Thursday, 18 February 2016

TEXTBOOK ANSWERS AND SOLUTIONS OF CBSE CLASS VIII SCIENCE CHAPTER 1 CROP PRODUCTION AND MANAGEMENT



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 _ 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 _ nutrients_ from 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 fertilizers     (c) Animal excreta, Cow dung urine and Plant waste
(iv) Organic manure          d) Wheat, gram, pea
                                        e) Paddy and maize



ANSWER:-

i)------e)
ii)-----d)
iii)-----b)
iv)------c)

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:
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:
Undesirable plants that grow along with the crop are known as weeds. Weeding is the process of removing these weeds. Xanthium, Parthenium, etc. are some common weeds. Weeds compete with the crop for nutrients, light, and space. As a result, crop plants get lesser nutrients, light, and
space for their development.

d)Threshing:
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:-

Fertilisers.                   

-Fertilizers are made from chemicals and they are rich in plant nutrients like nitrogen, phosphorus etc.
-Fertilizers are prepared in factories.
-Fertilizers do not provide any humus to the soil
-Fertilizers pollute water as they are made from chemicals

Manure
-Manures are made from cattle dung, human waste and plant residues. Manures are relatively less rich in plant nutrients as compared to fertilizers.
-Manures are prepared in the fields.
-Manure provides a lot of humus to the soil.
-Manures do not pollute water as they are made from natural substances.

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


ANSWER:-Irrigation is the process by which water is supplied to crops at different intervals. The time and frequency of irrigation varies according to different seasons, crops, and soil types

a) 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.


b)Drip system :
This system of irrigation is generally used to irrigate the gardens, trees and fruit plants. In this system the water falls drop by drop just at the position of roots. The places where water is not available in abundant, this method is very useful as the water is not wasted and the plants get regular supply of water.

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:-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:-Undesirable plants that grow along with crop plants are known as weeds we can control the weeds by different methods.

Tilling: Tilling of fields before sowing the seeds uproots the weeds. Weeds then dry up and mixed with the soil.

Manual removal: Weeds are removed manually with the help of trowel or harrow.

Weedicides: There are certain chemicals available to control weeds which are known as weedicides. These are sprayed on the fields to kill the fields.

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




ANSWER:-
The correct sequence is:
1. Preparation of soil
2. Ploughing the field
3. Sowing
4. Manuring
5. Irrigation
6. Harvesting
7. Sending crop to sugar factory

 11) Complete the following word puzzle with the help of clues given below.

Down
1. Providing water to the crops.-Irrigation
2. Keeping crop grains for a long time under proper conditions. - Storage
5. Certain plants of the same kind grown on a large scale.-crop across
3. A machine used for cutting the matured crop. - Harvester
4. A Rabi crop that is also one of the pulses. - Gram
6. A process of separating the grain from chaff. -winnowing



Written By Badal Paul
The author is a passionate blogger, writer and educationalist. This blog is created to ease troubles of the Cbse students. The author holds multiple blogs and the writer of the Novel KALCHAKRA, OOM AND THE CHOSEN FIVE.