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Q1. Why soil air is important?

Solution

Soil air is required by roots of plants to breathe. If plants will not get air, they will die.

Q2. How is soil formed?

Solution

Soil is formed by breaking down of rocks by the action of wind, water and climate. The bigger pieces of rocks get converted into small pieces of soil.

Q3. How soil is classified on the basis of formation and occurrence?

Solution

Soil is of three types on the basis of formation and occurrence. These are: a. Residual soil: This type of soil remains at its place of formation. Example - red soil. b. Transported soil: This type of soil is transported to distant places from its origin by various agents of erosion like wind, water like alluvial soil. c. Mountain soil: It is found in Himalayan region and northeastern states.

Q4. What is soil erosion? Discuss the effects of soil erosion.

Solution

The removal of fertile topsoil by the action of wind or water is called soil erosion. Effects of soil erosion: 1. The topsoil is removed leaving the land infertile. 2. As the land is infertile, it can no longer support agriculture resulting in the shortage of food grains. 3. It can cause floods as the rainwater is not stopped by the roots of trees or plants near the river banks.  

Q5. List any two positive attributes of sandy soil.

Solution

The two positive attributes of sandy soil are: a. It is rich in minerals. b. It has very high percolation rate thus it helps in recharging ground water.

Q6. What is the importance of soil moisture?

Solution

Soil moisture is necessary because plants take up water from soil and dissolved minerals with help of roots from the soil.

Q7. How humus prevents soil erosion?

Solution

Humus helps the soil to absorb surface water quickly and retain it. Thus, the soil remains wet and prevents soil erosion.

Q8. Why loamy soil is the most fertile soil?

Solution

Loamy soil is a mixture of sand, clay, silt and humus in right proportions. It contains sufficient amount of humus and thus provides all the necessary nutrients for the growth of plants.

Q9. Why clay is not suitable for growing plants?

Solution

Clay has smallest sized particles(less than 0.002 mm) thus it has very less soil air due to small intermolecular spaces. Its water absorbing and retaining capacity is very high thus it becomes waterlogged.

Q10. Why wheat and rice are majorly grown in Punjab?

Solution

In Punjab, five rivers flow which brings alluvial soil with them. Alluvial soil is the most fertile soil which is suitable for the growth of wheat and rice.

Q11. Which soil is best for growing masoor dal and why?

Solution

Loamy soil is best for growing masoor dal because it drains water easily.

Q12. Why water table is present over bed rock?

Solution

Because bed rock is impervious to water.

Q13. How desert soil could be made cultivable?

Solution

It can be made cultivable by adding humus and using proper irrigation techniques.

Q14. How acidic soil can be made fertile?

Solution

Acidic soil can be made fertile by adding lime to it.

Q15. Why loamy soil is the most fertile soil?

Solution

Loamy soil is a mixture of sand, clay, silt and humus in right proportions. It contains sufficient amount of humus and thus provides all the necessary nutrients for the growth of plants.

Q16. (i) Why major plantation of coconut is found in western ghats and eastern ghats? (ii) Which constituent of mountain soil makes it fertile?

Solution

(i) Major plantation of coconut is found in western and eastern ghats because it has lateritic soil which is most suitable for the growth of coconuts.(ii) Mountain soil is made up of sand, stones, clay limestone. It has the highest content of humus of all the soil types. This makes mountain soil very fertile.

Q17. (i) Why potato grows well in sandy soil? (ii) Does planting trees affect soil erosion? How?

Solution

(i) Because potato needs proper soil air and soil rich in plant nutrients so it can grow in less water.(ii) Yes, planting trees helps in reducing the soil erosion as the roots of the plants bind the soil particles together and thus, they hold soil particles and prevent soil erosion.

Q18. A farm is left without sowing any crops for the season. It rains heavily. How will this affect the soil?

Solution

The running water of the rains will carry away the fertile topsoil of the farm and the soil will lose its fertility.

Q19. Why the air above the land seems to shimmer?

Solution

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

Q20. Why the air above the land seems to shimmer?

Solution

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

Q21. How earthworms increase soil fertility?

Solution

Earthworms ingest soil, digest the organic matter present in it and excrete soil full of plant nutrients known as worm cast which makes soil fertile. They make burrows into the soil and thus they aerate the soil.

Q22. Does planting trees affect soil erosion? How?

Solution

Yes, planting trees helps in reducing the soil erosion as the roots of the plants bind the soil particles together and thus, they hold soil particles and prevent soil erosion.

Q23. Which soil is best for growing masoor dal and why?

Solution

Loamy soil is best for growing masoor dal because it drains water easily.

Q24. (i) Why percolation rate affects the fertility of soil?(ii) How humus prevents soil erosion?

Solution

(i) Percolation rate is the rate at which water drains from soil. If percolation rate of soil is less it will become water logged, if percolation rate of soil is high then no water will be available to plants. Thus, it will affect the fertility of soil.(ii) Humus helps the soil to absorb surface water quickly and retain it. Thus, the soil remains wet and prevents soil erosion.

Q25. Why lateritic soil is not much fertile?

Solution

Lateritic soil is not much fertile because the plant nutrients get washed away or seep to subsoil with rain water.

Q26. (i) Why percolation rate affects the fertility of soil?(ii) How humus prevents soil erosion?

Solution

(i) Percolation rate is the rate at which water drains from soil. If percolation rate of soil is less it will become water logged, if percolation rate of soil is high then no water will be available to plants. Thus, it will affect the fertility of soil.(ii) Humus helps the soil to absorb surface water quickly and retain it. Thus, the soil remains wet and prevents soil erosion.

Q27. How can soil pollution be prevented?

Solution

The following can help in the prevention of soil pollution: 1. Avoid using plastic bags; instead use paper, cloth or jute bags. 2. Plastics, discarded glass and metal objects should be sent for recycling. 3. Use of excessive pesticides and chemical fertilisers in agriculture should be minimised. 4. Appropriate steps should be taken to reduce the emission of harmful gases such as sulphur dioxide and nitrogen oxide from factories which are responsible for acid rains. 5. Industrial wastes should be treated to make them harmless before dumping in the soil. 

Q28. What is the importance of soil moisture?

Solution

Soil moisture is necessary because plants take up water from soil and dissolved minerals with help of roots from the soil.

Q29. What are the properties of desert soil?

Solution

The properties of desert soil are: a. Soil is sandy and porous. b. It is rich in soluble salts. c. It has poor water retention capacity.

Q30. Does the pH of soil affects fertility of soil?

Solution

Yes, pH of soil affects the fertility of soil as plants cannot grow in acidic or alkaline soil.

Q31. Soil is an important natural resource. Explain.

Solution

Soil supports the growth of plants, provides shelter to many organisms and is important for agriculture which provides us with food. Hence, soil is an important human resource.

Q32. Why alluvial soil is suited for growth of wheat and rice?

Solution

Alluvial soil is rich in humus and is loamy in texture. Thus it is suitable for growth of wheat and rice.

Q33. Why black soil is found in Deccan plateau?

Solution

Because Deccan plateau has a sleeping volcano so soil present there is formed by the erosion of that volcanic rock. Therefore, Deccan plateau has black soil.

Q34. Which properties of soil determine fertility of soil?

Solution

Following are the properties of soil which help in determining fertility of soil: a. Aeration. b. pH of soil. c. Water absorbing and water retaining capacity of soil. d. Amount of minerals and humus in soil.

Q35. List any two positive attributes of sandy soil.

Solution

The two positive attributes of sandy soil are: a. It is rich in minerals. b. It has very high percolation rate thus it helps in recharging ground water.

Q36. (i) Why fewer plantations are found in deserts?(ii) Why clay is not suitable for growing plants?

Solution

(i) Fewer plantations are found in desert because sand has very poor water holding capacity. So, vey less amount of water is available to the plants for their growth.(ii) Clay has smallest sized particles(less than 0.002 mm) thus it has very less soil air due to small intermolecular spaces. Its water absorbing and retaining capacity is very high thus it becomes waterlogged.

Q37. Why topsoil is best for plant growth?

Solution

The top soil particles are finest and porous so that it allows more water to retain in it. The top soil is darker in colour due to the presence of humus which makes it fertile and best for plant growth.

Q38. Which factors are common for weathering and erosion?

Solution

Wind and water are common  agents for weathering and erosion.

Q39. List any two properties of healthy soil.

Solution

The two characteristics of healthy soil are: a. It is a mixture of different sized particles. b. It is rich in humus.

Q40. How ground water gets recharged?

Solution

Rain water seeps through the soil towards bed rock where it gets collected and thus recharges ground water.