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    Soil Soil Document Transcript

    • SOILS IN INDIA Soil is the uppermost layer of Earth’s crust. Soil is the medium in which plants grow and thus it supports the lives on earth. How soils are formed? Soils are formed due to the weathering of rocks. WHAT IS SOIL? Soil is the thin layer of loose mixture of small rock particles and rotting organic matter that covers much of the world’s land surface. SOIL FORMATION Soil formation is a very long process. It begins with the weathering of rocks into small fragments. The rocks are also worn away by the agents of erosion like river, wind, sea and glacier. The sediments and tiny rock particles are then deposited by the agents of erosion. The accumulation of such sediments over the ages forms soil. Eventually, the plants that grow on the soil, shed their leaves which decay to form the topmost layer of soil called 'humus'. India is primarily an agricultural country. The success of agriculture depends upon the fertility of soils. The soils of India are classified into the following main groups depending upon the rock cover and climatic conditions. The most two important factors that determine the types of soil found in India are : i. The climate ii. The topography The soils of India on the basis of their formation are divided in the following two broad catagories. 1.Residual Soil 2.Transported Soil The major soil groups are: Black Soil Black soils are mainly found over the Deccan lava tract (Deccan Trap) including Maharashtra, Madhya Pradesh, Gujarat and Andhra Pradesh. These soils are found in river valley of Narmada, Tapi, Godavari and Krishna. These soils have been formed due to the weathering of the lava rocks. This is also known as the Regur soil and Cotton soil. These soils are rich in lime. iron, magnesia and alumina but lack in the phosphorus, nitrogen and organic matter. It is formed by the weathering of igneous rocks and the cooling of lava after a volcanic eruption. 1
    • In India, extensive deposits of black soil are found in the Deccan Plateau which includes parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, parts of Tamil Nadu. In the upper parts of Godavari and Krishna, the north western part of Deccan Plateau, black soil is very deep. BLACK SOIL IS:- Clayey, deep and impermeable They swell and become sticky when wet and shrink when dried During dry season, these soils develop wide cracks. Rich in lime and iron, magnesia and alumina Also contain potash Lack phosporus, nitrogen and organic matter Colour of the soil ranges from deep black of grey. Known as Black Cotton Soils. Dark in colour, suitable for cotton cultivation Are residual soils, i.e. they are formed at the place of their origin over the underlying rocks. Are formed in situ, i.e. formed where they are found. Therefore, they are essentially formed by weathering of Deccan Trap. Spread over an area of 5.4 sq. km., i.e. 16.6 % of the total land area of the country. CHARACTERISTICS: * Fine textured and clayey in nature . * Has high qualities of lime, iron, mangnesium, and generally poor percentage of phosphorous, nitrogen and organic matter. * Black in colour as it is formed from weathered lava rocks Soil’s colour also varies from Black to Chestnut brown Very clayey and therefore highly retentive of water. Because of high clay content, these soils expand when wet and become difficult to plough. During dry season, black soils shrink and develop big cracks which help in air circulation . Soil is very fertile in most of places. 2
    • Poor in nitrogen, phosphorous, potassium, and organic matter and rich in potash and lime. Needs irrigation support for cultivation Contains soluble salts in small quantities. Cultivation is done with the help of fertilizers . Suited for dry farming as it does not require much moisture. CROPS: Cotton cultivation Suitable for growing cereals, rice, wheat, jowar, oilseeds, citrus fruits and vegetables, tobacco and sugarcane. Their moisture –retentiveness makes them suitable for dry farming. RED SOIL These soils are found in Chhotanagpur plateau, Telangana, Nilgiris, Tamil Nadu, Karnataka, Andhra Pradesh and periphery areas of Deccan Plateau. These soils have been formed due to decomposition fo underlying igneous rocks under heavy rainfall. These are suitable for the cultivation of millets, pulses. Lin-seed, tobacco etc. These soils are poor in Lime, Nitrogen and humus. CHARACTERISTICS: Red soils are reddish in colour due to the presence of iron. This type of soil is found in south India as well as in the Chota Nagpur Plateau. Formed due to weathering of ancient crystalline and metamorphic rocks. Parent rocks are acid granites and gneisses. Occupy an area of about 3.5 lakh sq km – 10.6% of the total land area of the country . These are transported type soils. Found to a depth of 500 meters. Coarsest in the upper section of the valley, medium in the middle and finest in the delta region. Are mostly light to dark colour depending on new or old alluvium. Rich in potash and become fertile with the proper use of fertilizers and irrigation. Deficient in nitrogen, lime, magnesia, humus and phosphate Found mainly on the plateau region of peninsular India, the Malwa Plateau and the Chotanagpur Plateau. 3
    • It covers almost the whole of Tamil Nadu, Karnataka, Andhra Pradesh, south-eastern Maharashtra, eastern parts of Madhya Pradesh, parts of Orissa, Jharkhand and Bundelkhand. They practically encircle the entire black soil region on all sides.They extend northwards in the west along with the Konkan Coast of Maharashtra. Red due to its very high iron content. Colour varies from red to brown, chocolate and yellow. Are porous, friable in nature . Loose and aerated. Contains soluble salts in small quantities. LATERITE SOIL Laterite = brick (Latin word) These soils are formed under conditions of high temperature and heavy rainfall with alternate wet and dry periods. Thus its formation takes place strictly under monsoon conditions. Residual soils formed by leaching in areas of heavy rain. Leaching is a process in which the nutrients get percolated down below the soil due to heavy rainfall; thus leaving the top soil in Fertile. Also called DESILICATION. Laterite soils are found in elevated areas which receive very high rainfall As a result, top soil gets washed away. This process is called leaching. The soil, therefore, loses its fertility to a great extent. It covers an area of about 2.4 lakh sq km. These soils are found in the north- eastern state of Meghalaya in India. Is of coarse texture, soft and friable. Is red due to the presence of iron oxide which is formed by leaching. The soluble plant foods like potash are removed from the top soil leaving alumina and iron oxide. Is a porus soil, silica is removed from it by chemical action. Is poor in lime and magnesium, and deficient in nitrogen. Laterite soil is formed by weathering of lateritic rocks, low temperature and heavy rainfall with alternating dry and wet periods. TWO TYPES : Upland Laterites and Lowland Laterites 4
    • Upland laterite:- are formed over hills and uplands.From they were transported by steams towards lowlands. Such transported soils are known as Lowland Laterites. Laterite soil does not retain moisture and hence is not fertile. It suits only special crops like Tapioca, Cashewnuts, etc.It is acidic in nature as alkalis are leached. Laterite soils are found on the highland areas of the plateau. These are found in Karnataka, Kerala, Tamil Nadu and hilly regions of Assam, Rajmahal hills and Chhotanagpur plateau. These are shallow, acidic and less fertile soils. These soils are poor in lime but rich in iron. So these are suitable for plantation of crops like tea, rubber, coffee etc. Since low fertility because of high acidity and low moisture retention, manuring and other activities are required to make them suitable for growing crops such as ragi, rice and sugarcane. Paddy is grown on lower elevations whereas tea, cinchona, rubber, and coffee are grown on higher elevations. It is also suitable for building purpose. ALLUVIAL SOILS Alluvial Soil (Riverine soil) It covers about 40 percent of land area of the country. They are depositional soils, transported and deposited by rivers and streams. Through a narrow corridor in Rajasthan, they extend into the plains of Gujarath. These soils are formed by the deposition of fine sediments and silt by the rivers along their banks. In India, alluvial soils are mostly found in the Great Northern Plains, the coastal plains and river deltas In Peninsular region, they are found in deltas of the east coast and in the river valleys. These soils originate from the transported alluvium brought by the rivers. They can be divided into two types: 1. Young Khadar soils: these are newer alluvium of sandy, pale brown composition, found in lower areas of valley bottom which are flooded almost every year. It is non phorous, clayey and loamy. 2. Old Bhangar soils: these consist of older alluvium of clayey composition and are dark in colour. They are coarse in nature, contain kankar (lime nodules), pebbles, gravels. They are found 30 m above flood level of the rivers. They represent the ‘riverine alluvium’ brought down by Sutlej, Yamuna, Ghagra and other rivers of Indo- Gangetic Plains. These soils are the most widespread soils covering an area of 8 lakh sq. km from Punjab to Assam. These are found in the river basin, flood plains and coastal areas. These soils are deep soils rich in potash but poor in nitrogen. These soils are covering 22.16 per cent of total area of India. The major rivers which are contributing in the formation of the alluvial soils are :Ganga river, Brahmaputra river, Sutlej river, Mahanadi river , Godavari river , Krishna river CHARECTERISTICS Alluvial soils though differ greatly in texture, are very fertile on whole. They: 5
    • Respond well to irrigation and manuring. Good for both rabi and kharif crops. Suitable for wheat, sugarcane, rice, cotton and oilseeds. In delta region, they are ideal for jute cultivation. AREA/STATES Alluvial soils of two types: deltaic coastal and inland alluvial. Found in Uttaranchal, U.P., Bihar, W. Bengal, Punjab, Haryana & Assam. In south, found in the plains and deltas in Andhra Pradesh, Orissa, Tamil Nadu. Useful for agriculture since it is fertile. Soil is rich in potash and lime but poor in nitrogen and humus. Important crops – wheat, rice, sugarcane, cotton and jute. It is very suitable for jute. Other Soils: The other soils in the category of the Indian soils are as follows: DESERT SOIL These soils cover 2 lakh sq. km areas in dry areas of Rajasthan, Gujarat, Punjab, and Haryana. These coarse soils are suitable for cultivation of jowar, bajara, cotton etc. Saline and Alkaline Soils: These soils are found in the dry and marshy areas. These are locally known as Bhur, Rehu, Kallar. The accumulation of salts makes these soils infertile. Mountain Soils: Mountain soils are found in, as the name suggests, in mountainous regions. They are quite prone to soil erosion as a result of the top soil getting washed away due to the steep slopes of the mountains after a period of heavy rainfall. These soils are mostly thin and infertile. These include peat, meadow and forest hill soils. The major characteristics of this soil are: *they are rich in humus * are coarse and infertile. They are deficient in potash, phosphorous and lime. *Tea, coffee, spices and tropical fruits The states of Jammu and Kashmir, Himachal Pradesh and Uttaranchal, Assam, Sikkim as well as higher reaches of Arunachal Pradesh have mountain soil. 6
    • ARID AND DESERT SOILS Large part of arid and semi-arid region of Rajasthan and adjoining areas of Punjab and Haryana Desert soils are found in arid regions which receive very little rainfall. CHARECTERISTICS *Low rainfall and high temperature are reasons for the formation of this soil . *Having less than 50 cm rainfall . The high temperature adds to the loss of any remaining moisture in the soil. The soil is therefore sandy in nature. Thar Desert in Rajasthan has sandy soil. *Covers an area of about 1.4 lakh sq km * Originated from the mechanical disintegration of the ground rock of by deposition by wind * Desert soil contain 90% of sand and 5% of clay. It contains rich percentage of soluble salts, but lack in organic matter. * Are porous and coarse . * They respond well to irrigation and manuring , especially phosphate and nitrate.- it can improve the soil fertility as it is seen in the case of Indira Gandhi Canal in Rajasthan. * Only suitable for drought resistance crops like millets, barley, cotton, maize and pulses. SALINE AND ALKALINE SOILS Soils with high proportion of salts and alkalis are called saline and alkaline soils . They are formed due to accumulation of tidal water in adjoining coasts where drainage is poor. They are found in drier parts of Bihar, Rajasthan, U.P., Punjab, Haryana, Maharashtra. These soils contain many salts like sodium, magnesium and calcium which make them infertile and render unfit for agriculture. MARSHY SOIL Found in continuously water-logged areas, or marshy areas especially in the coastal regions near the sea or near the deltas. * It covers about 56,000 sq km. * They are formed as a result of water-logging * It contain iron and varying amount of decayed organic matter. * Found in southern parts of Siwaliks, Jammu and Kashmir, U.P. DENUDATION 7
    • Denudation is the process of wearing away of the earth’s surface. There are many agents of denudation. 1.Rivers 2.Glaciers 3.Winds 4.Sea waves, etc. SOIL EROSION Soil erosion is the main problem of our country . It is on the increase in recent years Main reasons : * Running water * overgrazing * faulty methods of agriculture * Over irrigation * Wind * Men, plants and animals Soil erosion happens when particles of soil come loose and are carried away by water or the wind. When it rains so much that the water cannot seep into the soil fast enough, the extra water flows down the slope, carrying soil particles with it. Many agricultural soils are easily eroded. The erosion problem is likely to be more severe on certain types of soils, on steep slopes, where there is intense rainfall, and where the vegetation is removed Indirectly soil erosion helps in the soil forming because from wherever the soil is removed it is deposited elsewhere. However it disturbs the agricultural pattern and should be prevented. There are several ways in which soil erosion takes place due to running water. a.Splash erosion b.Sheet erosion c.Gully erosion d.Rill erosion SPLASH EROSION 8
    • Splash erosion or rain drop impact represents the first stage in the erosion process. Splash erosion results from the bombardment of the soil surface by rain drops. Rain drops behave as little bombs when falling on exposed or bare soil, displacing soil particles and destroying soil structure. Studies have shown that splashed particles may rise as high as 0.6 metres above the ground and move up to 1.5 metres horizontally. Splash erosion results in the formation of surface crusts which reduce infiltration resulting in the start of runoff. It is the first stage in the erosion process . It results from the bombardment of the soil surface by raindrops .It is the primary cause of soil detachment and soil disintegration. It means that resettled sediment blocks soil pores resulting in surface crusting and lower infiltration. SHEET EROSION Sheet erosion Occurs when thin layers of the topsoil are moved by the force of the runoff water, leaving the surface uniformly eroded Cultivation on hill slopes is the main cause of soil erosion. RILL EROSION Rill erosion Caused by runoff water when it creates small, linear depressions in the soil surface. These are easily removed during land tillage GULLY EROSION Unlike rill erosion, gullies are too deep to be removed during normal cultivation with ordinary farm implements. They are formed from small depressions, which concentrate water and enlarge until several join to form a channel. The deepening channel undermines the head wall, which retreats upslope. The gully then widens as the side-walls are worn back. Sea or Shore erosion * Tidal waters of sea cause considerable damage to the soil along the sea coast. * Powerful waves dash against sea-coast and break hanging cliff rocks. * Broken material is then removed by the retreating sea waves. * This type of erosion is seen throughout the eastern and western coasts of India. Typical features of coastal erosion: from the initial cracks in less resistant rock through to arches, stacks, and stumps that can occur as erosion progresses. STREAM BANK EROSION: Stream bank erosion is common along rivers, streams and drains where banks have been eroded, sloughed or undercut. However, it is important to remember that a stream is a dynamic and constantly changing system. 9
    • It is natural for a stream to want to meander, so not all eroding banks which are slowly eroding are "bad" and in need of repair. Generally, stream bank erosion becomes a problem where development has limited the meandering nature of streams, where streams have been channelized, or where stream bank structures (like bridges, culverts, etc.) are located in places where they can actually cause damage to downstream areas. Stabilizing these areas can help protect watercourses from continued sedimentation, damage to adjacent land uses, control unwanted meander, and improvement of habitat for fish and wildlife. Streams and rivers change their courses by cutting one bank and depositing the silt on the others. During flash floods, the damage is much acclerated. Prevalent in the flood plains of Ganga, Yamuna, and other rivers. As a result, large areas of agricultural land in the states of U.P., Rajasthan, M.P. have been transformed into ravines. WIND: Soil erosion by wind on extensive flat lands which are subject to windy dry season for part of the year. The upper soil surface becomes loose and susceptible to wind erosion due to lack of moisture. OVERGRAZING Due to overgrazing, wind erosion occurs as the soil devoid of vegetation is directly exposed to the wind. FAULTY METHODS OF AGRICULTURE i)Shifting agriculture as in Northeast India ii)Lack of crop rotation iii)Wrong ploughing LEACHING In agriculture, leaching may refer to the loss of water-soluble plant nutrients from the soil, due to rain and irrigation. Soil structure, crop planning, type and application rates of fertilizers, and other factors are taken into account to avoid excessive nutrient loss. Leaching may also refer to the practice of applying a small amount of excess irrigation where the water has a high salt content to avoid salts from building up in the soil (salinity control). Where this is practiced, drainage must also usually be employed, to carry away the excess water. Leaching is an environmental concern when it contributes to groundwater contamination. As water from rain, flooding, or other sources seeps into the ground, it can dissolve chemicals and carry them into the underground water supply. Of particular concern are hazardous waste dumps and landfills, and, in agriculture, excess fertilizer and improperly stored animal manure. 10
    • SHEET EROSION: Removal of thin layer of soil from a large area. In sheet erosion a thin layer of soil is removed from a large area. RILL EROSION: A series of small channels on a slope carved by running water. GULLY EROSION: Large, wide channels carved by running water. As a rule of thumb, a gully is large enough that it cannot be smoothed out with conventional tillage equipment. SPLASH EROSION: Splash erosion where the soil is pulverised by the impact of heavy drops and hailstones as in case of convectional rainfall. SOIL EROSION DUE TO HUMAN FACTOR: * Loss of forest cover – annual rate- about 47,500 hectares * Leads to sheet erosion on hilly slopes because water instead of sinking into the ground washes the soil down. * In the second stage, in the absence of vegetation cover and washing off of the absorbent top soil, rills begin to appear on the landscape * In the third stage, the water run off during heavy rains may develop deep grooves causing Gully erosion. * The Outer Himalayas, the Western & Eastern Ghats are subjected to deforestation by man. * These areas receive heavy rainfalls. Removal vegetation cover for different land use like railway lines, roads, buildings, or even agriculture has caused Sheet, Rill or Gully erosion * Shifting cultivation – heavy rains wash away the bare soil from the slopes to the valleys below. * Uncontrolled gazing of domestic animals in the valleys and the upper slopes. WIND EROSION Wind erosion refers to the movement and deposition of soil particles by wind . It occurs when soil devoid of vegetation is exposed to high velocity wind. Wind moves soil particles 0.1 – 0.5 mm in size in bouncing or hopping fashion and those greater than 0.5 by rolling. The former is known as saltation and the latter as soil creep. The particles less than 0.1mm or the fines particles detach into suspension. Infact wind erosion is most visible in the suspension stage, as dust storms or subsequently as deposition along fence lines and across roads. CAUSES OF SOIL EROSION IN INDIA 1)Heavy population pressure on land: - forest cover as low as 20.55% of total area – population continues to rise at a rapid rate – more forests are destroyed – heavy pressure on land. 11
    • 2)Nature of Rainfall:- receives 80 to 90 per cent of rainfall in the monsoon season. – heavy downpour during during monsoon months causes floods. - remaining months – droughts – these affect soils 3)Overgrazing – number of domestic animals, esp cattle highest in world – cattle freely graze in open lands making them bare of vegetation-winds carry away dry soil particles - Rajasthan 4). Bad farming techniques – plough fields in traditional ways – small size of holdings, absence of terracing, contour cultivation, crop rotation, improper use of manure have caused erosion 5) Topography – North –Eastern parts of India, Shiwaliks and the hilly regions in south India are affected by soil erosion because of steep slopes and heavy rainfall. During heavy rainfall, soils are washed away by running water down the slope. 6) Deforestation: destruction of forests for cultivation – cutting of trees exposes the soil to water and wind which leads to soil erosion REGIONS OF SOIL EROSION *Rajasthan, Madhya Pradesh, Maharashtra, UP, Gujarat, Andhra Pradesh, Karnataka. Worst affected areas include: * The badlands of Chambal and Yamuna rivers * The piedmont zone of the western Himalayas * The Chotanagpur plateau region * The Tapi-Sabarmati valley region in Gujarat * The regur soil area of Maharashtra * The dry areas of Rajasthan, Gujarat and Haryana EFFECTS OF SOIL EROSION: * Loss of fertile top soil * Lowering of the underground water table and decreasing soil moisture * Drying of vegetation and extension of arid lands, increase in the frequency of droughts and floods * Silting of river and canal beds, Recurrence of landslides, adverse effect on economic prosperity and cultural development * Wind erosion reduces the productive capacity of soil, as most of the nutrients required by the plants are carried by the wind. PREVENTION OF SOIL EROSION AND SOIL CONSERVATION 1.Terrace Farming:- On hilly slopes, terraces act as bunds and prevent the soil from being washed away. 12
    • 2.Contour Ploughing: Ploughing along contourson a slope prevents soil being washed away by rainwater or by surface run off. Contours act like bunds. Terraces are levelled into step like small fields with even slope. 3)Afforestation: planting of trees along the edges of the fields, the waste land and on steepy slopes to prevent soil erosion as wellas to enahnce the capacity of the soil to retain water. * increase area under forests and indiscriminate felling of trees must stop. 4) Shelter Belts: Farmers plant trees in several rows to check wind erosion. Known as wind breaks. 5) Strip cropping: Crops are grown in alternate strips of land to check the impact of the winds. 6) Construction of dams: Rivers cause soil erosion. Dams are built in the upper course of rivers to control erosion of soil. This would check the speed of water and thereby save soil from erosion 7) Ploughing Gullies: The gullies made in the soil are plugged with deposition of silt during heavy rains. 8) Shifting or Jhuming or slash and burn type of agriculture should be banned. SOIL CONSERVATION SCHEMES 1. The centrally sponsored scheme of Integrated Watershed Management in the catchments of flood-prone rivers was launched during sixth Plan in eight flood-prone rivers of the Gangetic Basin covering seven States and one Union Territory. It aims at enhancing the ability of the catchment by absorbing larger quantity of rainwater, reducing erosion and consequent silt load in the stream and river beds and thus helping to mitigate the fury of floods in the productive plains. 2. A scheme for reclamation and development of ravine areas was launched in 1987-88 in MP, UP and Rajasthan. – included prepheral bunding to halt further ingress of ravines, afforestation of ravines, aforestaton of ravines for fuel, fodder and reclamation of shallow ravines. 3. Control of shifting cultivation is implemented since 1994-95 in the States of Arunachal Pradesh, Assam, Manipur, Meghalaya, Nagaland, Tripura The integrated programme envisages settling of families practising shifting cultivation. it helps them to practise terraced cultivation, raising of horticultural palantations and afforestation to support animal husbandry and to meet fuel and fodder requirements. 13
    • 4. In urban areas, rain water harvesting is means of checking soil erosion, besides recharging ground water. XXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXX SOLVED QUESTIONS 1.a. Name a rock from which black soils are formed? Write on characteristic of this soil? Ans. Igneous rock. The soil has a great capacity to retain moisture. b. Name the type of soil found on the summit of the Eastern Ghats. How is it formed? Ans. Laterite soil. Laterite soil is formed by leaching. c. i) Name any two regions where coastal alluvium is found. 14
    • ii.) Why is deltic alluvium more fertile than coastal alluvium? Ans.c. i) The coastal alluvium occurs in the coastal strips of peninsular India and the plains of Gujarat. ii. Deltic alluvium (Khaddar) is more fertile than coastal alluvium (Bhangar) as new layers are deposited year after year during monsoonal floods. d. State any three factors which affect the soil formation. Ans: i) WEATHERING: Extremes of temperature (as in the day and night temperatures in deserts), freezing and thawing of ice break down rocks, and favour soil formation. ii) VEGETATION: The growth and decay of vegetation determines the humus content of the soil. Roots of plants penetrate the soil and make it porous. iii. Bio-chemical processes taking place in the soil: Bacteria and fungi cause the decay of plants and animal remains. Some transform the atmospheric nitrogen into soil nitrogen. 2.a) Name one crop & one mineral associated with Black soil. Name two states in India where this type of soil is found. Ans: Crop: Cotton, Mineral: Iron State : Maharashtra and Madhya Pradesh b) How is Red soil formed? Mention two important properties of Red Soil. Ans: Red soil is formed djue to weathering of ancient crystalline and metamorphic rocks of the Peninsular plateau. The properties of red soil are: * it is loamy in deep depressions and in uplands, it consists of lose gravel- a highly coarse material. * It is deficient in lime, nitrogen, phosphorus, and humus but fairly rich in potash. C) Explain the following terms: i) Soil Erosion ii) Conservation of Soil i) SOIL EROSION: It is the removal of topsoil by different agents of weathering such as running water, wind, over grazing and faulty methods of agriculture used by farmers. ii) CONSERVATION OF SOIL: Conservation of soil is an effort made by humans to prevent soil erosion in order to retain fertility of soil. d. With which type of soil is the term leaching associated? Name two regions in India where this type of soil is found. Ans: Leaching is associated with laterite soil. TWO REGIONS: 1. Assam Hills 2) Hill summit of Eastern and Western Ghats Question: 3 a.Give a single word for the following: 15
    • i)The organic matter present in the soil formed by the decomposition of plants and animals - Humus ii)The soil which are carried down by agents of gradation such as river, wind – Transported soil. b. How does the soil of the Ganga Yamuna plain differ from that of central Maharashtra? Soil found in Ganga-Yamuna plain is alluvial soil, whereas soil found near central Maharashtra is black soil. The soil of Ganga-Yamuna plain has been formed from the sediments deposited by rivers whereas soils of central Maharashtra have been formed due to the weathering of the lava. c. Give reasons: i.Alluvial soil can hold moisture and is very fertile: Since the soil is made up of fine particles, it can hold a lot of water. ii.Black soil needs to be tilled after the first rain: When wet, the soil becomes sticky and is difficult to work with. So the soil needs to be tilted after the first rains. iii.Red soil is ideal for dry farming: It is suited for dry farming as it does not require much moisture. QUESTION 4 a.Read the feature of the soil carefully and identify the soil: i)It develops insitu as a result of leaching - Laterite soil ii)It develops on crystalline igneous rocks. - Red soil iii)It develops insitu from volcanic rocks. - Black soil iv) It is a transported soil and is formed by river sediments. – Alluvial soil b. Mention any four human factors responsible for soil erosion. (2) Deforestation, faulty methods of agriculture, urbanisation and industrialisation. c.Name any two crops association with following soils: (3) i. Alluvial soil - Rice and sugarcane ii. Red soil - Rice and wheat iii. Black soil - Cotton and wheat d.‘Proper farming techniques can help in soil conservation.’ Explain by giving three examples. * Terracing of hill slopes is effective in controlling soil erosion. Terracing is cutting into the hill slopes in a series of large steps made up of flat fields. * Constructing bunds across hill slopes and filed boundaries is effective in reducing soil erosion. Bunds are low mud walls or embankments that help to obstruct the flow of water. 16
    • * Contour ploughing should be practised. It involves ploughing along the outline of the field in a circular manner. This prevents the soil from being washed away by running water. 5A.Name four broad types of soils found in India. Red, black, alluvial and laterite soil. B.Give two reasons responsible for low fertility in laterite soil. * It is formed due to leaching. * It is poor in lime, phosphorous, nitrogen and potash which are fertile ingredients of a rich soil. C.What is conservation of soil? Why is it necessary? Soil conservation includes all those measures which help in protecting the soil from erosion and exhaustion It is necessary because soil is our most important natural resource. It alone assures prosperous agriculture. D.Mention any three characteristics of the northern plains. * These are constituted by two large river basins i.e. the Indus river basin and the Ganga-Brahmaputra basin. * These are very fertile plains. * These plains support some of the highest population densities. 6a. Differentiate between sheet erosion and gully erosion. 1. When top soil gets eroded from very large areas due to fast flowing rivers it is called sheet erosion. Gully erosion occurs when running water etches out deep rivers creating a badland topography in an otherwise normal landscape. 2. The unprotected lands are most susceptible to sheet erosion. Sheet erosion is particularly harmful because it removes the top layer which is finer and fertile. The main cause of gully erosion is the removal of vegetation, particularly of trees with their widespread binding roots. Gully erosion is also responsible for the formation of ravines. b. Explain the formation of soil. Name three various forces of nature which contribute to the evolution of soil. Soils are derived from parent rock material through the process of break up or wear and tear. Various forces of nature i) changing temperature, ii) running water, iii) wind contribute to the evolution of soil. QUESTION 7a. State two main differences between alluvial soil and red soil. 17
    • * Alluvial soil is a transported soil whereas red soil is residual. * Alluvial soil is highly moisture retentive while red soil is not. b. Why is laterite soil unsuitable for agriculture? Name an area in India where this soil is found. -Laterite soil is unsuitable for agriculture due to its high content of acidity and inability to retain moisture. It is poor in nitrogen and lime. c. How is Regur soil formed? Mention four important properties/ features of Regur Soil. These soils have been formed due to the solidification of lava spread over large areas during volcanic activity in the Deccan Plateau. Features: * it is well known for its capacity to hold moisture * it is a deep fine grained soil * it is dark in colour * it is rich in lime, iron, magnesium and potash * poor in phosphoric content. * made of extremely fine material i.e., clayey material. d. Mention two ways by which soil can get nitrogen. Soil can get nitrogen by : * By growing pulses as there are certain bacteria in the roots of pulses which have the ability to fix atmospheric nitrogen to form nitrogen compounds. * By applying NPK fertilizer. e. Explain the need for soil conservation in India. State two methods of soil conservation. i) Soil is the most precious asset of India. More than 60% of the population is dependent on agriculture. ii) Protective soil alone ensures progress of agriculture, forests and industrial development. METHODS: i) Afforestation ii) Proper farming technique 8.a. How is red soil formed? Why are red soils not suitable for agriculture? Red soil is formed due to weathering of ancient crystalline and metamorphic rocks. Red soils are not suitable for agriculture because these are not retentive of moisture and are deficient in nitrogen, lime, phosphoric acid and humus. It is light in texture. 18
    • b. With reference to red soils in India, i.Name two states where it found. ii.State two disadvantages of this soil. i. It is found in Tamil Nadu/Karnataka, Orissa, Andhra Pradesh, Goa. ii.It is poor in humus, nitrogen, lime, phosphorus AND Not retentive of moisture. 9. a. Mention two important characteristic of laterite soil. i. Laterite soils are acidic in nature, coarse and crumbly in texture. ii. Due to lack of nitrogen, potassium and organic elements laterite soils lack fertility. b.Name an area of black soil in India. Mention two crops grown in this soil. Malwa region of India having a concentration of Black soil. Major crops are cotton and sugarcane. c.How is alluvial soil formed? Why is this soil agriculturally important? Alluvial soil is formed after the sedimentation of alluvium by rivers. This soil is agriculturally most important because it is fertile and renewed every year by rivers. d.Name two important agents of erosion. For each, state one method of controlling the erosion caused. Two important agents of erosion are : i) Running water ii) Faulty agricultural activities. Construction of dam and river embankment can control the soil erosion caused by running water. Scientific methods of cultivation like contour ploughing, terrace farming and conservation of moisture is the important conservative measure. MORE QUESTIONS: 1.Name one area where laterite soils is found on large scale. Laterite soil is found in parts of Kerala, Goa, Tamil Nadu, Karnataka, Andhra Pradesh, on the summits of the Western and Eastern Ghats. 2. Name the type of soil found on the summits of the Eastern Ghats. Laterite soil. 3. Why is laterite soil unsuitable for agriculture? -unsuitable due to its high content of acidity and inability to retain moisture. It is poor in nitrogen and lime. 19
    • 4. What is laterite soil? Laterite soils are those formed under alternating wet and dry spells. They are composed of a mixture of hydrated oxides of aluminium and iron. They are poor in nitrogen, potash, lime. They are low in fertility but respond favourably to manuring and leaching of soil of its nutrients. 5. In which parts of India are laterite soils found? They are found in Kerala, Karnataka, Maharashtra, A.P., Orissa and on the summits of Eastern and Western Ghats. 6. What is the meaning of leached soil? It is the process by which soluble substances such as organic and mineral salts are washed out of the upper layer of soil into a lower layer by percolating rainwater 7. Name one Indian soil that has been formed by leaching. Laterite soil. 8.Name the soil known for its self-ploughing quality and capacity to hold moisture. Name one cash crop for which it is most suited? Black soil. The cash crop that grows best is Cotton/sugarcane. 9. How does the soil of the Ganga-Yamuna plain differ from that of central Maharashtra? Soil found in Ganga-Yamuna plain is alluvial soil, whereas soil found near central Maharashtra is black soil. Alluvial soil is transported soil. Black soil is formed in situ. 10. State one feature of Mountain soil. Name two crops that can be grown on it. * One feature of mountain soil is- it is rich in Iron but poor in lime. * It is coarse in texture, friable in nature. * Good for growing tea, coffee and fruits such as apples, plums, cherries. 11. Which soil is found suitable for growing coffee in Karnataka? The soil found suitable for growing coffee is Mountain soil or Laterite soil, or Red soil. 12. Name the soil which is formed due to high temperatures and heavy rainfall with alternating wet and dry periods. Name two states where this type of soil is found. Ans: Laterite soil. Found in Andhra Pradesh, Tamil Nadu, Assam and Kerala. 13. Write a short note on conservation of soil. 20
    • Ans: Soil conservation is a set of management strategies for prevention of soil being eroded from the earth’s surface or becoming chemically altered by overuse, salinization, acidification, or other chemical soil contamination. The following are the methods of soil conservation: 1) Afforestation: In some areas the original vegetation cover has been removed such as the Shiwalik Hills. In such areas afforestation and reforestation is needed to hold the soil. 2) Controlled grazing: The number of cattle grazing the slopes should be according to the carrying capacity of pastures. 3) Terraced agriculture: Slopes must be cut into a series of terraces for cultivation so as to slow down inflow of rainwater. 4) River dams: River dams should be built in the upper course of rivers to control floods and check soil erosion. 5) Contour ploughing: Contour ploughing terracing and bunding should be done to check soil wash on slopes. Ploughing is done at right angles to the hill slopes. 6) Crop methods: Crop rotation system should be adopted and the land should be allowed fallow for sometime. 7) Other methods: In areas of heavy rain, basin type of cultivation should be adopted. Tall trees should be grown as wind and shelter breaks belts in areas of strong winds. What is soil? Soil is a combination of four constituents: mineral material (sand, silt, clay and rocir and water. Soil is made from the breaking down of rocks and organic matter by physical, chemical and biological weathering processes. What do you understand by ‘pedology’? It is a branch of science which studies the soil. Xxxxxxxxxx 21
    • EXTRA QUESTIONS 1. a. Give a single word for the following: (2) i) The organic matter present in the soil formed by the decomposition of plants and animals - Humus ii) The soil which are carried down by agents of gradation such as river, wind – Transported soil. iii) The loose rock material, together with humus, forming the uppermost layer of the earth’s crust and serving as a source of food and moisture for plants”. soil iv) The process of percolation by which valuable mineral nutrients are washed down from the top layer of the soil only to deposit them in the lower layers, making thereby the topsoil infertile. b) How does the soil of the Ganga Yamuna plain differ from that of central Maharashtra? (2) * Soil found in Ganga-Yamuna plain is alluvial soil, whereas soil found near central Maharashtra is black soil. 22
    • * The soil of Ganga-Yamuna plain has been formed from the sediments deposited by rivers which are rich in potash but poor in nitrogen whereas soils of central Maharashtra have been formed due to the weathering of the lava which contains potassium, iron, magnesium and humus. * The soil of Yamuna-Ganga plain is suitable for the cultivation of a wide varieties of crops, i.e. rice, wheat, sugarcane, oil seeds, etc whereas the soil of the central Maharashtra region is most suitable for cotton crop. c. Give reasons: (3) Alluvial soil can hold moisture and is very fertile: Since the soil is made up of fine particles, it can hold a lot of water. Black soil needs to be tilled after the first rain: When wet, the soil becomes sticky and is difficult to work with. So the soil needs to be tilted after the first rains. Red soil is ideal for dry farming: It is suited for dry farming as it does not require much moisture. d. i) Name any two regions where coastal alluvium is found. ii.) Why is deltic alluvium more fertile than coastal alluvium?(3) Ans.c. i) The coastal alluvium occurs in the coastal strips of peninsular India and the plains of Gujarat. ii. Deltic alluvium (Khaddar) is more fertile than coastal alluvium (Bhangar) as new layers are deposited year after year during monsoonal floods. e. State any three factors which affect the soil formation. (3) Ans: i) WEATHERING: Extremes of temperature (as in the day and night temperatures in deserts), freezing and thawing of ice break down rocks, and favour soil formation. ii) VEGETATION: The growth and decay of vegetation determines the humus content of the soil. Roots of plants penetrate the soil and make it porous. iii. Bio-chemical processes taking place in the soil: Bacteria and fungi cause the decay of plants and animal remains. Some transform the atmospheric nitrogen into soil nitrogen. iv. CLIMATE : Climate is the most important single factor in the soil formation. the amount of rainfall and range of temperature are the most important climatic factors affecting soil formation. v. RELIEF: Low relief areas generally experience deposition and have deep layer of soil whereas the soils are generally shallow in the plateau areas. vi) PARENT MATERIAL: Parent rock determines the composition of soil. f. What is soil? How soil is important to man? (2) 23
    • Soil is the thin top cover of earth’s crust composed of mineral particles, humus, water and air in which plant grows. Most of our food items like cereals, pulses, fruits, vegetables, meat, eggs, milk, clothing, etc., are obtained directly or indirectly from the soil. A large number of human and economic activities depend on the soil. Fertile soil attracts a large number of people and human settlements. g. State the two most important factors that determine the types of soils found in India.(1) Parent material, relief, climate and natural vegetation are some of the major factors determining the types of soils found in India. h. What do you understand by humus? (1) It is the organic matter which is formed by the decomposition of plant remains, dead animals and manure. Humus content determines the fertility of the soil. i. Give reason: (5) i) Alluvial soil can hold moisture and is very fertile:- Alluvial soil can hold moisture and is very fertile because the alluvial soil is made up of fine particles. The soil is very fertile because it is rich in mineral nutrients like potash and lime. ii) Black soils needs to be tilled after the first rain: The soil is sticky and difficult to work unless tilled immediately after the first rain. iii) Red soil is ideal for dry farming: Red soil is ideal for dry farming because it does not require much moisture. iv) The percentage of organic matter in desert soil is very low:- The percentage of organic matter in desert soil is very low because of the dry climate and absence of vegetation. v) Red soil is less fertile:- Red soil is less fertile because it is deficient in phosphorous, nitrogen, lime and humus. j. Distinguish between ‘Khaddar’ and ‘Bhangar’. (3) Bhangar (old) Khaddar (new) It is non-porous, clayey soil It is porous and loamy soil. It is found higher up in the plains at river terraces away from rivers. It is found in the lower level in the plains near the rivers. It is less fertile as compared to khaddar It is more fertile compared to bhangar. This is due to deposition of new layers by floods during monsoon It belongs to old alluvium. It belongs to new alluvium. 24
    • 2. a. Read the feature of the soil carefully and identify the soil: (2) i) It develops insitu as a result of leaching - Laterite soil ii) It develops on crystalline igneous rocks. - Red soil iii) It develops insitu from volcanic rocks. - Black soil iv) It is a transported soil and is formed by river sediments. – Alluvial soil Mention any four human factors responsible for soil erosion. (2) Deforestation, faulty methods of agriculture, urbanisation and industrialisation. Name any two crops association with following soils: (3) i. Alluvial soil - Rice and sugarcane, wheat ii. Red soil - Rice and wheat iii. Black soil - Cotton and sugarcane iv. Desert - Barley and ragi v. Laterite - coffee and tea d. With reference to the type of soil only, state why: (3) i, Jowar is grown in Maharashtra. – Jowar is grown in Maharshtra because of its black soil. ii. Bajra is grown in Rajasthan – Bajra is grown in Rajasthan because of desert soil. iii) Sugarcane is grown in Uttar Pradesh – Sugarcane is grown in Uttar Pradesh because of well drained alluvial soil. e. Name four broad types of soils found in India. (2) Red, black, alluvial and laterite soil. f. Mention any three characteristics of the northern plains. (3) * These are constituted by two large river basins i.e. the Indus river basin and the Ganga-Brahmaputra basin. * These are very fertile plains. * These plains support some of the highest population densities. g. What is the importance of Northern plains for the Indian economy?(3) 25
    • * The plain supports some of the highest population densities depending upon purely agro-based economy in some of these areas. The extensive use of irrigation has made some parts of this plain, especially Punjab, Haryana and western part of Uttar Pradesh the granary of India. * The entire plan except the Thar Desert has a close network of roads and railways which has led to large scale industrialization and urbanization. h. Distinguish between Alluvial soil and Black soil keeping in mind texture, minerals and crops associated. (3) ALLUVIAL SOIL BLACK SOIL 1. TEXTURE: Coarse, in upper regions, medium in the middle and fine in the lower regions. Fine grained, moisture retentive. 2. MINERALS: Rich in potash. Rich in lime, iron and potash. 3. CROPS: Rice, wheat, and sugarcane. Cotton, sugarcane and tobacco. 4. FORMATION: It is formed due to deposition of sediments by the river. It is formed due to the weathering of the lava. 5. AREA: It covers more than 45% of the total land area of the country. It covers only 16% of the total land area of India. 6. FERTILITY: The soil is very fertile. The soil is less fertile as compared to alluvial soil.. i. Explain the formation of soil. Name three various forces of nature which contribute to the evolution of soil. (3) Soils are derived from parent rock material through the process of break up or wear and tear. Various forces of nature i) changing temperature, ii) running water, iii) wind contribute to the evolution of soil. j. State two main differences between alluvial soil and red soil. (2) Alluvial soil 26
    • Red soil Most of the alluvial soil is derived from the sediments deposited by the rivers. Most of the red soil has been formed due to weathering of ancient crystalline and metamorphic rocks. Alluvial soil is highly moisture retentive. Red soil is not moisture retentive. Alluvial soil is very fertile as it is rich in mineral nutrients like potash and lime. It is less fertile as it is deficient in phosphorous, nitrogen, lime and humus. k. Mention two ways by which soil can get nitrogen. (2) Soil can get nitrogen by : * By growing pulses as there are certain bacteria in the roots of pulses which have the ability to fix atmospheric nitrogen to form nitrogen compounds. * By applying NPK fertilizer or by adding manure, by crop rotation. l. Which minerals are found in regur soil? (1) Iron, lime, potash, calcium carbonate and magnesium carbonate are found in regur soil. m. Distinguish between Transported and ‘in-situ’ soils: (2) Transported soils In-situ soils These soils are carried down by the natural agents like water and winds. These soils are found where they are formed. Example: Alluvial soil Example: Black soil n. Distinguish between soils of Northern Plains and Soils of the Deccan Plateau. (3) SOILS OF NORTHERN PLAINS SOILS OF THE DECCAN PLATEAU Soils of the Northern plains are alluvial soils. Soils of the Deccan Plateau are Black soil or red soil. 27
    • They are very fertile, suitable for the cultivation of rice, wheat, sugar-cane, cotton, jute, oil seeds, etc They are also fertile, suitable for the cultivation of cotton, sugarcane, rice, tobacco, etc o.Distinguish between Inland alluvium and Coastal alluvium: (3) Inland Alluvium Coastal Alluvium Inland alluvial soils are found in the Indus river plains and the Ganga-Brahmaputra river plains. Coastal alluvial soils are found on the coastal regions of peninsular India. They are found in Punjab, Haryana, U.P. , Bihar, West Bengal. They are found in the Gujarat plains. p. Distinguish between Regur soils and Laterite Soils.(3) REGUR SOILS LATERITE SOILS Regur soils are black in colour. Latertite soils are red in colour. They are formed due to weathering of lava-flow rocks. They are formed due to weathering lf laterite rocks. They are of fine texture. They are of coarse texture. They are clayey in nature. They are soft and friable. They are rich in lime and magnesium. They are deficient in lime and magnesium. Retention of moisture is high. They do not retain moisture. Regur soils are very fertile. Laterite soils are not fertile. 28
    • They are suitable for cultivation of cotton, sugarcane, wheat, jowar, gram and linseed. They are suitable only for special crops like coffee, cashewnuts, tapioca , etc q. Distinguish between red and laterite soil. (2) Red soil Laterite soil Most of the red soil has been formed due to weathering of igneous and metamorphic rocks. ii. Rice, wheat, sugarcane and cotton can be cultivated. Most of the laterite soil has been formed due to leaching. Coffee, rubber and cashew are some of the crops cultivated on this soil. 3.a. Write two differences between intensive and extensive farming. (2) INTENSIVE AGRICULTURE EXTENSIVE FARMING 1. Production is increased by using higher inputs and new techniques. 1. Production is increased by bringing more and more area under cultivation. 2. This is done in thickly populated areas where no more land is available. 2. This is done in thinly populated areas. b. Give a single word for each of the following: (1 mark each) * The loose rock material , together with humus, forming the uppermost layer of the earth’s crust and serving as a source of food and moisture for plants. – Answer: Soil or Top soil * The process of percolation by which valuable mineral nutrients are washed down from the top layer of the soil only to deposit them in the lower layers, thereby making the top soil infertile. – Ans: leaching. c. Name the type of soil which is : (1 mark each) i) Useful for the cultivation of jute. - Alluvial soil ii) Formed by decomposition of metamorphic rocks. – Red soil iii) Covers 40% of the land area of India. - Alluvial Soil iv) Develops on old crystalline rocks under moderate to heavy rainfall. - Red Soil v) Alkaline in nature and contains a high proportionof salts. - Desert Soil. 29
    • vi) Agriculturally most significant - Alluvial Soil vii) formed due to volcanic activity - Black/Regur soil viii) Rich in iron but poor in silica – Laterite soil ix) rich in humus - Alluvial soil of the Ganga Delta x) Rich in potash but poor in phosphorus – Alluvial Soil xi) Rich in lime and potash but deficient in phosphorous and nitrogen – Laterite Soil d. What is dry farming? (1) Dry farming is the method of farming adopted in certain region having inadequate rainfall and devoid of irrigation facilities by conserving moisture in the soil and by raising drought-enduring crops. e. Explain the following terms: (1 mark each) i) In situ : - The soils which are found where they are formed. They are also called residual soil. e.g. Black Soil. b. Transported Soil: These are soils which are carried down by agents of gradation such as river, wind. e.g. Alluvial Soil c. Badland: it is a region with a large number of deep gullies which cannot be put to any use till soil restoration takes place. d. Soil profile: A soil profile is a section showing the successive layers of the soil which would appear if you cut straight down into the soil. e. Humus: It is the organic matter present in the soil formed by the decomposition of plants and animals. Humus content determines the fertility of the soil. f. Parent Rock: The weathered and partially broken rock from which a soil is formed is termed as parent rock. g. Soil Texture: The proportion of the various particle sizes in a soil. h) Deccan Trap: The word ‘trap’ is Swedish which means steps. The term describes the step-like rock formation that covers the north-western part of the Deccan Plateau. f. Place two broad categories the soils of India on the basis of their formation. (2) i) RESIDUAL SOILS: These are found where they are formed, hence called ‘in situ’. Black soil, Red Soil, and Laterite soil are the examples of residual soils. ii) TRANSPORTED SOILS: These are carried down by agents of gradation such as rivers, and wind. Alluvial soil and Loess are the examples of transported soils. The most important transported soil in India is alluvial soil. The states are West Bengal and Bihar. 30
    • g. Name the soils found abundantly in the following regions: (1 mark each) i) Hills of Assam and Meghalaya – Mountain Soil ii) Coastal strip of Deccan Plateau – Coastal alluvium iii) South-Western parts of Punjab – Desert Soil iv) Chhotanagpur Plateau – Laterite Soil v) Delta of Krishna - Deltaic alluvium vi) Sunderbans of West Bengal – Deltaic alluvium 4a) Explain the following terms: i) Soil Erosion ii) Conservation of Soil iii) Deforestation iv) Contour Ploughing v) Strip Cropping vi) Crop Rotation (1 mark each) i) SOIL EROSION: It is the removal of topsoil by different agents of weathering such as running water, wind, over grazing and faulty methods of agriculture used by farmers. ii) CONSERVATION OF SOIL: Conservation of soil is an effort made by humans to prevent soil erosion in order to retain fertility of soil. iii) DEFORESTAION: The removal of trees of an area of land by felling or burning is called deforestation. The process of deforestation is deliberate in order to make the land available for other uses. iv) CONTOUR PLOUGHING: It is the cultivation of soil according to contour lines, i.e. at the right angles to the hill slopes. v) STRIP CROPPING: It is the cultivation of crops in strips to check the fast-blowing winds. vi) CROP ROTATION: It is the cultivation of crops in a year in such a sequence that the fertility of the soil is not reduced. b.. Explain the need for soil conservation in India. State two methods of soil conservation. (3) i) Soil is the most precious asset of India. More than 60% of the population is dependent on agriculture. ii) Protective soil alone ensures progress of agriculture, forests and industrial development. METHODS: i) Afforestation ii) Proper farming technique iii) shelter belts iv) terraced cultivation c. Name two important agents of erosion. For each, state one method of controlling the erosion caused. (3) Two important agents of erosion are : i) Running water ii) Faulty agricultural activities. iii) wind 31
    • RUNNING WATER: Construction of dam, river embankment , terrace farming and afforestation can control the soil erosion caused by running water. FAULTY AGRICULTURAL ACTIVITIES: Scientific methods of cultivation like contour ploughing, terrace farming and conservation of moisture is the important conservative measure WIND: One method of controlling erosion caused by wind is planting of shelter belts alongside of desert. d. ‘Proper farming techniques can help in soil conservation.’ Explain by giving three examples. (3) * Terracing of hill slopes is effective in controlling soil erosion. Terracing is cutting into the hill slopes in a series of large steps made up of flat fields. * Constructing bunds across hill slopes and filed boundaries is effective in reducing soil erosion. Bunds are low mud walls or embankments that help to obstruct the flow of water. * Contour ploughing should be practised. It involves ploughing along the outline of the field in a circular manner. This prevents the soil from being washed away by running water. e. Differentiate between sheet erosion and gully erosion. (2) 1. When top soil gets eroded from very large areas due to fast flowing rivers it is called sheet erosion. Gully erosion occurs when running water etches out deep rivers creating a badland topography in an otherwise normal landscape. 2. The unprotected lands are most susceptible to sheet erosion. Sheet erosion is particularly harmful because it removes the top layer which is finer and fertile. The main cause of gully erosion is the removal of vegetation, particularly of trees with their widespread binding roots. Gully erosion is also responsible for the formation of ravines. f. Difference between Sheet erosion and wind erosion and sheet erosion and gully erosion.(3) SHEET EROSION WIND EROSION It is caused by running water or heavy rain . It is caused by wind.. It is found in hilly regions. It is found in desert and dry regions. Due to high speed of water, a layer of the soil on the surface is removed over a large area. Under this top fertile soil is blown away by high speed wind. 32
    • It is the first stage of water erosion. It is the third stage of water erosion. It is caused by running water or heavy rain in hill regions which lead to the removal of a large area by running rainwater through steep slopes. Gully erosion is caused due to running down of water in distinct path which results in the removal of soil in the path. Sheet erosion is also harmful since it removes fertile top soil of the land. Gully erosion is harmful since it cut up agricultural land. g. Man is largely responsible for soil erosion. How?(2) Soil erosion is the removal of soil by the forces of nature, particularly wind and water. Soil erosion mainly takes place due to man’s activities such as deforestation, overgrazing of cattle, faulty methods of cultivation. h. What is conservation of soil? Why is it necessary? (3) It is an effort made by man to prevent soil erosion, or at least to reduce the rate of soil erosion, to retain the fertility of the soil. It is necessary because soil is our most important natural resource. It alone assures prosperous agriculture. i. Explain the following terms: (1 mark each) i) Soil Erosion. ii) Conservation of Soil iii. Soil Texture iv. Contour Ploughing v. slip erosion vi. Strip cropping SOIL EROSION: It is removal of topsoil by different agents of weathering such as running water, wind, overgrazing and faulty methods of agriculture used by farmers. CONSERVATION OF SOIL: Conservation of soil is an effort made by humans to prevent soil erosion in order to retain fertility of soil. SOIL TEXTURE: soil texture refers to the size of particles in soil. The texture of soil ay be gravel, sand, silt or clay. CONTOUR PLOUGHING: It is a farming technique which is used in hilly areas to prevent soil erosion. It involves ploughing along the outline of the fields in the circular manner. SLIP EROSION: During heavy rains, water filters into the soil until it is unable to penetrate further by the underlying impervious rocks. 33
    • STRIP CROPPING:It is a farming technique in which different kinds of crops are grown in alternate rows instead of leaving strips of land uncultivated. j. What are the different types of soil erosion?(3) The types of soil erosion by different agencies are as follows: Soil erosion by running water: i) GULLY EROSION: This type of erosion is occurred due to heavy rainfall in hilly regions and as a result deep gullies are formed on bare soils when water gushes down. ii) SHEET EROSION: This type of erosion takes place due to slow removal of a thin layer of soil by running water on account of destruction of the vegetation. iii) LEACHING: It occurs during the rainfall when the nutrients in the soil are washed away. iv) RILL EROSION: In this type of erosion finger like rills appear on the surface of the land which are formed due to cutting of soil by flowing down of water. v) STREAM BANK EROSION: It takes place on the banks of rivers and stream by the flowing water. vi) SHORE EROSION: It occurs due to tidal water along the coast during the rainy season. k. How does the soil of the Ganga-Yamuna plain differ from that of central Maharashtra? (2) Soil found in Ganga-Yamuna plain is alluvial soil, whereas soil found near central Maharashtra is black soil. Alluvial soil is transported soil. Black soil is formed in situ. l. Define : Gully erosion ii) Sheet Erosion (1 mark each) GULLY EROSION: Gully erosion takes place when running water cuts deep ravines in the absence of vegetation. This type of erosion makes soil unfit for cultivation. SHEET EROSION: When top soil gets eroded from very large areas due to fast flowing rivers or due to heavy monsoons, it is called sheet erosion.. Soil erosion by wind: Soil erosion by wind mainly occur in dry areas such as western Rajasthan and Southern Punjab where strong wind blows away the loose sand in the form of dust and as a result top soil is removed. m. What are the causes of soil erosion in: (1 mark each) i) Shiwaliks or the Outer Himalayas: Destruction of vegetation is the main cause of soil erosion in hilly areas because when vegetation is removed, the soil surface becomes loose and is more easily removed by running water.Due to this , a large amount of debris domes down the slopes of Shiwaliks and chokes up the rivers and causes floods. Hence, land slides and land slips are very frequent. ii) North-Eastern parts of India: Heavy rainfall which leads to frequent floods is responsible for soil erosion in Assam, West Bengal and hilly regions of North-east. 34
    • iii) Arid regions of India: In deserts and dry regions like Rajasthan, Southern Punjab and south-western areas of Haryana, where there is little or no vegetation, wind is the most powerful agent of soil erosion, blowing away fine particles of sand depositing them in other areas making both areas unproductive. iv) Hilly areas of the South: In this region, steep slopes, heavy rainfall and unscientific methods of cultivation are responsible for the soil erosion. n. Name a part of India where: (1) a. Wind is the main agent of erosion - Rajasthan b. Water is the main agent of erosion - Meghalaya o. How is the migration of sand dunes from Thar desert checked? (1) By building shelter belts, the migration of sand dunes from Thar desert checked. p. Name any four states which have been affected by gully erosion. (1) U.P. , M.P. , Bihar and Rajasthan. q. What are the main causes of soil erosion? (2) Main causes of soil erosion are: * Steep slopes * Deforestation * Torrential rainfall * Strong winds * Over grazing * Unscientific methods of cultivation r. What are the different methods of soil conservation? (3) AFFORESTATION: Afforestation or planting of trees in deforested areas saves the soil from erosion caused both by water and wind. CONSTRUCTION OF CHECK DAMS: is an important method of checking soil erosion in the upper course of the rivers. OVERGRAZING should be checked. Grazing should be limited according to the size of the pasture. GULLIES should be plugged by stone dams, wire netting or by raising trees across gullies to check the flood water. SHELTER BELTS of trees and shrubs should be planted to check wind velocity in arid regions. PROPER FARMING TECHINIQUES, i.e. strip cropping, contour ploughing and terracing of hills should be adopted for soil conservation. s. Discuss important soil conservation measures undertaken by the Government of India.(3) 35
    • * A scheme for reclamation and development of ravine areas was launched in 1987-88 in Madhya Pradesh, Uttar Pradesh and Rajasthan. The scheme for control of shifting cultivation is being implemented since 1994-95. In urban area, rain water harvesting is a means of checking soil erosion besides recharging ground water. The centrally sponsored scheme of Integrated Watershed Management in the catchments of flood-prove rivers was launched during Sixth Plan in eight flood-prove rivers of the Gangetic Basin covering seven States and one Union Territory. t. Name two methods of soil conservation adopted in the mountainous areas. (1) i) Terrace cultivation ii) Contour ploughing u. State how destruction of vegetation cover increases the soil erosion. (2) Vegetation cover protects the soil from erosion as the roots of the trees and plants hold the soil particles together and strengthen the soil. Therefore, the destruction of vegetation cover increases the soil erosion. RED SOIL 5.a. How is Red Soil formed? Mention two important properties of Red Soil. (2) Red soil is formed due to weathering of ancient crystalline and metamorphic rocks of the Peninsular plateau. The properties of red soil are: * Red soils are rich in iron contents , hence, they are red in colour. * It is loamy in deep depressions and in uplands , it consists of loose gravel – a highly coarse material. * It is deficient in lime, nitrogen, phosphorous and humus but fairly rich in potash. * The productivity of the red soils increases with regular use of fertilizers. * They are porous in nature but not retentive to moisture. * They are suited for dry farming as it does not require much moisture. b. Why are red soils not suitable for agriculture? or State two reasons for the low productivity of red soil. (2) Red soils are not suitable for agriculture because these are not retentive of moisture and are deficient in nitrogen, lime, phosphoric acid and humus. It is light in texture. 36
    • c. With reference to red soils in India, i) Name two states where it found. ii. State two disadvantages of this soil. (2) It is found in Tamil Nadu/Karnataka, Orissa, Andhra Pradesh, Goa. i. It is poor in humus, nitrogen, lime, phosphorus ii. It is coarse, porous, crumbly and does not retain moisture . It needs irrigation support for cultivation as it is loose and aerated. d. Red soil is red in colour. Give reason. (1) Red soil is red in colour due to the presence of iron oxides. e. Give three reasons for the low fertility of Red soils. (3) # Red soils are less fertile as they lack nitrogenous, phosphorous and organic matter. # On uplands, they abound in loose gravels and are less fertile. # Their coarse grains lack sustenances of fertility. f. Where are Red soils found in India? (1) Red soils are found in the states of Kerala, Tamilnadu, Karnataka, Goa, eastern part of Andhra Pradesh, Orissa, and on the Chhota Nagpur Plateau of Jharkand. g. Mention some properties of Red soils. (3) * Red soils are formed in situ by weathering of the ancient crystalline and metamorphic rocks. * Red soils are rich in iron contents, hence, they are red in colour. * The productivity of the red soils increases with regular use of fertilizers. * These soils are deficient in nitrogen, lime, phosphoric acid and humus. * They are rich in potash, porous, friable but not retentive of moisture. 37
    • * They are suited for dry farming as it does not require much moisture. i. Name the state in India which mostly has red soil. (1) Tamilnadu and Karnataka j. State two disadvantages of red soil. (2) * The soil lacks in nitrogen, organic and phosphoric acid contents and is less fertile. * Red soils are porous in nature but not retentive to moisture. k. Give three reasons for the low fertility of the Red soil. (3) * Red soils are less fertile as they lack nitrogenous, phosphorous and organic matter. * On uplands, they abound in loose gravels and are less fertile. * Their coarse grains lack sustenance of fertility. BLACK SOIL 6.a. Mention two characteristics of black soil. Why is this soil agriculturally important? (2) # The black soils are made of extremely fine material. # These soils are rich in nutrient. # It develops cracks when dry which helps in aereation. # It has a self-ploughing quality. It is agriculturally important because it is rich in lime,iron and potash. Because of high clay content, these soils expand when wet and become difficult to plough. During the dry season, the black soils shrink and develop big cracks which help in air circulation. The moisture-retentiveness makes them suitable for dry farming. Black soil is also called regur soil or cotton soil. Cotton is the most important crop grown in these soil. After alluvial soils it occupy largest areas in the country. It covers 16% area of the country. b. Name an area of black soil in India. Mention two crops grown in this soil.(2) Deccan Plateau is an area of black soil in India. Two crops grown in this soil are cotton and sugarcane. c. Black soils are called ‘Black Cotton Soils’. Why? (1) Black soils are called ‘Black Cotton Soils’ because these soils are most suitable for the cultivation of cotton. 38
    • d. How black soils or Black cotton soils or Regur soils are formed? Which minerals are found in regur soil? Name the most important crop grown on it. (3) Black soils are formed in situ, that is , formed where they are found. These soils are formed from solidification of basic lava spread over large areas of Deccan Plateau during volcanic activity. Hence, these are formed by weathering of Deccan Trap. Lime, iron, potash, alluminium, calcium and magnesium carbonate. It is deficient in phosphorous, nitrogen and organic matter. The most important crop grown on it is cotton. e. Name the soil known for its self-ploughing quality and capacity to hold moisture. Name one cash crop for which it is most suited? (2) Black soil. The cash crop that grows best is Cotton/sugarcane. f. How is Regur soil formed? Mention four important properties of Regur Soil. Name two states where Regur soils are found. Name two cash crops grown best on these soils. (3) These soils have been formed due to the solidification of lava spread over large areas during volcanic activity in the Deccan Plateau. Features: * Black soils are well known for its capacity to hold moisture * It is a deep fine grained soil * They vary in colour from deep balck to chestnut brown. * They are rich in lime, calcium, iron, magnesium and potash and deficient in phosphorous, nitrogen and organic matter. * They are made of extremely fine material i.e., clayey material. * These soils are best-suited for cotton and sugarcane cultivation. * Black soils are widely spread over the Deccan Plateau, comprising large areas of Maharashtra, Gujarat, and Madhya Pradesh. * They are also know as Regur soils in Maharashtra and Black Cotton soils in Peninsular India. States – Maharshtra and Gujarat Cash crops – cotton and sugarcane. 39
    • g. Large tracts in Mahatrashtra are covered with Black soil. Give reason. (1) Large tracts in Maharashtra are covered with Black soil because it is made up of lava tracts which after weathering is reduced to black soil. h. Give two characteristic features of the soil found most suitable for growing cotton and sugarcane in Maharashtra. (2) The most suitable soil for growing cotton and sugarcane in Maharasthtra is black soil. Its characteristics are: * It is rich in iron, potash, lime, calcium carbonate, aluminium and magnesium. * Its self-ploughing characteristic helps in aeration due to deep and wide cracks during dry season. * highly retentive of moisture * Sticky when wet, dry when fine grained. * It is volcanic in origin. i. Name a rock from which black soils are formed? Write on characteristic of this soil? What is the advantage of ‘clay’ contents in Black soils.(2) Igneous rock. The soil has a great capacity to retain moisture. Clay contents increase the capacity of black soils to retain moisture. During dry period, they develop deep cracks which help in aeration or air circulation. j) Name one crop & one mineral associated with Black soil. Name two states in India where this type of soil is found. (2) Crop: Cotton, Mineral: Iron State: Maharashtra and Madhya Pradesh k. Name one soil of volcanic origin commonly found in India. (1) The black soils are of volcanic origin. l. Mention an two advantages of the black soil. OR What is the advantage of ‘clay’ contents in black soils? (2) * The black soil has the ability to retain moisture which is due to its clay contents. * During dry period, they develop deep cracks which help in aeration or air circulation. m. Name the soil which occupies largest area after alluvial soil. (1) Black soil or Regur soil. n. What are the advantages and disadvantages of black soil or clayey soil? (2) 40
    • ADVATAGES: * As it has the ability to retain moisture, so the moisture is released to the plants during dry spells * During dry period, it develops deep cracks which help in aeration or air circulation.. DISADVANTAGES: Very difficult toplough when wet because it becomes sticky when wet. ALLUVIAL SOIL 7.a. How is alluvial soil formed? Why is this soil agriculturally important? (2) Alluvial soil is formed by the deposit of silt brought down by rivers. This soil is agriculturally important because it is very fertile.It is rich in potash, humus and lime and soil is renewed every year by rivers. b. What type of soil is widely distributed over the Gangetic Plain? (1) Alluvial soil is widely distributed over the Gangetic Plain. c. Name the transported soil most widely found in India. State the two sub cateogories into which it is generally divided. What are local names and which one of them is superior to the other? (2) Transported soil most widely found in India is Alluvial soil. Sub-categories – Old alluvium/Bangar, New alluvium/Khadar. Khadar is more superior to them, as the floods replenish it. d. What are the differences between the alluvial soil found in the upper course of rivers and that found in the lower courses? (2) In the upper course of the river, the soil particles are somewhat bigger in size and are more coarse. Soil particles are large and not uniform. The soil in this region is less fertile. In the lower course of the river, the soil particles are fine and less coarse. Silt and clay are found in abundance. the soil in this region is more fertile. e. By what other name alluvial soil is known? Justify your answer. (1) Riverine; because it is mainly found in river basins. f. How are the soils of Gangetic Plains formed? (1) Alluvial soil is formed by the deposit of silt brought down by the rivers Ganga and Brahamaputra. This soil is agriculturally important because it is very fertile.It is rich in potash, humus and lime and soil is renewed every year by rivers. g. On regional level what are three different types of alluvium? (3) # Deltaic alluvium in West Bengal and Orissa 41
    • # Coastal alluvium in Peninsular India # Inland alluvium in Punjab, Haryana, Delhi, Uttar Pradesh, Bihar, West Bengal, Assam and Orissa. h. Mention the main characteristics of alluvial soils. (3) # Alluvial soils are transported soils as they have come into existence because of the silt deposition brought by rivers and wind. # They are very fertile as they are rich in minerals like potash and lime. # They are fine- grained. # They are rich in humus contents. # the soils of the Ganga valley are faint yellow and consist of a mixture of sand, clay and organic matter. # The soils of the Godavari and Krishna valleys are clayey, non-porous and brown in colour as these rivers flow over black soil. i. What is the difference between Inland alluvium and Coastal alluvium? (2) Inland alluvium is the soil found on the plains of the Indus, the Ganga and the Brahmaputra rivers. Coastal alluvium is of tidal origin and is found in coastal strips of Peninsular India. LATERITE SOIL 8.a. Name one area where laterite soils is found on large scale. (1) Laterite soil is found in parts of Kerala, Goa, Tamil Nadu, Karnataka, Andhra Pradesh, on the summits of the Western and Eastern Ghats. b. Name the type of soil found on the summits of the Eastern Ghats. (1) Laterite soil. c. Name the soil which is formed due to high temperature and heavy rainfall with alternating wet and dry periods. Name two states where this type of soil is found. (1) Laterite soil develops as a result of leaching in areas of heavy rain. The soil is found in Tamil Nadu and Orissa. d. What is laterite soil? (1) Laterite soils are those formed under alternating wet and dry spells. They are composed of a mixture of hydrated oxides of aluminium and iron. They are poor in nitrogen, potash, lime. They are low in fertility but respond favourably to manuring and leaching of soil of its nutrients. e. In which parts of India are laterite soils found? (1) 42
    • They are found in Kerala, Karnataka, Maharashtra, A.P., Orissa and on the summits of Eastern and Western Ghats. f. What is the meaning of leached soil? (1) It is the process by which soluble substances such as organic and mineral salts are washed out of the upper layer of soil into a lower layer by percolating rainwater g. Name one Indian soil that has been formed by leaching. (1) Laterite soil. h. Name the soil which is formed due to high temperatures and heavy rainfall with alternating wet and dry periods. Name two states where this type of soil is found. (2) Laterite soil. Found in the highland of Western Ghats, Andhra Pradesh, Tamil Nadu, Assam and Kerala. i. With which type of soil is the term leaching associated? Name two regions in India where this type of soil is found. (2) Ans: Leaching is associated with laterite soil. TWO REGIONS: 1. Assam Hills 2) Hill summit of Eastern and Western Ghats j. How laterite soils formed? Why is it acidic in nature? Give one difference between laterite soil and regur soil. (3) Laterite soil is formed by weathering of rocks under monsoon climatic conditions. It is acidic in nature because alkalis are leached out. Laterite soil is of coarse texture while Regur soil is fine textured. k. Give one difference between Laterite soil and Regur soil. (1) Laterite soil is of coarse texture while Regur soil is fine textured. l. Mention two important characteristic of laterite soil. (2) * Laterite soils are leached soils because alternating dry and wet spells cause the soluble silica to be removed. * Laterite soils are acidic in nature, coarse and crumbly in texture. * Due to lack of nitrogen, potassium and organic elements, laterite soils lack fertility. * They are poor in most minerals. 43
    • * They are porous in nature. * These soils support pastures and scrub forests. * With the use of manure, coffee, rubber, cashew, etc., can be grown on these soils. m. Why is laterite soil unsuitable for agriculture or less fertile? Name an area in India where this soil is found. (2)  Laterite soil is unsuitable for agriculture due to its high content of acidity and inability to retain moisture.  It is poor in nitrogen, phosphorous, potash and lime.  It is formed as a result of leaching which r enders the topsoil infertile. The soil becomes hard like a brick when it dries up. n.Give two reasons responsible for low fertility in laterite soil. (2) * It is formed due to leaching. * It is poor in lime, phosphorous, nitrogen and potash which are fertile ingredients of a rich soil. o. Name the type of soil found on the summit of the Eastern Ghats. How is it formed? (2) Laterite soil. Laterite soil is formed by leaching. p. Why is laterite soil found in the Western Coastal regions? (1) These regions receive very heavy rainfall which results in intense leaching and helps in the formation of laterite soil. q. Define the term ‘leaching’. In which region, south of the Tropic of Cancer can one find soil formed by leaching? Name the soil which is formed as a result of leaching. Leached soils are red in colour. Why? (4) Leaching is the movement of the organic matter and mineral salts from the upper region of the soil into the lower region of the soil due to heavy rainfall. On the highland areas of Western Ghats, one can find the laterite soil formed by leaching. Laterite soil is formed as a result of leaching. Red colour of leached soil is due to presence of iron oxide, which is reddish in colour. r. Which soil is found suitable for growing coffee in Karnataka? In Karnataka, laterite soil is suitable for growing coffee. MOUNTAIN SOIL 44
    • 9.a. State one feature of Mountain soil. Name two crops that can be grown on it.(3) One feature of mountain soil is-  It is rich in Iron but poor in lime.  It is coarse in texture, friable in nature.  It is good for growing tea, coffee and fruits such as apples, plums, cherries. b. State one advantage of Mountain soil. (1) * It is moisture retentive. * It is rich in iron, potash, lime and humus. * This soil does not undergo leaching. DESERT SOIL 10.a. Why is the desert soil alkaline in nature? OR ‘The desert soil contains high proportion of salts’. Why? (1) The desert soil is alkaline in nature as there is no rainfall to wash away and dissolve soluble salts. b. Why are desert soils coarse? Why are they not suitable for agriculture? Name two places, in India, where this soil is found. (3) Because fine topsoil particles are removed by fast-blowing winds. Because of low water retention power and very low humus content, desert soils are unsuitable for farming. However, under irrigation they can yield rich crops. Rajasthan, North Gujarat and Southern Punjab c. Give one advantage and one disadvantage of sandy soil. (1) ADVANTAGE: Plant roots are well aerated since water and air easily penetrate through the soil. DISADVANTAGE: The soil requires a lot of water as it dries up easily. d. What are the characteristics of Desert soils? (3) # These soils are coarse in texture. # They are most saline and alkaline. # The content of organic matter is low in these soils because of dry climate and lack of vegetation. # These sand and porous soils are not fertile but with irrigation crops like wheat, gram, jowar, bajra, etc., 45
    • can be grown. OBJECTIVE QUESTIONS (.5 MARKS EACH) 11.Which soil is found suitable for growing coffee in Karnataka? * The soil found suitable for growing coffee is Mountain soil or Laterite soil. 12.a.Red soil is being formed as a result of decomposition of metamorphic rocks. True or false. True b.Alluvial soil occupies the largest area in the country. True or False True c.Alluvial soil is formed by the deposition being brought down by river. True or False True d. .Black soil is a transported soil. True or False False e. .Regur soil is red in colour. True or false. False f. Black soils need to be tilled after the first rains. Because it becomes sticky in presence of the rain water. * FILL IN THE BLANKS 1. Alluvial soil is formed by the deposition being brought down by river. 2. Black soil is most suitable for the cultivation of cotton. 3. The black colour of regur soil is due to its iron content. 4. Laterite soil has been developed as a result of leaching. 5. Laterite soil is the typical soil causing for the monsoon type of climates. 6. Soil containing high proportion of salts and alkali is called saline soil. 46
    • * Name the soils 1. Rich in humus – Mountain soil 2. Rich in potash, poor in phosphorus – Alluvial soil 3. Rich in iron, poor in silica – Laterite soil 4. Rich in lime and potash but deficient in phosphorus and nitrogen – Black soil 5. Contains high proportion of soluble salts – Desert soils DEFINE SOIL EROSION: It is the removal of topsoil by different agents of weathering such as running water, wind, overgrazing, and faulty methods of agriculture used by farmers. CONSERVATION OF SOIL: is an effort made by humans to prevent soil erosion in order to retain fertility of soil 47