RBSE Class 9 Science Notes Chapter 15 Natural Resources and Agriculture

Rajasthan Board RBSE Class 9 Science Notes Chapter 15 Natural Resources and Agriculture

Any component of the natural environment that can be utilized by man, to promote his welfare is called a natural resource.

Natural resource are classified into three categories:
1. Natural resources,
2. Human resources,
3. Man-made resources.

Natural resources are classified on the basis of their availability and abundance.
- Renewable Resources are a type of exhaustible natural resources that can be successfully managed, so that these resources are continuously regenerated.
- Non-renewable: Resources are a type of exhaustible resource, which cannot be regenerated once they are used up.
Human Resources: The number of humans, their abilities, education, health, etc., are studied in,this resources.
Man made resources: This resources is made by humans with the help of natural resources, e.g. machine, tools, palace, buildings, etc.

Significance of Air, Water and Soil:

Air is a mixture of many gases like nitrogen, oxygen, carbon dioxide and water vapour. The precise composition of these gases makes life possible on earth. The composition of air on earth is nitrogen: 78% oxygen: 20.95%, carbon dioxide: 0.031%, argon: 0.93% and helium, neon, ozone, ammonia constitutes 0.04%. The atmosphere containing air covers the earth like a protective blanket. Air is a bad conductor of heat so, the atmosphere prevents the sudden increase in temperature, during the daylight hours.
Water is an inexhaustible natural resource. It occupies very large area of the earth’s surface. Some amount of water exists in the form of water vapour in the atmosphere. Most of the water on earth’s surface, is saline. Freshwater is found as frozen ice caps at poles and on snow-covered mountains. The underground water and the water in rivers, lakes and ponds is also fresh water.
Soil is the outermost layer of earth’s crust, which provides support for the growth of plants. Soil is a mixture of small particles of rocks, bits of decayed living organisms and partially decomposed plant and animal matter. It also contains various forms of micro-organisms. The main constituent of soil are minerals, air, water, organic matter and living organisms. The type of soil is decided by the average size of particles, found in it and quality of soil is decided by the amount of humus and microscopic organisms, found in it.

Movement of Air:

Winds are the result of changes that take place in our atmosphere, due to heating of air and formation of water vapour.
When solar radiations fall on the earth, majority of these radiations are reflected back b’ land and water bodies and some of them are absorbed. These reflected solar radiation heat the atmosphere from below. Due to this, convection currents are set-up in air. Since, land gets heated faster than water, the air over land would also be heated faster than the air, over water bodies.
In coastal regions, during the day time, the air above the land gets heated faster and starts rising. As this air rises, a region of low pressure is created and air over the sea moves to this area of low pressure. The movement of air from one region to the other create winds. Direction of wind would be from sea to the land during the day.
Other factors that influence the winds are rotation of earth and the presence of mountain ranges in the path of wind.

Pollution:
The environment is affected by human activities. Discharge of any harmful substance into earth, water or air which may
change their natural composition is called pollution.

Definition and types of environmental pollution:

Such changes in physical, chemical and biological state of the environment, which may harm the human beings, animals, plants and our cultural heritage, is called environmental pollution. Environmental pollution is classified into following types:
- Air pollution
- Water Pollution
- Soil pollution
- Noise pollution

Air pollution:
Atmosphere: The invisible gaseous envelope, which surrounds the earth all around is called atmosphere.

The various components of air are as follows:

Oxygen-20.94%, Nitrogen-78.09%, Carbon dioxide – 0.03%, Inactive gases (neon, helium,krypton,radon and xenon) – 0.92%. In addition to these, air contains water vapour (in variable percentage), methane and hydrogen gases in very less quantity.
Air pollution: Any qualitative and quantitative change in composition of air is called air pollution.

Causes of air pollution are as follows:

Explosion of volcanoes and storms.
Human activities such as cutting of trees and forests.
Industrial wastes (gases and particles).
Smoke and gases emitted by various automobiles like cars, buses, engines, etc. Manufacture of sulfuric acid and fertilizers on large scale, electricity plants and automobiles release sulfur dioxide.

Harmful effects of sulphur dioxide are as follows:

It causes cancer of lungs, cough, asthma, breathlessness and bronchitis.
It causes decaying of leaf tissues (necrosis), in plants. The crops of cotton, wheat, barley and apple are very sensitive to sulphur dioxide.
It is harmful for paper, clothes and marble.
Smog is produced in low temperature areas, due to sulphur dioxide. It causes troubles for the living beings.
Sulphur dioxide causes irritation and burning sensation in eyes and throat.
Acid Rain: Oxides of nitrogen and sulphur present in the atmosphere are oxidized by oxygen or ozone, and react with water vapors present in the atmosphere to produce acids.
NO + O₃→ NO₂ + O₂
NO₂+ O₃ → NO₃ + O₂
NO₂ + NO₃→ N₂O₅N₂O₅+ H₂O →2HNO₃ (Nitric acid)
2SO₂ + O₂ + 2H₂O → 2H₂SO₄ (Sulphuric acid)
The acidic substances, thus formed fall on the earth along with rain drops, which is known as acid rain.

Harmful effects of acid rain:

Acid rain damage buildings, statues etc., made of marble, lime-stone, slates, etc., due to erosion.
Bridges and other such structures are weakened by the acid rain, so there is risk of their giving way, any time.
Acid rain can kill the fishes and other small creatures living in lakes, ponds etc.
Acid rain increases the acidity of the soil, so production of crops is affected adversely.
Heavy metals like cadmium, zinc copper, nickel, etc., from minerals react with acid rain-water to form soluble salts. These salts flow with rain water into lakes and rivers and pollute the water. However, this process is useful and important for the plants, as it provides fertilizers to the soil, by fixing atmospheric nitrogen.

Small particles of matter which are present in air are called particulate matter. These small particles are produced due to some natural events and human activities, e.g.

Particulate matter is given out in large quantity, in volcanic eruptions.
Particles are produced in the form of smoke, on burning coal, wood, oil or any organic matter, and by automobile vehicles.
Industrial activities like mining, grinding of minerals and cutting or crushing of stones etc. produce particulates.
Fly ash is given out in large quantity from thermal energy plants and other industrial furnaces.
Fiber particles are given out in cloth industries.
Particles of dust, lime, cement, etc. mix in air, where construction work of roads, bridges, buildings, dams, etc., is going on.

Harmful effects:
The particulate matter in air causes harm to the respiratory system and gives rise to diseases, like asthma, bronchites and cancer. People working in coal mines suffer from black lung disease. Silica or coal dust gets deposited in their lungs, causing bronchitis, harm to nervous system and also damage metals, clothes, paper and leather.

Automobile Exhaust:
Different kinds of motor vehicles (scooter, car, bus, tractors, auto rickshaws, etc.) use petrol or diesel as fuel, which on combustion release carbon monoxide, hydrocarbons, oxides of nitrogen, suspended particulate matter and lead compounds in the air. In addition to these, aldehyde and compounds of sulphur are also discharged in small quantity by motor vehicles.

Main effects of pollution from motor vehicles:

People suffer from asthma, cough and breathing troubles. ‘
Hydrocarbons and suspended particulate matter cause cancer.

Measures to reduce pollution:
Improvement in design of engine, use of good fuel (L.P.G or C.N.G ) and suitable care can reduce air pollution.

Effects of Carbon Monoxide and Possible care:

Carbon monoxide is produced by the incomplete combustion of fossil fuels, such as coal, petrol, kerosene, coke, etc., Carbon monoxide is a colorless and non-irritant gas, but is highly toxic (poisonous). When carbon monoxide is inhaled it combines with hemoglobin and forms carboxy-hemoglobin, so it blocks the normal transport of oxygen in the body. The deficiency of oxygen in blood causes headache, paralysis, dizziness, cardiac failure, suffocation and even death in human beings.
Many persons die every year, due to carbon monoxide. Charcoal braziers should not be used in closed rooms, otherwise due to incomplete combustion of fuel, carbon monoxide poisoning will take place.
It harms respiratory system.
If air contains even 0.1% of carbon monoxide, it causes headache and nausea, within one hour .If air contains 1 % carbon monoxide, it causes-unconsciousness in 5 minutes and death within 10 minutes.
Smoking bidi and cigarettes produces carbon monoxide gas, due to incomplete combustion of dried leaves of tobacco. This causes cancer of mouth, throat, lungs and kidney.

Water Pollution:

Water is an inexhaustible natural resources. The main sources of water are rivers, lakes, ponds and snow covered
mountains.
Water pollution is undesirable change in the physical, biological or chemical quality of water, due to addition of unwanted and harmful substances. Water pollution adversely affects living organisms by making water unsuitable for us.

Causes of water pollution:

Water dissolves the fertilizers and pesticides from agricultural fields and take them to the nearby water bodies, where it causes harmful to aquatic life.
Dumping of sewage and other wastes into water bodies, adversely affect the water quality.
Industries use water for cooling various machines and later releases hot water into water bodies. This causes sudden changes in the temperature of water, that affects the breeding of aquatic organisms.

Sewage:
Sewerage is a fluid waste containing human excreta, waste water from kitchen and bath¬rooms, dust and garbage swept from houses and streets. Sewerage is discharged into ponds, lakes or rivers around the cities, due to which water is polluted. As the amount of organic wastes increase in water, bacteria and other organisms multiply very fast, by using the dissolved oxygen present in the water thus, making it deficient in oxygen. This lack of oxygen, in turn kills the fishes and other aquatic animals.

Biological Oxygen Demand:
Biological oxygen demand indicates the quality of waste water. BOD refers to the amount of dissolved oxygen needed by bacteria in decomposing the organic waste present in water. It is expressed in milligrams of oxygen per liter of water.

Water Pollution by Industrial Effluents:

All the industries use water in large quantity for different processes. After the process waste water is released into nearby water bodies. Effluents contain metal particles, oil, grease, plastics, phenol, toxins, etc.
Many of these are not decomposed and pollute the water. Some metals like copper, chromium, zinc, cadmium, lead, mercury, etc. are toxic and affect the health adversely. Animals like cow, buffalo, dog, pig, etc., enter into water bodies and pollute the water. Humans wash clothes and clean utensils in the pond or river water. Even dead bodies are thrown in rivers. This causes water pollution.

Insecticides and Pesticides:
Pesticides and other chemicals used in the crop fields enter the water sources due to rain, e.g. DDT. These enter the food chain and keep on accumulating at each tropic level, as these chemicals cannot be decomposed. This increase in concentration of toxicants with an increase in the tropic level, is called biological magnification.

Effect of polluted water:

The germs present in polluted water cause several bacterial diseases, such as typhoid, cholera, paratyphoid, etc., when polluted water is drunk. Virus present in polluted water can cause polio, jaundice and infectious hepatitis. Parasites like round and tapeworm enter our bodies through the medium of polluted water.
Effect of external contact with polluted water: Bathing in polluted water of ponds and rivers is also dangerous, because parasites enter the body through skin and cause diseases.

Noise Pollution:
Sound which is not pleasant for the ears and is not necessary or desired at the place at that time unwanted noise, that causes sound pollution or noise pollution e.g., the sound of loud speaker in daytime seem to be normal, but the sound of a loud speaker at midnight is felt as troublesome and is considered to be sound pollution.

Measurement of sound pollution:
The unit of measurement of intensity of various sound is mentioned in following table.

Intensity of various Sound:

Source of sound	Sound Intensity
1. Breathing 2. Ticking of wrist watch 3. Normal conversion 4. Noise created in office 5. Truck moving on road (50 feet away) 6. Shouts 7. Noise produced by motor cycle 8. Sound of sirens	10 dB 20 dB 35 to 60 dB 60 dB to 80 dB 90 dB 100 dB 105 dB 105 dB to 160 dB

Effect of noise pollution:
A man can tolerate a sound up to 80 dB easily. Effects of high intensity of sound on human health are mentioned in the table given below:
Effects of noise pollution on human health:

S.No. Sound intensity	Effect on Human Health
1. 80 dB	Causes frustration
2. 80 dB	Decreases hearing power
3. 90 dB	Excitement & frustration
4. 110 dB	Irritation of skin
5. 120 dB	Becomes agonizing
6. 130 to 135 dB	Vomiting and vertigo
7. 140 dB	Pain in ears, mental imbalance
8. 150 dB	Burning sensation of skin
9. 160 dB	Continuous noise, damage eardrums
10. 180 dB to 190 dB	Heavy loss to ears and to other parts organs of human body, in very short time.

Audiological effects: Man can bear a sound of maximum 80 dB. Ear feels uneasy and tiresome in the noise of 90 dB. Living amidst the sound of 100 dB makes a man deaf. If the intensity of sound is very much, the ear drum may burst and the person may become permanently deaf.
Physiological effects: Sound pollution produces harmful effects on eye, head, respiratory system and brain. Headache, diseases of intestines, irritation in skin, nausea and vertigo are caused, due to sound pollution.
Psychological effects: Sound pollution causes mental tension, anger, emotional and behavioral stress. Sound pollution may also cause quarrels among the affected people.
- Other effects:
  Noise or sound in surroundings interferes in the speech and conversation with one another,
  Noise interferes in peaceful study and in sleep,
  Sound or noise causes loss of memory and fatigue, (iv) The working efficiency of a person goes down.

Soil Pollution:

Due to the increasing rate of population, the requirement of food is also increasing and thus large areas of land are cultivated to get the higher yield, artificial fertilizers are used, which can pollute the soil. Moreover, when the yield is more, insecticides and pesticides are used to protect the crop, which also in their turn, causes soil pollution. The fertilizers, insecticides, pesticides, etc., reduce the productivity of the soil in due course of time.
The soil is made of solids, liquids and gases. It forms the upper most layer of earth’s surface. For plants growth, soil is very essential because the roots anchor to the soil and transfer nutrients and water to stem and leaves. By soil pollution, the life of burrowing animals, e.g., earthworms, insects, snakes, rats, etc., is also adversely affected. Soil is an exhaustible and non-renewable resource. It takes several years to renew the soil.

Sources of Soil Pollution:

Acid rain water and water from mines are main sources of soil pollution.
Mixing of debris, waste products with the soil causes soil pollution.
By excessive use of pesticides and fertilizers, the soil is polluted.
When industrial wastes are discharged in the soil, they also pollute the soil.
Insecticides like D.D.T is very dangerous substance. When these enter the body of consumers from producers, their concentration is increased because these are non-degradable substances. Moreover, these can remain in the atmosphere for up to 15 years.

Effects of Soil Pollution:

Waste dumps
- Industrial solid waste and sludge toxic to both plants and animals.
- Industrial emissions pollute the surrounding land, come back to earth sooner or later and pollute the soil.
- Nuclear plants and nuclear testing laboratories contaminate soil with radio active materials, that remain in the soil for very long periods, as they have long half-life.
Municipal wastes
- Municipal wastes, including domestic and kitchen wastes, market wastes, livestock and poultry wastes, waste metals, etc. Damage the landscape, create foul smell and destroy natural beauty. Present in the soil for very long periods. With time, affect flora and fauna.
Agrochemicals
- Pet and weed control agricultural systems. Contaminate the soil and cause death of micro-organisms; animals and certain plants. Contaminate the surface and ground water resources. Change chemical properties of soil and have damaging effects of soil organisms.
Mining operation
- Opencast mining, a process where the surface of the earth is dug open, to extract out the underground mineral deposits. Completely damage the land and pollute the top soil and contaminate the area with toxic metals and chemicals.

Management of Pollution:

There is a need to protect or improve the environment thus create ecological balance.
The various steps that can be taken in order to protect the environment are:
To prepare plans for conservation of environment and to get them implemented, in all parts of the country.
To organise and carry on discoveries and research works in the field of environmental studies.
To get prepared books, code of conduct and directories relating to environment and to publish the same.
To decide the norms of the characteristics of good environmental conditions.
To fix the limits of pollutants discharged in the environment.
To take proper safety measures, to check accidents or mishaps, due to environmental pollution and to take steps for remedy and relief, in case some accident happens.
To decide the locations where industries can be established .
To inspect industrial procedures, products and other substances which may be the cause of pollution and to restrict the same by law.

Light and Radiation:
Light is essential for living organisms. Many plant physiological processes, like transpiration, photosynthesis, plant growth, respiration, absorption and plant hormones are depended on light. Light plays an important role in species composition. Visible spectrum is a part of radiant energy which can be visible. The radiation comes to earth are of 300 nm to 1000 nm of wave-length, in which only 390 nm to 760 nm is visible, known as visible light. When light is passed through prism it is dispersed into its different colors.

Spectrum of sun contains seven colors, namely, Violet, Indigo, Blue, Green, Yellow, Orange, Red. Violet color rays are deviated the most and red color rays are deviated the least. Deviation of Yellow color is the mean between red and violet. There are invisible parts of spectrum also beyond the red and violet regions, known as infra-red and ultra violet region, respectively.

Manure and Fertiliser:

Food is material substance that provides a living organism, energy for body functions and materials for growth, repair, development and health. It provides the body with proteins, carbohydrates, fats, vitamins and minerals. Human beings obtain food from both plants and animals. Food yielding plants and animals are reared by human beings, under their own supervision. The two specialized field are agriculture and animal husbandry.
India is very populous country. More than one billion people, and it is still growing. We will soon need more than a quarter of a billion tonnes of grains every year. We do not have any major scope for increasing the area of land under cultivation. Therefore, it is necessary to increase our production efficiency, of both crops and livestock.
Nutrient management: 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, while soil supplies the other thirteen nutrients to plants. Amongst these thirteen nutrients, six are required in large quantities and are called macro-nutrients. Other seven nutrients are used by plants in small quantities and are called micro-nutrients.
- Plant nutrients are of two types –
  Macro nutrients, i.e., nitrogen, phosphorus, potassium, calcium, magnesium and sulphur;
  Micro nutrients, which are iron, manganese, boron, zinc, copper, molybdenum and chlorine.
These are used in a very small quantities, but essential for plant growth. Nitrogen, phosphorus and potassium are primary plant nutrients. Plants get them from soil.
Manures are natural bulky organic matter, e.g., farmyard manure, compost, green manure and vermicompost. Manures restore the soil texture, for water retention and soil aeration. Manures provide food for soil organisms, like bacteria and fungi. They decompose organic matter and provide nutrients to plant. FYM is decomposed mixture of cattle’s excreta, roughage or unused fodder. It provides nitrogen, phosphorus and potassium to the crop. Compost is vegetable and animal refuge of town area, like animals, excreta, faecal matter of humans and sewage waste. It is decomposed by micro-organisms. It also contains the same nutrients as FYM.
Green manuring is growing of leguminous and non- leguminous crops in the field, ploughing and mixing with the soil. These are decomposed in the soil by micro-organisms. This is done before rains. Leguminous plants provide nitrogen to the soil.
Fertilisers are chemicals produced by the factories. These are inorganic, e.g. ammonium sulphate and organic like urea. Fertilisers are nitrogenous, phosphatic, potassic and complex like nitrophosphate, ammonium phosphate, urea ammonium phosphate, providing two or more nutrients. Bio fertilisers add nitrogen to the soil. These are cyanobacteria, phosphate solubilising micro organisms, rhisobium, blue-green algae, and mycorrhiza.
Man is using agricultural practices since ancient times. He was fully dependent on natural resources. Over population and over exploitation of natural resources has led to the concern for sustainable agriculture.
The aims of improving seeds are high yield, improved quality, varieties resistant to biotic and abiotic stresses, early and uniform maturity, wider adaptability, etc.
The improved varieties of some important crops are:
Cereal crops:
- Wheat – HD 2285, C- 306, HD 2687, Sonara, HW 157, etc.
- Rice – IR 36, Pusabasmati, Navjot, Ganga 5, etc.
Pulse crops:
- Chicken pea – Pusa 240, Pant 114, H 208 etc.
- Pigeon pea – UPAS 120, Pusa ageti, etc..
- Urad bean – Pant 430, PSI, T 9, etc.
- Moong bean – S 8, T44, K 851, etc.
Oil seed crops:
- Mustard- Kranti, Pusa agarni, RH 30, etc.
- Soyabean – P K 327, Pusa 24, Durga, PK 262, etc.
- Sunflower – BS H 1 , Morden, Paras, etc.
- Ground nut – ICG 81, M 37, TMV 12, etc.

Variety of crops: Improvement of crop yields:
The major groups of activities for improving crop yields can be classified as:

Crop variety improvement,
Crop production improvement,
Crop protection management

Crop variety improvement: Varieties or strains of crops can be selected by breeding for various useful characteristics such as disease resistance, response to fertilizers, product quality and high yields. Hybridization refers to crossing
between genetically dissimilar plants. Another way of improving the crop is by introducing a gene that would provide the
desired characteristics.

Some of the factors for which variety improvement is done are:

Higher yield
Biotic and abiotic resistance
Improved quality
Desirable agronomic characteristics
Wider adaptability
Change in maturity duration

Crop production management: It is the money or financial conditions that allow farmers to take up different farming practices and agricultural technologies. Therefore, production practices can be at different levels like “No cost’ production, ‘low cost’ production and ‘high cost’ production practices.

Crop Pattern:

Cropping patterns: Different ways of growing crops can be used to give maximum benefit.
Mixed Cropping: Practice of growing two or more crops together at the same time, such as pulses with maize; jowar and bajra; sorghum + pigeon pea and ground nut + sun flower. Factors for mixed cropping are separate nutritional demands for both crops, different water requirement, different duration of maturity, different types of root growth and different size of both the crops.
Advantages of mixed cropping: No crop failure, improvement of soil fertility, crop yield increases, increased variety of the product, and reduced just damage.
Inter cropping: In inter cropping, two or more crops are grown together, either mixed or in separate rows.
Multiple cropping: Harvesting of more than two crops in a field, in one year.
Crop protection is to protect the crop from pests, i.e. fungi, insects, bacteria, worms, viruses, rodents, etc., Insects are killed by insecticides, fungi are destroyed by fungicides. Chemicals used to kilf pests are called pesticides. Pesticides are either sprayed, dusted over crops, or mixed with seeds and soil.

Few preventive measures for the crops:

Resistant varieties of crop plants, crop rotation, multiple cropping and summer ploughing are used.
Contact insecticides are malathion, lindane and thiodon. They are sprayed on stem and leaf cutting and boring insects.
Systemic insecticides are dimethoate and metasystox. These are also sprayed. These are absorbed by the plants. When sap sucking insects feed on plants, they are killed.
Sucking insecticides are aphids, pyrilla, plant bugs, like red cotton bug. Plant borers are sugarcane borers, chick pea, pod borers, cotton boll weevil and grain weevil.
Weeds are small size unwanted plants, growing along with cultivated crop in the field. They supress the growth of crop plants and use nutrients of the soil. For example, motha, jangli jowar, chaulai, sathi, jangli jar, bathua and hirankhuri. Chemicals used for destroying weeds are 2, 4- Dichlorophenoxy acetic acid, atrazine, fluchoralin, etc. Biological control is done by cochineal insects for Opuntia; grass carp for aquatic weeds, etc.
Pests of stored grains are pulse beetle damage grams, rice weevil damage rice, wheat weevil, grain and flour moth of rice, wheat, maize, etc., rust red flour beetle/rice moth and lesser grain borer. Their adults or larva or both, damage the grains and their flour.
Grains are stored in gunny bags and FCI silos.
For storage of grains, temperature of storage houses should not be more than 30°C and moisture content should be 14% or less by weight. More humidity causes the development of fungus. Storage places should be well cleaned, free from cracks or holes in the walls, etc., gunny bags should be well stitched, after filling grains and if needed, the place is fumigated. Spray insecticides over grain-filled gunny bags. Insecticides are gammaxene or benzene hexachloride wettable powder, pyrethrum and malathion.
Fumigants are ethylene dibromide, ethylene dichloride plus carbon tetrachloride, in liquid form; aluminium phosphide in solid state and methyl bromide in gaseous state.

Irrigation:
In India, success of crops in most areas is dependent on timely monsoons and sufficient rainfall. Under such conditions, several different kind of irrigation systems are adopted. These include wells, cannals, rivers and tanks. Fresh initiatives for increasing the water available for agriculture, include rainwater harvesting and watershed management.

Agriculture:

The science of cultivating land, to raise crops is called agriculture. Sustainable agriculture means successful management of resources for agriculture, to satisfy the changing human needs, while maintaining or enhancing the quality of environment and conserving natural resources. Due to steady increase of human population, it is necessary to increase the crops production, that can be achieved by efficient management of natural resources such as soil, water, forest, fertilizers, pesticides, etc.
Measures of increasing productivity are use of seeds of high yielding varieties and modern techniques of farming, such as mixed farming, mixed cropping, crop rotation and breeding and selection of new varieties of seeds.
The system of farming, soil management and manuring practices, etc., influence the productivity of soils and crop yields, obtained from them. The production of larger yields through improved varieties of crops and intensive cultivation will increase the depletion of nutrients, still further. To supplement the natural nutrients and for improving the productive capacity of the soils, some methods are:
Add organic matter to the soil, whose decay furnish a continuous supply of nutrients for crops.
Restore or increase the amount of deficient nutrients, by the application of fertilizers. The urgent need of the constantly expanding agricultural production and to meet the requirements of the continually increasing human and cattle population in India, it is necessary to supply additional plant nutrients through fertilizers and organic manures.

Weeds:

Weeds are those undesirable plants which also grow along with the cultivated crops in the field. Sometime, when another crop plant grows a long with any crop it is called as weed. These weeds adversely affect the growth of crop plants, because they also consume nutrition, water and manure and take sunlight for photosynthesis. This causes the decrease in the growth of crop plants. Thus, presence of weeds in agricultural land is harmful. The weeds that grow in rice and wheat fields are:
- Amaranthus (chulai)
- Chenopodium (Bathua)
- Convolvulus (hirartkhuri)
- Wild oat (Jangli jaoiu) and
- Grasses (ghass).
Weeds reduce production of main crops, reduces the land price, quality and quantity of product reduced. Death among weed grazing animals, as well as allergy, irritation and poisoning in human beings can also occur.

Plant Disease:

Disease caused by viruses, bacteria, and fungi harm crops. The main factors which damage crops are:
- Viral disease in plants,
- Bacterial disease of plant,
- Fungal diseases of plants.
A number of insects are serious pests of crop plants. They do harm the plants at all stages, all parts and products of plants. They causes heavy economic loss to the farmers. Some insects destroy all sorts of crop plants by cutting plants, by their chewing mouth parts, e.g., locusts, grasshoppers, caterpillar larva, etc. Some insects suck the cell sap and some are internal feeders and live inside the parts of crop plants.
Different types of insects, pets can be controlled by mixing insecticides in soil or by spraying or dusting. The contact insecticides being sprayed are dimethoate, metasystox, etc.

Animal Husbandary:

Animal husbandry deals with the breeding, feeding, rearing, shelter and caring of domestic and meat and egg giving animals, etc. The objective of animal husbandry is to improve cattle and live stock breeds, to get higher yield, of meat, milk, eggs, wool, etc.
Improved Indian breeds of cows are Red Sindhi and Tharparkar of Andhra Pradesh, Gir of Gujrat, Sahiwal of Punjab and Harayana, etc.
Exotic breeds are imported breeds brought from european countries. These are high milk yielding cows, e.g. Swiss, Jersey, Holstein and Friesian.
Improved cow- breeds developed by NDRI, Karnal are Karan Swiss, Karan Friesian and Frieswall.
Buffalo breeds are Murrah of Punjab and Haryana, important and Surti of Gujrat.
Sheeps are reared for milk, meat, wool and hide. Their important breeds are Gaddi and Rampuri of Himalayan region, Bikaneri, Marwari and Deccani.
Goat’s important breeds are Kashmiri, Gaddi and Surti.

Poultry:

Poultry breeds are white leghorn, Minorcha and Rhode Island red. They lay about 200 to 300 eggs per year.
Desi or indigenous breeds like Brahma, Chittagong, Aseel Basara, etc., lay only 60 to 75 eggs per year. Their eggs are smaller in size. But these are good sitters.
Improved poultry cross breeds are B-77, HH 266 and ILS – 80.

Apiculture:

Bee-keeping: Bee-keeping for making honey has become an agricultural enterprise. In addition to honey, the beehives
are a source of wax, which is used in various medicinal preparations. The Italian bees have high honey collection capacity.
Honey consists of 20 – 40% sugar, 60 – 80% moisture, 0.22 – 0.3 minerals, 0.2 – 0.5% vitamins, enzymes and pollen grains.
Honey, bee wax, royal jelly and bee venom are products obtained from bee keeping.
Apis mellifera, an exotic variety is domesticated in India, to increase the yield of honey.
Queen is the ‘mother of the colony’, which lays about 2000 eggs in a day.
Drone are smaller, but stouter than the queen. They are males of the colony.
Workers are the most active members of the colony. They are female by instinct, but they are sterile.
To obtain good quality and high yield of honey, bee-hive should be developed near pasturage.
The selected honey bees should show less of swarming. They should be .protected from diseases and pests.

Fishery:

Fish farming is called pisciculture. Fish is good source of meat. Fish-liver oil is rich in Vitamin A and D and it is an unsaturated oil.
Marine fishes are salmon, sharks, etc.
Fresh water fishes are rohu, catla and mrigal. These are called major carps. Other fishes are wallago, mystus, clarias and singhi.
Artificial fish breeding is done in Indian Veterinary Research Institute, Izatnagar, Bareilly.
Fresh water fishes are cultured in hatcheries, bunds, rivers, ponds, etc.