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

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

KSEEB Class 8 Science Chapter 21 Textual Questions & Answers

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

Question 1.
Rhizobium bacteria is associated with the absorption of
(a) oxygen
(b) Carbon dioxide
(c) Nitrogen
(e) Water vapor
Answer:
(c) Nitrogen

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

Question 3.
One of the arguments against too much use of Chemical Fertilizers in that they.
(a) decrease the taste of the food
(b) reduce the nutrients of food
(c) affect the soil bacteria
(d) consume too much water
Answer:
(b) reduce the nutrients of food

Question 4.
One of the advantages of growing chili plants between two rows of green gram dhal plants is that
(a) chili plants are protected by the shade of dhal plants.
(b) nitrogenous fertilizer prepared by green gram plants can be utilized by chili plants.
(c) Chili plants get water from green gram plants.
(d) dhal plants are protected from pests in the presence of chili plants.
Answer:
(b) nitrogenous fertilizer prepared by green gram plants can be utilized by chili plants.

II. Fill in the blanks with suitable words.

Question 1.
Father of the green revolution in India is ………….
Answer:
Dr. M.S. Swaminathan

Question 2.
NPK fertilizer has the elements nitrogen, phosphorus, and ………..
Answer:
Potassium

Question 3.
Urea which is a Chemical Fertilizer is a rich source of the element ……….
Answer:
Nitrogen

Question 4.
By using animal dung and organic waste we can make organic manure called ……………
Answer:
Compost

III. Match the following:
KSEEB Solutions for Class 8 Science Chapter 21 . 1
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 of using chemical fertilizers

  • Include all the vital nutrients essential for plant growth.
  • They Contain the nutrients in the specific ration in a readily usable form
  • Can assess the requirement by soil testing and can adjust their usage to suit the requirements
  • Can choose the fertilizers that provide a single nutrient or mixed depending on the need.
  • Cost-effective and can supply plants with the proper balance of N, P, arid K

Disadvantages of using chemical fertilizers

  • As chemical fertilizers add several salts to the soil, some have the tendency to accumulate and alter the soil characteristics.
  • May harm and destroy the soil fauna
  • Increased use of chemical causes pollution of land and water
  • Water pollution caused by chemical fertilizers affects aquatic organisms and their habitats.
  • Chemicals may enter into the food chain and cause biomagnifications.

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

  1. Adding fresh organic matter such as dead plants, animal material and animal droppings.
  2. Adding organic manure such as compost.
  3. Soil organisms transform their organic matter into humus.

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

  • Manures supply both nutrients and humus to the soil
  • May not provide all the nutrients in the required quantity
  • Farmers cannot choose according to their requirements
  • Bind loose soil and increase their water holding capacity, helps in aeration which improves microbial activity
  • Do not cause soil or water pollution.

Chemical fertilizers

  • Chemical fertilizers supply only nutrients to the soil
  • Provide all the nutrients in specific ratios in a readily usable form
  • Farmers can choose according to their requirements.
  • Have the tendency to accumulate and alter the soil characteristic which may harm Ho soil and fauna.
  • Cause soil and water pollution and affect the aquatic organisms and their habits.

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

  • Prevent the erosion of topsoil which depletes the nutrients.
  • Crop rotation that which is an effective method of maintaining soil productivity is growing several crops one after another in a regular sequence.
  • Rotating the crops with legumes which enhances the nitrogen content.
  • Mixed cropping in which crops utilize soil nutrients more evenly.
  • Keeping land unused for a season and allowing goats and sheep to graze and set over the land so that the animal droppings will enrich the soil.
  • Adding organic manure like compost.
  • Adding biofertilizers like rhizobium, Azolla, etc.
  • Adding chemical fertilizers according to the requirement.

Question 5.
flow do you prepare compost manure?
Answer:
Following steps involving the preparation of compost.

  1. First, we must collect and stock up the organic material in a heap inside a pit or a vessel.
  2. The decomposition is more intense in a heap and covers it with a layer of soil.
  3. Sprinkle water over the heap to keep the matter moist go on heaping layer after layer until the pit is full.
  4. Keep adding water after each heap.
  5. Microbes break up the organic matter into simple forms.
  6. Adding earth warms as also enriches the manure.

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

  • deforestation
  • overgrazing of animals in grasslands
  • over-irrigation by gravity methods
  • unscientific use of soil
  • Measures to prevent soil erosion are
  • growing grass and trees so that the roots bind the soil firmly
  • ploughing at right angles in slope
  • growing crops that grow closely together, greatly help in preventing soil erosion.

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

  1. These are eco-friendly agricultural products which do not harm health.
  2. Biomagnification due to pesticides and fungicides can be prevented.
  3. Water and soil pollution can be avoided since the organic manures are bio-degradable.
  4. Soil productivity can be maintained.

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

  1. match the supply of irrigation water with crop demand.
  2. irrigation does not cause surface rain off or allow water to percolate below root zone.
  3. awareness of the root saturates zone of the crop and crop tolerance. To soil – water – depletion.
  4. use of better crops which need less water supply.
  5. Avoid overgrazing so that water percolates when it rains.

Question 9.
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 10.
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 by the following ways:

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

Question 11.
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 12.
How can we make agriculture more eco-friendly?
Answer:
We can make agriculture more eco-friendly by the following ways.

  1. Limiting farmland expansion
  2. Preserving biodiversity
  3. Reducing greenhouse gases
  4. Conserving water
  5. Protecting soil.

KSEEB Class 8 Science Chapter 21 Additional Questions & Answers

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

Question 2.
Write the needs of the farming community.
Answer:
The forming community needs,

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

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

Question 4.
Mention the role of soil in agriculture.
Answer:
The role of soil in agriculture are

  1. Crops take up their requirement such as water and minerals through the medium of soil
  2. It also provides anchorage for crops.
  3. It is the primary nutrient reservoir for plants.
  4. Thus, agriculture highlights the role of soil in the production of food.

Question 5.
Write the factors on which productivity depend.
Answer:
The factors are

  1. soil fertility
  2. water supply
  3. land slope depth of water table
  4. climate and cultivation

Question 6.
What is fertile soil?
Answer:
The soil that has a higher capacity to supply the required nutrient is called fertile soil.

Question 7.
Mention the factors that contribute to the depletion of the soil.
Answer:
Natural and human factors contribute to the depletion of the soil. This makes the soil increasingly less productive and renders agriculture unsustainable.

Question 8.
What do you mean by hydroponics?
Answer:
Growing of plants with their roots in a nutrient solution without soil is called hydroponics. The sequence is called crop rotation.
Eg: growing paddy or rage in one season followed by a legume crop like groundnut.

Question 9.
Explain the advantages of crop rotation.
Answer:
The advantages of crop rotations are:

  1. helps to increase the soil fertility
  2. crop rotation to help to prevent the loss of nutrients.
  3. crop-rotation gives higher protection against soil erosion.
  4. crops that grow closely together greatly help in preventing soil erosion.
  5. by increasing the nitrogen content by Rhizobium bacteria present in legume.
  6. prevent the loss of nutrients since it gives protection to soil erosion.
  7. extensive use of the same nutrient can be prevented.

Question 10.
Mention the advantages of mixed cropping.
Answer:
The advantages of mixed cropping are:

  1. Deficiency in a single nutrient is not happening since crops utilize soil nutrients more evenly and no extensive use of any single nutrient.
  2. Gives security for farming communities against failure.
  3. Secures the family requirement of cereals pulses, oilseeds and fooders simultaneously.

Question 11.
Write the two major uses of soil productivity.
Answer:
The two major uses of soil productivity are.

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

Question 12.
Mention the Techniques in soil management.
Answer:
The Techniques are:

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

Question 13.
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 in addition to crops like paddy maize, jowar, or bajra.

Question 14.
Define crop rotation?
Answer:
Growing different crops at different seasons but on the same piece of land in regular chemical fertilizers.

Question 15.
Write the role of organic manures in soil management.
Answer:
The presence of organic matter in the soil is fundamental to soil productivity, the widespread use of decomposed organic matter maintains and improves soil fertility. Organic manures bind loose soil, increase their water-holding power help in aeration, assist in penetration of roots, add plant nutrients, and increase microbial activity that are helpful for crops.

Question 16.
What is meant by Biofertilizers?
Answer:
The living organic which acts and fertilizers and enrich the soil are called bio-fertilizers.
Ex: Rhizobium, Azotobacter, Azolla, Nitrobacter and phoswastika.

Question 17.
Write the advantages of Bio-Fertilizers.
Answer:
The advantages of Bio-Fertilizers are:

  1. Increase soil fertility
  2. It promotes plant growth
  3. Safeguard the quality of crop products
  4. Rhizobium, blue-green algae help to mobilize phosphorous.
  5. Avoid soil and water pollution due to excess.
  6. The decomposition is more intense in a heap and covers it with a layer of soil.
  7. Sprinkle water over the heap to keep the matter moist go on heaping layer after layer until the pit is full.
  8. Keep adding water after each heap.
  9. Microbes break up the organic matter into simple forms.
  10. Adding earthworms also enriches the manure.

Question 18.
Write the role of chemical fertilizers in soil management.
Answer:

  1. Chemical fertilizers play an important role in crop production.
  2. They are synthetically prepared to include the vital nutrients essential for plant growth.
  3. They contain the nutrients in specific ratios in a readily usable form.
  4. Mixed fertilizers supply two or more nutrients.
    eg: NPK (Nitrogen, Phosphorus and Potassium)

Question 19.
List the disadvantages of using chemical fertilizers.
Answer:
As chemical fertilizers add several salts to the- soil, some have the tendency to accumulate and alter the soil characteristics.

  1. May harm and destroy the soil fauna.
  2. Increased use of chemical fertilizers also causes.
  3. Pollution of land and water.
  4. Water pollution affects aquatic organisms and their habitats.

Question 20.
Explain organic farming.
Answer:
Organic farming is an eco-friendly agricultural practice in which that relies the techniques such as crop rotation, green manure, compost, and biological pest control to maintain soil productivity and control pests on farm. It strictly limits the use of chemical fertilizers and synthetic pesticides and medicines.

Question 21.
What is meant by good water management in agriculture?
Answer:
Good water management means matching the supply of irrigation water with crop demand.

Question 22.
What are the factors that influence agricultural water management?
Answer:
The following factors influence, agricultural water management.

  1. Cost of irrigation
  2. Availability of water
  3. Crop characteristics
  4. Cropping season
  5. Type of soil and its characteristics.
  6. Comparability with other crops and farm operations.
  7. Knowledge of crops and their water requirement.
  8. Science and technology
  9. Social laws and practices

Question 23.
Name the two broad classes of irrigation systems.
Answer:
Two classes of irrigation systems are gravity – flow distribution pressurized – distribution.

Question 24.
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.

Question 25.
We need to manage the soil to maintain its quality and fertility. Give reason.
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.

KSEEB Solutions for Class 8 Science

1 thought on “KSEEB Solutions for Class 8 Science Chapter 21 Food Production : Soil and Water Management”

  1. please give the answer for the following questions
    1. difference between multiple cropping and mixed cropping
    2. what are the uses of chemical fertilizers

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