NCERT solutions for class 8 Science Chapter 1 Crop Production And Management

Solution for Exercise

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 ____________.


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NCERT solutions for class 8 science Chapter 1 crop production and management

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 ________ of the soil.


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

(b)The first step before growing crops is ____preparation___ of the soil.

(c) Damaged seeds would _________ on top of water.


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

(c) Damaged seeds would ___float__ on top of water.

(d) For growing a crop, sufficient sunlight and _________ and _________ from the soil are essential.


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

(d) For growing a crop, sufficient sunlight and _water_ and ___nutrients ___from the soil are essential.

Q.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


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NCERT solutions for class 8 science Chapter 1 crop production and management

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

Q.3. Give two example of each.
(a) kharif crops
(b) rabi crops


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

(a) Kharif crops- paddy, maize
(b) Rabi crops- wheat, grams

Q.4 Write a paragraph in your own words on each of the following.
(a) Preparation of soil (b) Sowing (c) Weeding (d) Threshing


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

(a) preparation of soil:
It is the first method to be followed before growing a crop. This method is usually employed for loosening the soil 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. Plants require nutrients for their proper growth and functioning. The process of loosening is called tilling or ploughing the soil. Tilling of soil brings the nutrient-rich soil to the top. This helps the plants to utilize the nutrients for their growth.
(b)sowing:
Sowing is another important step in crop production. It is the process of placing the seed in or on the soil for future growth. The seeds that are selected for growing should be of good quality. This will improve the net yield of the crop. Sowing is usually done with the help of either a traditional tool or a seed drill. The traditional tool is shaped like a funnel. It was used earlier for sowing seeds. Nowadays, seed drills that make the use of tractors are used for sowing seeds. This tool disperses seeds uniformly and sows seeds at proper depth. Sowing by this method saves time and also protects the seeds from birds.
(c) weeding:
Removal of unnecessary plants from the field is called weeding. Weeds compete with crop plants for nutrients and water. This will reduce the yield of the desired crops. Weeds also interfere while harvesting and gets mixed with crops. Some weeds are poisonous to animals and humans. Tilling is a common method which helps removal of weeds before sowing crops, manual methods like physical removal of plants are used to remove weeds. Weedicides are sprayed to get rid of weeds, but this method may affect the health of farmers because of chemicals used as weedicides.
(d) Threshing
Process of separating the chaff from the crop is known as threshing. Threshing is carried by a machine called ‘combine’ which is a harvester as well as a thresher. Threshing is also done by winnowing where to blow of wind is used to separate the chaff from crops.

Q.5 Explain how fertilisers are different from manure.


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

Fertilisers:
Fertilizer is an inorganic substance
Fertilizers are prepared artificially.
Prepared in factories
Does not provide Humus to the soil.
Rich in plant nutrition
Long term usage has adverse effects on soil.
Manure
Manure is an organic substance.
Manure is obtained by decomposition of animal, plant and human waste.
Prepared in field.
Provide humus to the soil.
Relatively less plant nutrients.
Long term usage improves soil fertility.

Q.6 What is irrigation? Describe two methods of irrigation which conserve water.


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

The supply of water to crops at regular intervals is called irrigation. Methods of irrigation which conserve water are
a) Drip Irrigation: Here the water goes drop by drop directly into the roots this method is very useful as it conserves the water and also helps in avoiding weeds.
b) Sprinkler system: This method is in use in mainly uneven land where sufficient water is not available. The perpendicular pipes, having rotating nozzles on top, are joined to the main pipeline at regular intervals. When water is allowed to flow through the main pipe under pressure with the help of a pump, it escapes from the rotating nozzles. It gets sprinkled on the crop as if it is raining.

Q.7 If wheat is sown in the kharif season, what would happen? Discuss.


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NCERT solutions for class 8 science Chapter 1 crop production and management

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.

Q.8 Explain how soil gets affected by the continuous plantation of crops in a field.


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

Plants require nutrients for their growth. Without optimum nutrients plants will die. Continuous plantation of crops results in depletion of certain nutrients like Nitrogen, Phosphorus, Potassium etc. This results in the decrease of yield due to loss of nutrients hence there should be a gap between crops in order to get a good yield.

Q.9 What are weeds? How can we control them?


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

In a field many other undesirable plants may grow naturally along with the crop. These undesirable plants are called weeds. Weeds can be controlled by methods called weeding. Tilling before sowing of crops helps in uprooting and killing of weeds, which may then dry up and get mixed with the soil. Weeds are also controlled by using certain chemicals, called weedicides.

Q.10 Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.
1. Sending crops to sugar factory
2. Irrigation
3.Harvesting
4.Sowing
5.Preparation of soil
6.Ploughing the field
7.Manuring


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

Flow chart of sugarcane crop production:
Preparation of soil
Ploughing the field
Sowing
Manuring
Irrigation
Harvesting
Sending crops to sugar factory

Q.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.


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NCERT solutions for class 8 science Chapter 1 crop production and management

Answer :

Down
1.IRRIGATION
2. STORAGE
5.CROP
Across
3. HARVESTOR
4.GRAM
6. WINNOWING



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