FST -1

19th Part

Q.  Write a detailed account of the origin of agriculture and civilization.

A.  After the stone age, the next period in the evolution of human society is known as the Bronze Age, the period when agriculture flourished and gave a major impetus to the spread of civilization in different parts of the world.

      Agriculture resulted from the understanding that plants could be grown from seeds and that the crops had some relation to the seasons. And, probably, the availability of water helped in this process. Cultivation led to permanent or semi-permanent settlements around regions that were climatically and soil-wise suitable for crop production. These settlements grew into villages, with some community life and leisure. The settlements emerged in regions that are most suitable for cultivation. Thus in this period, from about 4000 B.C. to 1500 B.C., the four great civilizations of Egypt, Mesopotamia, India, and China came into existence in the wide river valleys of the Nile, the Tigris and the Euphrates, the Indus, and the Hwang Ho. These civilizations further prospered as the people of those times understood the advantage afforded by the river for food production. They also realized that if the river could be systematically used through natural and artificial irrigation, food production could be increased manifold. 

          These civilizations further engaged in trade among themselves and with each other. For Barter trade, some places were identified as meeting places for the exchange of goods. Convenient sites were chosen for displaying goods and exchanging grain for cloth or spices or shopping for better tools and implements made by expert artisans. Evidence suggests that cities were founded by bringing together the population of several villages. The growth of cities led to the rise of an administrative class who could organize and coordinate production and exchange but did not take part in it directly. 

The civilization further progressed as the growth of cities was helped by the new mode of production. The man started producing much more than he could consume locally. Therefore. all people in agricultural Societies did not have to be agriculturists. They could produce other useful goods and even excel in music or dance. The surplus could be used to support craftsmen who made the agricultural implements and storage vessels, masons who built shelters, wheel-wrights who made pottery, and others who made carts. There were still others who worked as administrators and priests, and who were not directly involved in the process of production. These groups of people came to live in the cities. The surplus was transported by land, river, sea in exchange for other necessities of life and even luxury goods. This provided tremendous impetus for the development of transport, such as rafts, boats and small ships, which brought about new dimensions of trade, cultural contact, and exchange of techniques and science among different societies.

Q.  What have been the impediments of the growth of science in India?

A.  Till the middle of the 16th century, Indian science was at the same level as science anywhere else in the world. But, then European science took big strides forward and left Indian science way behind in the period that followed. Some of the impediments of growth of science in India afterward were - 

          One of the reason was the satisfaction in the social structure. In spite of periodic wars between the rulers of various regions and states in the country, there was very considerable stability in Indian society. The population was small, the land was fertile and even from small land holdings, Indian peasants were able to meet the requirements of subsistence. They could feed and clothe themselves. The overall satisfaction among the masses didn’t create the conditions for innovations or to question and to think beyond the prevalent scientific methods. 

        The second reason was religious orthodoxy. The grip of religion on the society particularly in the rural areas, and the existence and growing rigidity of the caste system prevalent in the society contributed to the decline of scientific progress in the society. People accepted their fate as god’s will and destiny. Such thinking did not allow pressures to build up for either enhancing production through technological innovation, or to change the society.

        Another reason was the lack of intellectual atmosphere during that time. Those who worked with their hands did not contribute to the stock of knowledge. And those who possessed even out-dated knowledge never had to test it on the touchstone of practice. Either the kingdoms fought wars or settled down to long periods of peace. It seems natural to think that in such a society there was no clamor to develop new products or new processes. Social stability and stagnation can easily go hand in hand. The rich had no need for change, the poor had no power to bring about change. 

         There was large scale illiteracy among the masses in India during that period. Education was mostly limited to religious teaching and the intellectual atmosphere was not in favor of challenging the established ways-of thinking. There was a complete lack of printed books. Rulers didn’t understand enriching people's lives on a large scale through the availability of cheaper books. This was in contrast to the sixteenth century Europe where the availability of printed word greatly helped the spread of knowledge that created a wider and deeper impact for bringing about social change. Thus a traditional, hierarchical society with a low level of discontent and conservatism promoted religion made scientific advance difficult in India. 

Q.  Discuss the salient aspects of the structure of the Sun and the various activities going on in it. 

A.  Sun is a star on which the whole Solar system depends. Nuclear reactions in the Sun convert about four hundred million tons of hydrogen into helium every second. The mass of the Sun is about 2 X 10^33 grams and the average density of the Sun, i.e. its mass per unit volume is about 1.4 g/cm3. It rotates about its axis once every 25 days. From time to time dark patches appear on the surface of the Sun, usually in pairs or in groups. These dark patches are called sunspots. Their movement is an indication of the Sun's rotation. Sunspot is a region on the surface of the Sun that consists of gases almost 1000*C cooler than those surrounding the area. The number of sunspots increases and decreases in a cycle every 11 years. 

Layers of the Sun - The Sun's body is made up of several layers. The layer that forms the visible surface of the Sun is called the photosphere. The photosphere is the area that demarcates the body of the Sun and its atmosphere. The temperature of the photosphere is about 6000°C. The innermost layer of the Sun is its core where its energy is produced through nuclear reactions. Like the Sun's body, the solar atmosphere too has several layers. The outermost layer of the Sun's atmosphere is called the corona which is visible during total Solar eclipse. The corona extends all the way up to the Earth's orbit and even beyond.

Solar Wind and Solar Flare - Streams of electrons and protons continuously flow out from the Sun's atmosphere and travel across the Solar System. This rapidly moving stream of charged particles is called the solar wind. About one million ton of material is removed every second from the Sun in the form of the solar wind. These charged particles react with the atoms of the Earth's atmosphere to produce northern lights, 'aurora borealis' at the North Pole and southern lights, 'aurora australis' at the South pole. The solar flare represents a tremendous release of energy in a very short time. Usually, it occurs in the neighborhood of a sunspot. There is a sudden brightening accompanied by a violent outflow of energy in the form of light, Radiowaves, X-rays and solar material like electrons and protons.

Q.  Describe the modern methods employed for the exploration of natural resources.

A.  The modern methods employed for the exploration of natural resources is Remote sensing and Resource mapping. 

1. Remote Sensing - The exploration is done by the analysis of photographs taken from air or spacecraft (satellites) and other data supplied by the sensors mounted on these vehicle by a method called' remote sensing'.

Remote Sensing - 

Remote sensing is a method of collecting information about ground objects like soil, water, vegetation, and minerals, from a remote place, such as an aircraft or a satellite. This technique not only enables us to locate various resources but also helps us to know about their quantity and quality. The simplest device could be a camera carried by an aeroplane to photograph large areas of land systematically. Television cameras could be mounted on satellites and they could take pictures showing details of clouds, water, forests or buildings on the earth. Both these are optical methods of remote sensing because visible light is used by the cameras. But one could send out radio waves from the satellites and observe how they are reflected or absorbed on the surface of the earth. Usually, radio waves of wavelengths as small as a few centimeters called 'microwaves', are used for such studies, because these waves penetrate through clouds and their reflections also go through the clouds to reach the satellite. Similarly, infra-red signals can be sent from the satellite and reflections studied to reveal the nature of the reflecting surface.

For water resources - Radio waves of the shortest known wavelengths are called 'gamma rays'. These are given off by atoms of several elements. The ground soil sends out gamma rays which can be picked up by detectors in the aeroplanes or satellites. This emission is affected by the presence of moisture or water in the soil and hence, it can be easily detected whether or not the soil holds water. Moreover, in the pictures taken from space, the wet soil will have an altogether different appearance compared to dry or water less soil. Due to the presence of moisture, the water rich soil will not only show day time (diurnal) variation in temperature on its surface, but will also have a cover of vegetation. Analysis of the type, density, and pattern of the vegetation growing on the wet soil helps us in locating the areas of potential ground water. Similarly. the belts of hot springs may be identified and will show up in thermal or infra-red detectors.

Survey of the vegetation cover -  Forests of deciduous trees which shed leaves in a certain season can be easily identified with the help of pictures taken from the spacecraft specially during autumn when the deciduous trees shed leaves and there is no snowfall as yet to conceal the vegetation. Vegetation cover can be surveyed by measuring and analyzing infra-red reflection, or with the help of photographs. The density of vegetation, shape, and size of the plants and even the size, orientation and health of the leaves can be studied from afar. The pattern of seasonal growth of deciduous trees is different from that of the coniferous trees like pine and deodar and thus the difference can be detected in the photos taken by the spacecraft.

Search for mineral deposits -

Aerial photos and satellite pictures show very clearly if there is a break in the continuity of layers of rock. or other unusual features on the surface of the earth. The distinctive linear features are found to be very common centers where mineral deposits and ground water are accumulated. Radio waves & magnetic measurements also provide information about minerals and oil under the surface.

2. Resource Mapping - It is another modern method for the exploration of natural resources. Several types of maps, based on the type of resources, are prepared. Some of these are:

Soil Maps showing the types of soil their composition and biological productivity.

Mineral Maps showing locations of various kinds of mineral deposits in relation to settings of the earth's crust.

Hydrological Maps show the presence of underground water aquifers,i.e. rock formation containing water in recoverable quantity, in terms of the depth of water table.

Snow Cover Maps demarcate the extent of snowpacks on high mountains.

Resource mapping

Using various techniques, Resource Mapping is done to locate different resources like water, minerals, forests. vegetation as well as the types of land. Mapping of resources makes it possible to visualize how land use could be managed to the best advantage. The rural land use map tells us about the health of forests and the state of deforestation, about pastures, and agricultural crops. It also tells us how much land and of what kind is unutilized. The urban land use maps show housing, commercial buildings, sports facilities, essential services such as roads, water supply and disposal of waste, etc. Likewise, the preparation of regional land use maps will focus upon the broader aspects of development such as land used for agriculture, industrialization and urbanization, for obtaining natural resources (forestry, mining etc.), water resource development (dams, reservoirs and canals), transportation network (rails, road etc.) and also the zones prone to natural hazards like floods, cyclones, earthquakes, landslides and avalanches etc.

Q.  How the application of scientific knowledge has made agriculture possible in arid zones, drylands, and hills?

A.  The advancements in our scientific knowledge have now enabled us to practice agriculture in arid zones, drylands, and hills.

 Arid Zones  - The chief arid areas of our country are confined to Rajasthan, Gujarat, Haryana, Karnataka, and Ladakh. They cover an area of about 400,000 square kilometers. Of this, Ladakh has a cold desert spread over 70,000 square kilometers.

Here, aridity and low temperature limit the agricultural season to about five months in a year. Therefore, crops that require a short period to mature and can withstand severe cold are grown. These are some cereals, oilseeds and fodder crops. In the hot desert regions, of Rajasthan, Gujarat, and Haryana, there is an abundance of sunshine which causes high rate of evaporation. Many of these areas have adequate reserves of ground-water which is scientifically tapped for irrigation. In the arid zone fruit trees like ber and pomegranate and fuel-wood yielding trees like Acacia (Kikar), Prosopis (Mosquite) and Eucalyptus (Safeda) are grown. In such areas, large scale planting of shelter-belts minimizes soil erosion caused by wind. It also helps in the establishment of pastures and grazing lands. Later on, this land is used for growing pearl millet and mungbean.

Dry Lands - Drylands constitute about 74% of our cultivated lands and produce about 42% of our food. These are entirely rain-dependent and crop fortunes are closely linked to the vagaries of the monsoon. Sometimes rains may set in very early or very late or may come on time but withdraw too soon. There may also be large breaks between showers. When evaporation and loss of water by seeping in the soil exceeds rainfall, these lands are plagued by drought, scarcity of drinking water and thus crop failure. Rain water is collected in ponds to support agriculture. In Dry lands with red soil, deep ploughing helps in conserving water while In black soils, sowing two crops at a time is possible with surface drainage and good water management. Leaves and crop residues, when mixed with soil improve its texture and water holding capacity. Crops like pigeon pea and castor that have deep roots are cultivated in these regions which improve the physical condition of the soil further, as the roots of these crops add organic matter. Varieties of sorghum, millets, sunflower, safflower, mustard, groundnut, various pulses and cotton are available which grow within a shorter time withstanding scarcity of water and also diversifying crops in drylands. A variety of crops and cropping patterns allow the farmer to make a proper choice of what to grow in different climates and soil types.

Hills - Based on a study of the slope and depth of the soil, and availability of water, scientists have devised an interesting agricultural system that requires low inputs and puts the land to most productive use without disturbing the ecosystem. Under this system, the upper reaches of the hills are devoted to forestry. The next zone is developed for growing fruit trees, perennial fodder grass and legumes. The roots of legumes fix nitrogen and improve the soil. In the third zone, a mix of crops are raised on terraces constructed with low-cost implements. Earthen dams are constructed with locally available material. These collect enough water to be utilized for irrigation.