Crop Production and Management – Class VIII, NCERT Science, Chapter 1

NCERT Textbook Exercise Questions (Important only)

Q.1: Select the correct word from the following list and fill in the blanks:

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 of crop, sufficient sunlight and ______and _____ from the soil are essential.

Ans: (a) Crop (b) Preparation (c) Float (d) Water, Nutrients.

Q.2: Match items in column ‘A’ with those in column ‘B’:

(A) (B)

i. Kharif crops

ii. Rabi Crops

iii. Chemical Fertilizers

iv. Organic Manure a) Food for cattle.

b) Urea and super phosphate.

c) Animal excreta, cow dung, urine & plant-waste.

d) Wheat, gram, pea.

e) Paddy and maize.

Ans: (i)-e (ii)-d (iii)-b (iv)-c

Q.3: Give two examples of each: (a) Kharif crop, (b) Rabi crop.

Ans: (a) Paddy and maize (b) Wheat and gram.

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

a) Preparation of soil

b) Sowing

c) Weeding

d) Threshing

Ans:

(a) Preparation of Soil

The preparation of soil is the first step before growing a crop. It includes the process of loosening and turning of the soil which is called Tilling or Ploughing. This is done by using ploughs which are pulled by bulls. Tractor driven cultivators are also used to till the soil. Tilling of the soils is important for following reasons:-

(i) This allows the roots to penetrate deep into the soil.

(ii) This allows the root to breathe easily.

(iii) The loosened soil helps in the growth of earthworms and microbes which further turn and loosen the soil and also help in adding humus to it.

(iv) This process brings the nutrient rich soil to the top so that plants can use these nutrients.

(b) Sowing

Sowing is the most important part of the crop production in which seeds are implanted in the prepared soil. Before sowing clean, healthy, good-variety and high yield seeds are selected. They are then sowed in the fields. In the traditional method of sowing seeds, a long pipe is used which has a funnel at its one end and the other end pierce into the soil through which seeds are placed. Now-a-days a machine or a tool known as seed drill is also used for sowing with the help of tractors. A seed drill saves time & labour. While sowing the seeds care should be taken to maintain proper distance and depth between the seeds to prevent damage of the seeds caused by birds and also to prevent overcrowding of the plants.

(c) Weeding

Unwanted plants growing along the crops are called weeds. The removal of weeds is called weeding. Weeding is necessary since these weeds absorb the water, nutrients, space and light meant for the crop plants. Weeding can be done manually with a ‘khurpi’ or mechanically with the help of a ‘seed drill’ or even using certain chemical called ‘Weedicides’. The best period for weeding is during their vegetative phase before flowering or bearing seeds.

(d) Threshing

When the crop is harvested, it is cut along with the stalks. They are then separated and the grains are removed. This process of separation of grains from the chaff is called ‘Threshing’. This whole process is carried out with a machine called ‘Combine’ which is in fact a combined harvester & thresher.

Q.5: Explain how fertilizers are different from manure?

Ans: The differences between fertilizers and manures are as follows:

(i) Fertilizers are chemical substances, while the manures are the organic substances (decay of plants & animal wastes).

(ii) Fertilizers are prepared in the factories, while the manures are prepared in fields.

(iii) Fertilizers don’t provide any humus to soil, while manures provide a lot of humus.

(iv) Fertilizers are rich in plant nutrients like- Nitrogen, Phosphorus & Potassium but manures are less rich in plant nutrients.

(v) There are certain advantages of adding manure like-

a) It enhances the water holding capacity of the soil,

b) It makes soil porous due to which exchange of gases becomes easy.

c) It improves the texture of soil and also increases the number of friendly microbes.

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

Ans: Watering the crops in the fields is called ‘irrigation’. Irrigation is done at different intervals. Irrigation should be done in a way in which water does not get wasted. Different sources of irrigation are like- wells, tube-wells, ponds, rivers. Two such methods which conserve water are:

(i) Sprinklers: Sprinklers work like fountains. Long perpendicular pipes having rotating nozzles on the top are joined to the main pipe lines at regular distances. When water is supplied, it comes out of these rotating nozzles which sprinkle water in all directions. Limited outflow of water, controls wastage of water. This method is more suitable for uneven and sandy soil.

(ii) Drip System: This system allows the water to flow drop by drop at the roots of the plants. It contains a main pipe which has further lateral pipes containing small nozzles for the outflow of the water. Nozzles are such placed that they throw water at the roots of the plants, which saves water from flowing around uselessly. This technique is best suited for watering fruit plants, gardens and trees where availability of water is poor.

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

Ans: If wheat is grown in kharif season, they would not grow as they don’t need much water to grow. The seeds would get destroyed in excess water due to rainy season.

Q.8: Explain how soils get affected by the continuous plantation of crops in a field.

Ans: Continuous plantation of crops drains off the nutrients of the soil. It leaves the land unfertile and unable to bear crop. It does not give any time to the soil to replenish the absorbed nutrients by the crops, thus unable to sustain any further healthy and good crop.

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

Ans: Weeds are the unwanted plants growing along crops. They share the nutrients meant for plants and thus are harmful for crop. We can control weeds with the help of chemicals Weedicides. The removal of weeds is called weeding. They are either removed manually or by chemicals. Manually this can be done with the help of Khurpi or Seed-drill. Weedicides are sprayed in the fields to kill the unwanted plants. These weedicides do not affect the main crop. Weeds are removed or killed during their vegetative phase before flowering or bearing seeds.

Short type Questions with their Answers
Q.1: Why does every living organism need food?

Ans: Every living organism needs food to grow and perform various other activities and body functions.
Q.2: Where do we get our food from?
Ans: We get our food from plants and animals.
Q.3: What is crop?

Ans: When same types of plants are grown at a large scale, it is called crop.

Q.4: Name the factors controlling crop production.

Ans: Soil, water, sunlight and air.

Q.5: Based on factors required to grow plants, how many crop seasons are observed in India?

Ans: Broadly two crop seasons: Rabi & Kharif.

Q.6: What are crumbs?

Ans: Crumbs are big pieces of soil present in fields, which require tilling.

Q.7: Which agricultural tools are used for tilling?

Ans: Plough, Hoe & Cultivators.

Q.8: Who supplies mineral nutrients to plants?

Ans: Soil.

Q.9: Which manure is called Organic manure?

Ans: Manure obtained from the dead bodies of plants and animals.

Q.10: Name any two important fertilizers.

Ans: Urea, NPK (Nitrogen, Phosphorus, Potassium).

Q.11: What is a fallow?

Ans: An uncultivated field between two cropping is called a fallow.

Q.12: Which bacteria are present in the legumes of leguminous plants?

Ans: Rhizobium.

Q.13: What is harvesting?

Ans: Cutting of the crop after it is mature is called harvesting.

Q.14: How does reduction in moisture of newly harvested grains help in storage?

Ans: It prevents pests, insects, bacteria etc from attacking the grains.

Q.15: Name the places where grains are stored at large scale.

Ans: Granaries and silos.

Q.16: Write the names of various agricultural practices undertaken to produce a crop.

Ans: Following agricultural practices are performed to produce the crop:

1. Soil preparation,

2. Sowing,

3. Adding manure and fertilizers,

4. Irrigation,

5. Protection from weeds,

6. Harvesting &

7. Storage.

Q.17: Why is the soil turned and loosened before seeds are sown?

Ans: The soil is turned and loosened during the process of ploughing. The ploughing loosens the soil particles and turn the soil of upper surface. This allows the nutrients from the dead organism to be released back in the soil and better penetration and absorption of nutrients by plant roots.

Q.18: What is the role of water in production of crops?

Ans: Water is essential for all plants. Crops should get enough water at different stages of their growth. Different crops require different amount of water in the field. The wheat crop requires moderate amount of water at the time sowing, flowering and ripening of crop. Therefore, crops should be irrigated properly according to their needs.

Q.19: What are the different methods of irrigation?

Ans: Supply of water to crops at appropriate intervals is called irrigation. Various sources of irrigations are- wells, tube wells, ponds, lakes, rivers, canals etc. Different methods of irrigation are adopted on the basis of the soil types, size of the field, requirement of water by the crop and of course, the availability of water. Some of the traditional methods of irrigation include water supply through moat (Pulley-system), chain pump, dhekli and rahat (lever-system).

Modern methods of irrigation help us to use water most economically. Two such methods are- Sprinkler system and Drip system.

Q.20: What is humus? How is it formed?

Ans: Humus is a kind of soil rich in nutrients. It is formed by the microbial action on dead decaying bodies of plants and animals. It’s generally formed on those spots where – there are dense layers of trees. The soil below it becomes dark having more number of pathogenic bacteria.

Q.21: Why does a farmer rotate crops in the field? (Crop-rotation)

Ans: If the same crop is grown in the field year after year, it will lead to the deficiency of certain minerals. It is due to this fact that the same crop requires same type of nutrients.

To solve this problem farmers are encouraged to grow one pulse crop in – between two cereal crops in the field. So the method of successive cultivation of different crops in an orderly manner on the same fields, in contrast to a one-crop-system or to haphazard crop successions is known as crop rotation. For example, growing legumes as fodder in one season and wheat in the next season. The roots of legumes have so many nodules which contain nitrogen fixing bacteria. These convert free atmospheric nitrogen into nitrates and increase the fertility of the soil. (Replenishing of soil with nitrogen)

Q.22: What safety measures are to be taken in handling pesticides and weedicides?

Ans: Weedicides and pesticides are highly poisonous chemicals. They kill the pests. They can harm the human also. So, certain precautionary measures should be taken while spraying pesticides and weedicides.

• They should be kept away from the reach of children.

• They should not be inhaled while spraying. Gloves and mouth covers should be used while spraying them.

• Hands should be washed properly after their use.

Q.23: Distinguish between pesticides and weedicides.

Ans: Weeds are controlled by using certain chemicals called weedicides. These chemicals don’t cause any damage to the crop.

Pesticides are the chemicals which are used to kill the pests growing on the crops. They kill the eggs and larvae of the insects.

Q.24: Why should the harvested grains is protected from moisture?

Ans: The harvested grains should be protected from moisture because of the following reasons:

(i) It promotes the growth of insects.

(ii) Moisture helps in germination of seed.

(iii) It promotes the growth of fungi.

(iv) It speedily spoils the quantity and quality of grains.

Long type Questions with their Answers

Q.1: Write a paragraph on the various methods used to replenish the nutrients in the fields.

Ans: When crops are grown in the fields, they use all the nutrients present in the soil. These nutrients have to be replenished for the further cropping. Various methods and products are used for this purpose.

(i) Fertilizers: Fertilizers are the chemicals which replenish the soil with all the nutrients. They are produced in the factories and are inorganic products. Every fertilizer is rich in a particular nutrient. Some examples of fertilizers are urea, ammonia sulphate, potash, NPR etc. They help in getting better and healthy yields. But, excessive use of these chemicals is also harmful.

(ii) Manure: Manures are the organic products, which are obtained by the processing of dead bodies of plants and animals. Dead bodies of plants and animals are dumped in pits. They get decomposed to become manure. Using manure not only improves the texture of the soil but also, improves the water holding capacity of the soil.

(iii) Fallowing: Sometimes continuous growing of crops makes the soil barren or infertile. It needs to be left uncultivated so that it can regain its nutrients and fertility. This process of leaving soil uncultivated for one crop season is called fallowing.

(iv) Crop Rotation: If the same crop is grown in the field year after year, it will lead to the deficiency of certain minerals. It is due to this fact that the same crop requires same type of nutrients. To solve this problem farmers are encouraged to grow one pulse crop in – between two cereal crops in the field. So the method of successive cultivation of different crops in an orderly manner on the same fields, in contrast to a one-crop-system or to haphazard crop successions is known as crop rotation. For example, growing legumes as fodder in one season and wheat in the next season. The roots of legumes have so many nodules which contain nitrogen fixing bacteria. These convert free atmospheric nitrogen into nitrates and increase the fertility of the soil. (Replenishing of soil with nitrogen)

Q.2: Write a short note on Threshing & Winnowing.

Ans: When a farmer cut his crops, he ahs to separate the grain seeds from chaff. This process is called threshing. Mechanically it can be done with the help of threshers and combine. Farmers with small holdings of land do the separation of grain and chaff by winnowing. The grains are thrown from the height in the direction of air. The air carries away the lighter chaff or dried stems and leaves and the heavier grain drop down in the form of a heap. This whole process is called winnowing.

Objective type Questions with their Answers

Q.1: Fill in the blanks:

a. ____ is used for sowing of seeds.

b. Loosening the soil is also called _____.

c. ____ is the second agricultural practice.

d. _____ and ____ are used to add nutrients in the soil.

e. Manures are the ___ substances.

f. ____ is a weedicides.

g. ____ is the economical method of irrigation.

h. Leaving field uncultivated is called ______.

i. _____ is used to separate seed from the chaff.

j. Crops sown in the rainy season are called ______.

Ans: a. seed drill, b. tilling, c. sowing, d. manures and fertilizers, e. organic, f. metachlor, g. drip irrigation, h. fallow, i. thresher, j. rabi crops.

Q.2: Write ‘True/False’ for the following statements:

(i) Many plants are first grown in kindergartens and then sown in fields. (False)

(ii) Seeds can only be sown by using seed drills. (False)

(iii) Earth worms are farmer friendly. (True)

(iv) Substances that kill pests are called weedicides. (False)

(v) Cutting and gathering of mature crops is called harvesting. (True)

(vi) Process of beating grains to separate them crop plants is called winnowing. (False)

(vii) Excess use of fertilization is not good for crops & soil. (True)

(viii) Animals which provide us with eggs and flesh are called milch animals. (False)

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