V. Answer the following questions in two sentences.

1. What is weathering of rocks?

Ans. The action of natural factors that lead to breaking of rocks into smaller and smaller pieces is known as weathering of rocks.

2. Differentiate between loamy and sandy soil.

Ans. Loamy soil: 1. It contains equal amount of sand and silt and lesser amount of clay.

2. It contains good amount of humus.

3. It holds good amount of air and water.

4. Plants grow will in this type of soil.

Sandy soil: 1. It contains mostly sand.

2. It doesn't contain humus.

3. It cannot hold water.

4. Plants don't grow in this type of soil.

3. What do you understand by percolation rate of soil?

Ans. Percolation rate of soil is the measure of how fast water flows or percolates through the soil.

4. Excessive use of fertilizers is not beneficial for soil. Why?

Ans. Excessive use of chemical fertilizers reduce the fertility of the soil. It makes the soil hard and less porous. It also kills the soil organisms which keep the soil fertile.

5. Why do farmers grow cover crops?

Ans. A cover crop is grown to cover the land after harvesting the main crop. Cover crops prevent the soil from being exposed to wind and flowing water.

6. What are shelter belts?

Ans. The plants which are grown on the boundaries of field to reduce the force of wind and water are called shelter belts.

VI. Answer the following questions in about four to five sentences.

1. Why do plants grow well in loamy soil?

Ans. Plants grow well in loamy soil. Loamy soil contains an equal amount of sand and silt and lesser amount of clay. It also contains good amount of humus, which keeps the soil fertile. Loamy soil can hold necessary amount air and water to help growing plants.

2. What is compost? Why is it beneficial to soil?

Ans. Compost is a natural fertiliser made out of plant animal waste.

Compost improves the quality of soil. It loosens the soil and helps air and water to move freely. It holds moisture and plant nutrients. It also serves as food for soil microorganisms, which make the soil fertile.

3. How is sandy soil different from clayey soil?

Ans. Clayey soil: 1. Contains finer particles. 

2. Particles are tightly packed.

3. It is fertile.

4. High water retention capacity.

5. Lowest percolation rate of water.

Sandy soil: 1. Contains larger particles.

2. Particles are loosely packed.

3. It is not fertile.

4. Low water retention capacity.

5. Highest percolation of water.

4. Explain the main horizons of soil.

Ans. The distinct layer of soils are called soil horizons. Main horizons of soils are discussed below.

Horizon A:- It is the uppermost layer of soil. It contains sand, silt, clay and pebbles. It is rich in humus.  This layer supports plant lives. 

Horizon B:- It is ther layer just below Horizon A. Besides sand, silt and clay, it contains a large amount of pebbles. It contains very little organic material or humus. It is a storehouse of minerals.

Horizon C:- The lowermost layer of the soil is horizon C. It contains mostly large pieces of rocks.