Humus is formed by decaying remains of plants and animals which are only found in topsoil.

Earthworms are called a farmer's friend because earthworms till the land by moving in soil when the land is watered.

Soil contains organic materials such as starch, cellulose, fats and proteins and remains of dead organisms. These give energy to the living organisms. Air, water and minerals present in soil also give enough energy to living organisms to sustain their lines.

(i) Soil is the most important natural resource. It supports the growth of plants by holding the roots firmly.
(ii) It helps in supplying water and nutrients to plants
(iii) It is the home of many organisms
(iv) It is essential for agriculture, which provides food, clothing and shelter for all. Soil is thus an inseparable part of our life.

On a hot summer day, the vapour coming out of the soil reflect the sunlight and the air above the soil seems to shimmer.

For planting paddy (rice), clayey soil that is rich in organic matter and have a good water retaining capacity is ideal

No, it is because different types of soil has different absorbing capacity of water.

No, soil from a field cannot be used to make toys. In order to make toys, the soil should be clayey.

The rotting dead matter in the soil is called humus.

The substances which pollute the soil are
polythene bags, plastics, waste products, chemicals, pesticides, etc.

The two major components of soil are weathered rock particles, i.e. non-living components and humus that consists of living organisms like fungi, bacteria, worm, insects, etc.

When dry soil is added in the water in a glass and stir it, bubbles appear. These bubbles are caused due to the air present in between the soil particles

The absorption percentage of water can be calculated by the formula given below
Percentage of water absorb
\(\frac { amount\quad of\quad water\quad absorted(in\quad ml) }{ amount\quad of\quad soil(in\quad gm) } x100\)

The soil has been categorised into four major groups, i.e.
(i) clay
(ii) silt
(iii) sand
(iv) gravel