Q 1 – What is soil?
Ans. The uppermost layer of land area of earth, which is a mixture of rock particles and humus is called soil.
Q 2 – What is soil profile ?
Ans. A vertical section through different layers of the soil is called the soil profile.
Q 3 – Write the formula for percolation rate.
Ans. Percolation rate (ml/min)
amount of water (ml)
percolation time (min).
Q 4 – Name the climatic factors affecting soil properties.
Ans. Soil is affected by wind, rainfall, temperature, light and humidity.
Q 5 – What is the ideal soil for paddy?
Ans. For paddy, soils rich in clay and organic matter, having a good capacity to retain water, are ideal
Q 6 – Which soil is suited for lentils?
Ans. For lentils (masoor) and other pulses, loamy soils, which drain water easily, are required.
Q 7 – Which soil is suitable for cotton?
Ans. For cotton, sandy-loam or loam, which drain water easily and can hold plenty of air, are more suitable.
Q 8 – What is soil erosion?
Ans. The removal of fertile topsoil by water, wind or ice is known as soil erosion.
Q 9 – Why is there a demand to ban polythene bags?
Ans. Polythene bags and plastics pollute the soil. They also kill the organisms living in the soil. That is why there is a demand to ban polythene bags and plastics.
Q 10 – Name the layers of soil formed when soil is dissolved in water and left undisturbed.
Ans. Humus, water, clay, sand and gravel.
Q 11 – What is soil horizon?
Ans. Each layer of soil differs in feel (texture), colour, depth and chemical composition. These layers are referred to as horizons.
Q 12 – What is B-horizon?
Ans. The second layer of soil has a lesser amount of humus but more of minerals. This layer is generally harder and more compact and is called the B-horizon or the middle layer.
Q 13 – Write about C-horizon.
Ans. The third layer of soil is the C-horizon, which is made up of small lumps of rocks with cracks and crevices. Below this layer is the bedrock, which is hard and difficult to dig with a spade.
Q 14 – Write briefly about the topsoil.
Ans. The uppermost horizon is generally dark in colour as it is rich in humus and minerals. The humus makes the soil fertile and provides nutrients to growing plants. This layer is generally soft, porous and can retain more water. It is called the topsoil or the A-horizon.
This provides shelter for many living organisms such as worms, rodents, moles and beetles. The roots of small plants are embedded entirely in the topsoil.
Q 15 – Write briefly about loamy soil.
Ans. The best topsoil for growing plants is loam. Loamy soil is a mixture of sand, clay and another type of soil particle known as silt. Silt occurs as a deposit in river beds. The loamy soil also has humus in it. It has the right water holding capacity for the growth of plants.
Q 16 – Write about soil erosion.
Ans. The removal of fertile topsoil by water, wind or ice is known as erosion. Plant roots firmly bind the soil. In the absence of plants, soil becomes loose. So it can be moved by wind and flowing water. So, cutting of trees and deforestation should be prevented and efforts should be made to increase the green areas.
Q 17 – Discuss the dependence of crop on soil type.
Ans. The climatic factors, as well as the components of soil, determine the various types of vegetation and crops that might grow in any region. Clayey and loamy soils are both suitable for growing cereals like wheat and gram. Such soils are good at retaining water. For paddy, soils rich in clay and organic matter and having a good capacity to retain water, are ideal.
For lentils (masoor) and other pulses, loamy soils, which drain water easily, are required. For cotton, sandy-loam or loam, which drain water easily and can hold plenty of air, are more suitable. Crops such as wheat are grown in the fine clayey soils because they are rich in humus and are very fertile.
Q 18 – What is the difference between rate of percolation and the amount of water retained?
Ans. Rate of percolation is the amount of water percolated per unit time through soil. Whereas the amount of water retained is the amount of water absorbed by soil. Thus, rates of percolation and water retention are opposite attributes.
Q 19 – Can you suggest any method to let more rainwater percolate and reach the water underground?
Ans. Plants roots increases the extent of percolation of water to groundwater. So by planting more and more trees, we can make more rainwater to percolate and reach the water underground.
Q 20 – Explain how soil is formed.
Ans. Soil is fonned by the breaking down of rocks by the action of wind, water and climate. This process is called weathering and further addition õf humus formed by the decomposition of organic matter on the earth’s surface make it fertile.
Q 21 – In how many groups the soil has been categorised? Name them.
Ans. The soil has been categorised into four major groups, i.e.
- clay
- silt
- sand
- gravel
Q 22 – Which soil is considered to be the most fertile and used for growing crops?
Ans. Loamy soil is the most fertile soil and used for growing crops.
Q 23 – Which type of soil absorbs more water but allows less wateMo percolate?
Ans. Clayey soil absorbs more water but allows less water to percolate.
Q 24 – When we add some dry soil to the water in a glass and stir it, bubbles are observed from the soil. What causes these bubbles to raise?
Ans. 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.
Q 25 – What is weathering?
Ans. Weathering is a natural process by which huge rock is broken down into tiny particles but at a very slow rate.
Q 26 – There is shimmering of air just above the soil during hot summer day. What does the term shimmering indicate?
Ans. The term shimmering means that the air shines with a slightly shaking light.
Q 27 – Name two soil types used for cultivation.
Ans. Clayey soil and loamy soil are rich in humus and are suitable for growing plants like wheat and gram.
Q 28 – Soil has particles of different sizes. Arrange the words given below in decreasing order of their particle size. Rock, clay, sand, gravel, silt
Ans. The soil particles with the decreasing order of their particle sizes can be shown as
Rock > gravel > sand > silt > clay
Q 29 – There are two components of soil one that comes from living thing and other from non-living thing. What are these two components?
Ans. 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.
Q 30 – It is necessary to ban the use of polythene bags and plastics. Do you agree? If yes, why?
Ans. Polythene bags and plastics pollute the soil as they kill the organisms living in the soil.
That’s why, it is necessary to ban the use of polythene bags and plastic
Q 31 – List the substances which pollute the soil.
Ans. The substances which pollute the soil are polythene bags, plastics, waste products, chemicals, pesticides, etc.
Q 32 – A special kind of soil is used for making matkas and surahis. Name it.
Ans. Clayey soil is used to make matkas and surahis.
Q 33 – Explain the term humus that is generally found in the uppermost layer of soil.
Ans. The rotting dead matter in the soil is called humus.
Q 34 – Can we make toys with the soil obtained from a field? Explain.
Ans. No, soil from a field cannot be used to make toys. In order to make toys, the soil should be clayey.
Q 35 – The percolation rate varies from soil to other soil. Which soil would have the highest and least percolation rate?
Ans. Percolation rate of water is highest in the sandy soil, while the lowest in the clayey soil.
Q 36 – How can a farmer convert acidic soil into neutral soil?
Ans. The farmer can convert acidic soil into neutral soil by adding a small quantity of quicklime or slaked lime solution to the soil.
Q 37 – Do all types of soil absorb water to the same extent? Give reason for your answer.
Ans. No, it is because different types of soil has different absorbing capacity of water.
Q 38 – For planting rice, which kind of soil would be most suitable?
Ans. For planting paddy (rice), clayey soil that is rich in organic matter and have a good water retaining capacity is ideal.