Here are extra questions from the chapter Crop Production and Management of NCERT Class 8 Science. Textbook solutions of this chapter can be found here.

1. What is a crop?

A crop is a plant of the same kind cultivated at a place on a large scale.

2. What are kharif crops? Give some examples.

The crops which are sown in the rainy season are kharif crops. In India, the rainy season is between June and September. Examples are: rice, maize, groundnut, soyabean and cotton.

3. What are rabi crops?

The crops grown in the winter season (October to March) are called rabi crops. Examples are: wheat, gram, pea, mustard, linseed

4. Pulses are usually grown in ………………………….

Summer

5. Why is paddy a Kharif crop

Paddy can only be grown in the rainy season because its cultivation requires a lot of water.

6. What do you mean by the term agricultural practices?

Agricultural practices are activities or tasks involved in the cultivation of crops. These include:

• The preparation of soil
• Sowing of seeds
• Addition of manure and fertilisers to the soil
• Irrigation
• Protecting crops from seeds
• Harvesting
• Storage

7. Why is it important to loosen the soil before sowing seeds?

Turning and loosening the soil allows roots to penetrate deep into the soil. If the soil is loose, the roots can breathe easily even when they are deep inside. In addition, the loosening of the soil allows the growth of earthworms and friendly microbes that further turn the soil. Turning and loosening also bring the nutrient rich soil to the top and thus facilitate the growth of plants.

8. What is tilling or ploughing?

This is the process of turning and loosening the soil.

9. What are crumbs?

These are the big clumps of soil found in ploughed land.

10. Name some tools used for breaking the crumbs.

Plough, hoe, cultivator

11. Why do damaged seeds float on water?

Damaged seeds become hollow and hence they are lighter. Therefore, they float on water.

12. What are manure and fertilisers?

These are substances containing nutrients added to the soil for the healthy growth of plants.

13. Why do farmers have to add nutrients to the soil?

Continuous cultivation of the soil makes it poor in nutrients. Hence, farmers have to add manure to replenish the lost nutrients. This process is called manuring.

14. What is manure?

Manure is an organic substance obtained from the decomposition of plants or animal wastes. In order to produce manure, farmers dump animal waste or plants into open pits and allow them to decompose. The decomposed matter is used as organic manure.

15. What are fertilisers?

Fertilisers are chemicals rich in a particular nutrient. They are produced in factories. Some examples are urea, ammonium sulphate, super phosphate, potash and NPK.

16. What are the disadvantages of using fertilisers?

Fertilisers have certainly allowed farmers to get good yields. However, excessive use of fertilisers also makes the soil less fertile. In addition, when fertilisers mix with water, it leads to water pollution.

17. Why is it important to substitute fertilisers with organic manure whenever possible?

Excessive use of fertilisers makes the soil less fertile and also leads to water pollution. By contrast, organic manure only increases soil fertility. It also improves the water retaining capacity of the soil. Manure makes the soil porous and also increases the presence of friendly microbes in the soil. Hence, it is important to substitute chemical fertilisers with organic matter whenever possible.

18. Mention some ways to retain the fertility of the soil.

• Limit the use of chemical fertilisers.
• Substitute chemical fertilisers with organic manure.
• Leave the land uncultivated in between two crops.
• Crop rotation is another way to replenish the soil with nutrients.

19. What is crop rotation?

It is a method of replenishing the nutrients in the soil by growing different crops alternatively.

20. How does growing legumes improve the fertility of the soil?

The Rhizobium bacteria which can fix atmospheric nitrogen is present in the nodules of the roots of leguminous plants. Hence, growing legumes in one season increases the amount of nitrogen in the soil and helps the growth of crops grown in the next season.

21. Difference between fertilizer and manure.

Fertilizer

• It is a man-made inorganic substance
• It is produced in factories.
• It is very rich in plant nutrients like nitrogen, phosphorus and potassium.
• It does not add any humus to the soil.

Manure

• Manure is an organic substance obtained from decomposed plants and cattle dung.
• It is prepared in open fields or pits.
• Manure adds humus to the soil and increases its water retaining capacity.
• Compared to chemical fertilizers, manure is less rich in plant nutrients.

22. What is irrigation?

Irrigation is the process of supplying water to crops at regular intervals.

23. Mention some traditional ways of irrigating crops

• Moat (pulley system)
• Chain pump
• Dhekli
• Rahat (lever system)

24. Write a brief note on modern methods of irrigation

Sprinkler system

This is suitable for irrigating uneven land. In sprinkler system, perpendicular pipes with rotating nozzles on top are joined to the main pipeline at regular intervals. When water flows through the main pipe, due to pressure it escapes through the nozzles and gets sprinkled on the crops. This is a good method for watering lawns, coffee plantations etc.

Drip irrigation system

In drip irrigation system water falls directly near the roots drop by drop. This is good for watering trees, fruit plants etc.

25. What are weeds?

Weeds are undesirable plants that grow naturally alongside the crop.

26. What is weeding?

Weeding is the removal of weeds. Weeds should be removed because weeds compete with crop plants for water, nutrients, light and space.

27. What are weedicides?

Weedicides are chemicals used to control weeds.

28. What is harvesting?

Harvesting is the cutting of crops after they mature.

29. What is threshing?

Threshing is the process of separating grain seeds from the chaff.

30. What is a combine?

A combine is a machine that serves the purpose of both a harvester and a thresher.

31. What is winnowing?

Winnowing is another method of separating grains from chaff.

32. How should grains be stored?

Harvested grains should be protected from moisture, rats, insects and microorganisms. Harvested grains contain more moisture and hence they should be dried before they are stored. Dried grains are less likely to be attacked by pests, bacteria and fungi.

33. What is animal husbandry?

Animal husbandry is the process of rearing animals on a large scale in farms or at home.