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CBSE Board NCERT Solutions for Class 8th Science Chapter1:Crop Production and Management
NCERT Solutions for Class 8th Science Chapter 1 : Crop Production and Management
Page No: 13
Excercise
1. Select the correct word from the following list and fill in the blanks.
float, water, crop, nutrients, preparation
(a) The same kind of plants grown and cultivated on a large scale at a place is called _________.
(b) The first step before growing crops is ________ of the soil.
(c) Damaged seeds would _________ on top of water.
(d) For growing a crop, sufficient sunlight and _________ and _________ from the soil are essential.
Answer:
(a) The same kind of plants grown and cultivated on a large scale at a place is called crop.
(b) The first step before growing crops is preparation of the soil.
(c) Damaged seeds would float on top of water.
(d) For growing a crop, sufficient sunlight and water and nutrientsfrom the soil are essential.
2. Match items in column A with those in column B.
A B
(i) Kharif crops (a) Food for cattle
(ii) Rabi crops (b) Urea and super phosphate
(iii) Chemical fertilisers (c) Animal excreta, cow dung, urine and plant waste
(iv) Organic manure (d) Wheat, gram, pea
(e) Paddy and maize
Answer:
A B
(i) Kharif crops (e) Paddy and maize
(ii) Rabi crops (d) Wheat, gram, pea
(iii) Chemical fertilisers (b) Urea and super phosphate
(iv) Organic manure (c) Animal excreta, cow dung, urine and plant waste
3. Give two examples of each.
(a) Kharif crop
(b) Rabi crop
Answer:
(a) Kharif crop: Paddy, maize
(b) Rabi crop: Wheat, gram
4. Write a paragraph in your own words on each of the following.
(a) Preparation of soil
(b) Sowing
(c) Weeding
(d) Threshing
Answer
(a) Preparation of soil is the first step before growing of crop. It helps to turn the soil and loosen it to allow the root to penetrate deep into it. The loosening of the soil helps in the growth of several soil microbes, earthworms etc., which enrich the soil with humus and other essential nutrients. The process of turning and loosening is called ploughing.This is done using a plough, hoe and cultivators.
(b) Sowing is the process of putting the seeds into the soil for growing crops. We need to use quality seeds for sowing. Sowing is done manually are mechanical equipment like Seed Drill. Seeds of few plants like rice is first grown in a separate area and then transplanted in the fields.
(c) In a field many other undesirable plants may grow along with the crop. These undesirable plants are called weeds. Farmers use many ways to remove weeds. Methods to control weeds are: Tilling before sowing of crops, physical removal of weeds by uprooting or cutting them close to the ground, using certain chemicals called weedicides etc.
(d) Threshing is the process of separating grains or seeds from chaff. It is done after harvesting the crop. It is usually carried out with the help of a machine known as ‘Combine’. This machine is a combined harvester and thresher. It harvests plants as well as cleans grains.
5. Explain how fertilisers are different from manure.
Answer:
| Fertiliser | Manure |
| Fertilisers are commercially available plant nutrients. | Manure is a natural substance prepared by the decomposition of animal excreta and plant wastes. |
| They can be organic or inorganic in nature. | Manure is known to have a large quantity of organic materials and very little amount of plant nutrients. |
| They ensure healthy growth and development of plants by providing them with nitrogen, phosphorus, potassium, etc. | They help in enriching the soil with organic matter and nutrients. |
| The addition of fertilisers to the soil requires special guidelines such as dose time, post addition precautions, etc., to be followed. | The addition of manure does not require any special guidelines. |
| A fertiliser does not provide any humus to the soil. | Manure provides humus to the soil and increases soil fertility. |
| Its excessive use causes water pollution. It cannot replenish organic matter of soil. | It protects the environment and helps in recycling farm waste. |
6. What is irrigation? Describe two methods of irrigation which conserve water.
Answer:
Supply of water to crops at appropriate intercals is called irrigation. The time and frequency of irrigation varies according to different seasons, crops, and soil types.
Two methods of irrigation which help in conservation of water are:
→ Sprinkler system: This system is more useful on uneven land, having fewer water supplies. In this method, water is supplied using pipes to one or more central locations within the field. When water is allowed to flow under high pressure with the help of a pump, it gets sprinkled on the crops.
→ Drip system: In this system, water is delivered at or near the roots of plants, drop by drop. This is the most efficient method of irrigation as there is no wastage of water at all. This method is important in areas where water availability is poor.
7. If wheat is sown in the kharif season, what would happen? Discuss.
Answer:
If wheat is sown in the kharif season (from June to October), then the whole crop might get destroyed because of many factors such as lack of optimum temperature, adaptability, availability of pests, etc. Kharif season includes the rainy season, which is not favourable for the growth of wheat crop. Therefore, wheat crop should not be sown during this season.
8. Explain how soil gets affected by the continuous plantation of crops in a field.
Answer:
If continuous plantation of crops is done in the fields then the soil will become poor in necessary nutrients like nitrogen, phosphorus, potassium, etc. Plants require nutrients for their proper growth and functioning. When a farmer continues to grow crops one after the other, then all nutrients available in the soil reduce and the crop yield decreases automatically.
9. What are weeds? How can we control them?
Answer:
Weeds are unwanted wild plants that grow in the field. Weeds compete with the crop for nutrients, light, and space. As a result, crop plants get lesser nutrients, light, and space for their development.
Some important weeding methods are:
→ Weeds can be controlled using weedicides. It is a chemical, which is sprayed in the fields to kill all available weeds. Weedicides are not harmful to crops.
→ Tilling before sowing of crops also helps in removing weeds. Tilling uproots the weeds. The best time for the removal of weeds is before they produce flowers and seeds.
→ The manual method of removing weeds is with the help of a khurpi. It involves regular uprooting or cutting of weeds close to the ground.
10. Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.
Answer:
11. Complete the following word puzzle with the help of clues given below.
Down
1. Providing water to the crops.
2. Keeping crop grains for a long time under proper conditions.
5. Certain plants of the same kind grown on a large scale.
Across
3. A machine used for cutting the matured crop.
4. A rabi crop that is also one of the pulses.
6. A process of separating the grain from chaff.
Answer:
Down
1. IRRIGATION
2. STORAGE
5. CROP
Across
3. HARVESTOR
4. GRAM
6. WINNOWING
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