Institutional Factors of Agriculture (1) Land Tenure and Land Tenancy (ii) Land Holding

Institutional Factors of Agriculture

(1) Land Tenure and Land Tenancy

(ii) Land Holding

LAND REFORMS IN INDIA

The basic objective of land reform is to do social justice with the tillers, land owners, landless labourers, and rural community with the set objective to provide security to the cultivators, to fix a rational rent, the conferment of title to the tiller and to increase the agricultural productivity.The entire concept of land reforms aims at the abolition of intermediaries and bringing the actual cultivator in direct contact with the state.

The scheme of land reforms includes:

  • abolition of intermediaries,and
  • tenancy reforms, i.e. regulation of rent, security of tenure for tenants, and confirmation of ownership on them
  • ceiling on land holdings and distribution of surplus land to landless labourers and small farmers,
  • agrarian reorganization including consolidation of holdings and prevention of subdivision and fragmentation,
  • organisation of co-operative farms, and
  • improvement in the system of land record keeping.

Abolition of Intermediaries

Mahalwari System

Ryotwari System

Tenancy Reforms

Rent Control

Ceiling of Landholdings

Consolidation of Holdings

  • Consolidation of holdings means to bring together in compact block, all the fields of land of a farmer which are well scattered in different parts of the village.
  • Under the scheme, all land in the village is first pooled into one compact block and it is divided into smaller blocks called chaks, and allotted to individual farmer.
  • This is a useful scheme which helped in overcoming the problem of fragmentation of holdings.
  • But unfortunately, the scheme has not been implemented in all the states of the country.
  • There are many hurdles in the implementation of consolidation of holdings in some of the states.

Computerized Land Records

  • The centrally sponsored scheme on computerization of land records was started in 1988-89.
  • At present, the scheme has been implemented in 582 districts out of the 640 districts of the country, leaving those districts where there are no proper land records.

 

WHITE REVOLUTION IN INDIA

WHITE REVOLUTION IN INDIA

 

  • The package programme adopted to increase the production of milk is known as White Revolution in India.
  • The White Revolution in India occurred in 1970, when the National Dairy Development Board (NDDB) was established to organize the dairy development through the co-operative societies.
  • Varghese Kuerin was the father of White Revolution in India.
  • The dairy development programme through co-operative societies was first established in the state of Gujarat.
  • The co-operative societies were most successful in the Anand District of Gujarat. The co-operative societies are owned and managed by the milk producers.
  • These co-operatives apart from financial help also provide consultancy.
  • The increase in milk production has also been termed as Operation Flood.

Objectives

  1. The procurement, transportation, storage of milk at the chilling plants.
  2. Provide cattle feed.
  3. Production of wide varieties of milk products and their marketing management.
  4. Provide superior breeds of cattle (cows and buffaloes), health service, veterinary treatment, and artificial insemination facilities.
  5. Provide extension service.

 

Achievements

  • Some of the important achievements of the White Revolution are as under:
  1. The White Revolution made a sound impact on rural masses and encouraged them to take up dairying as a subsidiary occupation.
  2. India has become the leading producer of milk in the world.
  3. The import of milk and milk production has been reduced substantially.
  4. The small and marginal farmers and the landless labourers have been especially benefitted from the White Revolution.
  5. To ensure the success of Operation Flood Programme, research centres have been set up at Anand, Mehsana, and Palanpur (Banaskantha). Moreover, three regional centres are functioning at Siliguri, Jalandhar, and Erode. Presently, there are metro dairies in 10 metropolitan cities of the country, beside 40 plants with capacity to handle more than one lakh litres of milk.
  6. Livestock Insurance Scheme was approved in February 2006 and in 2006-07 on a pilot basis in 100 selected districts across the country. The scheme aims at protecting the farmers against losses due to untimely 2. In most of the villages the cattle are kept under unhygienic conditions.death of animals.
  7. To improve the quality of livestock, extensive cross breeding has been launched.
  8. For ensuring the maintenance of disease-free status, major health schemes have been initiated.
  9. The government implemented livestock insurance on pilot basis in 2005-06.

 

Problems and Prospects

  1. Collection of milk from the remote areas is expensive, time consuming, and not viable economically.
  2. In most of the villages the cattle are kept under unhygienic conditions.
  3. There are inadequate marketing facilities. The marketing infrastructure needs much improvement.
  4. The breeds of cattle is generally inferior.
  5. The extension service programme is not effective.

 

Plate tectonics

 

The uppermost outer solid and rigid layer of the earth is called crust. Its thickness varies considerably. It is as little as 5 km thick beneath the oceans at some places but under some mountain ranges it extends upto a depth of 700km. Below the crust denser rocks are found, known as mantle crust. This upper part of mantle upto an average depth of 100 km from the surface is solid. This solid mantle plus upper crust form a comparatively rigid block termed as lithosphere. Mantle is partially molten between 100 to 250 km depth. This zone is said to be asthenosphere, also known as Mohr discontinuity, a simplification of Mohorovicic, the name of the seismologist who discovered it.
The lithosphere is broken into several blocks. These blocks are known as plates, which are moving over asthenosphere. There are seven major plates.

 

While the continents do indeed appear to drift, they do so only because they are part of larger plates that float and move horizontally on the upper mantle asthenosphere. The plates behave as rigid bodies with some ability to flex, but deformation occurs mainly along the boundaries between plates.

 

 

 

The plate boundaries can be identified because they are zones along which earthquakes occur.Plate interiors have much fewer earthquakes.

There are three types of plate boundaries:

  1. Divergent Plate boundaries, where plates move away from each other.
  2. Convergent Plate Boundaries, where plates move toward each other.
  3. Transform Plate Boundaries, where plates slide past one another.

Divergent Plate Boundaries

These are oceanic ridges where new oceanic lithosphere is created by upwelling mantle that melts, resulting in basaltic magmas which intrude and erupt at the oceanic ridge to create new oceanic lithosphere and crust. As new oceanic lithosphere is created, it is pushed aside in opposite directions. Thus, the age of the oceanic crust becomes progressively older in both directions away from the ridge.

Because oceanic lithosphere may get subducted, the age of the ocean basins is relatively young. The oldest oceanic crust occurs farthest away from a ridge. In the Atlantic Ocean, the oldest oceanic crust occurs next to the North American and African continents and is about 160 million years old (Jurassic)

. In the Pacific Ocean, the oldest crust is also Jurassic in age, and occurs off the coast of Japan.

Because the oceanic ridges are areas of young crust, there is very little sediment accumulation on the ridges. Sediment thickness increases in both directions away of the ridge, and is thickest where the oceanic crust is the oldest. Knowing the age of the crust and the distance from the ridge, the relative velocity of the plates can be determined.

Relative plate velocities vary both for individual plates and for different plates.

Sea floor topography is controlled by the age of the oceanic lithosphere and the rate of spreading.

If the spreading rate (relative velocity) is high, magma must be rising rapidly and the lithosphere is relatively hot beneath the ridge. Thus for fast spreading centers the ridge stands at higher elevations than for slow spreading centers. The rift valley at fast spreading centers is narrower than at slow spreading centers. As oceanic lithosphere moves away from the ridge, it cools and sinks deeper into the asthenosphere. Thus, the depth to the sea floor increases with increasing age away from the ridge.

 

Convergent Plate Boundaries

When a plate of dense oceanic lithosphere moving in one direction collides with a plate moving in the opposite direction, one of the plates subducts beneath the other. Where this occurs an oceanic trench forms on the sea floor and the sinking plate becomes a subduction zone. The Wadati-Benioff Zone, a zone of earthquakes located along the subduction zone, identifies a subduction zone. The earthquakes may extend down to depths of 700 km before the subducting plate heats up and loses its ability to deform in a brittle fashion.

As the oceanic plate subducts, it begins to heat up causing the release water of water into the overlying mantle asthenosphere. The water reduces the melting temperature and results in the production of magmas. These magmas rise to the surface and create a volcanic arc parallel to the trench. If the subduction occurs beneath oceanic lithosphere, an island arc is produced at the surface (such as the Japanese islands, the Aleutian Islands, the Philippine islands, or the Caribbean islands

Transform Plate Boundaries

Where lithospheric plates slide past one another in a horizontal manner, a transform fault is created. Earthquakes along such transform faults are shallow focus earthquakes.

Most transform faults occur where oceanic ridges are offset on the sea floor. Such offset occurs because spreading takes place on the spherical surface of the Earth, and some parts of a plate must be moving at a higher relative velocity than other parts One of the largest such transform boundaries occurs along the boundary of the North American and Pacific plates and is known as the San Andreas Fault. Here the transform fault cuts through continental lithosphere

Triple Junctions occur at points where thee plates meet.

Hot Spots

Areas where rising plumes of hot mantle reach the surface, usually at locations far removed from plate boundaries are called hot spots. Because plates move relative to the underlying mantle, hot spots beneath oceanic lithosphere produce a chain of volcanoes. A volcano is active while it is over the vicinity of the hot spot, but eventually plate motion results in the volcano moving away from the plume and the volcano becomes extinct and begins to erode.

Because the Pacific Plate is one of the faster moving plates, this type of volcanism produces linear chains of islands and seamounts, such as the

  • Hawaiian – Emperor chain, the Line
  • Islands, the Marshall-Ellice Islands,
  • and the Austral seamount chain

 

Tropical and temperate cyclones

 

 

The atmospheric disturbances which involve a closed circulation about a low pressure centre,
anticlockwise in the northern atmosphere and clockwise in the southern hemisphere are called
cyclones. They fall into the following two broad categories: (a) Extra-tropical or Temperate and (b) tropical cyclones.

(a) Temperate Cyclones
Temperate cyclones are formed along a front in mid-latitudes between 35° and 65° N and S. They blow from west to east and are more pronounced in winter season.Temperate cyclones are mainly observed in Atlantic Ocean and North West Europe . They are generally extensive having a thickness of 9 to 11 kilometers and with 1040-1920 km short and long diametres respectively. Each such cyclone alternates with a high pressure anticyclone. The weather associated with the cyclone is drizzling rain and of cloudy nature for number of days. The anticyclone weather is sunny, calm and of cold waves.
(b) Tropical Cyclones
Tropical cyclones are formed along the zone of confluence of north-east and south-east trade winds. This zone is known as the Inter Tropical Convergence Zone (ITCZ). Cyclones generally occur in Mexico, South-Western and North Pacific Ocean, North Indian Ocean and South Pacific Ocean. These cyclones differ from temperate cyclones in many ways. There are no clear warm and cold
fronts as temperature seldom differs in Inter Tropical Convergence Zone. They do not have well-defined pattern of winds and are energised by convectional currents within them. Generally, these are shallow depressions and the velocity of winds is weak. These are not accompanied by anticyclones. The arrangement of isobars is almost circular. These are not extensive and have the diametres of 160-640km. However, a few of them become very violent and cause destruction in the regions of their influence. They are called hurricanes in the Carribean Sea, typhoons in the China, Japan and phillipines,

 

 

 

 

 

 Evaporation and Condensation: dew, frost, fog, mist and cloud, rainfall types

 Evaporation 

 

Evaporation is the process of which water changes from its liquid state to gaseous form. This process takes place at all places, at all times and at all temperatures except at dew point or when the air is saturated. The rate of evaporation is affected by several factors. Important among them are as under:
(i) Accessibility of water bodies :-The rate of evaporation is higher over the oceans than on the continents.
(ii) Temperature :-when the temperature of an air is high, it is capable of holding more moisture in its body than at a low temperature. It is because of this that the rate of evaporation is more in summers than in winters. That is why wet clothes dry faster in summers than in winters.
(iii) Air moisture :-If the relative humidity of a sample of air is high, it is capable of holding less moisture. On the other hand if the relative humidity is less, it can take more moisture. Hence, the rate of evaporation will be high. Aridity or dryness of the air also increases the rate of evaporation. During rainy days, wet clothes take more time to dry owing to the high percentage of moisture content in the air, than on dry days.
(iv) Wind :-If there is no wind, the air which overlies a water surface will get saturated through evaporation. This evaporation will cease once saturation point is reached. However, if there is wind, it will blow that saturated or nearly saturated air away from the evaporating surface and replace it with air of lower humidity. This allows evaporation to continue as long as the wind keep blowing saturated air away and bring drier air.
(v) Cloud cover :-The cloud cover prevents solar radiation and thus influences the air temperatures at a place. This way, it indirectly controls the process of evaporation.

Condensation

Condensation the process by which water vapor (gas) in the atmosphere turns into water (liquid state). It is the opposite of evaporation. This stage is very important because it is the cloud formation stage. Cool temperatures are essential for condensation to happen, because as long as the temperature in the atmosphere is high, it can hold the water vapor and delay condensation.

When a gas is cooled sufficiently or, in many cases, when the pressure on the gas is increased sufficiently, the forces of attraction between molecules prevent them from moving apart, and the gas condenses to either a liquid or a solid.

  • Example: Water vapor condenses and forms liquid water (sweat) on the outside of a cold glass or can.
  • Example: Liquid carbon dioxide forms at the high pressure inside a CO2 fire extinguisher.

The temperature of the air falls in two ways. Firstly, cooling occurs around very small particles of freely floating air when it comes in contact with some colder object. Secondly, loss in air temperature takes place on a massive scale due to rising of air to higher altitudes. The condensation takes place around the smoke, salt and dust particles which attract water vapour to condense around them. They are called hygroscopic nuclei. When the relative humidity of an air is high, a slight cooling is required to bring the temperature down below dew point. But when the relative humidity is low and the temperature of the air is high, a lot of cooling of the air will be necessary to bring the temperature down below dew point. Thus, condensation is directly related to the relative humidity and the rate of cooling.

here are four types of condensation and the worst period for such problems is September to May:-

  1. Surface condensation. This is the most familiar type of condensation, taking the form of water on window panes, cold wall surfaces and tiles.
  2. Interstitial condensation. This is condensation forming between walls or within the building structure.
  3. Reverse condensation. This is also called “Summer condensation”. If rains drenches a wall and strong sunlight then dries it, the heat can actually force water vapour into the wall. When it then meets an insulated surface, it forms condensation at that barrier.
  4. Radiation condensation. This is sometimes called “clear night condensation“. If there is a sudden temperature drop at night, it can cause condensation on the underside of roof coverings, for example: often this drips onto the insulation quilting and causes a distinctive mottled effect upon the quilting.

 

Dew, Frost, Fog, Mist and Cloud

Dew: When the atmospheric moisture is condensed and deposited in the form of water droplets on cooler surface of solid objects such as grass blades, leaves of plants and trees and stones, it is termed as dew. Condensation in dew form occurs when there is clear sky, little or no wind, high relative humidity and cold long nights. These conditions lead to greater terrestrial radiation and the solid objects become cold enough to bring the temperature of air down below dew point. In this process the extra moisture of the air gets deposited on these objects. Dew is formed when dew point is above freezing point. Dew formation can be seen if the water is poured into a glass from the bottle kept in a refrigerator. The outer cold surface of the glass brings the temperature of the air in contact with the surface down below dew point and extra moisture gets deposited on the outer wall of the glass.
Frost: When the dew point is below freezing point, under above mentioned conditions, the condensation of extra moisture takes place in the form of very minute particles of ice crystals. It is called frost. In this process, the air moisture condenses directly in the form of tiny crystal of ice. This form of condensation is disastrous for standing crops such as potato, peas, pulses, grams, etc. It also creates problems for road transport system.
Mist and Fog: When condensation takes place in the air near the earth’s surface in the form of tiny droplets of water hanging and floating in the air, it is called mist. In mist the visibility is more than one kilometer and less than two kilometers. But when the visibility is reduced to less than one kilometer, it is called fog. Ideal conditions for the formation of mist and fog are clear sky, calm and cold winter nights.
Cloud: Clouds are visible aggregates of water droplets, ice particles, or a mixture of both along with varying amounts of dust particles. A typical cloud contains billions of droplets having diameters on the or- der 060.01 to 0.02 mm; yet liquid or solid water accounts for less than 10 parts per million of the cloud volume. Clouds are generally classified on the basis of their general form or appearance and alti- tude.

Rainfall types.

Precipitation or Rainfall is defined as water in liquid or solid forms falling to the earth. It happens when continuous condensation in the body of air helps the water droplets or ice crystals to grow in size and weight that the air cannot hold them and as a result these starts falling on the ground under the force of gravity.

Different types of Rainfall are:-

  • Convectional Rainfall :-Excessive heating of the earth’s surface in tropical region results in the vertical air currents. These currents, lift the warm moist air to higher strata of atmosphere. When-the temperature of such a humid air starts falling below dew point continuously, clouds are formed. These clouds cause heavy rainfall which is associated with lightning and thunder. This type of rainfall is called conventional rainfall. It is very common in equatorial region where it is a daily phenomenon in the afternoon
    (b) Orographic or Relief Rainfall :-Orographic rainfall on formed where air rises and cools because of a topographic barrier. When their temperature fall below dew point, clouds are formed. These clouds cause widespread rain on the windward slopes of the mountain range. This type of rain is called orographic rainfall. However when these winds cross over the mountain range and descend along the leeward slopes, they get warm and cause little rain. Region lying on the leeward side of the mountain receiving little rain is called rainshadow area (see figure 12.4). A famous example of orographic rainfall is Cherrapunji on the southern margin of the Khasi Hills in Meghalaya India.
    (c) Convergence or Cyclonic Rainfall:-Convergence rainfall, produced where air currents converge and rise. In tropical regions where opposing air currents have comparable temperatures, the lifting is more or less vertical and is usually accompanied by con- vention. Convectioned activity frequently occurs along fronts where the temperature of the air masses concerned are quite different. Mixing of air along the front also probably contributes to condensation and therefore to the frontal rainfall. When two large air masses of different densities and temperature meet, the warmer moist air mass is lifted above the colder one. When this happens, the rising warm air mass condenses to form clouds which cause extensive down pour. This rainfall is associated with thunder and lightning. ‘This type of rainfall is also called frontal rainfall. This type of rainfall is associated with both warm and cold fronts, (fig. 12.5) It is gener- ally steady and may persist for a whole day or even longer.

 

 

SECOND GREEN REVOLUTION

SECOND GREEN REVOLUTION

The main objectives of the second Green Revolution are:

(i) To raise agricultural productivity to promote food security

(ii) More emphasis on bio-technology

(iii) To promote sustainable agriculture

(iv) To become self-sufficient in staple food, pulses, oil seeds, and industrial raw material

(v) To increase the per capita income of the farmers and to raise their standard of living.

 

Green Revolution in India

Green Revolution in India

  • A term coined to describe the emergence and diffusion of new seeds of cereals.
  • Norman-e-Borlaug is the Father of Green Revolution in the world, while Dr. M.S. Swami Nathan is known as the Father of Green Revolution in India.
  • The new cereals were the product of research work and concentrated plant breeding with the objective of creating High Yielding Varieties (HYVs) of use to the developing countries.
  • New varieties of wheat were first bred in Mexico in the 1950s and that of rice, like IR-8 (miracle rice) at the International Rice Research Institute, Manila, (Philippines in the 1960s).
  • The increase in the yield from the new seeds has been spectacular as during the last forty years, agricultural production, particularly of wheat and rice, has experienced a great spurt and this has been designated as the Green Revolution.
  • The Green Revolution has been used to mean two different things. Some experts of agriculture use it for referring to a broad transformation of agricultural sector in the developing countries to reduce food shortages.
  • Others use it when referring to the specific plant improvements, notably the development of HYVs.
  • Whatsoever the meaning of Green Revolution may be taken as, the adoption and diffusion of new seeds of wheat and rice has been considered as a significant achievement as it offered great optimism.
  • In fact, these varieties of seeds have revolutionised the agricultural landscape of the developing countries and the problem of food shortage has been reduced.
  • In India, hybridisation of selected crops, i.e. maize, bajra (bulrush millets), and millets began in 1960.
  • The Mexican dwarf varieties of wheat were tried out on a selected scale in 1963-64. Exotic varieties of rice such as Taichung Native I were introduced in India in 1964.
  • The diffusion of HYVs, however, became fully operational in the country in the Kharif season of 1965-66.
  • The diffusion of the new seeds was mainly in the Satluj-Ganga Plains and the Kaveri Delta.
  • Subsequently, a number of varieties of wheat and rice were developed by the Indian scientists and adopted by the Indian farmers.

 

Merits of the High Yielding Varieties

The High Yielding Varieties have certain advantages over the traditional varieties of cereals which are given as under:

 

  1. Shorter Life Cycle
  2. Economize on Irrigation Water
  3. Generate more Employment

Geographical Constraints in the Adoption of New Seeds

The new seeds are less resistant to droughts and floods and need an efficient management of water, chemical fertilisers, insecticides and pesticides.

The conditions required for the good harvest of new seeds have been described below:

 

  1. Irrigation
  2. Availability of Chemical Fertilisers
  3. Plant Protection Chemicals
    • The new seeds are very delicate and highly susceptible to pests and diseases.
    • The danger of pests and insects may be reduced by using plant protection chemicals.

 

  • The problems of crop disease and pests may also be tackled by timely application of insecticides and pesticides

 

  1. Capital Constraint
  1. Mechanization
  1. Marketing and Storage Facilities
  1. Extension Service
  1. Human Factor

Environmental and Ecological Implications of Green Revolution

Some of the environmental and ecological problems that emerged out of the cultivation of the High Yielding Varieties are depletion of forests, reduction in pastures, salination, water-logging, depletion of underground water-table, soil erosion, change in the soil chemistry, reduction in bio-diversity, decline in soil fertility, silting of rivers, increase in weeds, emergence of numerous new plant diseases, and health hazards.

 

An overview of these environmental and ecological problems has been given here.

  1. Salination

 The saline and alkaline affected tracts, locally known as kallar or thur in Punjab and kallar or reh in Uttar Pradesh have expanded and increased in area.The problem of salinity and alkalinity can be solved by use of manure (cow dung, compost, and green manure) and by a judicious selection of leguminous crops in the rotation

 

  1. Waterlogging

Water logging is the other major problem associated with over-irrigation.The progressive and ambitious cultivators of the irrigated areas of these districts have changed their cropping patterns and have introduced rice and wheat in place of bajra, pulses, cotton, and fodder.Repeated irrigation of these crops in the summer and winter seasons have resulted into waterlogged condition, especially along the canals.

 

  1. Soil erosion
  2. Pollution:
  3. Lowering of the Underground Water-Table:
  4. Deforestation
  5. Noise Pollution:
  6. Health Hazards:

 

Green Revolution—Achievements, Problems and Prospects

Green Revolution—Achievements

The main achievements of Green Revolution may be summarized as under:

 

  1. The production and productivity of wheat, rice, maize, and bajra has increased substantially.
  2. India has become almost self-sufficient in the matter of staple foods.
  3. The double cropped area has increased; thereby intensification of the Indian agriculture has increased.
  4. In the areas where Green Revolution is a success, the farmers have moved from subsistent to market oriented economy, especially in Punjab, Haryana, western Uttar Pradesh, and the plain districts of Uttarakhand (Hardwar and Udhamsinghnagar).
  5. The adoption of High Yielding Varieties under the Green Revolution has generated more rural and urban employment.
  6. Green Revolution has increased the income of farmers and landless labourers, especially that of the big farmers and the semi-skilled rural workers. Thus Green Revolution has increased rural prosperity.
  7. Green Revolution has created jobs in the areas of biological (seed fertilisers) innovations, and repair of agricultural equipments and machinery.

 

Green Revolution—Problems and Prospects

  1. Depletion of soil owing to the continuous cultivation of soil exhaustive crops like rice and wheat.
  2. Depletion of underground water table due to over-irrigation of more moisture requiring crops like rice and wheat.
  3. Green Revolution has increased the income disparity amongst the farmers.
  4. Green Revolution led to polarization of the rural society. It has created three types of conflicts in the rural community, namely, between large and small farmers, between owner and tenant farmers, between the employers and employees on agricultural farms.
  5. Green Revolution has displaced the agricultural labourers, leading to rural unemployment. The mechanical innovations like tractors have displaced the agricultural labour. 6. Agricultural production in the Green Revolution areas is either stationary or has shown declining trend.
  6. Some valuable agricultural lands have submerged under water (water-logging) or are adversely affected by salinity and alkalinity.
  7. Green Revolution is crop specific. It could not perform well in the case pulses and oil-seeds.
  8. The traditional institution of Jijmani system has broken. Consequently, the barbers, carpenters, iron-smith, and watermen have migrated to the urban areas.
  9. The soil texture, structure, soil chemistry, and soil fertility have changed.
  10. About 60 per cent of agricultural land in the country remains unaffected by Green Revolution.
  11. Green Revolution technologies are scale neutral but not resource neutral.
  12. Punjab feeds the nation but farmers in the state, especially in the Malwa region fall prey to cancer. The take ‘Cancer Train’ to Bikaner for cheap treatment.

 

Interior of earth,

 

Most of the knowledge we have about Earth’s deep interior comes from the fact that seismic waves penetrate the Earth and are recorded on the other side.  Earthquake ray paths and arrival times are more complex than illustrated in the animations, because velocity in the Earth does not simply increase with depth. Velocities generally increase downward, according to Snell’s Law, bending rays away from the vertical between layers on their downward journey; velocity generally decreases upward in layers, so that rays bend toward the vertical as they travel out of the Earth . Snell’s Law also dictates that rays bend abruptly inward at the mantle/outercore boundary (sharp velocity decrease in the liquid) and outward at the outer core/inner core boundary (sharp velocity increase).

Major Points to remember about P S and Love waves

  • P wave or primary wave. This is the fastest kind of seismic wave, and, consequently, the first to ‘arrive’ at a seismic station.
  • The P wave can move through solid rock and fluids, like water or the liquid layers of the earth.
  • P waves are also known as compressional waves.
  • S waveor secondary wave, which is the second wave you feel in an earthquake. An S wave is slower than a P wave and can only move through solid rock, not through any liquid medium.
  • Travelling only through the crust, surface wavesare of a lower frequency than body waves, and are easily distinguished on a seismogram as a result.

 

Earth’s Layers – Earth’s Composition

The Crust of Earth

It is the outermost and the thinnest layer of the earth’s surface, about 8 to 40 km thick. The crust varies greatly in thickness and composition – as small as 5 km thick in some places beneath the oceans, while under some mountain ranges it extends up to 70 km in depth.

The crust is made up of two layers­ an upper lighter layer called the Sial (Silicate + Aluminium) and a lower density layer called Sima (Silicate + Magnesium).The average density of this layer is 3 gm/cc.

The Mantle of Earth

This layer extends up to a depth of 2900 km.

Mantle is made up of 2 parts: Upper Mantle or Asthenosphere (up to about 500 km) and Lower Mantle. Asthenosphere is in a semi­molten plastic state, and it is thought that this enables the lithosphere to move about it. Within the asthenosphere, the velocity of seismic waves is considerably reduced (Called ‘Low Velocity

The line of separation between the mantle and the crust is known as Mohoviricic Discontinuity.

 

The Core of Earth

Beyond a depth of 2900 km lies the core of the earth.The outer core is 2100 km thick and is in molten form due to excessive heat out there. Inner core is 1370 km thick and is in plasticform due to the combined factors of excessive heat and pressure. It is made up of iron and nickel (Nife) and is responsible for earth’s magnetism. This layer has the maximum specific gravity.The temperatures in the earth’s core lie between 2200°c and 2750°c. The line of separation between the mantle and the core is called Gutenberg­Wiechert Discontinuity.

 

 

 

 

DRY FARMING IN INDIA

DRY FARMING IN INDIA

  • The spread in the regions where the average annual rainfall is less than 75 cm.
  • rainfall is scanty and uncertain, where hot and dry conditions prevail.
  • It is not only that the average annual rainfall is low, the variability of rainfall in these areas varies between 25 to 60 per cent.
  • Agriculture belongs to fragile, high risking and low productive agricultural ecosystem.
  • The areas in which more than 75 cm of average annual rainfall is recorded are known as the areas of rain-fed agriculture.
  • In India dry-lands cover about 32 million hectares or about 25 per cent of the total arable land.
  • The dry farming areas cover the greater parts of Rajasthan and Gujarat. Moreover, there are small tracts of dry land farming in Punjab, Haryana, Maharashtra, Andhra Pradesh, Karnataka, Himachal Pradesh, Jammu and Kashmir, harkhand, Orissa, Uttarakhand, Uttar Pradesh, West Bengal and Tamil Nadu.
  • These areas having scanty rainfall and high variability of rainfall are adversely affected by erratic precipitation, frequent droughts, high temperature, and high wind velocity resulting in soil erosion.

 

Significant Features of Dry Farming

  • Moisture conservation is basic to dry farming. In order to achieve this objective, the field is ploughed repeatedly, especially during the rainy season.
  • Sowing of crops in alternate years or fallowing of land after each harvesting of crop. The fallowing of agricultural land helps in the recuperation of soil fertility.
  • Pulverisation of the soil before sowing.
  • Regular hoeing and weeding of the crop. Hoeing is generally done before sun-rise so that the night dew may be mixed into the soil to provide moisture to the crops.
  • Covering of the land with straw to prevent evaporation of the soil moisture and to control soil erosion.
  • Livestock keeping and dairying are also important allied agricultural activities in the dry farming regions.

Crops

  • The main crops grown in the dry farming areas are coarse, grains (maize, millets, bajra), pulses, groundnut, oilseeds and fodder.
  • Though 75 per cent of the total population of dry-farming regions are directly or indirectly dependent on agriculture, their per capita income, and standard of living are significantly low.

 

Main Problems of Dry Farming

The main problems of dry farming agriculture are as under:

  1. Scarcity of precipitation, erratic occurrence of rains leading to famines, droughts, and floods.
  2. The soils, being sandy, lack in humus and organic nutrients.
  3. The dry farming areas are highly vulnerable to soil erosion.
  4. These are low yields per unit area.
  5. In the absence of moisture and irrigation, the use of High Yielding Varieties and new technology is not possible.
  6. Most of the farmers in the dry farming regions being poor are not able to apply the new costly inputs.
  7. These areas are not having the basic irrigation and other infrastructural facilities, like roads, marketing and storage

 

Strategy for Development

  • As stated earlier, agriculture is a highly vulnerable occupation in the scanty rainfall recording areas in which dry farming is practiced.
  • In dry farming areas, water harvesting should be done. The government and other non-government agencies should provide the necessary guidance to the people.
  • Seeds of food crops which are drought resistant should be provided to the farmers at a subsidized rate.
  • Efforts should be made to check soil erosion by adopting soil conservation practices.
  • The farmers should space their crops at a wide gap and there should be regular weeding and hoeing.
  • Seeds of the quick and short duration maturing crops should be developed.
  • Cultivation of crops requiring more moisture should be done in the low lying areas, especially in the lower parts of the catchment.
  • Cotton should be grown only in the areas where rainfall is more dependable or sprinkle irrigation is available.
  • Soil fertility should be enhanced by applying cow dung and compost manures.
  • Repeated tilling of the field is required during the rainy season.
  • Research should be promoted in the dry land farming.

 

Composition, Structure and Stratification of the atmosphere

 

An atmosphere is a layer of gases surrounding a planet or other material body, that is held in place by the gravity of that body. Many of the planets in this solar system have atmospheres, but none that we know of have an atmosphere quite like ours – one that can support life.

The air is a mixture of several gases. The air encompasses the earth from all sides. The air surrounding the Earth is called the atmosphere. The atmosphere is an integral part of our Earth. It is connected with the earth due to the gravitational force of the earth. It helps in stopping the ultra violet rays harmful for the life and maintain the suitable temperature necessary for life. The air is essential for the survival of all forms of life on the earth.

Composition of the atmosphere

 

The atmosphere is made up of different types of gases, water vapors and dust particles. The composition of the atmosphere is not static. It changes according to the time and place.

  • Nitrogen N2  78%
  • Oxygen O2 20.9%
  • Argon Ar 9.34%
  • Carbon dioxide CO2 3.84 %
  • Neon
  • Helium
  • Methane
  • Krypton
  • Hydrogen
  • Nitrous oxide
  • Xenon
  • Ozone

Water vapor is unique in that its concentration varies from 0-4% of the atmosphere depending on where you are and what time of the day it is.  In the cold, dry artic regions water vapor usually accounts for less than 1% of the atmosphere, while in humid, tropical regions water vapor can account for almost 4% of the atmosphere.  Water vapor content is very important in predicting weather.

Greenhouse gases whose percentages vary daily, seasonally, and annually have physical and chemical properties which make them interact with solar radiation and infrared light (heat) given off from the earth to affect the energy balance of the globe.

The atmosphere also change composition with height and can be divided into two layers. The lower layer is called the homosphere and has the composition we talked about earlier. It’s top is approximately the mesopause.

Above the homosphere lies the heterosphere, a layer in which the gases are stratified into four shells. The lowermost shell is dominated by molecular nitrogen (N2); next, a layer of atomic oxygen (O) is encountered, followed by a layer dominated by helium atoms (He), and finally, a layer consisting of hydrogen atoms (H).

Importance of various components of atmosphere are:-

(i) Oxygen is very important for the living beings.
(ii) Carbon dioxide is very useful for the plants.
(iii) Dust particles present in the atmosphere create suitable conditions for the precipitation.
(iv) The amount of water vapour in the atmosphere goes on changing and directly affects the plants and living beings.
(v) Ozone protects all kinds of life on the earth from the harmful ultra violet rays of the sun.

 

Structure  and stratification of the atmosphere

Variations of temperature, pressure and density are much larger in vertical directions than in horizontal. This strong vertical variations result in the atmosphere being stratified in layers that have small horizontal variability compare to the variations in the vertical.

The atmosphere can be divided into five layers according to the diversity of temperature and density.
(a) Troposphere :-It is the lowest layer of the atmosphere. The height of this layer is about 18 kms on the equator and 8 kms on the poles. The main reason of higher height at the equator is due to presence of hot convection currents that push the gases upward.
This is the most important layer of the atmosphere because all kinds of weather changes take place only in this layer. Due to these changes development of living world take place on the earth. The air never remains static in this layer. Therefore this layer is called changing sphere or troposphere.
The environmental temperature decreases with increasing height of atmosphere. It decreases at the rate of 1 C at the height of 165 metre. This is called Normal lapse rate.
The upper limit of the troposphere is called tropopause. This is a transitional zone. In this zone characteristics of both the troposphere and ionosphere are found.

(b) Stratosphere :-This layer lies above the troposphere and spread upto the height of 50 kms from the Earth’s surface. Its average extent 40 kms.
The temperature remains almost the same in the lower part of this layer upto the height of 20 kms. After this the temperature increases slowly with the increase in the height. The temperature increases due to the presence of ozone gas in the upper part of this layer.
Weather related incidents do not take place in this layer. The air blows horizontally here. Therefore this layer is considered ideal for flying of aircrafts.

(c) Mesosphere :-It spreads above the stratosphere upto the height of 80 kms. from the surface of the earth. It’s extent is 30 kms. Temperature goes on decreasing and drops upto – 100 C.

(d) Ionosphere :-The ionosphere lies from about 80-400 km in height and is electrically charged as short wave solar radiation ionizes the gas molecules. The electrical structure of the atmosphere is not uniform and is arranged into three layers, D, E, and F. Since the production of charged particles requires solar radiation, the thickness of each layer, particularly the D and E layers, changes from night to day. The layers weaken and disappear at night and reappear during the day. The F layer is present during both day and night. This change in height of the various electrically charged layers doesn’t effect the weather, but does effect radio signals.

The auroras also take place in the ionosphere since this is the electrically charged layer. The aurora borealis (northern lights) and aurora australis (southern lights) is closely correlated to solar flare activity.

(e) Exosphere:-This is the last layer of the atmosphere located above ionosphere and extends to beyond 400 km above the earth.  Gases are very sparse in this sphere due to the lack of gravitational force. Therefore, the density of air is very less here.

 Global warming

 

  • An increase in the average temperature of Earth’s near surface air and oceans since the mid-20th century
  • 4th assessment report of IPCC: global temperature increased 74+0.18 degree C during the 20th century.
  • Caused by greenhouse gases
    • Water vapour, Co2, Methane, Nitrous Oxide, Ozone, CFCs (in order of abundance)
  • Since the industrial revolution, the burning of fossil fuels has increased the levels of Co2 in the atmosphere from 280 ppm to 390 ppm.

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