Solved examples for class 8 science : Chapter 1
Crop Production and Management
I. Multiple Choice Questions (MCQs).
Q.1. Same type of plants being cultivated at one place on a large scale is called a
Answer (d) crop
Q.2. A crop grown for its seed grain, which is rich in starch and fibre, is
a) cereal crop
b) b) fibre crop
d) none of these
Answer(a) cereal crop
Q.3. The process of loosening and turning of soil is called
c) both (a) and (b)
d) none of these
Answer. (b) ploughing
Q.4. A tractor driven implement for ploughing is known as
d) none of these
Answer. (c) cultivator
Q.5. What should be removed from the grain just before its storage?
Answer (a) Moisture
II. Fill in the blanks by selecting appropriate words from the given list:
List: Levelling, Weeding, pests, seeds, Rabi
Q.1. ……………………………crops are harvested in the month of March or April.
Q.2. …………………………..is done to make the surface of the soil uniform after the process of ploughing.
Q.3. A farmer should select good quality …………………………..to ensure maximum grain production and to avoid wastage.
Q.4. …………………………….should always be done before the weeds produce flowers.
Q.5. Rodents, birds and insects causing damage to the crops are known as ………………………….
III. Match the items of Column A with those of Column B.
Answer: 1-e , 2- a, 3-d, 4-c , 5- b,
IV. Write ‘T’ for the true and ‘F’ for the false statements.
Q.1. Granaries are tall cylindrical storage structures with openings.
Q.2. Seeds can be sown at any distance from each other.
Q.3. Seeds of rice and some other plants can be sown directly into the field.
Q.4. Weeding is necessary because weeds compete with crop plants for space, light and nutrients and thus affect the growth of crop plant.
Q.5. All nutrients are transported in the plant body using soil as a medium.
Answer: 1-F, 2-F, 3-F, 4-T, 5-F
V. Very Short Answer Questions.
Q.1. Name two oil yielding crops.
Answer: Sunflower and mustard
Q.2. Write two Rabi crops.
Answer: Wheat and gram
Q.3. Mention two Kharif crops.
Answer: Paddy and sugarcane
Q.4. Write three common fertilisers.
Answer: Urea, ammonium sulphate and potash
Q.5. Write two modem methods of irrigation.
Answer: Drip irrigation and sprinkler system
VI. Short Answer Questions.
Q.1. What do you mean by crops? Write main types of crops based on the useful products obtained from them.
Answer: Same type of plants being cultivated at one place on a large scale is called a crop. For example – rice, wheat, etc.
Based on the useful products obtained from them, crops can be classified into:
i. Cereal Crops
ii. Fibre Crops
iii. Pulses or Legumes
iv. Oil yielding crops
Q.2. What are the cropping patterns followed in India based on seasons or their climatic conditions? Ans: Two types of cropping patterns are followed in India based on seasons or their climatic conditions like temperature, rainfall, humidity, etc. These cropping patterns are
• Rabi crops and
• Kharif crops
Q.3. Write the agricultural practices undertaken by farmers over a period of time.
Answer: Agricultural Practices undertaken by farmers over a period of time are listed below:
(a) Preparation of soil
(b) Selection and sowing of seeds
(c) Irrigation (d) Weeding
(e) Crop protection
Q.4. What do you understand by ploughing? Write some agricultural implements used in this process. Also describe advantages of ploughing.
Answer: The process of loosening and turning of soil is called tilling or ploughing.
Agricultural implements used in ploughing are plough, hoe or cultivator.
Advantages of Ploughing:
(i) It provides aeration to the roots as air spaces are created, making it easy to breathe.
(ii) Roots can grow deep into the soil.
(iii) Weeding is easier in loose soil.
(iv) Helps in growth of earthworms and microbes in soil which are important decomposer providing nutrients and making the soil humus rich.
(v) It becomes easier for the farmer to apply fertilizers.
(vi) Ploughing brings nutrient rich soil on the top, so that plants can use it easily.
Q.5. (a) Describe levelling and its advantages.
(b) Why is adding of manures and fertilisers to the soil essential? Describe briefly.
Answer: a) Levelling is done to make the surface of the soil uniform after the process of ploughing. It is done with the help of a wooden or iron Leveller. Advantages of Levelling
i. Bigger chunks of soil are broken down to smaller pieces.
ii. Prevention of soil erosion by wind or water.
iii. Promotes uniform irrigation thus helping in water conservation and prevents water logging.
b) Substances which are added to the soil in the form of nutrients for the healthy growth of plants are called manure and fertilisers.
• Application of fertilizers helps in increasing crop yield.
• Manures enhance water holding capacity of soil.
• Manures make the soil porous for easy exchange of gases.
• Manures make the soil rich in humus and increase the number of friendly microbes.
• Manures improve the soil texture as well as its water retaining capacity.
Q.6. Why are selection of seeds essential? Describe tools for sowing seeds and methods of sowing seeds briefly.
Answer: Selection of seeds is essential to ensure maximum grain production and to avoid wastage.
Tools for Sowing Seeds
Q.1. Traditional tool: It is a funnel shaped tool attached to the plough. Seeds are filled in the funnel and passed through 2 or 3 pipes piercing the soil and placing the seeds in soil.
Q.2. Seed drill: A seed drill consists of a set of vertical tubes with a funnel at the top. Seeds are put in the funnel and distributed through these vertical tubes while attached to the plough.
Q.3. Broadcaster: A wide mouthed tube that spreads seeds randomly on the ground.
Methods of sowing seeds
1. Broadcasting: Scattering of seeds randomly in the field is known as broadcasting. It can be done by hands or by using mechanical broadcasters.
2. Sowing by seed drills: By seed drills, seeds are sown uniformly at proper distances and depths. This helps the plant to obtain proper nutrition, protects the seeds from birds and saves time and labour.
3. Transplantation: Seeds of rice and some other plants cannot be sown directly into the field. Their seeds are first grown in a nursery till the seedling stage. Healthy seedlings are then selected from the nursery beds and transplanted to the field by hand.
VII. Long Answer Questions.
Q.1. Define irrigation. Why do plants need water? Describe some traditional and modern methods of irrigation briefly.
Answer: Supply of water to crops at different intervals is known as irrigation.
Plants need water
• For proper growth and development of flowers, fruits and seeds of plants.
• Roots absorb mineral and fertilisers dissolved in water.
• Seed germination requires presence of water.
• Water protects the crop from frost and hot air currents.
• ALL nutrients are transported in the plant body using water as a medium.
Some of the traditional methods of irrigation are:
(i) Moat (Pulley System) : A pulley system is used to lift water from the well.
(ii) Chain pump: It consists of a pump having endless chains running over a drum or wheel by which it is moved and water is raised.
(iii) Dhekli: A very crude system using a Log of wood to pull out water from the well.
(iv) Rahat: It is a simple Lever system consisting of a wheel attached to a number of buckets. The wheel rotates which pulls out water and distributes it to the field.
Some modern methods of irrigation are:
(i) Drip irrigation : It uses underground pipes having small holes at regular intervals positioned at the roots. Thus, they carry water directly to the roots and prevent evaporation and flooding. (ii) Sprinkler system : It consists of a main pipeline connected with several perpendicular pipes having rotating nozzles at the top. Water flows through the main pipe under pressure with the help of a pump, and escapes from the rotating nozzles. It gets sprinkled on the crop like rain.
(iii) Furrow irrigation: The field is divided into ridges and furrows. Plants are grown on ridges and water flows in the furrows through a pump.
(iv) Basin irrigation: The field is converted into a basin and filled with water. Useful for the crops which require standing water.
Q.2. (a) Describe weeding and methods of weeding.
(b) Describe crop protection and methods of crop protection.
Answer. (a) Undesirable plants growing naturally along with the crop are known as weeds e.g., Amaranthus, Chenopodium. Removal of the weeds is known as weeding.
Methods of Weeding
• Tilling : Tilling before sowing is done to uproot weeds.
• Manual method : Weeds can be removed either by pulling them out manually or with the help of a harrow or trowel.
• Chemical method : Weeds can be controlled by using certain chemicals called weedicides, Like 2, 4-D, Metachlor, Siziazine, MCPA, etc. Weedicides are diluted with water and sprayed on the fields with a sprayer. They should be sprayed before the weeds start flowering and seed formation.
b) To ensure a good yield, crops should be protected from stray animals, birds and pests.
Methods of crop protection
(i) Fencing of the field can be done to protect the crops from stray animals. (ii) Using a scare crow and beating drum is an effective method to protect the crops from birds.
(iii) Crop plants are always prone to fungal, bacterial and viral disease. Treating the seeds with fungicides and spraying insecticides, pesticides can help the farmers to have a disease free crop.
Moreover disease resistant seeds should be sown to avoid infection.
(iv) Rodents, birds and insects causing damage to the crops are known as pests. Pests can be controlled by spraying diluted pesticides. Example, BHC, malathion, polythion, etc.
Q.3. (a) What do you understand by harvesting and storage of crops? Describe them briefly.
(b) What do you mean by crop rotation and mixed cultivation? Describe them briefly.
Answer. a) The process of cutting and gathering of a crop upon its maturation is known as harvesting. A crop gets ready for harvesting in about 3-4 months. Harvesting can be done manually with a sickle or with a machine called harvester.
Storage of crops:
Once the grains have been harvested, they have to be stored in a proper manner so that they are available throughout the year in every place. Following factors should be kept in mind while storing grains:-
• Storage area should be dry, free from moisture as moisture promotes microbial growth.
• Storage area should be free from rodents and insects.
• There should be no open spaces like window from where birds can come m • and out to eat grains.
b) The practice of growing two or more dissimilar crops on same plot of land alternately is known as crop rotation. When we keep on growing the same crop over and over again, the Land becomes deprived of nutrients. Crop rotation with crops such as pulses is done to replenish the nutrients. Leguminous plants contain nitrogen fixing bacteria in the root nodules which help to overcome nitrogen deficiency.
The process of growing two or more different types of crops in a particular field at the same period of time is known as mixed cultivation. Leguminous plants and cereals can be grown close to each other. The nutrients required by one crop are fulfilled by the other. Thus two crops can be grown at the same time.