Class 8 science chapter 1 question 51-57

51. Question
State two beneϐicial effects of -ploughing the ϐields (or loosening and
turning the soil).
Answer
Loosening and turning the soil is very important for cultivation of
crops. The loosening and turning the soil by ploughing is beneϐicial
because of the following reasons:
(i) The loose soil allows the roots to breathe easily even when they go
deep into the soil.
(ii) The loosened soil helps in the growth of earthworms and microbes
present in the soil.
52 A. Question
State the function of Food Corporation of India.
Answer
The government agency like food corporation of India (FCI) buy food
grains from farmers and storing them properly so that they can be
supplied throughout the country.
52 B. Question
What is done to protect tile grains stored in gunny bags in big go downs
from damage ?
Answer
Pesticide solution are sprayed on the gunny bags in big go downs from
time to time to protect the grains from damage.
53. Question
Deϐine manure. What are the advantages of manure ?
Answer
Manure is an organic substance obtained by the decomposition of
plants or animals wastes.
Advantages of manure:
● it enhances the water holding capacity of the soil.
● it makes the soil porous due to which exchange of gases becomes
easy.
● it increases the number of friendly microbes.
● it improves the texture of the soil
54. Question
What is a fertilizer ? Name any two fertilizers. State two harmful effects
caused by the excessive use of fertilizers.
Answer
Fertilisers are chemical substances which are rich in a particular
nutrient. Some examples of fertilizers are urea, potash, NPK (nitrogen,
phosphorus, potassium), etc.
Harmful effects caused by the excessive use of fertilizers are-
(i) Excessive use of fertilizers makes the soil less fertile.
(ii) Excessive use of fertilizers causes water pollution.
55. Question
Explain how, soil gets affected by the repeated growing of croping the
same ϐields. How does use of fertilizers help the farmers ?
Answer
Plants require nutrients for their proper growth and functioning. If
continuous plantation of crops is done in the ϐields then the soil will
become poor in necessary nutrients like nitrogen, phosphorus,
potassium, etc. This affect the yield and also affects the quality of soil.
So, the nutrients once consumed by crop must be replenished so that
soil get all its nutrients back and it will be ready for the next harvest.
Fertilizers help the farmers to get better yield of crops such as wheat,
paddy and maize.
56. Question
What is weeding? Why is weeding necessary ?
Answer
The removal of weeds is called weeding. Weeding is necessary since
weeds compete with the crop plants for water, nutrients, space and
light. Thus, they affect the growth of the crop. Some weeds interfere
even in harvesting and may be poisonous for animals and human beings.
57. Question
What are weedicides? Name one weedicide.
Answer
Weedicides are special chemicals which are used to control weeds. 2,4-
D is an example of weedicide

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