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Crops Production and Management by Abhinav Sir

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Crop Production and Management - Class 8 Science Notes

Crop Production and Management

Class 8 Science Notes (S Chand & NCERT Syllabus)

Title Slide
Crop Production and Management
Introduction to Crops
Introduction to Crops
Plant Sciences
Plant Sciences
Agricultural Implements
Agricultural Implements
Crop Rotation
Crop Rotation
Food from Animals
Food from Animals

Definition

A crop is a group of plants of the same kind grown on a large scale for food, fodder, or other purposes. Agriculture is the science and practice of cultivating crops and rearing animals.

Importance

  • Provides food for humans and animals.
  • Supplies raw materials for industries (e.g., cotton for textiles).
  • Supports economic development through farming.

Types of Crops

  • Kharif Crops: Sown in June-July (monsoon), harvested in September-October. Examples: Paddy, maize, soybean, cotton.
  • Rabi Crops: Sown in October-March (winter), harvested in spring. Examples: Wheat, barley, gram, mustard.
  • Zaid Crops: Grown in March-June (summer). Examples: Watermelon, cucumber, muskmelon.

Explanation: Seasonal classification ensures crops are grown under suitable climatic conditions, optimizing yield.

Overview

Crop production involves a series of steps to ensure healthy growth and high yield. The seven key practices are:

  1. Preparation of soil
  2. Sowing
  3. Adding manure and fertilizers
  4. Irrigation
  5. Weed control
  6. Harvesting
  7. Storage

Details

Ploughing/Tilling: Loosening and turning the soil using a plough to improve aeration, enable root penetration, and mix organic matter.

Levelling: Breaking soil clumps and leveling the field with a leveller for uniform water distribution.

Manuring: Adding organic matter (e.g., compost) to enhance soil fertility.

Tools

  • Traditional: Wooden or iron plough, drawn by bullocks.
  • Modern: Tractor-driven ploughs for efficiency.

Importance: Enhances soil structure, improves water retention, and facilitates nutrient uptake.

Explanation: Soil preparation is the foundation of crop production, ensuring optimal conditions for seed germination and growth.

Details

Definition: Planting seeds in the soil at the correct depth and spacing.

Seed Selection: Healthy seeds sink in water; damaged ones float due to being hollow.

Methods

  • Traditional: Broadcasting (scattering seeds by hand) or using funnel-shaped tools.
  • Modern: Seed drills (tractor-driven) for uniform sowing.

Importance: Proper sowing ensures healthy plant growth and maximizes yield.

Explanation: Quality seeds and precise sowing prevent overcrowding and ensure healthy crop development.

Details

Manure: Organic material from decomposed plant/animal waste. Provides nutrients gradually and improves soil structure.

Fertilizers: Chemical substances (e.g., nitrogen, phosphorus, potassium) for quick nutrient supply.

Biofertilizers: Microorganisms (e.g., Rhizobium) that enhance nutrient availability.

Crop Rotation: Alternating crops to replenish soil nutrients naturally.

Comparison

  • Manure: Eco-friendly, slow-acting, improves long-term soil health.
  • Fertilizers: Fast-acting, nutrient-specific, but overuse harms soil and environment.

Explanation: Balanced nutrient management ensures sustainable crop production and soil fertility.

Details

Definition: Supplying water to crops at regular intervals to support growth.

Traditional Methods

  • Moat: Pulley system to lift water from wells.
  • Chain Pump: Uses buckets and chains to draw water.
  • Dhekli: Lever system for lifting water.

Modern Methods

  • Sprinkler System: Sprays water like rain, suitable for uneven land.
  • Drip Irrigation: Delivers water drop-by-drop to roots, highly water-efficient.

Drought-Resistant Crops: Examples include sorghum and pearl millet.

Explanation: Modern methods conserve water, crucial for water-scarce regions.

Details

Definition: Weeds are undesirable plants competing with crops for nutrients, water, and sunlight. Examples: Wild oat, Amaranthus.

Control Methods

  • Manual: Hand-pulling or using a trowel/khurpi.
  • Mechanical: Tilling before sowing to remove weeds.
  • Chemical: Using weedicides (e.g., 2,4-D).

Importance: Weed control prevents yield loss and ensures crop health.

Explanation: Eco-friendly methods like manual weeding are preferred to minimize chemical use.

Details

Definition: Cutting and collecting mature crops from the field.

Methods

  • Manual: Using a sickle for small-scale farming.
  • Modern: Harvesters or combine machines for large-scale farming.

Processes

  • Threshing: Separating grains from stalks (e.g., using threshers).
  • Winnowing: Separating grains from chaff using wind or machines.

Explanation: Timely harvesting ensures maximum yield and grain quality.

Details

Definition: Storing harvested grains to protect from pests, moisture, and microorganisms.

Methods

  • Grains are dried to reduce moisture content.
  • Stored in silos, godowns, or airtight containers.
  • Use of pesticides or neem leaves to deter pests.

Importance: Proper storage prevents spoilage and maintains grain quality.

Explanation: Effective storage ensures food security by preserving grains for future use.

Grain Storage

Details

Definition: Breeding and caring for animals for products like milk, eggs, meat, and wool.

Relation to Crop Production: Animals provide manure and assist in ploughing.

Explanation: Animal husbandry complements crop production, creating an integrated farming system.

Details

Traditional Practices: Labor-intensive, using manual tools (plough, sickle) and organic inputs.

Modern Practices: Mechanized tools (tractors, seed drills, harvesters) and chemical inputs for efficiency.

Environmental Concerns: Overuse of fertilizers and weedicides reduces soil fertility and pollutes water.

Explanation: Modern practices increase productivity but require sustainable approaches to minimize environmental harm.

Activity 1 (NCERT, Page 4)

Take a beaker, fill it halfway with water, add wheat seeds, and stir. Observe.

Solution: Healthy seeds sink due to higher density; damaged or hollow seeds float.

Explanation: This activity demonstrates seed selection, ensuring only viable seeds are sown for better crop yield. The sinking of healthy seeds indicates they are dense and viable, while floating seeds are hollow or damaged, unsuitable for planting.

Activity 2 (NCERT, Page 5)

Visit a nearby farm and observe the tools used for ploughing.

Solution: Common tools include wooden or iron ploughs (traditional) and tractor-driven ploughs (modern).

Explanation: Ploughing loosens soil, improves aeration, and prepares it for sowing. Observing tools helps understand their design and efficiency in soil preparation.

Activity 3 (NCERT, Page 7)

Collect different types of seeds (e.g., wheat, rice, gram) and compare their size, shape, and color.

Solution: Wheat seeds are small, oval, and brownish; rice seeds are elongated and white; gram seeds are round and yellowish-brown.

Explanation: Comparing seeds helps identify crop-specific characteristics, aiding in selection and understanding crop diversity.

Activity 4 (NCERT, Page 9)

Visit a field and observe irrigation methods used by farmers.

Solution: Farmers may use traditional methods (moat, dhekli) or modern methods (sprinkler, drip irrigation).

Explanation: Observing irrigation methods highlights their efficiency and suitability for different terrains, emphasizing water conservation in modern systems.

Activity 5 (NCERT, Page 11)

Discuss with a farmer about the methods used to protect crops from pests and weeds.

Solution: Farmers may use manual weeding, natural pest control (e.g., neem leaves), or chemical weedicides/pesticides.

Explanation: This activity shows the balance between eco-friendly and chemical methods, promoting sustainable practices for weed and pest control.

Definition

Agricultural implements are tools or machines used in farming to perform tasks like soil preparation, sowing, weeding, and harvesting.

Types and Details

  • Plough: Used for tilling soil to improve aeration and mix nutrients. Traditional ploughs are wooden or iron, drawn by bullocks; modern tractor-driven ploughs are faster. Advantage: Enhances soil structure. Disadvantage: Traditional ploughs are labor-intensive.
  • Hoe: A hand tool for breaking soil clumps, weeding, and harvesting root crops. Advantage: Precise for small-scale farming. Disadvantage: Time-consuming for large fields.
  • Seed Drill: A machine for sowing seeds at uniform depth and spacing. Advantage: Ensures even germination, improving yield. Disadvantage: Expensive for small farmers.
  • Sickle: A curved hand tool for manual harvesting of crops like wheat or rice. Advantage: Affordable and effective for small farms. Disadvantage: Slow and labor-intensive.
  • Harvester/Combine: A modern machine that cuts, threshes, and winnows crops in one operation. Advantage: Highly efficient for large-scale farming. Disadvantage: High cost and maintenance.
  • Leveller: Used to smooth soil for uniform irrigation and sowing. Advantage: Prevents waterlogging. Disadvantage: Limited to specific tasks.
  • Thresher: Separates grains from stalks after harvesting. Advantage: Speeds up grain processing. Disadvantage: Requires fuel or electricity.

Explanation: Agricultural implements reduce labor and increase efficiency, but choosing between traditional and modern tools depends on farm size, cost, and sustainability goals.

Definition

Crop rotation is the practice of growing different crops in succession on the same land to maintain soil fertility and reduce pest and disease buildup.

Principles

  • Alternate crops with different nutrient needs (e.g., nitrogen-fixing legumes with cereals).
  • Vary root depths to improve soil structure.
  • Include pest-repellent crops to reduce chemical use.

Examples

  • Maize-Legumes-Wheat: Maize depletes nitrogen; legumes (e.g., beans) fix nitrogen; wheat benefits from improved soil.
  • Rice-Mustard: Rice grows in wet conditions, followed by mustard in dry winter conditions, balancing soil moisture.

Benefits

  • Replenishes soil nutrients naturally, reducing fertilizer use.
  • Controls pests and weeds by disrupting their life cycles.
  • Improves soil structure and prevents erosion.

Explanation: Crop rotation enhances sustainable farming by maintaining soil health and reducing reliance on chemicals, benefiting crops like maize and wheat.

Definition

Food from animals includes products like milk, eggs, meat, and honey, obtained through animal husbandry, which complements crop production.

Examples and Sources

  • Milk: From cows, buffaloes, and goats. Used for dairy products like cheese, butter, and yogurt.
  • Eggs: From hens and ducks. Rich in protein and used in various dishes.
  • Meat: From poultry (chickens), goats, and sheep. Provides protein and nutrients.
  • Honey: From bees through apiculture. Used as a natural sweetener and in medicines.

Integration with Crop Production

Animals provide manure for crops, and crop residues (e.g., straw) feed livestock, creating a sustainable farming cycle.

Explanation: Animal-derived foods enhance food security and nutrition, while animal husbandry supports crop production through manure and labor, fostering integrated farming.

Male and Female Gametophyte Development

Definition: Gametophytes are the reproductive structures in plants that produce male and female gametes (sex cells).

  • Male Gametophyte: Develops in the anther of a flower. Pollen grains are formed through meiosis, each containing two male gametes (sperm cells).
  • Female Gametophyte: Develops in the ovule within the ovary. The embryo sac forms through meiosis, containing the egg cell and other cells.

Explanation: In crops like wheat or maize, the male gametophyte (pollen) and female gametophyte (embryo sac) are crucial for sexual reproduction, leading to seed formation.

Pollination

Definition: Pollination is the transfer of pollen grains from the anther (male part) to the stigma (female part) of a flower.

  • Self-Pollination: Pollen transfers within the same flower or plant (e.g., peas).
  • Cross-Pollination: Pollen transfers between different plants, often aided by wind, insects, or water (e.g., maize, mustard).

Explanation: Pollination ensures genetic diversity in cross-pollinated crops, improving resilience and yield, while self-pollination maintains uniformity.

Fertilization

Definition: Fertilization is the fusion of male and female gametes to form a zygote.

Process: After pollination, a pollen tube grows from the stigma to the ovule, delivering male gametes. One sperm fuses with the egg to form the zygote (future embryo), and another fuses with polar nuclei to form the endosperm.

Explanation: In crops like rice, this double fertilization ensures the embryo develops into a plant and the endosperm provides nutrients.

Sexual Incompatibility

Definition: Sexual incompatibility prevents self-pollination or fertilization in certain plants to promote cross-pollination.

Mechanism: Chemical barriers in the stigma or style block pollen from the same plant, ensuring genetic diversity.

Explanation: In crops like mustard, incompatibility enhances cross-breeding, leading to stronger, more adaptable plants.

Endosperm and Embryo Development

Endosperm: Formed during double fertilization, it provides nutrients (starch, proteins) to the developing embryo. In cereals like wheat, it forms the bulk of the seed.

Embryo: Develops from the zygote into a baby plant with root (radicle), shoot (plumule), and seed leaves (cotyledons).

Explanation: The endosperm supports embryo growth, ensuring seeds are viable for germination, critical for crops like maize.

Polyembryony

Definition: Polyembryony is the formation of multiple embryos in a single seed.

Examples: Seen in citrus crops like oranges, where extra embryos form from nucellar tissue.

Explanation: This increases the chances of successful germination and can produce genetically identical plants, useful in agriculture.

Apomixis

Definition: Apomixis is seed formation without fertilization, producing offspring identical to the parent.

Examples: Found in some grasses and citrus plants.

Explanation: Apomixis ensures uniform crop traits, beneficial for maintaining high-yield varieties without cross-breeding.

Seed Development

Process: After fertilization, the ovule develops into a seed, containing the embryo, endosperm, and a protective seed coat.

Importance: Seeds store food and protect the embryo, enabling plants to survive adverse conditions and germinate later.

Explanation: In crops like gram or beans, seed development ensures the next generation of plants, vital for food production.

Question 1

Select the correct word: float, water, crop, nutrients, preparation.

  • (a) The same kind of plants grown and cultivated on a large scale is called \(\text{crop}\).
  • (b) The first step before growing crops is \(\text{preparation}\) of the soil.
  • (c) Damaged seeds would \(\text{float}\) on top of water.
  • (d) For growing a crop, sufficient sunlight and \(\text{water}\) and \(\text{nutrients}\) from the soil are essential.

Solution: (a) crop, (b) preparation, (c) float, (d) water, nutrients.

Explanation: Defines crops as plants grown on a large scale, identifies soil preparation as the initial step, explains that damaged seeds float due to lower density, and lists water and nutrients as essential for crop growth.

Question 2

Give two examples of Kharif and Rabi crops.

Solution: Kharif: Paddy, maize; Rabi: Wheat, gram.

Explanation: Kharif crops thrive in the rainy season (June-October), while Rabi crops require cooler winter conditions (October-March), reflecting their seasonal adaptability.

Question 3

Explain how fertilizers differ from manure.

Solution: Manure is organic, slow-acting, and improves soil structure; fertilizers are chemical, fast-acting, and nutrient-specific.

Explanation: Manure, derived from plant/animal waste, enhances long-term soil health but releases nutrients slowly. Fertilizers provide immediate nutrients but can degrade soil if overused. Sustainable options include biofertilizers and crop rotation.

Question 4

What is irrigation? Describe two water-conserving methods.

Solution: Irrigation is supplying water to crops at regular intervals. Two water-conserving methods: Sprinkler system (sprays water like rain, suitable for uneven land) and drip irrigation (delivers water drop-by-drop to roots).

Explanation: Sprinkler and drip irrigation minimize water wastage, making them ideal for water-scarce regions, unlike traditional flood irrigation.

Question 5

What is meant by weeding? Why is it necessary?

Solution: Weeding is the removal of unwanted plants (weeds) that compete with crops. It is necessary to prevent weeds from reducing crop yield by competing for nutrients, water, and sunlight.

Explanation: Weeds like wild oat can stunt crop growth. Manual or mechanical weeding is eco-friendly, while chemical weedicides are effective but should be used cautiously.

Question 6

What is harvesting? How is it done?

Solution: Harvesting is cutting and collecting mature crops. It is done manually with sickles or mechanically with harvesters.

Explanation: Manual harvesting is labor-intensive but suitable for small farms. Modern harvesters combine cutting, threshing, and winnowing, saving time and labor.

Question 7

Why is storage of grains important?

Solution: Storage protects grains from pests, moisture, and microorganisms, ensuring food security and quality.

Explanation: Proper drying and storage in silos or airtight containers prevent spoilage, maintaining grain quality for consumption or sale.

Question 8

What is crop rotation? Give an example.

Solution: Crop rotation is growing different crops in succession on the same land. Example: Growing maize followed by beans.

Explanation: Rotation prevents nutrient depletion, as legumes like beans fix nitrogen, benefiting subsequent crops like maize, and reduces pest buildup.

Question 9

Name two traditional tools used for sowing seeds.

Solution: Funnel-shaped tool and hand broadcasting.

Explanation: Traditional tools are simple but less precise, often leading to uneven seed distribution compared to modern seed drills.

Question 10

What are biofertilizers?

Solution: Biofertilizers are microorganisms (e.g., Rhizobium) that enhance nutrient availability in soil.

Explanation: They promote sustainable agriculture by naturally enriching soil, reducing reliance on chemical fertilizers.

Question 1

Define lodging. How does it happen? [MSE Chandigarh 2008, 2006]

Solution: Lodging is the falling of crop plants at the grain maturation stage due to untimely rains and strong winds.

Explanation: Weak stems or waterlogged soil cause crops to bend or fall, reducing yield. Proper timing and strong crop varieties prevent lodging.

Question 2

Mention two important uses of tilling the soil. [MSE Chandigarh 2008]

Solution: Improves air circulation and allows deeper root penetration.

Explanation: Tilling aerates the soil, aiding microbial activity, and loosens it for better root growth, enhancing crop health.

Question 3

Name two natural methods of replenishing soil nutrients.

Solution: Use of manure and crop rotation.

Explanation: Manure adds organic nutrients, while crop rotation (e.g., legumes fixing nitrogen) maintains soil fertility naturally.

Question 4

Name the tool used for tilling soil.

Solution: Plough.

Explanation: Ploughs (wooden, iron, or tractor-driven) loosen soil, preparing it for sowing and nutrient mixing.

Question 5

What is threshing? How is it done?

Solution: Threshing is separating grains from stalks. It is done manually by beating or using threshers.

Explanation: Manual threshing involves striking stalks against a surface, while mechanical threshers automate the process for efficiency.

Question 6

Why is levelling important in agriculture?

Solution: Levelling ensures uniform water distribution and prevents waterlogging.

Explanation: A level field allows even irrigation and seed placement, improving crop growth and yield.

Question 7

What is winnowing?

Solution: Winnowing is separating grains from chaff using wind or machines.

Explanation: Lighter chaff is blown away, leaving heavier grains, ensuring clean grain collection for storage or sale.

Question 8

Name one chemical weedicide.

Solution: 2,4-D.

Explanation: 2,4-D selectively kills weeds without harming crops but should be used sparingly to avoid environmental damage.

Question 9

What is the role of animals in agriculture?

Solution: Animals provide manure and assist in ploughing.

Explanation: Manure enriches soil, and animals like bullocks pull ploughs, supporting traditional farming practices.

Question 10

Why is drip irrigation considered efficient?

Solution: Drip irrigation delivers water directly to roots, minimizing wastage.

Explanation: It reduces evaporation and runoff, making it ideal for water-scarce regions and improving crop yield.

Question 1 (MCQ)

Which of the following is a Rabi crop?

a) Rice b) Maize c) Wheat d) Soybean

Solution: c) Wheat

Explanation: Wheat is sown in winter (October-March), making it a Rabi crop, unlike rice, maize, and soybean, which are Kharif crops.

Question 2 (MCQ)

The process of loosening and turning the soil is called:

a) Irrigation b) Tilling c) Harvesting d) Weeding

Solution: b) Tilling

Explanation: Tilling prepares soil for sowing by improving aeration and mixing nutrients, distinct from irrigation, harvesting, or weeding.

Question 3 (MCQ)

Which of the following is a modern irrigation method?

a) Moat b) Dhekli c) Sprinkler d) Chain pump

Solution: c) Sprinkler

Explanation: Sprinkler systems spray water efficiently, unlike traditional methods like moat, dhekli, or chain pump.

Question 4 (MCQ)

Which crop is grown in the summer season?

a) Wheat b) Cucumber c) Gram d) Barley

Solution: b) Cucumber

Explanation: Cucumber is a Zaid crop grown in summer (March-June), while wheat, gram, and barley are Rabi crops.

Question 5 (MCQ)

The chemical used to kill weeds is called:

a) Fertilizer b) Pesticide c) Weedicide d) Manure

Solution: c) Weedicide

Explanation: Weedicides like 2,4-D target weeds, unlike fertilizers (nutrients), pesticides (pests), or manure (organic matter).

Question 6

Why is it necessary to dry grains before storage?

Solution: Drying reduces moisture content, preventing microbial growth and pest infestation.

Explanation: High moisture can lead to spoilage, reducing grain quality and shelf life.

Question 7

What is the advantage of using a seed drill?

Solution: A seed drill sows seeds at uniform depth and spacing, ensuring optimal growth.

Explanation: Unlike broadcasting, seed drills prevent overcrowding and ensure even germination, improving yield.

Question 8

Why is crop rotation beneficial?

Solution: Crop rotation maintains soil fertility and reduces pest and disease buildup.

Explanation: Different crops have varied nutrient needs; rotating legumes with cereals replenishes nitrogen, enhancing soil health.

Question 9

What is the role of Rhizobium in agriculture?

Solution: Rhizobium fixes nitrogen in leguminous crops, enriching soil.

Explanation: As a biofertilizer, Rhizobium converts atmospheric nitrogen into compounds plants can use, reducing fertilizer needs.

Question 10

Why is manual weeding preferred over chemical weeding?

Solution: Manual weeding is eco-friendly and does not harm soil or crops.

Explanation: Chemical weedicides can pollute soil and water, while manual methods are sustainable but labor-intensive.

Question 11

What is the purpose of adding manure to soil?

Solution: Manure adds nutrients and improves soil structure.

Explanation: Organic matter in manure enhances water retention and microbial activity, promoting long-term soil health.

Question 12

How does a combine harvester work?

Solution: A combine harvester cuts, threshes, and winnows crops in one operation.

Explanation: It automates multiple harvesting steps, saving time and labor on large farms.

Question 13

What is the disadvantage of over-irrigation?

Solution: Over-irrigation causes waterlogging, reducing soil aeration and crop growth.

Explanation: Excess water suffocates roots, leading to poor yields and potential crop damage.

Question 14

Name one crop that requires less water.

Solution: Pearl millet.

Explanation: Pearl millet is drought-resistant, thriving in low-water conditions, ideal for arid regions.

Question 15

Why is broadcasting less effective than using a seed drill?

Solution: Broadcasting scatters seeds unevenly, leading to overcrowding or sparse growth.

Explanation: Seed drills ensure precise placement, optimizing space and resources for better yields.

Question 16

What is the role of nitrogen in plant growth?

Solution: Nitrogen promotes leaf and stem growth.

Explanation: As a key nutrient, nitrogen is essential for photosynthesis and protein synthesis, critical for healthy plants.

Question 17

How does drip irrigation save water?

Solution: Drip irrigation delivers water directly to roots, minimizing evaporation and runoff.

Explanation: It targets water delivery, reducing wastage compared to flood or sprinkler irrigation.

Question 18

What is the purpose of winnowing?

Solution: Winnowing separates grains from chaff.

Explanation: Lighter chaff is blown away, ensuring clean grains for storage or processing.

Question 19

Why is animal husbandry important in agriculture?

Solution: It provides manure and labor (e.g., ploughing).

Explanation: Manure enriches soil, and animals like bullocks support traditional farming tasks.

Question 20

What is the advantage of using organic manure?

Solution: Organic manure improves soil fertility and structure without environmental harm.

Explanation: Unlike chemical fertilizers, manure is sustainable, enhancing soil health over time.

Question 21

What is the role of phosphorus in plant growth?

Solution: Phosphorus supports root development and flowering.

Explanation: It aids energy transfer and strengthens plant structure, crucial for crop yield.

Question 22

Why is timely harvesting important?

Solution: Timely harvesting prevents over-ripening and pest damage.

Explanation: Harvesting at the right time ensures maximum grain quality and yield.

Question 23

What is a silo?

Solution: A silo is a tall, airtight structure for storing grains.

Explanation: Silos protect grains from moisture and pests, ensuring long-term storage.

Question 24

How does levelling help in irrigation?

Solution: Levelling ensures even water distribution across the field.

Explanation: It prevents water pooling, ensuring all plants receive adequate water.

Question 25

What is the difference between threshing and winnowing?

Solution: Threshing separates grains from stalks; winnowing separates grains from chaff.

Explanation: Threshing detaches grains, while winnowing removes lighter chaff, completing the grain cleaning process.

Question 26

Why are weeds harmful to crops?

Solution: Weeds compete with crops for nutrients, water, and sunlight.

Explanation: This competition reduces crop growth and yield, necessitating weed control.

Question 27

Name two crops that fix nitrogen in soil.

Solution: Peas, beans.

Explanation: Leguminous crops host Rhizobium, which converts atmospheric nitrogen into usable compounds.

Question 28

What is the purpose of a seed drill?

Solution: A seed drill sows seeds at uniform depth and spacing.

Explanation: It ensures optimal germination and growth, improving crop yield.

Question 29

Why is irrigation essential for crops?

Solution: Irrigation provides water for plant growth in areas with insufficient rainfall.

Explanation: Water is critical for photosynthesis and nutrient uptake, ensuring healthy crops.

Question 30

What is the disadvantage of chemical fertilizers?

Solution: Overuse reduces soil fertility and pollutes water bodies.

Explanation: Chemical runoff harms ecosystems, making organic alternatives preferable.

Question 31

What is the role of potassium in plant growth?

Solution: Potassium regulates water uptake and strengthens plant resistance.

Explanation: It enhances disease resistance and supports overall plant vigor.

Question 32

Why is soil aeration important?

Solution: Soil aeration improves oxygen supply to roots and microbes.

Explanation: Aerated soil supports root respiration and microbial activity, enhancing crop growth.

Question 33

What is the advantage of sprinkler irrigation?

Solution: Sprinkler irrigation distributes water evenly, suitable for uneven land.

Explanation: It mimics rainfall, reducing wastage compared to traditional methods.

Question 34

What is a combine harvester?

Solution: A combine harvester is a machine that cuts, threshes, and winnows crops.

Explanation: It streamlines harvesting, making it efficient for large-scale farming.

Question 35

Why is pest control important in agriculture?

Solution: Pest control prevents crop damage and yield loss.

Explanation: Pests consume crops or spread diseases, necessitating control measures like neem or pesticides.

Question 36

What is the benefit of using neem leaves in storage?

Solution: Neem leaves act as a natural pesticide, repelling insects.

Explanation: They are eco-friendly, protecting grains without chemical residues.

Question 37

Why is soil testing important before sowing?

Solution: Soil testing determines nutrient levels and guides fertilizer use.

Explanation: It ensures crops receive adequate nutrients, preventing overuse or deficiency.

Question 38

What is the role of a leveller?

Solution: A leveller smooths soil for uniform irrigation and sowing.

Explanation: It prevents water pooling and ensures even crop growth.

Question 39

Why are Zaid crops grown in summer?

Solution: Zaid crops are suited to warm, short-season conditions.

Explanation: Crops like watermelon thrive in summer’s high temperatures, filling the gap between Kharif and Rabi seasons.

Question 40

What is the purpose of a thresher?

Solution: A thresher separates grains from stalks.

Explanation: It automates threshing, making it faster and less labor-intensive than manual methods.

Question 41

What is the difference between traditional and modern ploughing tools?

Solution: Traditional tools (wooden/iron ploughs) are manual and bullock-driven; modern tools (tractor-driven ploughs) are mechanized.

Explanation: Modern tools are faster and cover larger areas, improving efficiency over labor-intensive traditional methods.

Question 42

Why is waterlogging harmful to crops?

Solution: Waterlogging reduces soil aeration, suffocating roots.

Explanation: Excess water limits oxygen supply, hindering root respiration and growth.

Question

If wheat is sown in the Kharif season, what would happen? Discuss.

Solution: Wheat, a Rabi crop, requires cool, dry conditions (sown November-April). Sowing it in the Kharif season (June-October) with high rainfall and humidity leads to:

  • Poor germination due to waterlogging.
  • Increased pest and disease susceptibility (e.g., fungal infections).
  • Reduced yield due to lodging (plants falling due to weak stems in wet conditions).

Explanation: Wheat’s growth cycle is suited to winter’s low temperatures and moderate water needs. Kharif’s heavy rains and high temperatures disrupt its development, leading to crop failure.

© 2025 Class 8 Science Notes | By Abhinav Sir

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About Abhinav Anand
I am an exceptional teacher, passionate and approachable. I simplify complex ideas with clarity and creativity, fostering a supportive classroom where students thrive. My patience and enthusiasm inspire confidence, and I encourage curiosity while making every student feel valued.

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