Class 8 Science NCERT Solutions for Chapter – 1 Crop Production and Management

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 __________.
Answer:
Crop

(b) The first step before growing crops is ___________ of the soil.
Answer:
Preparation

(c) Damaged seeds would ___________ on top of water.
Answer:
Float

(d) For growing a crop, sufficient sunlight, __________ and __________ from the soil are essential.
Answer:
water
Nutrients

Question 2.
Match items in column A with those in column B.

AB
Kharif cropsPaddy arid maize
Rabi CropsUrea and super phosphate
Chemical fertilizersAnimal excreta, cow dung, urine and plant waste
Organic manureWheat, gram, pea

Answer:

AB
Kharif cropsPaddy arid maize
Rabi CropsWheat, gram, pea
Chemical fertilizersUrea and super phosphate
Organic manureAnimal excreta, cow dung, urine and plant waste

Question 3.
Give two examples of each :

(a) Kharif crop

Answer:

  • Paddy
  • Maize

(b) Rabi crop

Answer:

  • Wheat
  • Gram

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

Answer:
(a) Preparation of soil : It is the first step before growing a crop. One of the most important task in agriculture is to turn the soil and loosen it. This allows the roots to penetrate deep in the soil. The process of loosening and turning of soil is called tilling or ploughing which is done by a plough.

Ploughs are made of wood or iron. The ploughed fields may have big pieces of soil called crumbs. These crumbs are broken and the field is levelled for sowing and for irrigation.

(b) Sowing : It is the process of putting seeds in the soil. For this purpose good quality seeds are selected which are clean, healthy, of good variety and give high yield. Seeds are sown with the help of a traditional funnel shaped tool or a seed drill. An appropriate distance between the seeds is also important to avoid overcrowding.

(c) Weeding : In a crop field many other undesirable plants may grow naturally along with the crop. These are called weeds. Weeds should be removed to protect the crops. The process of removal of weeds is called weeding. Weeding is necessary because weeds compete with the cultivated plants for space, light, water and nutrients.

Some weeds are poisonous for animals and human beings. Tilling before sowing of crops helps in uprooting and killing of weeds, which may then dry up and get mixed with the soil. The weeds must be removed before they produce flowers and seeds. They are removed either manually or by using weedicides.

(d) Threshing: After harvesting, the crops are threshed for removing grain seeds from the chaff. This is carried out with the help of thresher or a machine called ‘combine’ which is in fact a combined harvester and thresher.

Question 5.
Explain how fertilizers are different from manure ?

Answer:
The substances which are added to the soil in the form of nutrients for the healthy growth of plants are called manure and fertilizers.
Fertilizers are different from manure in the following ways :

S.No.FertilizerManure
1.Fertilizers are prepared in the  fertilizersManure is prepared in the fields.
2.Fertilizers do not provide any humus to the soil.Manure provides a lot of humus to the soil.
3.Fertilizers are very rich in plant nutrients like nitrogen, phos­phorus and potassium.Manure is not very rich in plant nutrients.
4.Fertilizer is an inorganic substance.Manure is a natural substance obtained by the decomposition of cattle dung, human waste and plant residues.

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

Answer:
The supply of water to crops at different intervals is called irrigation.The two methods of irrigation in which water is conserved are the sprinkler system and the drip system.

(1) Sprinkler system : This system is mostly used on the uneven lands where water is available in smaller quantity. In this system, perpendicular pipes having rotating nozzles on the top are joined to the main pipe line 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 is sprinkled on the crop as if it is raining. It is very useful for the sandy soil.

(2) Drip system: In this system, the water falls drop by drop just at the position of the roots. So, it is called drip system. It is the best technique for watering fruit plants, gardens, trees, etc. This system consists of a main pipe to which lateral pipes are joined.

The specially prepared nozzles are attached to these lateral pipes. The nozzles are grounded just near the roots of the plants. It provides water drop by drop to plants. Water is not wasted at all. So, it is a boon in regions where availability of water is poor.

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

Answer:
In Kharif season, we have lot of rainfall, whereas wheat needs winter (cold) season and not the heavy rainfall. So, if wheat were sown in kharif season, the crop will damage due to heavy rainfall as well as water logging (collection of water in the field).

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

Answer:
Continuous growing of crops makes the soil deficient in certain nutrients. To avoid this, following practices should be facilitated :

  1. Crop rotation
  2. Manuring the soil
  3. Leaving field fallow

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

Answer:
The undesirable plants in the field that grow naturally are called weeds. Weeds must be removed, otherwise our own crop plants may not get sufficient water, nutrients, space and light. So, they are removed either by manual method or by using weedicides.

The manual removal includes physical removal of weeds by uprooting or cutting them close to the ground from time to time. This is done with the help of a khurpi or a harrow. By using weedicides also, we can remove weeds. These weedicides damage only weeds and do not harm crops, e.g., 2, 4-D.

Question 10.
Arrange the following boxes in proper order to make a flow chart of sugarcane crop production :
NCERT Solutions for Class 8 Science img 2

Answer:
The boxes should be arranged as follows
NCERT Solutions for Class 8 Science img 3

Question 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.

Answer:
NCERT Solutions for Class 8 Science img 1

InText Questions and Answers

Activity 1.1

Question 1.
Where are the tools like khurpi, sickle, shovel and plough used ?

Answer:
These tools are used in various agricultural practices :

ToolAgricultural practice
Khurpiloosening of soil and weeds
Sicklefor harvesting
Shovelfor loosening of soil and removing weeds
Ploughturning and loosening of soil

Question 2.
Can you recall how do green plants synthesise their own food ?

Answer:
Green plants synthesise their own food by the process of photosynthesis. In this process, plants synthesise food in the presence of sunlight using CO2 and water.

Question 3.
Where do animals get their food from ?

Answer:
Animals get their food from plants and other animals.

1.3 Preparation of Soil

Question 4.
Why does the loosening of soil allow roots to breathe easily ?

Answer:
Loosening of soil allows air to reach up to the roots of the plants so that roots easily trap air and breathe.

Question 5.
Why does the soil need to be turned and loosened ?

Answer:
Reasons for the soil need to be turned and loosened are as follows.

  1. Roots can breath easily.
  2. Only a few cons of the top layer soil supports plant growth, turning and loosening brings the nutrient rich soil to the top.
  3. Turning and loosening of soil brings the nutrient-rich soil to the top so that plants can use these nutrients. That is why soil needs to be turned and loosened.

1.4 Sowing

Question 6.
Which type of seeds are called good quality seeds ?

Answer:
Good quality seeds are clean and healthy seeds of a good variety.

Question 7.
How can we check whether the seeds are healthy or damaged ?

Answer:
If we put the seeds in a container containing water, the damaged seeds float on the surface of water while healthy seeds settle down at the bottom of the container.

Question 8.
Why do damaged seeds float on water ?

Answer:
Damaged, seeds become hollow and are thus lighter. Therefore, they float on water.

1.5 Adding Manure and Fertilizers

Question 9.
I saw a healthy crop growing in a farm. In the neighbouring farm the plants were weak. Why do some plants grow better than others ?

Answer:
Plants that get proper nutrients and water grow better than the plants which do not get these sufficiently.

Activity 1.2

Question 1.
Did all the plants in all the, glasses grow at the same pace ?

Answer:
No.

Question 2.
Which glass showed better growth of plants ?

Answer:
Glass A and glass B showed better growth of plants; because in addition to soil these glasses contain cow dung and urea respectively.

Question 3.
In which glass the growth was fastest?

Answer:
In glass B, because of the presence of urea in that glass.

1.6 irrigation

Question 10.
In summer, the frequency of watering is higher. Why is it so ?

Answer:
This is because in summer, the rate of evaporation of water from the soil and leaves increased.

1.7 Protection from Weeds

Question 11.
In a field are all plants planted purposely ?

Answer:
No, some of them may not have been purposely grown. In a crop field many other undesirable plants may grow naturally along with the crops. These undesirable plants are called weeds.

1.9 Storage

Question 12.
Why do we use dried neem leaves for storing food grains at home ?

Answer:
Dried neem leaves protect the grains from pests and microorganisms. That is why, these are used for storing food grains.

1.10 Food from Animals

Activity 1.3

Question 13.
Make the following table in your notebook and complete it.

Answer:

S. NoFoodSources
1.MilkCow, buffalo, she-goat, she- camel
2.MeatGoat, chicken
3.EggHen, duck
4.OilFish

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