CBSE NOTES CLASS 9 SCIENCE CHAPTER 15
IMPROVEMENT IN FOOD RESOURCES
Need to Improve Food Resources
There is a need to improve production efficiency of crops and livestock because
1. We need to provide for the food requirements of rapidly increasing population.
2. There is no major scope of increasing area of land under cultivation.
3. Green revolution and white revolution have increased the production of crops and dairy products. These revolutions have caused damage to our natural resources to the point of destroying their balance completely.
4. Apart from the quantity of food, we need good quality food products.
Hence increase in food production without degrading our environment and disturbing the ecological balance i.e. sustainable practices are required in agriculture and animal husbandry.
A large increase in crop production achieved by the use of artificial fertilizers, pesticides, and high-yield crop varieties.
It was the biggest dairy development program in the world. It transformed India from a milk-deficient nation into the world's largest milk producer and increased the milk available per person.
Food security means both availability of food and access to it.
Simply increasing grain production for storage in warehouses cannot solve the problem of malnutrition and hunger.
People should have money to purchase food.
Increasing the incomes of people in the agricultural sector is necessary to combat the problem of hunger.
Green revolution and white revolution have increased the production of crops and dairy products. These revolutions have caused damage to our natural resources to the point of destroying their balance completely.
To avoid harmful effects to the ecosystem, scientific management practices should be undertaken to obtain high yields from farms. For sustained livelihood mixed farming, intercropping, and integrated farming practices, for example, combine agriculture with livestock/poultry/fisheries/bee-keeping, etc. should be used.
Cereals (Wheat, rice, maize, millets and sorghum) provide us carbohydrates.
Pulses (Grams, pea and lentil) provide us proteins.
Oil seeds (Soya bean, ground nut, sesame, and castor) provide us fats.
Vegetables, spices and fruits provide us a range of minerals, nucleic acids and vitamins.
Animal Foods - Milk, Meet, Egg, Fish, Honey.
Types of Crops by Season
The crops grown in rainy season are called as Kharif crops. They are grown from June to October.
Examples - Paddy, Soya bean, pigeon pea and maize, bajra, cotton, green gram and black gram (urad).
The crops grown in winter season are called Rabi crops. They are grown November to April. Examples - Wheat, gram, peas, and mustard, linseed.
Why different crops are cultivated at different times?
Different crops require different climatic conditions, temperature and photoperiods for their growth and completion of their life cycle.
Duration of availability of sunlight per day is called photoperiod.
Photosynthesis, growth, flowering etc. are all related to the duration of sunlight.
Hence different crops are cultivated at different times of the year.
Activities in Improving Crop Yield
The major groups of activities for improving crop yields can be classified as:
- Crop variety improvement - choice of seeds for planting.
- Crop production improvement - nurturing of the crop plants.
- Crop protection management - protection of the growing and harvested crops from loss.
Crop Variety Improvement
The factors for which variety improvement is done are:
- Higher yield: To increase the productivity of the crop per acre.
- Improved quality: Quality considerations of crop products vary from crop to crop. Baking quality is important in wheat, protein quality in pulses, oil quality in oilseeds and preserving quality in fruits and vegetables.
- Biotic and abiotic resistance: Crops production can go down due to biotic and abiotic reasons
- Biotic reasons - diseases, insects and nematodes
- Abiotic reasons - drought, salinity, water logging, heat, cold and frost
Varieties resistant to these stresses can improve crop production.
- Change in maturity duration: The shorter the duration of the crop from sowing to harvesting, the more economical is the variety. Such short durations allow farmers to grow multiple rounds of crops in a year.
- Short duration also reduces the cost of crop production.
- Uniform maturity makes the harvesting process easy and reduces losses during harvesting.
- Wider adaptability: Developing varieties for wider adaptability will help in stabilising the crop production under different environmental conditions. One variety can then be grown under different climatic conditions in different areas.
- Desirable agronomic characteristics:
Tallness and profuse branching are desirable characters for fodder crops. Dwarfness is desired in cereals, so that less amount of nutrients are consumed by these crops. Thus developing varieties of desired agronomic characterss help give higher productivity.
- Hybridization: It refers to crossing between genetically dissimilar plants.
Type of Hybridization
- Genetically modified crops (GMCs, GM crops, or biotech crops) are plants whose DNA has been modified by introduction of gene which would provide the desired characteristic.
The Crop production improvement or Crop Production Management
Availability of money or financial conditions of the farmers decides different farming practices and agricultural technologies. There is a correlation between higher inputs and yields.
No cost production – no input cost, meager output
Low cost production – Some input cost, but not able to meet latest technologies and practices will result into low output.
High cost production – Latest technology, good quality seed and best practices leads to high yield.
Practices in Crop Production Management
They include nutrient management, irrigation and cropping patterns.
Plants require nutrients for growth. Nutrients are supplied to plants by air, water and soil. There are sixteen nutrients which are essential for plants.
- Air supplies carbon and oxygen,
- Hydrogen comes from water, and
- Soil supplies the other thirteen nutrients to plants.
Out of these thirteen nutrients, six are required in large quantities and are therefore called macronutrients.
The other seven nutrients are used by plants in small quantities and are therefore called micro-nutrients.
Nutrients supplied by air, water and soil
nitrogen, phosphorus,potassium, calcium, magnesium, sulphur
iron, manganese, boron, zinc, copper, molybdenum, chlorine
Deficiency of any of the nutrients affects physiological processes in plants including reproduction, growth and susceptibility to diseases. To increase the yield, the soil can be enriched by supplying these nutrients in the form of manure and fertilizers.
Manure is prepared by the decomposition of animal excreta and plant waste. The manures need around 30 days for absorption by plants.
Advantages of Using Manure
- Manure helps in enriching soil with nutrients and organic matter and increasing soil fertility. The bulk of organic matter in manure helps in improving the soil structure.
- It increases the water holding capacity in sandy soils.
- In clayey soils, the large quantities of organic matter help in drainage and in avoiding water logging.
- Use of manures protects our environment from excessive use of fertilizers.
- Using biological waste material also helps in recycling farm waste.
Types of Manures
(i) Compost and vermi-compost
The process in which farm waste material like livestock excreta (cow dung etc.), vegetable waste, animal refuse, domestic waste, sewage waste, straw, eradicated weeds etc. is decomposed in pits is known as composting.
The compost is rich in organic matter and nutrients.
Compost is also prepared by using earthworms to hasten the process of decomposition of plant and animal refuse. This is called vermi-compost.
(ii) Green manure
Prior to the sowing of the crop seeds, some plants like sun hemp or guar are grown and then mulched by ploughing them into the soil. These green plants thus turn into green manure which helps in enriching the soil in nitrogen and phosphorus.
Fertilizers are commercially produced plant nutrients. Fertilizers are a factor in the higher yields of high-cost farming.
Advantages of Fertilizers
- Fertilizers supply nitrogen, phosphorus and potassium.
- The chemicals are absorbed instantaneously.
- They help in good vegetative growth (leaves, branches and flowers), giving rise to healthy plants.
Harmful Effects of Fertilizers
- Fertilizers should be applied carefully in terms of proper dose, time, and observing pre and post-application precautions for their complete utilisation.
- Sometimes fertilizers get washed away due to excessive irrigation and are not fully absorbed by the plants leading to water pollution.
- Continuous use of fertilizers in an area can destroy soil fertility because the organic matter in the soil is not replenished and micro-organisms in the soil are harmed by the fertilizers used.
Comparison of Manure & Fertilizers
Manure is prepared by the decomposition of animal excreta and plant waste
Chemical fertilizers are commercially produced plant nutrients.
It is cheap and prepared in rural homes and fields
It is costly and is prepared in factories
It is voluminous and bulky. It is inconvenient to store, transport and handle.
It is compact and concentrated. It is easy to store, transport and handle.
It is not nutrient specific.
It is nuteient specific and can provide specifically nitrogen, phosphorus etc.
Adds humus to the soil.
Does not add humus to the soil.
Organic farming is a farming system with
- Minimal or no use of chemicals as fertilizers, herbicides, pesticides etc.
- Maximum use of organic manures, recycled farm-wastes (straw and livestock excreta),
- Use of bio-agents such as culture of blue green algae in preparation of biofertilizers,
- Use of neem leaves or turmeric as bio-pesticides,
- Use of healthy cropping systems [mixed cropping, inter-cropping and crop rotation], which are beneficial in insect, pest and weed control besides providing nutrients.
Most agriculture in India is rain-fed.
The success of crops is dependent on timely monsoons and sufficient rainfall spread through most of the growing season. Hence, poor monsoons cause crop failure.
Ensuring that the crops get water at the right stages during their growing season can increase the expected yields of any crop.
Due to wide variety of water resources and a highly varied climate, several different kinds of irrigation systems are adopted to supply water to agricultural lands depending on the kinds of water resources available, i.e., wells, canals, rivers and tanks.
- Wells: There are two types of wells, namely dug wells and tube wells. In a dug well, water is collected from water bearing strata. Tube wells can tap water from the deeper strata. From these wells, water is lifted by pumps for irrigation.
- Canals: This is an elaborate and extensive irrigation system. In this system canals receive water from one or more reservoirs or from rivers. The main canal is divided into branch canals having further distributaries to irrigate fields.
- River Lift Systems: In areas where canal flow is insufficient or irregular due to inadequate reservoir release, the lift system is more rational. Water is directly drawn from the rivers for supplementing irrigation in areas close to rivers.
- Tanks: These are small storage reservoirs, which intercept and store the run-off of smaller catchment.
- Check-dams: These are small dams which help in rain water harvesting and watershed management. The check-dams stop the rainwater from flowing away, reduce soil erosion and help increase ground water levels.
Different ways of growing crops can be used to give maximum benefit.
1. Mixed cropping is growing two or more crops simultaneously on the same piece of land, for example, wheat + gram, or wheat + mustard, or groundnut + sunflower.
2. Inter-cropping is growing two or more crops simultaneously on the same field in a definite pattern. A few rows of one crop alternate with a few rows of a second crop, for example, soyabean + maize, or finger millet (bajra) + cowpea (lobia).
Advantages of Mixed cropping and Inter cropping
- The crops are selected such that their nutrient requirements are different. This ensures maximum utilisation of the nutrients supplied,
- It also prevents pests and diseases from spreading to all the plants belonging to one crop in a field. This way, both crops can give better returns.
- This reduces risk and gives some insurance against failure of one of the crops.
3. Crop Rotation - The growing of different crops on a piece of land in a pre-planned succession is known as crop rotation.
Depending upon the duration, availability of moisture and irrigation facilities crop rotation is done for different crop combinations.
Advantages of Crop Rotation
If crop rotation is done properly then two or three crops can be grown in a year with good harvests. It also increases soil fertility and reduces soil erosion. It also helps in growing more than one crop on the same piece of land during a year.
All these methods reduce the need for fertilizers. These methods also help in controlling weeds and the growth of pathogens and pests in crops.
Crop Protection Management
Field crops are infested by a large number of weeds, insect pests and diseases.
Need - If weeds and pests are not controlled at the appropriate time then they can damage the crops so much that most of the crop is lost.
1. Weeds are unwanted plants in the cultivated field, for example, Xanthium (gokhroo), Parthenium (gajar ghas), Cyperinus rotundus (motha). They compete for food, space and light. Weeds take up nutrients and reduce the growth of the crop. Therefore, removal of weeds from cultivated fields during the early stages of crop growth is essential for a good harvest.
2. Insect pests attack the plants in three ways:
(i) they cut the root, stem and leaf,
(ii) they suck the cell sap from various parts of the plant, and
(iii) they bore into stem and fruits.
They thus affect the health of the crop and reduce yields.
3. Diseases in plants are caused by pathogens such as bacteria, fungi and viruses.
These pathogens can be present in and transmitted through the soil, water and air.
Methods of Crop Protection
(i) Use of pesticides namely,
- herbicides (kill weeds),
- insecticides (kill insect pests) and
- fungicides (kill fungi).
These chemicals are sprayed on crop plants or used for treating seeds and soil.
Harmful effects of pesticides
Excessive use of these chemicals creates problems, since they can be poisonous to many plant and animal species and cause environmental pollution.
(ii) Weed control methods also include mechanical removal.
(iii) Preventive methods
- Proper seed bed preparation
- Timely sowing of crops
- Intercropping and crop rotation
- Use of resistant varieties
- Summer ploughing, in which fields are ploughed deep in summers to destroy weeds and pests.
Storage of Grains
Factors responsible for storage losses
- Biotic - insects, rodents, fungi, mites and bacteria,
- Abiotic - inappropriate moisture and temperatures in the place of storage.
These factors cause losses leading to poor marketability.
The damages include
- Degradation in quality
- Loss in weight
- Poor germinability
- Discolouration of produce, all
These factors can be controlled by
- Proper treatment and
- Systematic management of warehouses.
Preventive and control measures are used before grains are stored.
- Strict cleaning of the produce before storage,
- Proper drying of the produce first in sunlight and then in shade, and
- Fumigation using chemicals that can kill pests.
It is a scientific management of animal livestock.
The main aspects of animal husbandry are feeding, breeding and diseases control.
Animal-based farming includes Cattle farming, Poultry farming, Fish farming, and Bee keeping.
Need for Animal Husbandry
- As the population increases and as living standards increase, the demand for milk, eggs and meat is also going up.
- Growing awareness of the need for humane treatment of livestock has brought in new limitations in livestock farming.
Thus, livestock production also needs to be improved.
Cattle husbandry is done for two purposes - milk and draught labour for agricultural work such as tilling, irrigation and carting.
Indian cattle belong to two different species, Bos indicus or cows, and Bos bubalis or buffaloes.
Milk-producing females are called milch animals (dairy animals), while the ones used for farm labour are called draught animals.
Milk production depends on the duration of the lactation period meaning the period of milk production after the birth of a calf. So, milk production can be increased by increasing the lactation period.
Exotic or foreign breeds (for example, Jersey, Brown Swiss) are selected for long lactation periods.
Local breeds (for example, Red Sindhi, Sahiwal) show excellent resistance to diseases.
The two can be cross-bred to get animals with both the desired qualities.
Good Management Practices in Care of Animals
- Proper Sanitation: Proper cleaning for cows and buffaloes for humane farming, for the health of the animals and for production of clean milk.
- Proper shelter: They should be sheltered under well-ventilated roofed sheds that protect them from rain, heat and cold. The floor of the cattle shed needs to be sloping so as to stay dry and to facilitate cleaning.
- Proper food: Cattle need balanced rations containing all nutrients in proportionate amounts. Good food is needed for,
- Maintenance requirement, which is the food required to support the animal to live a healthy life, and
- Milk producing requirement, which is the type of food required during the lactation period.
Animal feed includes
- Roughage, which is largely fibre,
- Concentrates which are low in fibre and contain relatively high levels of proteins and other nutrients.
- Feed additives containing micronutrients promote the health and milk output of dairy animals.
- Protection from Diseases
- The diseases may cause death,
- My reduce milk production.
Diseases may be caused due to,
- Internal parasites, a) worms affect stomach and intestine b) flukes damage the liver.
- External cause skin diseases
Bacteria and viruses
Bacteria and viruses cause infectious diseases.
We should consult veterinary doctors and provide for proper medication of for the cattle for good quality and quantity of animal products. Vaccinations are given to farm animals against many major viral and bacterial diseases.
Purpose of Poultry Farming
To raise domestic fowl for
- egg production and
- chicken meat
Different types of poultry birds
Layers: The birds which are reared for laying eggs.
Broilers:The birds which are reared for meat.
Indian Pure Breeds: Aseel, Chittagong or Malay, Kadaknath, Busra
Exotic or Foreign Breeds: Leghorn, Minocra, Ancona etc.
The cross-breeding programmes between Indian and foreign breeds for variety improvement are done for the following desirable traits,
(i) number and quality of chicks;
(ii) dwarf broiler parent for commercial chick production;
(iii) summer adaptation capacity/tolerance to high temperature;
(iv) low maintenance requirements;
(v) reduction in the size of the egg-laying bird with ability to utilise more fibrous cheaper diets formulated using agricultural by-products.
Egg and Broiler Production
- Feathering, Carcass quality and body weight are desired characteristics of broilers.
- Broiler chickens are fed with protein-rich and vitamin-rich supplementary feed for good growth rate and better feed efficiency.
- For egg layers roughage and calcium rich diet is required.
Good management practices for Poultry farming
- Maintenance of temperature
- Hygienic conditions in housing and poultry feed,
- Prevention and control of diseases and pests.
Disease Control in Poultry
- Poultry fowl suffer from a number of diseases caused by virus, bacteria, fungi, parasites, as well as from nutritional deficiencies.
- These necessitate proper cleaning, sanitation, and spraying of disinfectants at regular intervals.
- Appropriate vaccination can prevent the occurrence of infectious diseases and reduce loss of poultry during an outbreak of disease.
Fish is a cheap source of animal protein for our food.
Fish production includes
- the finned true fish and
- shellfish such as prawns and molluscs.
There are two ways of obtaining fish,
- From natural resources, called capture fishing.
- By fish farming, called culture fishery.
The water source of the fish can be
- Seawater (marine fishing) or
- Fresh water (rivers and ponds)
- Popular marine fish varieties
- bombay duck
- Marine fish are caught using fishing nets and boats.
They are located using satellites and echo-sounders.
- Special marine fish of high economic value are
- finned fishes like mullets, bhetki, and pearl spots
- shellfish such as prawns, mussels, oysters and seaweed.
- Oysters are also cultivated for the pearls they make.
As marine fish stocks get depleted, the demand for more fish can only be met by culture fisheries, called mariculture.
Fresh water resources include canals, ponds, reservoirs and rivers.
Brackish water resources, where seawater and fresh water mix together, such as estuaries and lagoons are also important fish reservoirs.
Capture fishing in inland water bodies does not have high yield.
Rearing of aquatic animals like fish for food is called aquaculture.
Fish culture is sometimes done in combination with a rice crop, so that fish are grown in the water in the paddy field and the agricultural waste can be fed to fish.
Composite Fish Culture
Both local and imported fish species are used in such a system.
Combination of five or six fish species is are used in a single fishpond.
These species are selected so that they do not compete for food among them having different types of food habits. As a result, the food available in all the parts of the pond is used.
For example, Catlas are surface feeders, Rohus feed in the middle-zone of the pond, Mrigals and Common Carps are bottom feeders, and Grass Carps feed on the weeds.
Hence together these species can use all the food in the pond without competing with each other.
This increases the fish yield from the pond.
Problem of good quality seed
A major problem in fish farming is the lack of availability of good quality seed.
Many of the fish breed only during monsoon, hence it is difficult to collect the seed from the wild. Even if fish seed is collected from the wild, it can be mixed with that of other species as well.
To overcome this problem, ways have now been worked out to breed these fish in ponds using hormonal stimulation. This has ensured the supply of pure fish seed in desired quantities.
Bee-Keeping or Api-Culture
Advantages of beekeeping
- Honey is widely used hence beekeeping has become an agricultural enterprise.
- It requires low investments so farmers use it as an additional income generating activity.
- The beehives are a source of wax which is used in various medicinal preparations.
Indian varieties of bees
- Apis cerana indica, commonly known as the Indian bee,
- A. dorsata, the rock bee and
- A. florae, the little bee.
An Italian bee variety, A. mellifera, is also used to increase yield of honey. This is the variety commonly used for commercial honey production.
Desired characteristics in bees
- Should have high honey collection capacity
- Should sting less
- Should stay in a given beehive for long periods,
- Should breed very well.
The bee farms are called apiaries.
The value or quality of honey depends upon
- Adequate quantity of pasturage,
- Kind of flowers available will determine the taste of the honey.