sun. That’s how we get seasons.
Earth’s orbit around the sun is slightly elliptical, Earth is actually slightly closer to the sun in the winter than it is in the summer.It is the tilt of Earth’s axis that causes the seasons.
Before starting lets take a look at the Grade 2 lessons
Plant – Types of plants
Plants – Parts we eat
Plants : Uses of different plants
Responsible for reproduction
Colour and fragarence of flowers attract insects who act as pollinators.
Flower parts that we eat :
Stems are the aboveground structures that bear the plant’s leaves and flowers. The stem provides a host of services to the plant:
- It provides a pathway for transporting water up to the leaves, and moving the sugars produced in the leaves down to nourish the roots.
- It acts as a sturdy mast to hold up the leaves and help orient them for maximum exposure to sunlight.
- It can act as a storage site for carbohydrates.
Root is the underground part of the plants body. It fixes the plant within the soil and absorbs water and mineral nutrients from the soil. It also stores excess food.
Function of roots
- Roots attach the plant body to the ground. It provides support to the plant and helps in holding the plant firmly in the ground.
- Root hairs of the plant absorb water and mineral from the soil and pass it to the stem.
- Some roots like carrot, radish etc. store food.
- Root bind the soil which otherwise may be blown away by wind or washed away by water. Root prevents soil erosion.
Types of roots