NCERT CLASS 8 SCIENCE CH-1 SOLUTION

                      NCERT CLASS 8 SCIENCE CH-1

                  

                Crop Production and Management

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

ANS.A)CROP

            B)PREPARATION

            C)FLOAT

            D)WATER,NUTRIENTS

Question 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 superphosphate
( iii ) Chemical fertilizers	(c) Animal excreta, cow dung, urine and plant  waste
( iv ) Organic manure	(d) Wheat, gram, pea
	(e) Paddy and maize

ANS.1)e

         2)d

         3)b

         4)c

Question 3.

 Give  to example of each

A)Kharif crop

B)Rabi crop

ANS. Kharif crop: Paddy and maize

          Rabi crop: wheat and gram

Question 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: Soil preparation is necessary before growing a crop. It involves tilling and loosening the soil. This allows the roots to penetrate deep in the soil and to breath easily even when they are deep.

(b)Sowing:  The process of putting seeds into the soil is called sowing. The tool used traditionally for sowing seeds is funnel-shaped. Nowadays a seed drill is used for sowing with the help of tractors. This tool sows the seed uniformly at a proper distance and depth.

(c) Weeding:  Some undesirable plants grow along with crop and these unwanted plants are called weeds. The process of removing these unwanted plants is called weeding.

(d) Threshing:  The process of separating the grain seeds from the chaff is called threshing.

Question 5.

Explain how fertilisers are different from manure.
Answer:

Fertilisers	Manures
( i ) A fertilizer is an inorganic salt.	(i) Manure is a natural substance obtained by the decomposition of cattle dung, human waste and plant residues.
(ii) A fertilizer is prepared in factories.	(ii) Manure can be prepared in the fields.
(iii) A fertilizer does not provide any humus to the soil.	(iii) Manure provides a lot of humus to the soil.
(iv) Fertilizers are very rich in plant nutrients like nitrogen, phosphorus and potassium.	(iv) Manure is relatively less rich in plant nutrients.

   Question 6

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

ANS. The supply of water to crops at regular intervals is called irrigation. Methods of irrigation which conserve water are as follows:

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 mainly in 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.

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

ANS: Wheat crops may get destroyed if sown in the Kharif season because of unfavorable temperatures, pests and adaptable conditions for the plants to grow. Kharif comes during the rainy season; hence it is not a wise idea to grow wheat in the Kharif season.

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

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

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

ANS: 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 the crops helps in uprooting and killing weeds, which may then dry up and get mixed with the soil. Weeds are also controlled by using certain chemicals called weedicides.

10. Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.

ANS:

11. Complete the following word puzzle with the help of the 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 are grown on a large scale.

Across

3. A machine used for cutting the matured crop.

4. A rabi crop, which is also one of the pulses.

6. A process of separating the grain from the chaff.

ANS: