The pattern of land-use of a country at any particular time is determined by the physical, economic & institutional framework taken together. In other words, the existing land-use pattern in different regions in India has been evolved as the result of the action & interaction of various factors, such as the physical characteristics of land, the institutional framework, the structure of other resources (capital,labour,etc.) available & the location of the region in relation to other aspects of economic development, e.g. those relating to transport as well as to industry & trade. The present pattern can,therefore, be considered to be in some sort of static harmony & adjustment with the other main characteristics of the economy of the region. In the dynamic context, keeping in view the natural endowments & the recent advances in technology, the overall interests of a country may dictate a certain modification of or a change in the existing land-use pattern of a region. A close study of the present land-use patterns & the trends during recent years will help to suggest the scope for planned shifts in the patterns.
Out of the total geographical area of 328 million hectares, the land-use statistics are available for roughly 306 million hectares, constituting 93 percent of the total. During 1970-71 the latest year for which the land-use data are available, the arable land (the net area sown plus the current & fallow lands) was estimated at 161.3 million hectares or 52.7 percent of the total reporting area. Around 65.9 million hectares or 21.6 percent of the total area was under forests. Land put to non-agricultural uses was estimated at 16.1 million hectares(5.2 percent of the total) & the barren & unculturable land at 30.2 million hectares or 9.9 percent of the reporting area. Permanent pastures & other grazing land were estimated at 13 million hectares(4.2 percent), land under miscellaneous tree crops & groves, not included in the net area sown, at 4.3 million hectares(1.4 percent) & the culturable waste-land at another 15.2 million hectares or 5 percent. These figures add up to 306 million hectares of the reporting area.
The area,for which data on the land-use clasification are available, is known as the 'reporting area'. In areas where the land-use classification figures are based on land records, the reporting area is the area according to village papers or records maintained by the village revenue agency & the data are based on a complete enumeration of all the areas. In some cases, village papers are not maintained; but the estimates of the area under different classes of land are based on the sample survey or other methods to complete the coverage.
The reporting area is the aggregate of the areas based on these two methods. The areas for which no statistics are available are called 'non-reporting area'. The whole of the reporting area is neither completely surveyed cadastrally nor completely covered by complete enumeration of sample surveys. There are still pockets of areas in a few states for which only 'ad-hoc estimates' are prepared. Of the total geographical area, only 80.7 percent is cadastrally surveyed. Of the cadastrally surveyed areas, 91.4 percent has a permanent reporting agency, whereas 8.6 percent has no reporting agency.
Tuesday, December 23, 2008
MEDICINAL PLANTS
India is endowed with a rich wealth of medicinal plants.These plants have made a good contribution to the development of ancient Indian materia medica. One of the earliest treatises on Indian medicine,the Charak Samhita(1000 B.C),records the use of over 340 drugs of vegetable origin. Most of these continue to be gathered from wild plants to meet the demand of the medical profession.Thus, despite the rich heritage of knowledge on the use of plants drugs, little attention had been paid to grow them as field crops in the country till the latter part of the nineteenth century.
During the past seven or eight decades, there has been a rapid extension of the allopathic system of medical treatment in India. It generated a commercial demand for pharmacopoeial drugs and products in the country, Thus efforts were made to introduce many of these drug plants into Indian agriculture, and studies on the cultivation practices were undertaken for those plants which were found suitable and remunerative for commerical cultivation. In general, agronomic practices for growing poppy, isabgol, senna, cinchona, ipecac, belladonna, ergot and a few others have been developed and there is now localized cultivation of these medicinal plants commercially. The average annual foreign trade in crude drugs and their phytochemicals is between 60 and 80 million rupees and this accounts for a little over 0.5 per cent of the world trade in these commodities.
The curative properties of drugs are due to the presence of complex chemical substances of varied composition (present as secondary plants metabolites) in one or more parts of these plants. These plants metabolites in one, according to their composition, are grouped as alkaloids, glycosides, corticosteroids, essential oils, etc. The alkaloids form the largest group, which includes morphine and codein (poppy), strychnine and brucine(nux vomica), quinine(cinchona), ergotamine(ergot), hypocyamine,(beeladona) ,scolapomine(datura), emetine(ipecac), cocaine(coco), ephedrine(ephedra), reserpine(Rauwolfia), caffeine(tea dust), aconitine(aconite), vascine(vasaca). santonin(Aremisia), lobelin(Lobelia) and a large number of others. Glycosides form another important group represented by digoxin(foxglove), stropanthin(strophanthus), glycyrrhizin(liquorice), barbolin (aloe), sennocides (senna),etc. Corticosteroids have come into prominence recently and diosgenin(Dioscorea), solasodin(Solanum sp.),etc. now command a large world demand. Some essential oils such as those of valerian kutch and peppermint also possess medicating properties and are used in pharmaceutical industry. However, it should be stated in all fairness that our knowledge of the genetic and physiological make-up of most of the medicinal plants is poor and we know still less about the biosynthetic pathways leading to the formation of active constituents for which these crops are valued.
During the last two decades, the pharmaceutical industry has made massive investments on pharmacological, clinical and chemical researches all over the world in an effort to discover and still more potent plants drugs ; in fact, a few new drug plants have suceessfully passed the tests of commercial screening. However, benefits of this labour would reach the masses when the corresponding support for agricultural studies for commercial cultivation is provided. Infact, agricultural studies on medicinal plants, by its very nature, demand an equally large investment and higher priority. India, in particular, has a big scope for the development of the pharmaceutical and phytochemical industry.
During the past seven or eight decades, there has been a rapid extension of the allopathic system of medical treatment in India. It generated a commercial demand for pharmacopoeial drugs and products in the country, Thus efforts were made to introduce many of these drug plants into Indian agriculture, and studies on the cultivation practices were undertaken for those plants which were found suitable and remunerative for commerical cultivation. In general, agronomic practices for growing poppy, isabgol, senna, cinchona, ipecac, belladonna, ergot and a few others have been developed and there is now localized cultivation of these medicinal plants commercially. The average annual foreign trade in crude drugs and their phytochemicals is between 60 and 80 million rupees and this accounts for a little over 0.5 per cent of the world trade in these commodities.
The curative properties of drugs are due to the presence of complex chemical substances of varied composition (present as secondary plants metabolites) in one or more parts of these plants. These plants metabolites in one, according to their composition, are grouped as alkaloids, glycosides, corticosteroids, essential oils, etc. The alkaloids form the largest group, which includes morphine and codein (poppy), strychnine and brucine(nux vomica), quinine(cinchona), ergotamine(ergot), hypocyamine,(beeladona) ,scolapomine(datura), emetine(ipecac), cocaine(coco), ephedrine(ephedra), reserpine(Rauwolfia), caffeine(tea dust), aconitine(aconite), vascine(vasaca). santonin(Aremisia), lobelin(Lobelia) and a large number of others. Glycosides form another important group represented by digoxin(foxglove), stropanthin(strophanthus), glycyrrhizin(liquorice), barbolin (aloe), sennocides (senna),etc. Corticosteroids have come into prominence recently and diosgenin(Dioscorea), solasodin(Solanum sp.),etc. now command a large world demand. Some essential oils such as those of valerian kutch and peppermint also possess medicating properties and are used in pharmaceutical industry. However, it should be stated in all fairness that our knowledge of the genetic and physiological make-up of most of the medicinal plants is poor and we know still less about the biosynthetic pathways leading to the formation of active constituents for which these crops are valued.
During the last two decades, the pharmaceutical industry has made massive investments on pharmacological, clinical and chemical researches all over the world in an effort to discover and still more potent plants drugs ; in fact, a few new drug plants have suceessfully passed the tests of commercial screening. However, benefits of this labour would reach the masses when the corresponding support for agricultural studies for commercial cultivation is provided. Infact, agricultural studies on medicinal plants, by its very nature, demand an equally large investment and higher priority. India, in particular, has a big scope for the development of the pharmaceutical and phytochemical industry.
MUSHROOM PRODUCTION
Selection of Strains:
For successful mushroom production, it is necessary for each grower to produce as economically and efficiently as possible the highest quality of mushrooms. This can be accomplished among other requirements, by selecting the best strains which should be high yielding , visually attractive, having desirable flavour, and resistance to adverse climate and pests and diseases. Presently, there are many strains of white, cream and brown varieties in cultivation. The brown variety is the natural mushroom and considered to be the most vigorous form. It tolerates and adverse conditions better than the white variety.
A snow white mushroom first appeared amongst a bed of mushroom in the USA and ever since the variety has dominated the mushroom industry throughout the world, although it has a very high limited shelf-life. Where growing conditions tend to be on the dry side and humidity cannot be correctly controlled the brown mushroom should be grown. New superior strains are through selection, hybridization and induced mutations continually introduced by mushroom research laboratories and spawn makers. In India, S 11, S 649 and S791 are the good strains available. These strains were originally introduced from reowned commercial spawn makers, Somycel and darlington. Now these strains are well adapted in the Indian climate and are very popular with the growers.
Maintenance of Strains:
Three methods are known by which strains can be propagate. these are multispore culture, tissue culture and mycelium transfer. By periodic subculturing of the mycelium on a suitable agar medium, the span strains can be kept for many years in a fairly good state. However, the frequent subculturing of the strain may result in its degeneration. Maintenence of strain by multisporous culture is only possible if new multispore cultures are compared with the original strain before the original multisporous culture would show much genetic variation.
In the tissue culture, small pieces of fruit bodies are cut under sterile conditions and inoculated on a nutrient medium. Mycelium growing out of these tissue can provide the starting point for subsequent spawn production. However, it is commonly observed that tissue cultures often give lower yields than the original cultures. Of these 3 methods, mycelium transfer is most reliable but it is essential that the performance of the mycelium is continually checked in order to detect any degeneration-like slow-growing matted mycelium or fluffy mycelium with abnormal growth rate.
Spawn:
The propogating material used by the mushroom growers for planting beds is called spawn. The spawn is equivalent to vegetative seed of higher plant. Quality of spawn is basic for the successful mushroom cultivation.
At present, the pure culture spawn has been the basis of modern spawn production units all over the world. The manufacture of the pure culture spawn is done under scientifically controlled conditions which demand a standard of hygiene as in a hospital operation theatre. Equipment and substrate used for spawn are autoclaved and filtered air is passed during the inocluation ensures complete freedom from contamination.
For successful mushroom production, it is necessary for each grower to produce as economically and efficiently as possible the highest quality of mushrooms. This can be accomplished among other requirements, by selecting the best strains which should be high yielding , visually attractive, having desirable flavour, and resistance to adverse climate and pests and diseases. Presently, there are many strains of white, cream and brown varieties in cultivation. The brown variety is the natural mushroom and considered to be the most vigorous form. It tolerates and adverse conditions better than the white variety.
A snow white mushroom first appeared amongst a bed of mushroom in the USA and ever since the variety has dominated the mushroom industry throughout the world, although it has a very high limited shelf-life. Where growing conditions tend to be on the dry side and humidity cannot be correctly controlled the brown mushroom should be grown. New superior strains are through selection, hybridization and induced mutations continually introduced by mushroom research laboratories and spawn makers. In India, S 11, S 649 and S791 are the good strains available. These strains were originally introduced from reowned commercial spawn makers, Somycel and darlington. Now these strains are well adapted in the Indian climate and are very popular with the growers.
Maintenance of Strains:
Three methods are known by which strains can be propagate. these are multispore culture, tissue culture and mycelium transfer. By periodic subculturing of the mycelium on a suitable agar medium, the span strains can be kept for many years in a fairly good state. However, the frequent subculturing of the strain may result in its degeneration. Maintenence of strain by multisporous culture is only possible if new multispore cultures are compared with the original strain before the original multisporous culture would show much genetic variation.
In the tissue culture, small pieces of fruit bodies are cut under sterile conditions and inoculated on a nutrient medium. Mycelium growing out of these tissue can provide the starting point for subsequent spawn production. However, it is commonly observed that tissue cultures often give lower yields than the original cultures. Of these 3 methods, mycelium transfer is most reliable but it is essential that the performance of the mycelium is continually checked in order to detect any degeneration-like slow-growing matted mycelium or fluffy mycelium with abnormal growth rate.
Spawn:
The propogating material used by the mushroom growers for planting beds is called spawn. The spawn is equivalent to vegetative seed of higher plant. Quality of spawn is basic for the successful mushroom cultivation.
At present, the pure culture spawn has been the basis of modern spawn production units all over the world. The manufacture of the pure culture spawn is done under scientifically controlled conditions which demand a standard of hygiene as in a hospital operation theatre. Equipment and substrate used for spawn are autoclaved and filtered air is passed during the inocluation ensures complete freedom from contamination.
THE FORGING PROCESS
Forging is a metal forming process used to produce large quantities of identical parts, as in the manufacture of automobiles, and to improve the mechanical properties of the metal being forged, as in aerospace parts or military equipment. The design of forged parts is limited when undercuts or cored sections are required. All cavities must be comparatively straight and largest at the mouth, so that the forging die may be withdrawn. The products of forging may be tiny or massive and can be made of steel (automobile axles), brass (water valves), tungsten (rocket nozzles), aluminum (aircraft structural members), or any other metal. This process is also used for coining, but with slow continuous pushes.
The forging metal forming process has been practiced since the Bronze Age. Hammering metal by hand can be dated back over 4000 years ago. The purpose, as it still is today, was to change the shape and/or properties of metal into useful tools. Steel was hammered into shape and used mostly for carpentry and farming tools. An axe made easy work of cutting down trees and metal knives were much more efficient than stone cutting tools. Hunters used metal-pointed spears and arrows to catch prey. Blacksmiths used a forge and anvil to create many useful instruments such as horseshoes, nails, wagon tires, and chains.
Militaries used forged weapons to equip their armies, resulting in many territories being won and lost with the use and strength of these weapons. Today, forging is used to create various and sundry things. The operation requires no cutting or shearing, and is merely a reshaping operation that does not change the volume of the material.
Forging changes the size and shape, but not the volume, of a part. The change is made by force applied to the material so that it stretches beyond the yield point. The force must be strong enough to make the material deform. It must not be so strong, however, that it destroys the material. The yield point is reached when the material will reform into a new shape. The point at which the material would be destroyed is called the fracture point.
The forging metal forming process has been practiced since the Bronze Age. Hammering metal by hand can be dated back over 4000 years ago. The purpose, as it still is today, was to change the shape and/or properties of metal into useful tools. Steel was hammered into shape and used mostly for carpentry and farming tools. An axe made easy work of cutting down trees and metal knives were much more efficient than stone cutting tools. Hunters used metal-pointed spears and arrows to catch prey. Blacksmiths used a forge and anvil to create many useful instruments such as horseshoes, nails, wagon tires, and chains.
Militaries used forged weapons to equip their armies, resulting in many territories being won and lost with the use and strength of these weapons. Today, forging is used to create various and sundry things. The operation requires no cutting or shearing, and is merely a reshaping operation that does not change the volume of the material.
Forging changes the size and shape, but not the volume, of a part. The change is made by force applied to the material so that it stretches beyond the yield point. The force must be strong enough to make the material deform. It must not be so strong, however, that it destroys the material. The yield point is reached when the material will reform into a new shape. The point at which the material would be destroyed is called the fracture point.
HEAT TREATMENT THROUGH HARDENING
Hardening just the surface layer of steels is called case hardening. A very hard case, or "skin" resists wear and is supported by a core of lower hardness, depending on the type of steel, which is more tough and ductile, resisting breakage.
Carburizing and carbonitriding are the two most common types of case hardening processes and are designed for only certain types of steels. When steel at proper temperature is surrounded by certain elements, such as carbon and nitrogen, it will absorb those elements into its surface. The added elements form a "case" which can be very hard.
For a quality job, it is vital for the heat treater to closely control furnace atmosphere, temperature, time, convection system plus the orientation of the parts in the furnace. Selective hardening may be accomplished by masking with high temperature tape, copper paint or copper plating.
CarburizingThis is a form of case hardening in which the furnace atmosphere is adjusted to deposit carbon into work when it is held at critical temperature. This layer of increased carbon can then achieve very high hardness when quenched. Since the sub-surface area has a lower carbon content, it does not harden as much or at all during this process. This leaves a more tough, ductile core than a through-hardening alloy or tool steel with the same surface hardness potential Case hardening is usually specified with a Rockwell C hardness range of three points, such as Rc 58-60, plus a "case depth" within the range of .010" to .080" or more. Interestingly, the rate of carburization will increase in depth either with temperature or over time. Since too high a temperature causes undesirable grain growth and a long period at lower temperature raises costs, a quality heat treater will start with a high temperature and then lower it to refine the grain before quenching.
Since carburized parts are designed for maximum surface hardness, they are sometimes NOT tempered after the hardening quench as is typical. This is especially the case with shallow case depths. In the tough core offsets the brittleness inherent in untempered steel.
Although many types of steels respond to carburizing, classic alloys for this purpose are 8620 and 9310. These "low alloy" steels can not only exceed Rc 60 when carburized, but produce a tough core of good hardness (Rc 30-38). These alloys are the choice of gear makers. Low carbon steels such as 1018 or 1117, while not offering as much toughness, can also be carburized for a low cost solution.
Carburizing and carbonitriding are the two most common types of case hardening processes and are designed for only certain types of steels. When steel at proper temperature is surrounded by certain elements, such as carbon and nitrogen, it will absorb those elements into its surface. The added elements form a "case" which can be very hard.
For a quality job, it is vital for the heat treater to closely control furnace atmosphere, temperature, time, convection system plus the orientation of the parts in the furnace. Selective hardening may be accomplished by masking with high temperature tape, copper paint or copper plating.
CarburizingThis is a form of case hardening in which the furnace atmosphere is adjusted to deposit carbon into work when it is held at critical temperature. This layer of increased carbon can then achieve very high hardness when quenched. Since the sub-surface area has a lower carbon content, it does not harden as much or at all during this process. This leaves a more tough, ductile core than a through-hardening alloy or tool steel with the same surface hardness potential Case hardening is usually specified with a Rockwell C hardness range of three points, such as Rc 58-60, plus a "case depth" within the range of .010" to .080" or more. Interestingly, the rate of carburization will increase in depth either with temperature or over time. Since too high a temperature causes undesirable grain growth and a long period at lower temperature raises costs, a quality heat treater will start with a high temperature and then lower it to refine the grain before quenching.
Since carburized parts are designed for maximum surface hardness, they are sometimes NOT tempered after the hardening quench as is typical. This is especially the case with shallow case depths. In the tough core offsets the brittleness inherent in untempered steel.
Although many types of steels respond to carburizing, classic alloys for this purpose are 8620 and 9310. These "low alloy" steels can not only exceed Rc 60 when carburized, but produce a tough core of good hardness (Rc 30-38). These alloys are the choice of gear makers. Low carbon steels such as 1018 or 1117, while not offering as much toughness, can also be carburized for a low cost solution.
NATURAL GAS
Natural gas is a fossil fuel source of energy, which represents more than one fifth of total energy consumption in the world. It has been the fastest growing fossil fuel since the seventies.
Due to economical and ecological advantages that it presents as well as its safety qualities (e.g. reduced flammable range), natural gas is an increasingly attractive source of energy in many countries. At present, natural gas is the second energy source after oil. According to Energy Information Administration, natural gas accounted for 23% of world energy production in 1999. It has excellent perspectives for future demand. Natural gas is considered the fossil fuel of this century, as petroleum was last century and coal two centuries ago.
Natural gas presents a competitive advantage over other energy sources. It is seen as economically more efficient because only about ten per cent of the natural gas produced is wasted before it gets to final consumption. In addition, technological advances are constantly improving efficiencies in extraction, transportation and storage techniques as well as in equipment that uses natural gas.
Natural gas is considered as an environmentally friendly clean fuel, offering important environmental benefits when compared to other fossil fuels. The superior environmental qualities over coal or oil are that emissions of sulphur dioxide are negligible or that the level of nitrous oxide and carbon dioxide emissions is lower. This helps to reduce problems of acid rain, ozone layer or greenhouse gases.
Natural gas is also a very safe source of energy when transported, stored and used.
Although resources of natural gas are finite and natural gas is a non-renewable source of energy, these resources are plentiful all over the world. Natural gas reserves are continuously increasing as new exploration and extraction techniques allow for wider and deeper drilling.
Due to economical and ecological advantages that it presents as well as its safety qualities (e.g. reduced flammable range), natural gas is an increasingly attractive source of energy in many countries. At present, natural gas is the second energy source after oil. According to Energy Information Administration, natural gas accounted for 23% of world energy production in 1999. It has excellent perspectives for future demand. Natural gas is considered the fossil fuel of this century, as petroleum was last century and coal two centuries ago.
Natural gas presents a competitive advantage over other energy sources. It is seen as economically more efficient because only about ten per cent of the natural gas produced is wasted before it gets to final consumption. In addition, technological advances are constantly improving efficiencies in extraction, transportation and storage techniques as well as in equipment that uses natural gas.
Natural gas is considered as an environmentally friendly clean fuel, offering important environmental benefits when compared to other fossil fuels. The superior environmental qualities over coal or oil are that emissions of sulphur dioxide are negligible or that the level of nitrous oxide and carbon dioxide emissions is lower. This helps to reduce problems of acid rain, ozone layer or greenhouse gases.
Natural gas is also a very safe source of energy when transported, stored and used.
Although resources of natural gas are finite and natural gas is a non-renewable source of energy, these resources are plentiful all over the world. Natural gas reserves are continuously increasing as new exploration and extraction techniques allow for wider and deeper drilling.
IRON ORE MINING
Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in colour from dark grey, bright yellow, deep purple, to rusty red. The iron itself is usually found in the form of magnetite (Fe3O4), hematite (Fe2O3), goethite, limonite or siderite. Hematite is also known as "natural ore". The name refers to the early years of mining, when certain hematite ores contained 66% iron and could be fed directly into blast furnaces. Iron ore is the raw material used to make pig iron, which is one of the main raw materials to make steel. 98% of the mined iron ore is used to make steel.
Minnesota's iron ore was actually discovered while prospectors were searching for gold. Since the object of their search was gold, the iron was ignored. It turned out the iron would become much more valuable to northern Minnesota than the small amount of gold found.Iron ore was discovered on the three iron ranges at different times. The first ore shipped from the Vermilion Range was in 1884, the Mesabi Range in 1892, and the Cuyuna Range in 1911.
World consumption of iron ore grows 10% per annum on average with the main consumers being China, Japan, Korea, the United States and the European Union.Iron ore mining methods vary by the type of ore being mined. There are four main types of iron ore deposits worked currently, depending on the mineralogy and geology of the ore deposits. These are magnetite, titanomagnetite, massive hematite and pisolitic ironstone deposits.
Hematite ore
Hematite iron ore deposits are currently exploited on all continents, with the largest intensity of exploitation in South America, Australia and Asia. Most large hematite iron ore deposits are sourced from metasomatically altered banded iron formations and rarely igneous accumulations.Hematite iron is typically rarer than magnetite bearing banded iron formations or other rocks which form its main source or protolith rock, but it is considerably cheaper and easier to beneficiate the hematite ores and requires considerably less energy to crush and grind. Hematite ores however can contain significantly higher concentrations of penalty elements, typically being higher in phosphorus, water content (especially pisolite sedimentary accumulations) and aluminium (clays within pisolites).
Minnesota's iron ore was actually discovered while prospectors were searching for gold. Since the object of their search was gold, the iron was ignored. It turned out the iron would become much more valuable to northern Minnesota than the small amount of gold found.Iron ore was discovered on the three iron ranges at different times. The first ore shipped from the Vermilion Range was in 1884, the Mesabi Range in 1892, and the Cuyuna Range in 1911.
World consumption of iron ore grows 10% per annum on average with the main consumers being China, Japan, Korea, the United States and the European Union.Iron ore mining methods vary by the type of ore being mined. There are four main types of iron ore deposits worked currently, depending on the mineralogy and geology of the ore deposits. These are magnetite, titanomagnetite, massive hematite and pisolitic ironstone deposits.
Hematite ore
Hematite iron ore deposits are currently exploited on all continents, with the largest intensity of exploitation in South America, Australia and Asia. Most large hematite iron ore deposits are sourced from metasomatically altered banded iron formations and rarely igneous accumulations.Hematite iron is typically rarer than magnetite bearing banded iron formations or other rocks which form its main source or protolith rock, but it is considerably cheaper and easier to beneficiate the hematite ores and requires considerably less energy to crush and grind. Hematite ores however can contain significantly higher concentrations of penalty elements, typically being higher in phosphorus, water content (especially pisolite sedimentary accumulations) and aluminium (clays within pisolites).
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