Crop production and managment. Science class 8 ch 1 solution

 NCERT Solutions for Class 8 Science, Chapter 1 - Crop Production & Management:

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 _____________.

Answer (a):

Crop.

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

Answer (b):

Preparation.

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

Answer (c):

Float.

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

Answer (d):

Water, nutrients

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

Solution (2):

       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

Solution (3):

(a) Example of Kharif crop: Maize & soyabean

(b) Examples of Rabi crop: Gram & pea

4. Write a paragraph in your own words on each of the following.

(a) Preparation of soil

(b) Sowing

(c) Weeding

(d) Threshing

Solution (4):

(a) Preparation of soil:

Turning up the soil and loosening it is the first step before growing a crop. This allows the roots to penetrate deep into the soil. The loose soil allows the roots to breathe easily even when they go deep into the soil. The loosened soil helps in the growth of earthworms and microbes present in the soil. These organisms are friends of the farmer since they further turn and loosen the soil and add humus to it.

(b) Sowing:

Sowing of seeds at proper depths and distances gives a good yield. High-grade variety of seeds are sown after the selection of healthy seeds. Sowing is done by seed drills.

(c) Weeding:

Weeding involves the removal of unwanted and uncultivated plants called weeds. Weeding is essential as weeds compete with the crop plants for water, nutrients, space and light. It affects the growth of the crop. Some weeds are even poisonous for animals and human beings.

(d) Threshing:

Separation of the grains from the chaff is called threshing. It is either done manually by sickle or by a machine called harvester.

5. Explain how fertilisers are different from manure.

Solution (5):

Difference between fertilisers and manure:

 

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

Solution (6):

The supply of water to crops at regular intervals is called irrigation.

Two methods of irrigation which conserve water are

(i) Drip system: In this system, the water falls drop by drop directly near the roots. It is the best technique for watering fruit plants, gardens and trees.

(ii) Sprinkler System: In this system, 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. The sprinkler is very useful for lawns, coffee plantation and several other crops.

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

Solution (7):

Wheat is Rabi Crop and is sown in the winter season (October to March) and it needs very less water. If it is sown in Kharif season or rainy season (from June to September), the excess water may damage the crop. Extreme weather conditions may result in very less or no crop yield.

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

Solution (8):

Soil supplies mineral nutrients to the crop plants. These nutrients are essential for the growth of plants. Continuous cultivation of crops makes the soil poor in nutrients and crop yield decreases as plants do not get proper nutrients.

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

Solution (9)

Undesirable plants that grow naturally along with the crop are known as weeds. It can be controlled by the process of weeding. Weeding involves the removal of unwanted and uncultivated plants called weeds. Weeding is essential as weeds compete with the crop plants for water, nutrients, space and light. It affects the growth of the crop. Some weeds are even poisonous for animals and human beings.

Some methods to control weeds are

Physical removal of weeds by uprooting or cutting them close to the ground, from time to time.

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.

Solution (10)

 

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.

Solution (11):

 

 

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