Improvement in Food Resources Class 9 Science Complete Revision Notes

The chapter “Improvement in Food Resources” is an important part of Central Board of Secondary Education CBSE class 9 Science syllabus. These improvement in food resources class 9 science notes help students understand how farmers increase the production of crops, milk, eggs, and fish by using modern farming methods and better management practices. In this chapter, students learn about crop variety improvement, nutrient management, irrigation systems, animal husbandry, poultry farming, fisheries, and sustainable agriculture in simple way.

These Class 9 Science notes are prepared according to the latest CBSE syllabus of the CBSE Board and are useful for quick revision before exams. Many students also search for improvement in food resources class 9 science notes pdf because PDF notes are easy to download and study anytime. Along with theory, students can also practice improvement in food resources class 9 questions and answers to improve their understanding and exam preparation.

The chapter is very scoring if students read concepts carefully and revise regularly. These notes of improvement in food resources class 9 pdf ncert solutions also explain important topics like organic farming, mixed cropping, crop protection, food security, and storage of grains. Overall, this chapter helps students know how science is connected with agriculture and daily human life, which is very usefull for future studies also.

What is Food Resources?

Food is a fundamental necessity for all living organisms. Scientifically, food is defined as a combination of organic substances and compounds that:

• Supply energy for metabolic activities
• Provide materials for repair and replacement of worn-out body tissues
• Support growth and reproduction
• Regulate body secretions and metabolic activities

With India's population exceeding 1.4 billion, ensuring sustainable and sufficient food production is one of the most critical challenges of our time. This chapter explores the scientific strategies and agricultural practices that help improve food resources from both plant and animal sources.

Main Branches of Agricultural Science

Classification of Crop Plants

Plants are the primary source of human food. Based on their use and nutritional value, crop plants are classified as follows:

Crop Seasons in India

Different crops require specific climatic conditions including temperature, photoperiod (duration of sunlight), and seasonal cycles. Indian agriculture recognizes two primary crop seasons:

Kharif Crops (Rainy/Monsoon Season)

• Grown during the monsoon season (June to October)
• Require warm and wet weather
• Sown in June–July, harvested in September–October
• Examples: Rice, Jowar, Bajra, Cotton, Groundnut, Moong, Urad

Rabi Crops (Winter Season)

• Grown during winter (October to April)
• Require cold and dry weather
• Sown in October–November, harvested in March–April
• Examples: Wheat, Barley, Gram, Mustard, Potato

Zaid crops are a third category grown during a short season between Rabi and Kharif (March–June), e.g., watermelon, cucumber, and bitter gourd.

Improvement in Crop Yield

Between 1960 and 2004, India achieved a fourfold increase in food grain production, even though cultivable land area expanded by only 24%. This remarkable achievement was made possible through three interconnected strategies:

1. Varietal Improvement – Genetic manipulation to develop superior crop varieties
2. Crop Production Management – Improved agronomic practices
3. Crop Protection Management – Effective control of pests, diseases, and weeds

Varietal Improvement Through Genetic Manipulation

The principal aim of varietal improvement is to combine as many desirable economic characters as possible into a single crop variety.

Aims of Crop Improvement

• Developing high-yielding varieties (HYVs)
• Improved quality (nutritional value, taste, shelf life)
• Early and uniform maturity for planned harvesting
• Insensitivity to light and temperature for broader cultivation
• Wider adaptability across different soil and climate types
• Lodging-resistant varieties (crops that do not fall due to wind/rain)
• Desirable agronomic characters (plant height, branching, etc.)

Plant Breeding

Plant breeding is the scientific technique of developing improved crop varieties by introducing desired characters into existing varieties. Scientists engaged in this work are called plant breeders.

New varieties developed through plant breeding possess:

• Higher yield potential
• Resistance to heat, frost, and drought
• Pest and disease resistance
• Early-maturing characteristics

Methods of Genetic Improvement

(A) Introduction

The transfer of superior crop varieties from their native region to areas where they were not previously cultivated. For example, high-yielding dwarf wheat varieties were introduced into India during the Green Revolution.

(B) Selection

The process of picking plants with the best desired characters from a population and using their seeds for future cultivation.

Selection may be:

Natural – Based on survival of the fittest

Artificial – Based on human-defined needs and preferences

Examples of crops represented mainly by cultivated varieties: Maize and Cabbage.

(C) Hybridization

Cross-breeding of two genetically dissimilar varieties each carrying a specific desirable trait to produce a new variety combining both traits. The resulting plants are called hybrid varieties or High-Yielding Varieties (HYVs).

Hybridization may be:

• Inter-varietal – Between two different varieties of the same species
• Inter-specific – Between two species within the same genus
• Inter-generic – Between plants belonging to entirely different genera

The Green Revolution

The Green Revolution (late 1960s–early 1970s) was a landmark period when India's production of wheat, rice, maize, and other food grains increased dramatically through:

• Introduction of High-Yielding Varieties (HYVs) of wheat and rice
• Increased use of fertilizers and pesticides
• Improvement of irrigation infrastructure

Dr. M.S. Swaminathan, a renowned plant geneticist, is widely recognized as the Father of the Green Revolution in India. In 1967, he developed the high-yield dwarf wheat variety Sharbati Sonara, which transformed Indian agriculture and helped India achieve food self-sufficiency.

Crop Production Management

Successful crop production depends on:

• Understanding how crops develop and grow
• Identifying factors that influence growth
• Modifying and managing these factors effectively

Approaches include:

Nutrient Management

Plants require 16 essential nutrients for growth, development, and reproduction. Of these, 13 are absorbed from the soil, while carbon, oxygen, and hydrogen come from air and water.

Sources of Plant Nutrients:

Carbon, oxygen, and hydrogen are called framework elements.

Classification of Nutrients

Macronutrients (Major elements): Required in relatively large amounts. Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Sulphur

Micronutrients (Minor/Trace elements): Required in very small or trace amounts. Iron, Manganese, Boron, Zinc, Copper, Molybdenum, Chlorine

Deficiency of nutrients affects physiological processes, reproduction, growth, and disease resistance in plants.

Manures and Fertilizers

Manures

A manure is a mixture of decomposed organic substances including dead leaves, agricultural waste, animal dung, and crop residues broken down by microbial action.

Characteristics of Manures:

• Organic substances derived from plant/animal residues
• Contain large amounts of organic matter
• Contain nutrients in low concentrations (require large quantities)
• Not nutrient-specific
• Improve soil texture, aeration, and water-holding capacity
• Eco-friendly do not cause pollution
• Bulky and inconvenient to transport

Types of Manures:

Vermicomposting: Composting assisted by earthworms. Earthworms break down organic waste, and their excreta enrich the compost with nutrients, producing high-quality humus.

Fertilizers

Fertilizers are commercially manufactured inorganic salts or organic compounds containing one or more essential plant nutrients (Nitrogen, Phosphorus, Potassium), used to increase soil fertility.

Characteristics of Fertilizers:

• Contain high concentration of nutrients (required in small amounts)
• Water-soluble and easily absorbed by plants
• Nutrient-specific
• Manufactured in factories; easy to transport and store
• Only urea is an organic fertilizer among commercial fertilizers

Types of Fertilizers:

Hazards of Excessive Fertilizer Use:

• Continuous use degrades soil structure and reduces porosity
• Causes water pollution and eutrophication nitrates and phosphates washed into water bodies stimulate algal blooms, depleting dissolved oxygen and killing aquatic life
• Fertilizers should be applied judiciously and in limited quantities

Eutrophication

Eutrophication: The process by which excessive nutrient runoff causes explosive algal growth in water bodies, leading to depletion of oxygen and death of aquatic organisms.

Differences Between Manures and Fertilizers:

Biofertilizers

Biofertilizers are microorganisms bacteria, algae, and fungi used singly or in combination to enrich soil fertility naturally.

Common biofertilizers:

• Legume–Rhizobium symbiosis – Fixes atmospheric nitrogen in root nodules
• Azolla–Anabaena symbiosis – Aquatic fern used in rice paddies
• Azotobacter – Free-living soil bacteria that fix nitrogen
• Cyanobacteria (Anabaena, Nostoc) – Photosynthetic nitrogen fixers
• Mycorrhiza – Symbiotic association of fungi with plant roots, improving mineral absorption

Irrigation

Irrigation is the controlled supply of water to crops through canals, reservoirs, wells, tube wells, and other systems. Water requirements depend on:

• Crop type – e.g., paddy needs continuous standing water; wheat does not
• Soil type – Sandy soils need more frequent irrigation than clay soils

Major Irrigation Systems in India:

Fertigation: An innovative technique of applying fertilizers through drip irrigation, maximizing farm productivity with minimal water use.

Cropping Patterns

Mixed Cropping

Growing two or more crops simultaneously on the same piece of land, selected so that each crop's products or residues benefit the other.

Common combinations:

• Wheat + Gram
• Cotton + Groundnut
• Groundnut + Sunflower
• Turmeric + Groundnut

Selection criteria: Duration, growth habit, root pattern, water needs, and nutrient demands.

Intercropping

An improved form of mixed cropping where two or more crops are grown simultaneously in a definite row pattern (e.g., 1:1, 1:2, 1:3).

Types:

• Row Intercropping – Alternating rows of different crops
• Strip Intercropping – Wide strips that allow independent mechanized harvesting

Advantages of Intercropping:

• Increases productivity per unit area
• Economizes space and time
• Maintains soil fertility

Crop Rotation

Growing different crops in sequence on the same land across seasons, in a pre-planned succession.

Types by duration:

• 1-year rotation: Rice–Wheat; Maize–Mustard
• 2-year rotation: Maize–Potato–Sugarcane–Peas
• 3-year rotation: Maize–Mustard–Sugarcane–Methi–Rice–Wheat

Benefits of Crop Rotation:

• Prevents depletion of specific soil nutrients
• Spreads agricultural work throughout the year
• Increases overall yields compared to monoculture
• Reduces incidence of weeds, pests, and diseases

Comparison: Mixed Cropping vs. Intercropping

Crop Protection Manageme

Crop protection involves eradicating pests, pathogens, weeds, and other organisms that damage crops.

Threats to Crops

• Pests – Insects, rats, mites, fungi that damage or destroy crops (e.g., locusts, aphids, weevils)
• Pathogens – Disease-causing microorganisms including bacteria, fungi, and viruses
• Weeds – Unwanted plants competing with main crops for nutrients, water, and light

Pest Control Methods

Weed Control Methods

1. Mechanical – Weeding, ploughing, burning, and flooding
2. Chemical (Herbicides) – 2,4-D, Nitrofen, Atrazine
3. Biological – Using living organisms (e.g., Cassia plant suppresses parthenium weed; herbivorous fish consume aquatic weeds)
4. Cultural – Proper seed bed preparation, timely sowing, crop rotation, intercropping

Preventive Measures (Integrated Pest Management)

• Use of pest/disease-resistant hybrid varieties
• Selecting optimum cropping time
• Crop rotation and multiple cropping
• Clean cultivation and summer ploughing
• Sowing of disease-free, healthy seeds

Storage of Food Grains

An estimated 9.3% of food grains in India are lost each year due to inadequate and improper storage.

Causes of Storage Loss

Biotic factors (living organisms):

• Insects (weevils, beetles, aphids, termites, grasshoppers)
• Rodents, birds, mites

Abiotic factors (non-living):

• High temperature and humidity
• Moisture levels
• Quality of storage containers

Effects of Poor Storage

• Infestation by insects and microorganisms
• Degradation in nutritional quality
• Loss in weight
• Poor germination potential
• Discoloration and unpalatability
• Toxic contamination and lower market value

Preventive Measures for Safe Storage

1. Drying grains before storage to reduce moisture content
2. Maintaining hygiene in storage facilities
3. Plant-product treatment with protective chemicals
4. Prophylactic (fumigation) treatment – Using volatile gaseous chemicals that kill insects without affecting grain quality
5. Improved storage structures (e.g., silos, godowns)

Animal Husbandry

Animal husbandry is the scientific management of farm animals, encompassing their feeding, breeding, weeding (removal of unproductive animals), and heeding (disease control).

Sources of Animal Food

Nutritional Value of Animal Products

The Four Pillars of Animal Husbandry

• Breeding – Selecting and mating animals to produce offspring with desirable traits (high milk yield, high meat yield)
• Feeding – Providing balanced nutrition at appropriate times
• Weeding – Eliminating unproductive or economically unviable animals
• Heeding – Ensuring proper veterinary care and disease management

(A) The White Revolution – Operation Flood

Just as the Green Revolution transformed crop production, Operation Flood revolutionized India's milk production, leading to the White Revolution. It involved:

• High milk-yielding crossbreeds of dairy animals
• Scientific animal husbandry practices
• Nationwide cooperative dairy networks

Dr. V. Kurien, founder chairman of the National Dairy Development Board (NDDB), is credited as the Father of the White Revolution in India.

Silver Revolution = Large-scale increase in egg production Blue Revolution = Large-scale increase in fish production

(B) Cattle Farming

Breeds of Cows in India:

High milk-yielding indigenous breeds: Gir, Sahiwal, Red Sindhi Dual-purpose breeds (milk + draught): Haryana, Tharparkar, Deoni Exotic (foreign) breeds used for crossbreeding: Jersey (USA), Brown Swiss (Switzerland), Holstein-Friesian (Holland) Crossbred varieties developed in India: Karan Swiss, Frieswal, Karan-Fries

High milk-yielding buffalo breeds: Murrah (Punjab/Haryana), Mehsana, Surti, Nili, Jaffarabadi

Cattle Food Types:

• Roughage – High fibre content: green fodder, silage, hay
• Concentrate – High nutrients, low fibre: maize, oat, barley, jowar

Diseases of Dairy Animals:

(C) Poultry Farming

Raising chickens, ducks, geese, and turkeys for eggs and meat.

• Layer (egger): Birds raised for egg production
• Broiler: Birds raised for meat production

Indigenous breeds: Aseel, Ghagus (Kadaknath), Brahma, Cochin Exotic breeds used in India: White Leghorn, Rhode Island Red, Light Sussex

Advantages of Poultry Farming: Low investment, small area required, easy maintenance, quick returns.

(D) Fish Farming (Pisciculture)

Fish provide a cheap and high-quality source of animal protein.

Methods:

• Capture farming – From natural water bodies
• Culture farming – Controlled fish farming in ponds, lakes, and marine environments

Common freshwater species: Catla (fastest-growing carp), Rohu, Mrigal, Silver Carp, Grass Carp

(E) Bee Farming (Apiculture)

Rearing of bees for commercial honey production.

Key species:

• Apis indica – Indian bee
• Apis mellifera – Italian bee (domesticated in India for higher honey yield)

Organic Farmingha

Organic farming is a farming system that minimizes or completely avoids the use of chemical fertilizers, herbicides, and pesticides. Instead, it relies on:

• Manures and recycled farm waste
• Biofertilizers
• Natural biopesticides (e.g., neem leaves, turmeric for stored grain protection)

Advantages of Organic Farming

• Natural ecosystem is not disturbed
• Soil fertility is preserved long-term
• Harmful chemical effects on living organisms are avoided
• Air, water, and soil pollution does not occur
• Promotes biodiversity in agricultural ecosystems
• Produces healthier, chemical-free food

Improvement in Food Resources Class 9 Science Important Questions and Solutions

Q1. What is the difference between a Kharif crop and a Rabi crop? Give two examples of each.

Answer: Kharif crops are grown during the monsoon or rainy season (June to October). They require warm and wet weather conditions. Examples: Rice, Cotton, Maize, Groundnut.

Rabi crops are grown during the winter season (October to April). They require cold and dry weather conditions. Examples: Wheat, Mustard, Gram, Potato.

The key distinction lies in the climatic requirements: Kharif crops thrive in heat and humidity, while Rabi crops need cooler and drier conditions.

Q2. What is hybridization? Name the three types of hybridization.

Answer: Hybridization is the process of cross-breeding two genetically dissimilar varieties of crop plants, each carrying a specific desirable character, to produce a new variety that possesses both traits. The resulting plants are called hybrid varieties or high-yielding varieties (HYVs).

The three types of hybridization are:

1. Inter-varietal hybridization – Between two different varieties of the same species
2. Inter-specific hybridization – Between two different species belonging to the same genus
3. Inter-generic hybridization – Between plants belonging to entirely different genera

Q3. Distinguish between manures and fertilizers.

Answer: Manures are organic, natural substances derived from the decomposition of biological materials (plant and animal residues) by microorganisms. They contain nutrients in small concentrations but improve overall soil health by adding organic matter.

Fertilizers are commercially manufactured inorganic salts or organic compounds (only urea is organic) containing high concentrations of specific plant nutrients. They are nutrient-specific, easy to use, and required in small quantities, but their overuse causes water pollution through eutrophication.

The fundamental difference: Manures enrich the soil holistically and are eco-friendly, while fertilizers provide targeted nutrient supplementation but carry environmental risks.

Q4. What is eutrophication? How does excessive fertilizer use lead to it?

Answer: Eutrophication is the process by which excessive nutrients primarily nitrates and phosphates enter water bodies such as lakes, ponds, and rivers, triggering explosive growth of algae (algal blooms). When these algae die and decompose, the decomposing microorganisms consume the dissolved oxygen in the water. This oxygen depletion (hypoxia) kills fish, aquatic invertebrates, and other aquatic organisms.

The connection to fertilizers: When excessive nitrogenous and phosphatic fertilizers are applied to agricultural fields, rainwater washes them into nearby water bodies. The high nutrient load fuels uncontrolled algal growth, ultimately creating ecological dead zones.

Prevention: Using fertilizers judiciously, in recommended doses and at the right time, significantly reduces this risk.

Q5. What is crop rotation? State its benefits.

Answer: Crop rotation is the agricultural practice of growing different types of crops on the same piece of land in a planned sequence across successive seasons or years.

Benefits of crop rotation:

1. Soil fertility maintenance – Different crops utilize different nutrients, preventing depletion of any single nutrient
2. Reduced pest and disease pressure – Pathogens and pests specific to one crop do not persist when the host crop changes
3. Labour distribution – Agricultural operations are spread throughout the year, reducing seasonal work pressure
4. Higher yields – Rotating crops consistently yields more over time than growing the same crop repeatedly (monoculture)
5. Weed suppression – Varying crops disrupt weed life cycles

Q6. What is vermicomposting? How is it beneficial?

Answer: Vermicomposting is a composting process that uses earthworms to accelerate the breakdown of organic waste materials. Earthworms consume organic matter and their excreta (castings) are exceptionally rich in essential plant nutrients, beneficial microorganisms, and humus.

Benefits:

• Produces high-quality, nutrient-dense compost
• Converts agricultural and kitchen waste into a valuable soil amendment
• Improves soil aeration, structure, and water retention
• Environmentally friendly and sustainable
• Significantly faster than traditional composting

Q7. Name four common biofertilizers and explain how they work.

Answer:

Rhizobium (Legume–Rhizobium symbiosis): Rhizobium bacteria form symbiotic associations with the roots of leguminous plants (pea, gram, soybean), forming root nodules where they fix atmospheric nitrogen (N₂) into ammonium, which the plant can absorb.

Azotobacter: Free-living soil bacteria that independently fix atmospheric nitrogen, enriching the soil without requiring a host plant.

Cyanobacteria (Anabaena, Nostoc): Photosynthetic prokaryotes found in waterlogged rice paddies. They fix atmospheric nitrogen and also enrich soil organic matter. The Azolla–Anabaena symbiosis is particularly used in rice cultivation.

Mycorrhiza: Symbiotic associations of fungi with the roots of higher plants. The fungal hyphae greatly increase the root surface area, improving the plant's ability to absorb phosphorus and other micronutrients from the soil.

Q8. What is animal husbandry? What are its four main practices?

Answer: Animal husbandry is the branch of agricultural science that deals with the scientific management of farm animals, including their proper feeding, selective breeding, care, and disease control, to maximize their productivity and economic value.

The four main practices are:

1. Breeding – Selective mating of animals to produce offspring with superior traits like high milk yield or meat production
2. Feeding – Providing balanced and appropriate nutrition, including roughage (green fodder, silage) and concentrates (grains like maize, barley)
3. Weeding – Identifying and removing unproductive or economically unviable animals from the herd
4. Heeding – Maintaining animal health through regular veterinary care, vaccination, disease screening, and hygienic management

Q9. What is pisciculture? Name the main types of freshwater edible fish farmed in India.

Answer: Pisciculture, or fish farming (aquaculture), is the controlled cultivation of fish in freshwater or marine environments, including ponds, lakes, and tanks, for commercial food production.

Main freshwater edible fish cultivated in India:

• Indian major carps: Catla (the fastest-growing carp of great economic significance), Rohu, Mrigal (Cirrhina)
• Catfishes: Wallago, Mystus
• Exotic varieties: Silver Carp, Grass Carp

Fish are an economical and high-quality source of animal protein and are particularly important for food security in India's coastal and riverine communities.

Q10. Describe the Green Revolution. What were its causes, impact, and key contributor?

Answer: The Green Revolution was a transformative period in Indian agriculture during the late 1960s and early 1970s that achieved a dramatic and unprecedented increase in the production of food grains, particularly wheat and rice.

Causes and Mechanisms: India was facing severe food scarcity and dependence on food imports. To address this crisis, a multi-pronged scientific and agricultural strategy was implemented:

• High-Yielding Varieties (HYVs): Dwarf varieties of wheat and rice were introduced and developed. These varieties responded well to fertilizers and irrigation, producing significantly more grain per plant than traditional tall varieties.
• Increased fertilizer use: Chemical fertilizers, particularly nitrogenous ones, were made widely available to farmers.
• Improved irrigation: Canal networks, tube wells, and pump-based irrigation expanded access to water for year-round cultivation.
• Pesticide use: Crop protection through pesticides reduced losses due to insects and diseases.

Impact:

• India's food grain production increased fourfold between 1960 and 2004
• India achieved food self-sufficiency, eliminating dependence on food aid
• Wheat production, in particular, saw extraordinary gains in Punjab, Haryana, and western Uttar Pradesh
• Laid the foundation for subsequent agricultural research and development

Contributor:Dr. M.S. Swaminathan (Padma Vibhushan, Fellow of the Royal Society) is recognized as the Father of the Green Revolution in India. A plant geneticist by training, he pioneered the development of dwarf high-yielding wheat varieties in India and led the reorientation of the national crop breeding programme. In 1967, he developed the landmark wheat variety Sharbati Sonara, which delivered high yields while being compact enough to resist lodging.

Q11. Write a detailed note on the different methods of weed control in agriculture.

Answer: Weeds are unwanted plants that grow in agricultural fields alongside the main crop, competing with it for nutrients, water, light, and space. Effective weed control is essential for maximizing crop yield. Weeds can be controlled by four main methods:

1. Mechanical Methods: Physical removal of weeds from crop fields using tools such as harrows, hoes, and ploughs. Techniques include hand-weeding, interculture ploughing, burning of stubble, and flooding (which drowns weeds in paddy fields). This is the oldest and most traditional method of weed control.

2. Chemical Methods: Use of synthetic chemicals called herbicides (weedicides) to kill weeds. These chemicals are selectively toxic to weeds while being relatively safe for the main crop. Examples include:

• 2,4-D (2,4-Dichlorophenoxyacetic acid) – used against broadleaf weeds
• Nitrofen – effective against grassy weeds
• Atrazine – used in maize and sugarcane crops

Care must be taken with chemical weedicides as overuse can cause water pollution and harm non-target organisms.

3. Biological Methods: Employing living organisms (insects, animals, or competing plants) to control weeds naturally.

• The Cassia plant suppresses the growth of Parthenium weed (congress grass)
• Herbivorous fish consume aquatic weeds in ponds and irrigation channels

Advantages: Does not cause chemical pollution; biological agents are generally harmless to the main crop.

4. Cultural Methods: Agricultural practices that prevent weed establishment and growth:

• Proper seed bed preparation before sowing
• Timely and uniform seed sowing
• Intercropping and crop rotation (disrupts weed life cycles)
• Mixed cropping (provides competition that limits weed growth)

An Integrated Weed Management (IWM) approach combining two or more of these methods is the most effective and sustainable strategy.