KSEEB Solutions for Class 8 Science Chapter 21 Food Production : Soil and Water Management

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Karnataka State Syllabus Class 8 Science Chapter 21 Food Production : Soil and Water Management

KSEEB Class 8 Science Food Production : Soil and Water Management Textbook Exercise Questions and Answers

I. Four alternatives are given to each of the following incomplete statements/questions. Choose the right answer.

Question 1.
Rhizobium bacteria is associated with the absorption of
(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Water vapor

Question 2.
Green plants, normally do not suffer from the deficiency of the following mineral.
(a) Phosphorus
(b) Sulphur
(c) Iron
(d) Carbon

Question 3.
One of the arguments against too much use of chemical fertilizers is that they
(a) decrease the taste of the food
(b) reduce the nutrients of food
(c) affect the soil bacteria
(d) consume too much of water

Question 4.
One of the advantage of growing chilli plants between two row of green gram dhal plants, is that
(a) Chilli plants are protected by the shade of dhal plants.
(b) nitrogenous fertilizer prepared by green gram plants can be utilized by chilli plants.
(c) chilli plants get water from greet* gram plants
(d) dhal plants are protected from pests in the presence of chilli plants.

II. Fill in the blanks with suitable words.

Question:
1. Father of green revolution in India is _________.
2. N P K fertilizer has the elements nitrogen, phosphorus and _________.
3. Urea which is a chemical fertilizer is a rich source of the element _________.
4. Using animal dung and organic waste we can make an organic manure called _________.
Answer:
1. Dr. M.S. Swaminathan,
2. Potassium,
3. Nitrogen,
4. compost

III. Match the following:

Answer:
1. d,
2. e,
3. a,
4. f

IV. Answer the following:

Question 1.
List any two advantages and two disadvantages of using chemical fertilizers.
Answer:
Advantages

• Chemical fertilizers play an important role in crop production.
• They are synthetically prepared to include the vital nutrients essential for plant growth.

Disadvantages

• May harm and destroy the soil fauna.
• Increased use of chemical fertilizers also causes.

Question 2.
Why should farmers enhance the amount of humus in their farmland? How do they do that?
Answer:
Humusein the soil improves the soil structure, resists soil erosion, retains water and enriches the nutrients and ensures increased food production. Therefore farmers should enhance the amount of humus in their farmland. Farmers enhance the amount of humus in their farmland by the following methods:

• Adding fresh organic matter such as dead plants, animal material and animal droppings.
• Adding organic manure such as compost.
• Soil orgarisms transform there organic matter into humus.

Question 3.
Distinguish between organic manures and chemical fertilizers.
Answer:

1. Organic manures.
   • organic manures supply both nutrient and humus to the soil.
   • may not provide all the nutrients on the required quantity.
   • farmers cannot choose according to their requirements.
   • Bind loose soil to increase their water holding capacity, aeration which improves microbial activity.
   • Do not cause soil or water pollution.
2. Chemical fertilizers
   • The chemical fertilizers supply only nutrients to the soil.
   • It provides all the nutrients in a specific ration readily usable form.
   • Farmers can choose according to their requirements.
   • Have the tendency to accumulate and alter the soil characteristic which harms soil fauna.
   • Cause soil and water pollution.

Question 4.
List some agricultural practices that help to maintain the fertility of the soil.
Answer:

1. Prevent the erosion of topsoil which depletes the nutrient.
2. Crop rotation is growing several crops, one after another in a regular sequence.
3. Rotating the crop with legumes which enhances the nitrogen content.
4. Mixed cropping in which crops utilize soil nutrients more evenly.
5. Adding organic manure like compost.
6. Adding biofertilizers like rhizobium, Azolla, etc.
7. Adding chemical fertilizers according to the requirement.

Question 5.
How do you prepare compost manure?
Answer:
Collect and stock up the organic materials in a heap inside a pit or a vessel. The decomposition is more intense in a heap and covers it with a layer of soil sprinkle water over the heap to keep the matter moist Go on the heaping layer after layer until the pit is full. Keep adding water after each heap. Microbes break up the organic matter into simpler forms. Adding earthworms also enriches the manure.

Question 6.
List any three ways by which soil erosion occurs. State two measures to reduce the loss of topsoil.
Answer:
The cause of soil erosion are:

1. deforestation
2. overgrazing of animals in grasslands.
3. over-irrigation by gravity methods.
4. unscientific use of soil measures to prevent soil erosion are
5. Reduce soil erosion growing grass and trees so that the roots bind the soil firmly.
6. Ploughing at right angles in slope.

Question 7.
What are the advantages of organic farming?
Answer:

• Eco-friendly agricultural products which do not harm health.
• Biomagnification due to pesticides and fungicides can be prevented.
• Water and soil pollution can be avoided since the organic manures are biodegradable.
• Soil productivity can be maintained.

Question 8.
Suggest measures to conserve water in agriculture.
Answer:

• Match the supply of irrigation water with crop demand.
• Ensure that Irrigation does not cause surface rain off or allow water to percolate .below root zone.
• Awareness of root saturation zone of the crop and Ho crops tolerance To soil – water depletion.
• Use pressurized irrigation systems such as drip irrigation and sprinkler irrigation.
• Use of better crop varieties which need less water supply.
• Avoid overgrazing so that water percolates when it rains.

Think
Question 1.
What is your view on organic farming? If you were to have a piece of agricultural land, do you opt for chemical farming or organic farming? Give reasons for your choice.
Answer:
Organic farming is an integrated farming system that strives for sustainability, the enhancement of soil fertility, and biological diversity. If I were to have a piece of agricultural land, I will opt for organic farming because it maintains soil fertility.

Question 2.
How can we ensure food security for all the people of our country?
Answer:
We can ensure food security for all the people of our country in the following ways:

• Balance food and nutritional security.
• Embrace new technology for knowledge transfer amongst rural farmers.
• Take a balanced ‘landscape’ approach to agriculture.
• Stop the spread of non-native invasive species
• Create careers in agriculture for young people and woman

Question 3.
Why should we find ways for conserving water used in agriculture? What are your suggestions for the conservation of water?
Answer:
The increasing competition for water in urban areas and for energy uses will lesser what is now available for agriculture, s we should find ways for conserving water used in agriculture. So it is better to make use of rainwater and know at present 80 percent of globally cultivated land is done with rained farming, accounting for 60 percent of world food production.

Question 4.
How can we make agriculture more eco-friendly?
Answer:
We can make agriculture more eco- friendly in the following ways.

• Limiting farmland expansion
• Preserving biodiversity
• Reducing greenhouse gases
• Conserving water
• Protecting soil.

KSEEB Class 8 Science Food Production: Soil and Water Management Additional Questions and Answers

I. Answer the following:

Question 1.
What is meant by agriculture?
Answer:
Agriculture is the science and art of cultivating crops and raising livestock.

Question 2.
Mention the needs of the farming community.
Answer:
For getting the best out of agriculture, the farming community needs

1. Good seeds
2. Availability of fertile soil
3. Water and irrigation facilities.
4. Manures and fertilizers
5. The supportive social and economic environment
6. Crop pricing policy
7. Good prices for their produce
8. Science and technology

Question 3.
What is soil?
Answer:
Soil is the topmost layer of earth’s crust which contains water, minerals, dead organic matter and various types of living organisms.

Write the role of soil in agriculture.

• Crops take up their requirements such as water and minerals through the medium of soil.
• Soil provides anchorage for crops.
• It is the primary nutrient reservoir for plants.
• Thus, agriculture highlights the role of soil in the production of food.

Question 5.
Mention the factors on which productivity depends.
Answer:
The factors are soil fertility, water supply, land slope depth of water table, climate and cultivation.

Question 6.
What do you mean by hydroponics?
Answer:
Growing of plants with their roots in a nutrient solution without soil, is called hydroponics.

Question 7.
Mention the two major uses of soil productivity.
Answer:

• Identification of the ways and prevention of loss of nutrients in the soil.
• Taking steps to maintain and restore soil fertility.

Question 8.
Mention the techniques in soil management.
Answer:

• Control erosion of topsoil.
• Maintain the water balance and regulate soil temperature.
• Improve the soil structure and maintain a stock of organic matter.

Question 9.
What is meant by crop rotation?
Answer:
Growing different crops at different seasons on the same piece of land in a regular sequence is called crop rotation. Eg. growing paddy or ragi in one season followed by a legume crop like groundnut.

Question 10.
Mention the advantages of crop rotation.
Answer:

• helps to increase the soil fertility
• by increasing the nitrogen content by Rhizobium bacteria present in legumes
• prevent the loss of nutrients since it gives protection to soil erosion.
• extensive use of same nutrient can be prevented
• helps to keep the insect pest population under cheek since insects and pests are host specific.

Question 11.
What is meant by mixed cropping?
Answer:
Cultivation of one or two subsidiary crops together with one main crop in the same land is called mixed cropping.
Eg. growing potatoes, vegetables along with crops like paddy, maize, jowar or bajra.

Question 12.
Mention the advantages of mixed cropping.
Answer:

• Deficiency in any single nutrient is not happening since crops utilize soil nutrients more evenly and no extensive use of any single nutrient.
• Gives security for the farming community ‘ against crop failure.
• Secures the family requirements of cereals, pulses, oil seeds and fodder simultaneously.

Question 13.
What is meant by Bio-fertilizers?
Answer:
The living organisms which act and fertilize and enrich the soil are called bio¬fertilizers.
Ex. rhizobium, azotobacter, Azolla, Nitrobacter and phosphatic.

Question 14.
Mention the advantages of Bio-fertilizers.
Answer:

• Increase soil fertility
• Promote plant growth
• Safeguard the quality of crop products
• Rhizobium, blue-green algae help to mobilize phosphorus.
• Avoid soil and water pollution due to excess of chemical fertilizers.

Question 15.
What is meant by organic farming?
Answer:
Organic farming is an eco-friendly agricultural practice which relies On techniques such as crop rotation, green manure, compost and biological pests control to maintain soil productivity and control pest on the farm. It strictly limits the use of chemical fertilizers and synthetic pesticides and medicines.

Question 16.
What is meant by good water management in agriculture?
Answer:
Good water management means matching the supply of irrigation water with crop demand.

Question 17.
Mention the factors that influence agricultural water management.
Answer:

• Cost of irrigation
• Availability of water
• Crop characteristics
• Cropping season
• Type of soil and its characteristics
• Comparability with other crops and farm operations.
• knowledge of crops and their water requirement.
• Science and technology.
• Social laws and practices.

Question 18.
Mention the two broad classes of irrigation systems.
Answer:

• gravity flow distribution
• pressurized distribution

Question 19.
What is meant by gravity flow distribution?
Answer:
Gravity flow distribution is the traditional practice of surface irrigation. Furrow irrigation is another name for the gravity flow system. Water in this method flows from the surface and is distributed to the field through open canals and ditches, by gravity. Farmers control the water movement and direct it to the field. When the water is released along the upper end of the field, it flows throughout the field by means of open ditches above-ground pipe or underground pipe.

Question 20.
Mention the disadvantages of gravity flow distribution.
Answer:

1. Water cannot be supplied according to the requirement of the crop.
2. Water is wasted and soil moisture cannot be maintained throughout the day.
3. Water is not conserved by this method and topsoil may get eroded is also there.
4. Chances of decaying the crops due to excess of irrigation.

Question 21.
What is meant by pressurized irrigation? Mention two types of it
Answer:
Pressurized irrigation system consists of a network of pipes, fittings and other devices designed and installed to supply water under pressure to the farmland. The pressurized irrigation systems include sprinkler and trickle methods.

Question 22.
Drawagraphtoshowthecomparision of the three types of irrigation systems.
Answer:

Question 23.
What is meant by the Green Revolution?
Answer:
Green revolution refers to the boom in agricultural production that resulted from the introduction of high yielding varieties of seeds, increased use of fertilizers, and the introduction of improved irrigational practices.

Give scientific reasons for the following:

Question 1.
Farmers are called Kannada has.
Answer:
Whether poor or rich, everyone depends on farmers for their food therefore farmers are called as Kannada has.

Question 2.
Agriculture highlights the role of soil in the production of food.
Answer:
Crops take up their requirements such as water and minerals through the medium called soil. It also provides anchorage for crops. Thus agriculture highlights the role of soil in the production of food

Question 3.
We need to manage the soil to maintain its quality and fertility.
Answer:
Natural and human factors contribute to the depletion of the soil. This makes the soil increasingly less productive and renders agriculture unsustainable. Hence, we need to manage the soil to maintain its quality and fertility to enhance its performance.

Question 4.
N P K is the major concern of farming.
Answer:
Nitrogen, Phosphorus, and Potassium are required by the plants in larger quantities. Lack of one or more of these in the soil limits crop production. Hence it is a major concern for farming.

Question 5.
The fertility of the soil will never decline in the forests or grass lands untouched by human activities.
Answer:
Under natural conditions, all plant materials return to the soil itself. Therefore fertility of the soil will never decline in forest and grasslands untouched by human activity.

II. Fill in the blanks:

Question:
1. The soil that has a higher capacity to supply the required nutrients is called ________.
2. The soil that is unable to provide nutrients and support is called ________.
3. Natural and human factors contribute to ________ of the soil.
4. The causes of a fall in land productivity are ________ and ________.
5. Erosion of ________ depletes nutrients in soil.
6. Phosphotika is associated with mobilization of ________.
7. A fertilizer which has high content of both phosphorus and potassium is ________.
8. The fertilizer which provides only nitrogen content is ________.
9. The person who coined the work of Green Revolution is ________.
10. The architect of green revolution in India is ________.
11. The impact of green revolution in India was most impressive on the production of ________ and ________.
12. The success in Green Revolution certainly reduced India’s ________ substantially.
13. The 12 types of lands are described in ________ in Amara Kosha.
14. The chapter on Vaisyavargaha mentions the ________ for specific crops.
15. In ________ it states that the crops grown without manure will not give yield.
16. ________ mentions the use of cowdung, animal bones etc. as manure.
17. The application of excrete of sheep and goat was recommended by ________ to increase flowering and fruiting of trees.
18. In Bruhat Samhita ________ recommends the use of sesame plants as green manure.
19. Gurapala describes the ancient practice of preparing liquid manure called ________.
20. Krishi Parashara and ________ give simple models for predicting rains in a particular season.
21. In northern India prior to the invasion by Turks ________ was used for drawing water from well.
22. ________ mentions methods of irrigation and ways to locate ground water.
Answer:
1. fertile soil,
2. depleted soil,
3. depletion,
4. intense and prolonged agriculture,
5. topsoil,
6. phosphorus,
7. Mono potassium phosphate,
8. urea,
9. William Gaud,
10.Dr. M.S. Swaminathan,
11. Wheat and rice,
12. grain imports,
13. Bhumivargaha,
14. soil suitable,
15. Krishi – Parashara,
16. Kautilya,
17. Agnipurana,
18. Varahamihira,
19. Kunapa,
20. Bruhat Samhita,
21. Persian Wheel,
22. Surapala’s Vrikshayurveda