NCERT Solutions For Class 8 Science Chapter 1
| Class: | 8 |
| Subject: | Science |
| Chapter 1: | Crop Production and Management |
Class 8 Science Chapter 1 Answers
CBSE NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management is given below to download free in PDF. Video Format solution is also available for free. Download 8 Science App for offline use. All the solutions are updated for new session 2020-21.
Important Terms On Class 8 Science Chapter 1
1. Agricultural Practices
In this part of the content focuses how agricultural practices provide food for us with the science needed for adaptation in agriculture systems as well as the impacts of climate change, on food production systems and to develop strategies. You have learnt that all living organisms require food. We get energy from food, and it is utilised by organisms for carrying out their various body functions. Such as digestion, respiration, excretion etc. In order to provide food for a large population agriculture practices are needed. Generally, the ‘Crop’ refers, when the plants of the same kind are grown and cultivated at one place on a large scale, called crop. Cereals, vegetables and fruits are known as different types of crop. Remember, “wheat” was the first crop that the human started growing. Do you know that the climatic conditions like temperature, humidity and rainfall vary from one region to another? Despite this diversity, two broad cropping patterns can be identified as Kharif crops and Rabi crops.
2. Basic Practices Of Crop Production
In this part of chapter 1 of Class 8 Science, introduces the conventional agricultural practices with modern values that are adopted by the Indian farmers. Cultivation of crops involves several activities undertaken by farmers over a while. These activities or task are referred to as ‘Agriculture Practices’. Such as preparation of soil, sowing, it is adding manure and fertilisers, irrigation, protecting from weeds, harvesting and storage of food crops.
3. Preparation Of Soil
In this part of the content describes the system of agricultural practices which is essential for crop production and its growth. The preparation of the soil is the first step before growing a crop. One of the most critical tasks in agriculture is to turn the soil and loosen it, called ploughing or tilling. But why does the soil need to be turned and loosen? You have learnt that soil contains minerals, water, air, dead plants and animals and some living microorganisms. And the living organisms help to decompose that dead plants and animals. As a result, various nutrients are released back into the soil. These nutrients are again absorbed by the plants. As you can see, the turning and loosening of soil are essential for the cultivation of crops.
4. Sowing
Remember, sometimes manure is added to the soil before tilling. You may know that, before sowing the seeds, it is necessary to break the soil to the size of grains to get better yield. Sowing is an essential part of crop production. But why? Without sowing any seed, we cannot get any plants, and without any plants, we never get food grains from them. Remember, before sowing; good quality seeds are selected. Farmers prefer to use seeds which gave a high yield. And the appropriate distance between the seeds is also important to avoid overcrowding of plants. In this way every seed can get proper food, air and light for growth.
5. Adding Manure And Fertilisers
In this part of the chapter focuses on the importance of adding manure in the field of crop. You may saw that healthy crop growing on some farm, but in the neighbouring farm, the plants were weak. What is the reason behind that some plants grow better than others? Your answer will be due to fertilisers or manure. The substances which are added to the soil in the form of nutrients for the healthy growth of plants are called ‘Manure’ and ‘Fertilizers’. You learnt that soil supplies many mineral nutrients to the crop. The continuous growing of crops makes the soil weaker in particular nutrients. Therefore, farmers added manure to the fields to replenish the soil with nutrients.
6. The Differences Between ‘Manure’ And ‘Fertilizers’
Manure is an organic substance obtained from the decomposition of plant or animal wastes. The decomposed matter is used as organic manure. Moreover, fertilizers are chemical substances which are rich in a particular nutrient. Such as Urea, Potash, Ammonium sulphate etc. You are surprised to know that fertilizers have also become a source of water pollution. Hence, the other method of replenishing the soil with nutrients is through crop rotation. That means growing different crops alternately.
7. Irrigation
As you know, all living beings need water to live in. Water is essential for proper growth and development of flowers, fruits and seeds germination. And water is absorbed by the root of the plants. The supply of water to crops at different intervals is called ‘Irrigation’. Do you know, what are the sources of irrigations? Wells, ponds, dams, rivers, canals, and so many other water sources. In summer the plant needs more water. Do you know why? Generally, in the summer rate of evaporation of water is higher from the soil and the leaves.
8. Modern Methods Of Irrigation
Sprinkler systems are more useful than traditional systems on the uneven land where sufficient water is not available. It gets sprinkled on the crops as if it is raining. The sprinkler is very useful for sandy soil. In the other system, where the waterfalls drop by drop just at the position of the roots, called ‘Drip System’. It is a boon in that region where the availability of water is poor.
9. Protection From Weeds
You observed that, in many fields, undesirable plants grow along with the crop. These undesirable plants are called ‘Weeds’. Do you know why removing these weeds are necessary? Wedding is necessary because they compete with the crop plants for water, nutrient, space and light. Thus, they affect the growth of the crop.
10. Harvesting
The cutting of crop after its maturity called harvesting. It usually takes three to four months for a cereal crop to mature. In India, the period of harvest celebrated as Pongal, Baisakhi, Holi, Diwali and other festivals with great joy and happiness. In the harvested crop, the grain seeds need to be separated from the stalks. This process is known as ‘threshing’. And after that, the winnowing process is followed by the farmers.
11. Storage
The cutting of crop after its maturity called harvesting. It usually takes three to four months for a cereal crop to mature. In India, the period of harvest celebrated as Pongal, Baisakhi, Holi, Diwali and other festivals with great joy and happiness. In the harvested crop, the grain seeds need to be separated from the stalks. This process is known as ‘threshing’. And after that, the winnowing process is followed by the farmers.
Important Questions On Class 8 Science Chapter 1 For Practice
If Wheat Is Sown In The Kharif Season, What Would Happen? Discuss.
Wheat is a rabi crop, hence it requires cold climatic conditions to be grown properly. If it is sown in the kharif season, it will not grow or may get destroyed due to excessive rains in the kharif season.
Explain How Soil Gets Affected By The Continuous Plantation Of Crops In A Field.
Soil supplies mineral nutrients to the crop. These nutrients are essential for the growth of plants. Continuous growing of crops in the same field makes the soil poorer in certain nutrients. This makes the soil infertile. And then, to replenish the soil with nutrients farmers need to add manures to the soil.
What Are Weeds? How Can We Control Them?
The undesirable plants may grow naturally along with the crop are called weeds. There are many ways to remove weeds and control their growth. Weeds can be removed by uprooting or cutting them close to the ground, from time to time. This is done with the help of a khurpi.
Weeds are also controlled by using certain chemicals, called weedicides, like 2, 4–D. These are sprayed in the fields to kill the weeds.
What Is Irrigation? Describe Two Methods Of Irrigation Which Conserve Water.
The supply of water to crops at different intervals is called irrigation. The two methods of irrigation which conserve water are as follows:
(i) Sprinkler System:
Under this method, the perpendicular pipes, having rotating nozzles on top, are joined to the main pipeline 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 gets sprinkled on the crop as if it is raining.
(ii) Drip system:
In this system, the water falls drop by drop just at the position of the roots. It is the best technique for watering fruit plants, gardens and trees. Water is not wasted at all. It is a boon in regions where availability of water is poor.
Class 8 Science Chapter 1 MCQ With Answers
1. Which one of the following condition is not essential to grow maize?
(a) High temperature
(c) Low temperature
(b) Humidity
(d) Rainfall
2. The system of irrigation where in water is supplied drop by drop near the roots of plants, is called
(a) pulley system
(b) drip system
(c) sprinkler system
(d) lever system
3. The term used for the process of separation of grains from chaff is
(a) sieving
(b) threshing
(c) winnowing
(d) hand picking
4. Which of the following tools would a farmer use to remove weeds from the field?
(a) Hoe
(b) Plough
(c) Axe
(d) Cultivator
5. Which of the following statement is not true for organic manure?
(a) It enhances water holding capacity of soil.
(b) It has a balance of all plant nutrients.
(c) It provides humus to soil.
(d) It improves texture of soil.
6. Which of the following is not true for fertilisers?
(a) They increase the yield.
(b) Their excessive use disturbs the balance of nutrients in soil.
(c) They are generally used in small quantity.
(d) They are environment friendly.
7. Read the statements given below.
(i) Seeds require moisture for germination.
(ii) Plants can absorb nutrients mostly in dissolved form.
(iii) Irrigation protects crops from both frost and hot air currents.
(iv) Irrigation improves soil texture.
Choose the combination of statements which indicate the need to irrigate crops.
(a) i and ii
(b) i, ii, iii
(c) i, ii, iii, iv
(d) i and iii
8. Given below are statements about the harmful effects of weeds on crop plants.
(i) They interfere in harvesting.
(ii) They help crop plants to grow healthily.
(iii) They compete with crop plants for water, nutrients, space and light.
(iv) They affect plant growth.
Choose the correct combination of statements.
(a) i, iii, iv
(b) iii only
(c) iii, iv
(d) i, ii, iii, iv
9. The monsoon season in our country is during the months
(a) April to December
(b) June to September
(c) November to March
(d) January to May
10. The process of loosening and turning of soil is called
(a) irrigation and manuring
(b) digging and winnowing
(c) tilling and ploughing
(d) harvesting and storage
Answers Of Important Questions (MCQ)
1 (c)
2 (b)
3 (c)
4 (a)
5 (b)
6 (d)
7 (a)
8 (a)
9 (b)
10 (c).
Class 8 Science Chapter 1 Important Questions Set – 1
What Do You Mean By Production And Management?
Anything which is produced or create with the help of people or machine, called “production”.
To controlling or organizing any system or thing is called “management”.
Production and management deals with a set of activities that embrace planning, coordination, supervision, control and decision-making activities which contribute the growth of people and country
What Are The Necessary Element Or Steps To Provide Food For A Large Population?
In order to provide food for a large population— regular production, proper management and distribution of food is necessary.
Despite This Diversity Two Broad Cropping Patterns Can Be Identified”. What Are The Diversity?
India is a vast country. The climatic conditions like temperature, humidity and rainfall vary from one region to another. Although these are referred as diversity.
Discuss The Cropping Patterns With Examples.
The two broad cropping patterns are:
(i) Kharif Crops: The crops which are sown in the rainy season are called kharif crops. The rainy season in India is generally from June to September. Paddy, maize, soyabean, groundnut, cotton, etc., are kharif crops.
(ii) Rabi Crops: The crops grown in the winter season are called rabi crops. Their time period is generally from October to March. Examples of rabi crops are wheat, gram, pea, mustard and linseed.
Crop
When plants of the same kind are grown and cultivated at one place on a large scale, it is called a crop. For example, crop of wheat means that all the plants grown in a field are that of wheat. Crops are of different types like cereals, vegetables and fruits etc.
Class 8 Science Chapter 1 Important Questions Set – 2
What Is The First Step Before Growing A Crop Into The Soil? Why It Is So Important?
The preparation of soil is the first step before growing a crop.
One of the most important tasks in agriculture is to turn the soil and loosen as preparation of soil. This allows the roots to penetrate deep into the soil. The loose soil allows the roots to breathe easily even when they go deep into the soil. The loosened soil helps in the growth of earthworms and microbes present in the soil. These organisms are friends of the farmer since they further turn and loosen the soil and add humus to it.
Since only a few centimeters of the top layer of soil supports plant growth, turning and loosening of soil brings the nutrient-rich soil to the top so that plants can use these nutrients. Thus, turning and loosening of soil is very important for cultivation of crops.
“Before Sowing The Seeds It Is Necessary To Break Soil To The Size Of Grains To Get Better Yield”. Which Type Of Tools Are Used For This Purpose? Explain The Construction Of These Tools.
This is done with the help of various tools. The main tools used for this purpose are the plough, hoe and cultivator.
Plough: This is being used since ancient times for tilling the soil, adding fertilisers to the crop, removing the weeds, scraping of soil, etc. This implement is made of wood and is drawn by a pair of bulls or other animals (horses, camels, etc.). It contains a strong triangular iron strip called ploughshare. The main part of the plough is a long log of wood which is called a plough-shaft. There is a handle at one end of the shaft. The other end is attached to a beam which is placed on the bulls’ necks. One pair of bulls and a man can easily operate the plough.
The indigenous wooden plough is increasingly being replaced by iron ploughs nowadays.
Hoe: It is a simple tool which is used for removing weeds and for loosening the soil. It has a long rod of wood or iron. A strong, broad and bent plate of iron is fixed to one of its ends and works like a blade. It is pulled by animals.
Cultivator: Nowadays ploughing is done by tractor driven cultivator. The use of cultivator saves labour and time.
With The Help Of An Activity, Say How Seeds Are Selected By The Farmers?
Take a beaker and fill half of it with water. Put a handful of wheat seeds and stir well. Wait for some time. There are some seeds which float on water. And there are heavier seeds also which sink in water. Damaged seeds become hollow and are thus lighter. Therefore, they float on water. This is a good method for separating good, healthy seeds from the damaged ones.
How Traditional Tool And Modern Tool Are Used For Sowing Seeds?
Traditional tool: The tool used traditionally for sowing seeds is shaped like a funnel. The seeds are filled into the funnel, passed down through two or three pipes having sharp ends. These ends pierce into the soil and place seeds there.
Seed drill (Modern tool): Nowadays the seed drill is used for sowing with the help of tractors. This tool sows the seeds uniformly at proper distances and depths. It ensures that seeds get covered by the soil after sowing. This prevents damage caused by birds. Sowing by using a seed drill saves time and labour.
Farmer Maintained The Appropriate Distance Between Seeds”. Why?
An appropriate distance between the seeds is important to avoid overcrowding of plants. This allows plants to get sufficient sunlight, nutrients and water from the soil. Sometimes a few plants have to be removed to prevent overcrowding.
Agricultural Practices
Cultivation of crops involves several activities undertaken by farmers over a period of time. These activities or tasks are referred to as agricultural practices. These activities are listed below.
(i) Preparation of soil,
(ii) Sowing,
(iii) Adding manure and fertilisers,
(iv) Irrigation,
(v) Protecting from weeds,
(vi) Harvesting and
(vii) Storage.
Class 8 Science Chapter 1 Important Questions Set – 3
How Can We Make Manure?
Manure is an organic substance obtained from the decomposition of plant or animal wastes. Farmers dump plant and animal waste in pits at open places and allow it to decompose. The decomposition is caused by some microorganisms. The decomposed matter is used as organic manure.
Discuss The Process Of Manuring.
Process of manuring: Soil supplies mineral nutrients to the crop. These nutrients are essential for the growth of plants. In certain areas, farmers grow crop after crop in the same field. The field is never left uncultivated or fallow. Continuous growing of crops makes the soil poorer in certain nutrients. Thus, improper or insufficient manuring results in weak plants
Therefore, farmers have to add manure to the fields to replenish the soil with nutrients. This process is called manuring.
“But Excessive Use Of Fertilizers Has Made The Soil Less Fertile”. Explain The Statement.
Fertilisers are chemical substances which are rich in a particular nutrient. Fertilisers are produced in factories. Some examples of fertilisers are— urea, ammonium sulphate, super phosphate, potash, NPK (Nitrogen, Phosphorus, Potassium).
The use of fertilisers has helped farmers to get better yield of crops such as wheat, paddy and maize. But excessive use of fertilisers has made the soil less fertile. Fertilisers have also become a source of water pollution. Therefore, in order to maintain the fertility of the soil, we have to substitute fertilisers by organic manure or leave the field uncultivated (fallow) in between two crops.
Therefore, the use of manure improves soil texture as well as its water retaining capacity. It replenishes the soil with all the nutrients.
“But Excessive Use Of Fertilizers Has Made The Soil Less Fertile”. Explain The Statement.
Fertilisers are chemical substances which are rich in a particular nutrient. Fertilisers are produced in factories. Some examples of fertilisers are— urea, ammonium sulphate, super phosphate, potash, NPK (Nitrogen, Phosphorus, Potassium).
The use of fertilisers has helped farmers to get better yield of crops such as wheat, paddy and maize. But excessive use of fertilisers has made the soil less fertile. Fertilisers have also become a source of water pollution. Therefore, in order to maintain the fertility of the soil, we have to substitute fertilisers by organic manure or leave the field uncultivated (fallow) in between two crops.
Therefore, the use of manure improves soil texture as well as its water retaining capacity. It replenishes the soil with all the nutrients.
To Adding Manure Is The One Way Of Replenishing The Soil, What Is The Other? Justify Your Answer.
Another method of replenishing the soil with nutrients is through crop rotation. This can be done by growing different crops alternately.
Farmers in northern India used to grow legumes as fodder in one season and wheat in the next season. This helped in the replenishment of the soil with nitrogen. Farmers are being encouraged to adopt this practice.
Manure And Fertilizers
Manure is an organic substance obtained from the decomposition of plant or animal wastes. Fertilisers are chemical substances which are rich in a particular nutrient. The substances which are added to the soil in the form of nutrients for the healthy growth of plants are called manure or fertilisers.
Class 8 Science Chapter 1 Important Questions Set – 4
Write The Difference Between Fertilizers And Manure.
Fertiliser: A fertiliser is an organic salt. A fertiliser is prepared in factories. A fertiliser does not provide any humans to the soil. Fertilisers are very rich in plants nutrients like nitrogen, phosphorus and potassium.
In the other hand:
Manure: Manure is a natural substance obtained by the decomposition of cattle dung. Human waste and plant residues. Manual can be prepared in the fields. Manure provides a lot of humus to the soil. Manure is relatively less rich in plant nutrients.
The Organic Manure Is Considered Better Than Fertilizers”. Discuss, Why?
The organic manure is considered better than fertilisers. This is because:
(i) It enhances the water holding capacity of the soil.
(ii) It makes the soil porous due to which exchange of gases becomes easy.
(iii) It increases the number of friendly microbes.
(iv) It improves the texture of the soil.
What Is The Role Of Water In Crop Production?
All living beings need water to live. Water is important for proper growth and development of flowers, fruits and seeds of plants. Water is absorbed by the plant roots. Along with water, minerals and fertilisers are also absorbed.
Plants contain nearly 90% water. Water is essential because germination of seeds does not take place under dry conditions. Nutrients dissolved in water get transported to each part of the plant.
To maintain the moisture of the soil for healthy crop growth, fields have to be watered regularly. The supply of water to crops at different intervals is called “irrigation”.
The time and frequency of irrigation varies from crop to crop, soil to soil and season to season.
How Does Modern Methods Of Irrigation Help Us To Use Water Economically? Explain.
Modern methods of irrigation help us to use water economically. The main methods used are as follows:
(i) Sprinkler System: This system is more useful on the uneven land where sufficient water is not available. The perpendicular pipes, having rotating nozzles on top, are joined to the main pipeline 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 gets sprinkled on the crop as if it is raining. Sprinkler is very useful for sandy soil.
(ii) 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 and trees. The system provides water to plants drop by drop. Water is not wasted at all. It is a boon in regions where availability of water is poor.
Weeds And Its Removal
In a field many other undesirable plants may grow naturally along with the crop. These undesirable plants are called weeds.
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.
Class 8 Science Chapter 1 Important Questions Set – 5
Why Does Storage Of Crop Grains Consider As An Important Task For Farmers?
Storage of produce is an important task. If the crop grains are to be kept for longer time, they should be safe from moisture, insects, rats and microorganisms. The fresh crop has more moisture. If freshly harvested grains (seeds) are stored without drying, they may get spoilt or attacked by organisms, losing their germination capacity.
Hence, before storing them, the grains are properly dried in the sun to reduce the moisture in them. This prevents the attack by insect pests, bacteria and fungi.
Generally, farmers store grains in jute bags or metallic bins. However, large scale storage of grains is done in silos and granaries to protect them from pests like rats and insects. Dried neem leaves are used for storing food grains at home. For storing large quantities of grains in big go-downs, specific chemical treatments are required to protect them from pests and microorganisms.
Paheli Wants To Practice Crop Rotation In Her Field. Suggest A “Rabi Crop” And “Kharif Crop”. Which Will Replenish Her Filled With Nitrogen. Which Crop Replenishes Nitrogen And Why?
Rabi crops are wheat, pea, mustard while kharif crops are maize, paddy (rice), or soya-bean. These are grown in different seasons and therefore, can very well be rotated alternatively. Pea and soya-bean are leguminous plants which harbour bacteria, i.e. rhizobium in their nodules, thus help in fixing nitrogen.
These nitrogen fixing plants can replenish nitrogen in the field and hence, Paheli can easily practice crop rotation.
Explain, How Soil Gets Affected By The Continuous Plantation Of Crops In A Field.
Soil supplies minerals and nutrients to the crop. These nutrients are essential for the growth of plants. Continuous growing of crops in the same field makes the soil poorer in certain nutrients. This makes the soil infertile. And then, to replenish the soil with nutrients farmers need to add manures to the soil.
If You Are Given A Dry Place Of Land For Cultivation, What Will You Do Before Sowing The Seeds?
If the field is dry for cultivation of crops, the soil preparation is done accordingly before sowing of crops. Preparation of dry soil includes adequate watering to restore the moisture content and then tilled and ploughed to allow growth of microbes and aeration.
Finally, the soil is turned and its crumbs are levelled and manures are mixed. The soil is ready for sowing of crops in the field.
Organic Food
The crops that are cultivated using organic substances like manures etc. and prohibit the use of harmful chemical substances like fertilisers, pesticides, weedicides, etc. are called ORGANIC FOOD.