Soils of India: An Overview

After reading this article you will learn about the Soils of India:- 1. Soils of Bihar 2. Soils of Uttar Pradesh 3. Punjab 4. Haryana 5. Himachal Pradesh 6. Rajasthan 7. Gujarat 8. Maharashtra 9. Madhya Pradesh 10. Karnataka 11. Kerala 12. Tamil Nadu 13. Andhra Pradesh 14. Orissa 15. West Bengal 16. Assam 17. North Eastern Hill Regions.

Soils of India

1. Soils of Bihar
2. Soils of Uttar Pradesh
3. Soils of Punjab
4. Soils of Haryana
5. Soils of Himachal Pradesh
6. Soils of Rajasthan
7. Soils of Gujarat
8. Soils of Maharashtra
9. Soils of Madhya Pradesh
10. Soils of Karnataka
11. Soils of Kerala
12. Soils of Tamil Nadu
13. Soils of Andhra Pradesh
14. Soils of Orissa
15. Soils of West Bengal
16. Soils of Assam
17. Soils of North Eastern Hill Regions

1. Soils of Bihar:

Alluvial soils have covered the area between the Himalayas and the Ganges in north Bihar and between the Ganges and the Chota Nagpur plateau on the south Bihar.

Properties of the alluvial soils of Bihar vary widely because they were formed from different parent materials which were deposited by the tributaries of the Ganges.

Alluvial soils of Bihar have been classified into four broad groups on the basis of the differences in the composition of the parent alluvium, climate and vegetation:

(i) Calcareous Alluvial Soils of North Bihar,

(ii) Non-Calcareous Alluvial Soils of North Bihar,

(iii) Heavy Clayey Alluvial Soils of Southern Bihar, and

(iv) Sone Alluvial Soils of South Bihar.

A belt of calcareous alluvial soils extends from Gorakhpur district in Uttar Pradesh in the west to the Darbhanga district in the east. These soils partially cover the districts of Champaran, Saran, Muzaffarpur and Darbhanga.

They are whitish-grey to dark grey sandy loam to silty loam soils, containing high amounts of lime and are strongly alkaline in reaction. They contain low amounts of total nitrogen, available phosphorus and potash. They are saline and saline-alkali soils and are strongly alkaline in reaction in the more arid regions of Saran district.

The non-calcareous soils cover the rest of the area in the north Bihar. They are grey brown to dark brown sandy loam to clay loam soils of good physical condition. They are rich in potash but deficient in phosphorus and are alkaline in reaction except in the eastern parts of Purnea district where they are acidic in reaction (pH 5.0 to 6.0), rich in nitrogen but deficient in phosphorus and potash.

Heavy clayey soils cover part of Patna, Gaya and Sahabad districts in the south Bihar. They are dark grey at the surface and contain high amounts of clay almost uniformly distributed throughout the profile. They are poorly drained and contain a fair amount of total nitrogen and available phosphorus and potash and are usually neutral in reaction.

Some alluvial soils occur in the Valley of the river Sone and other Vindhyan rivers in the Sahabad district. They have been divided into three broad groups i.e. sand, sandy clay and clay. They are not fertile and are alkaline in reaction.

Red and yellow soils which cover Chota Nagpur division and parts of Singhbhum and south Sahabad and Mongher districts are usually brownish- yellow to red in colour and lighter in texture, although heavier soils have also been found in some pockets. They are acidic in reaction.

Greyish, neutral to slightly alkaline soils occur at the low land. Red and yellow soils contain low amounts of lime and magnesia and moderately amount of potash. They contain low amounts of available phosphorus because water soluble phosphorus has been precipitated as in soluble ferric and aluminum hydroxyl phosphate.

Most of Singhbum district is covered by mixed red and black soil which comprises of dark brown loamy soil to black clayey soils and frequently contains lime. A black soil which occurs in pockets of the Singhbhum district is clayey in texture and alkaline in reaction. Laterite soils also occur in small pockets within the red and yellow soil areas, which contain ferruginous concretion which are compacted into blocks of laterite.

2. Soils of Uttar Pradesh:

Hilly regions of Uttar Pradesh comprising Almora, Tehri Garhwal districts, major area of Dehra Dun district and parts of Garhwal, Uttarkashi and Chamoli districts are covered by brown hill soils which soils which originated from sandstone and shale under forest of Quercus sp and Pinus longifolia and grasses in humid temperate climate.

A moderate amount of organic matter is present in the surface soil. B horizon is brown. Sandy soils originated at a slope gradient of about 45° or more while loamy and clayey soils originated in less shaped lands. Parts of Nainital, Garhwal and Dehra Dun districts are covered by dark grey sandy loam to silty loam Tarai soils which are usually rich in organic matter and acidic in reaction. Some clay has been illuviated in the B horizon.

Haldwani, where the deep water table occurs, is covered by loamy soils containing gravel. But sandy soils occur at Kichha and Kashipur where the water table occurs at a depth of 4 to 10 feet. Grey loamy soils occur in Dehra Dun while dark grey slightly heavier soils occur at Doiwala.

Alluvial soils of Uttar Pradesh have been grouped as:

(i) Alluvial soils of western and north-western Uttar Pradesh of a lighter texture

(ii) Alluvial soils of central Uttar Pradesh of an intermediate texture; and

(iii) Alluvial soils of eastern Uttar Pradesh of a heavier texture.

(i) Alluvial Soils of Western and North-Western Uttar Pradesh:

Saharanpur, Muzaffarnagar and Meerut districts are covered by deep reddish brown to yellowish brown fertile sandy loam soils where the water table occurs at a depth of 8 to 15feets. Bijnor, Moradabad, Rampur, Bareilly and Pilibhit are covered by light yellow to red coloured heavy loam soils. They are usually slightly alkaline in reaction except at the east of Piliphit where they are slightly acidic in reaction.

(ii) Alluvial Soils of Central Uttar Pradesh:

Ukheri and Sitapur districts are covered by sandy loam soils which are slightly acidic in reaction, except in the eastern part of Kheri district and western part of Sitapur district where they are slightly alkaline in reaction. Sandy loam soils of Hardwar district are slightly acidic at the western part and slightly alkaline at the eastern part. Barabanki and Lucknow districts are covered by single grained slightly alkaline sandy loam soils.

(iii) Alluvial Soils of Eastern Uttar Pradesh:

There are two district types of soils locally known as Bhat and Bangar. A third type called Dhub occurs near the river banks which are liable to inundation. Single grained sandy loam to clay loam Bhat soils occur in low lying areas where the water table occurs at a depth of 1.5-4.5 metres.

These soils of high moisture retention capacity contain a high percentage of lime and are slightly to moderately alkaline in reaction. Bangar soils occur at relatively elevated areas where the water table occurs at a depth of 15-30 feet below the surface.

These sandy loam to loam soils of pH 6.0 to 8 contain less lime than the Bhat soil. Sugarcane is grown extensively on these soils under irrigated conditions. Loam soils possessing a high water holding capacity and a zone of accumulation of calcium carbonate are called Dhan kar in Varanasi district, which are suitable for paddy cultivation.

Dark clayey soils which resembles the black cotton soils of central India, occur in low lying, basin shaped areas in both old and new alluvium. The rivers which drained the trap rocks of Bundelkhand brought down the products of decomposition of basalt and deposited this basaltic alluvium at these basin shaped areas, where these dark clayey alluvial soils were formed. There is little textural variation in this uniform dark grey to black coloured soil profile.

The organic matter content of these soils decreases form 1.14 per cent at the surface to about 0.69 per cent at a depth of 1.3 to 1.8 metres. They are neutral to moderately alkaline in reaction. Calcium forms 75 per cent of the bases, and magnesium forms 20 per cent of the basics. The Base Exchange capacity of these soils is about 70 milliequivalents per 100gms.

The Bundelkhand region comprising the districts of Jhansi, Jalaun, Hamirpur and Banda is covered by black and red soils. Black soils are very sticky and plastic when wet but when they dry, wide and deep creacks appear on their surface.

Crops can be grown on these soils without applying irrigation water because they can retain a high quantity of moisture. They are locally known as MAR and KABAR. Mar is less clayey than Kabar. Red soils include two types called PARWA AND RAKAR.

Parwa is a brownish grey loam to sandy or clay loam, a fairly good soil which responds to manuring and irrigation. Rakar is the eroded soil which is commonly found at higher elevation. Red loam soils have developed on Vindhyan parent materials in Benaras and Mirzapur districts.

About 13 lakh hectares of land are affected by salinity and alkalinity in Uttar Pradesh; over 40,000 hectares of land are affected by salinity and alkalinity in each of the districts of Aligarh, Mainpuri, Etawah, Kanpur, Unnao and Pratapgarh; 20,000 to 40,000 hectares of land are affected by salinity and alkalinity in each of the districts of Bulandshahar, Farrukhabad, Hardoi, Lucknow, Rae-Bareili, Fatehpur, Allahabad, Sultanpur, Jaunpur and Azamgarh.

The characteristics of Saline, Saline-alkali and alkali soils of Uttar Pradesh are as follows:

(i) Saline Soils:

The land surface is covered by extensive white or ash coloured salts. These lands occur near canals or rivers where the natural drainage is restricted. These loamy sand to loam soils have an open structure and no hardpan or kankar layer in the sub soil. Soluble salts are mainly chloride and sulphate of sodium and calcium. The soil pH is less than 8.5.

(iii) Saline-Alkali Soils:

These lands occur in low lying pockets of the upland and possess a hard indurated clay or kankar pan through which water cannot pass. Sulphates and carbonates of sodium occur in the surface. The international drainage is very restricted if sodium carbonate is the predominant salt when the soils are very compact. But internal drainage can be easily established if sodium sulphate is the important salt.

(iii) Alkali Soils:

Clay to clay loam surface soils occur above the heavier indurated and columnar sub-soil. When wet, soils are very gummy and plastic. Usually a thick and highly cemented bed of bigger sized kankar is to be found in the sub soil which may be cemented like rocks. Water does not pecolate down the profile. The exchangeable sodium percentage of these soils is more than 15 and pH is more than 9.0, often more than 10.

3. Soils of Punjab:

Soils of Gurdaspur developed in a hot humid climate. Clayey soils containing kaolinite occur near the Government Agricultural Farm where calcium carbonate is absent.

The districts of Amritsar, Jullandhar, Ropar and Patiala and parts of Ludhiana have been covered by new alluvial soils which do not possess a well-developed soil profile and are sandy loam to clay loam in texture.

Soils of Amritsar, Jullandhar, Patiala and Ludhiana districts were formed in a hot semi-arid to semi humid climate. Alluvial soils contain enough phosphorus and potash for crop growth but are deficient in humus and nitrogen.

The Ferozepur district is covered by darker, coloured clayey old alluvial soils. Calcareous sierozemic soils occur in Sangrur, Bhatinda and parts of Ludhiana. These soils are also grouped under alluvial soils because of their alluvial region. These are light, coloured clayey soils which are neutral to slightly alkaline in reaction and deficient in phosphorus. 2:1 clay minerals dominate the clay mineralogy of these soils.

Almost all the districts of Punjab except perhaps Jullandhar and Ropar are adversely affected by soil salinity and alkalinity. All the salt incrusted lands are called Thur land and the saline efflorescence is called Thur, and consists mainly of sodium sulphate and sodium chloride.

These soils are usually lighter in texture and alkaline in reaction, Bari soils are very difficult to plough, because they are very hard and impermeable. When these soils are dried, a crust rich in clay is formed at the surface. Calcium carbonate occurs at a depth of about four feet.

Bari soils are typical saline-alkali soils of Punjab because they contain high amounts of sodium sulphate and sodium chloride. Rakar is the typical non- saline alkali soil which possesses an upper, highly impervious layer and contains calcium carbonate in the sub soil.

4. Soils of Haryana:

Soils of Haryana were formed in hot humid climates (Ambala) to hot arid climates (Karnal, Hissar, Gurgaon, Rohtak). Ambala, Karnal, parts of Rohtak and Gurgaon districts are covered by new alluvial soil, while calcareous sierozemic soil which is of alluvial origin, occurs in Hissar, Jind and small areas in Rohtak and Gurgaon districts.

The majority of alluvial soils are sandy loam or loam in texture, where genetic horizons have not been developed. Soluble salts are usually present in the alluvial soils; the lower horizons also contain lime kankar nodules. They are alkaline in reaction and contain adequate amounts of phosphorus and potash but lack organic matter and nitrogen.

Calcareous sierozemic soils have developed from the alluvium brought by the Indus river system. These soils are covered by a mantle of blown sand, which combined with the arid climate, results in poor soil development.

They are usually lighter, coloured deeper sandy loam, loam to clay loam soils. Clay and lime have been washed down the profile. A layer of calcium carbonate occurs below 150 cm. They are neutral to alkaline in reaction and are deficient in phosphorus.

Alluvial soils and also the calcareous sierozemic soils are adversely affected by soil salinity and alkalinity. These soils are locally known as Kallar, Reh and Usar. Excessive amounts of sulphate and chloride of calcium, magnesium and sodium and carbonate of sodium and potassium occur in the saline and alkali soils. Soluble salts accumulate in the semi-arid climate with an annual rainfall of less than 500 mm.

Application of saline irrigation water on these soils results in the development of soil salinity, as has happened in large areas in Gurgaon, Rohtak and Hissar districts where the water table has come up 150 cms below the surface of lands.

Saline soils contain a high amount of sulphate and chloride of sodium and calcium, and calcium carbonate and are alkaline in reaction. They usually have a lighter texture and do not possess compact layers.

Saline-alkali and alkali soils chiefly occur in the Karnal district where a calcareous pan is present that restricts the downward movement of water. Soils of an I.A.R.I, farm at the Karnal district are sandy loam in texture and contain about 1.14 per cent calcium carbonate.

Soils of Patti in the Karnal district are clayey in texture and contain about 1.20 per cent calcium carbonate. The clay micelle is saturated by sodium ions (20 to 23 per cent). It is regarded as sodium-magnesium clay because magnesium ions increase to about 28 per cent of the exchangeable cations in the sub soil. Alkali soils of the Karnal district also contain toxic amounts of water soluble boron. Alkali soils are deficient in humus and nitrogen.

5. Soils of Himachal Pradesh:

Himachal Pradesh is covered by a belt of Brown Hill Soil from the Kangra to the Sirmur district. These soils have developed from varieties of parent material like sandstone, grey micaceous sandstone and shale. The surface soils are dark brown loam to silty clays, which are moderately rich in organic matter.

These soils do not contain lime and are therefore slightly acidic to neutral in reaction. B horizon is fairly thick (50 to 80 cm) and of silty loam to clay loam in texture. Chamba, Lahul-spiti, Kulu and Kinnaur districts are mostly covered by sub- mountain soils (Podzolic) which have developed from sandstone and shales under conditions of high rainfall which support coniferous vegetation.

Dark brown sandy loam soils contain loose under-composed organic matter up to a depth of 15cms from the surface. Up to another 15 cm thickness the sub soil is lighter coloured, followed by layer below this brown to reddish brown compact sandy clay up to a depth of another 100cms.

These soils do not contain lime and are therefore acidic in reaction. In general, soils of Himachal Pradesh contain good amounts of plant nutrients like nitrogen, phosphorus and potash. Soil becomes heavier in texture and their pH decreases with the increase in the altitude.

6. Soils of Rajasthan:

Churu, Bikaner, Jodhpur, Barmer about three-fourths of Jaisalmer, the western half of Nagpur, the eastern half of Jalore and small areas in Jhunjhunu and Ganganagar districts are covered by deep, yellowish brown to pale brown coloured regosolic soils which are low in humus but contains a fair amount of weatherable minerals. Some soils are highly saline in the lower horizon.

An appreciable amount of gypsum is present in the lower horizons of some regosolic soils of Bikaner. The regosolic soils contain free calcium carbonate, soluble salts and are alkaline, in reaction. Soils develop salinity, and alkalinity in some of the courses of ancient rivers. Alkali soils are in a poor physical condition.

One fourth of the land area of eastern Jaisalmer district is covered by lithotomic soil, which consists of a thin layer of gravel or sand over bed rocks. Certain xerophytic plants grow wherever there are sandy soils of a depth of about 10 to 15 cm, because these soils retain enough moisture for the growth of xerophytic plants. No soil profile develops, because thin sandy layer is continuously shifted from place to place.

The southern part of Jhunjhunu, Sikar and the eastern half of the Nagpur districts, Pali, Sirohi and one-third of the western part of the Udaipur districts, are covered by grey brown soils of alluvial origin. They consist of lighter coloured sandy loam surface soil and darker sub soil which is of a heavier texture than the surface soil.

Calcium carbonate is uniformly distributed in the surface; soil calcium carbonate is also uniformly distributed throughout the profile. Therefore the calcium ion is the major cation absorbed by the clay micelle. Hence these soils are neutral to alkaline in reaction and contain low amounts of nitrogen and phosphorus though enough potash.

A belt of red and yellow soils cover parts of Ajmer, Bhilwara, Udaipur and Dungarpur districts. These soils as studied at Pisanganj in the Ajmer district, are sandy loam in texture, contain calcium carbonate and are alkaline in reaction.

About two-thirds of the Kotah districts are covered by medium black soil. The rest of the Kotah district, Bundi, Chitorgarh and the Bhilwara districts are covered by mixed red and black soil. The black soils are fairly deep where some clay has been illuviated in the B horizon.

These soils crack during the summer and are fairly well drained. The B horizon contains calcium carbonate. Grey brown to dark grey brown clay with an alkaline reaction occur at the surface. In a predominant red soil area, black soils occur in patches in the low lying area. Alternately in the predominantly black soil area, red soils have originated from granite, granitoid gneiss, while black soils have developed from basalt.

7. Soils of Gujarat:

Kheda, Ahmedabad, major areas in Surendranagar and a small area in Banaskantha and Vadodara districts are covered by grey-brown soils which were developed from alluvial parent material in the semi-arid climate of Gujarat.

The B horizon soil is heavier in texture than A horizon soil. Calcium carbonate is uniformly distributed in the soil profile. So calcium is the most important cation absorbed by the clay micelle. Hence the soils are neutral to alkaline in reaction. These soils, known as “GORADU” in Ahmedabad,

Mehsana and Kaira districts are usually fertile and respond to manuring and irrigation. In the Vadodara district, soils developed from older deposits of alluvium are called Bhata. Both Gorat and Bhata soils are deep, poor in organic matter and nitrogen but fairly rich in phosphate and potash. Deep black soils (120cms deep) occur in Surat, Bharauch, and Vadodara and Bhavanagar districts. Medium black soils occur in Rajkot, Jamnagar and Bhavanagar districts.

Black soils are dark coloured clayey soils. They possess a high moisture retension capacity. They contain abundant iron, fairly high quantities of lime, magnesia and alumina. They are poor in humus, nitrogen and phosphorus but not in potash. The smectite group of clay minerals dominate that these soils.

Saline soils that usually contain sodium chloride as the important salt occur in the Rann of Kutch. They are black clayey to silty clayey soils. The sub soil is of a lighter texture than the surface soil. Gypsum is present in the soil profile. These soils are alkaline in reaction (pH 7.8 to 8.4).

8. Soils of Maharashtra:

Maharashtra is mainly covered by black soils which are of three kinds i.e:

(i) Shallow,

(ii) Medium; and

(iii) Deep black soils.

Shallow black soils have developed from the basalt of the Deccan trap. They are dark yellowish brown silty loam to dark brown clays of a granular or weakly blocky structure and contain lime grains or nodules. Cracks appear on the surface during the summer. They are well drained and moderately alkaline in reaction. Shallow black soils occur in the districts of Nimar, Wardha and west of Nagpur.

Medium black soils have developed from a variety of rocks which include basaltic trap, basic granite, gneiss and hornblende schist which have weathered to form darker silty clay to clay soils, rich in basic elements, and organic matter and alkaline in reaction. They are fairly well drained and contain lime nodules and low amount of phosphorus. Medium black soils occur at Nagpur and Akola.

Deep (120cms) black soils occur in the Vidarbha, Jalgaon, Dhule, Parbani and Ahmedanagar districts. These are the result of weathering of Basalt. They are silty clay to clay in texture, contain lime nodules and are moderately alkaline in reaction.

Laterite soils occur in Ratnagiri. They are rich in coarser material and plant nutrients except lime. Darker, deep clayey coastal alluvium occurs along the west coast, which is frequently inundated with the saline sea water.

9. Soils of Madhya Pradesh:

Shallow black oils have developed from the weathering of the Deccan trap in parts of Betul, Chindawara, Balaghat, Seoni and Mandla districts. They are dark yellowish brown silty loam to dark brown clay in texture and are alkaline in reaction. They are poor in humus, nitrogen and phosphorus but not in potash and lime.

Vast areas of northern, western and central Madhya Pradesh are covered by medium black soil (50 to 120cms). These silty clay to clay soils are moderately rich in humus and lime.

Deep black soils (120cms) occur in central Madhya Pradesh. They have developed from Basalt. They are rich in lime and alkaline in reaction. They are rich in 2:1 type of clay mineral.

Bastar, Chanda and parts of Durg districts are covered by red sandy soils which have developed from acidic parent material like granite, quartzite, sandstone etc. These soils are rich in coarse and medium sand.

Usually kaolinite or illite is present. They are usually coated with red haematite or yellow limonite. They have a moderately deep A horizon of pale reddish brown to red coloured coarse sand to loamy sand. The B horizon is dark reddish brown loam or sandy clay loam.

Red and yellow soils occur in the eastern part of Madhya Pradesh. These gently sloping and upland soils have developed from granite gneiss and quartzite schist complexes. The fairly deep, yellow, brown and reddish coloured soils are coarse to medium in texture in the A horizon and finer in texture in the B horizon. These well drained acidic soils contain iron concretion.

10. Soils of Karnataka:

Medium to deep black soils occur in Gulbarga, Bijapur, Belgaum, and parts of Dharwar, Raichur and the Chickmagalur districts. This dark greyish brown silty clay to black clay soils were formed from varieties of rock site basaltic trap and Dharwar schist. They are plastic and sticky when wet.

Cracks appear on the surface of land when they dry. They are rich in the smectite group of clay minerals. They are moderately rich in humus and nitrogen and lime and magnesia and soluble salts. Lime nodules are present in the sub soil. These soils are alkaline in reaction.

Mixed red and black soils occur at Raichur, Dharwar, Belgaum, Bellary and Chitradurga districts. They were formed from Granite and Granite-Gneiss containing lime and albite. Red soils usually occur at the elevated areas and Black soils occur at the bottom land.

Fine clay and plant nutrients are washed down from red soils occurring at the elevated areas to black soils occurring at the bottom land. Consequently, red soils are coarser in texture and poorer in plant nutrients than the black soils. Black soils possess a high moisture retention capacity and are therefore more suitable for growing Rabi crops.

Red sandy soils occur at Mysore, Mandya, Bangalore, Kolar, Tumkur, Hassan, Chickmagalur, Shimoga, Dharwar and Bellary districts. These red, yellow to brown stony and coarse gravelly to clay loam soils (Black coloured clay loam soils also occur in Mandya and Mysore districts are open in texture, well drained, low in humus, total nitrogen, total and available phosphorus and lime.

Moderately well drained red sandy soils occur in the Bangalore district and are loamy sand to sandy loam in texture. They have originated from granite. A thick layer of ferruginous gravel and quartz occurs in the sub oil. These soils are poor in organic matter and acidic in reaction.

Moderately deep to deep gently sloping, yellowish red, dark red and brown coloured sandy clay loam and clay loam soils occur in the Bangalore district. They contain a fair amount of humus and are slightly acidic to alkaline in reaction.

Loamy red soils are predominant in the plantation districts of Shimoga, Hassan and Kadur. Some of these shallow pale brown to greyish brown sandy loam soils occur at the uplands; some occur at the lowlands which contain enough potash, phosphorus and nitrogen for growing paddy.

Laterite soils occur in the western part of Shimoga, Bangalore, Kadur, Kolar and Mysore districts. Some of them are well drained brown clay loam soil occurring on hill tops. Some of them are shallow yellowish brown loam soil. Bases have been washed down from these soils and they are still not very acidic in reaction. They are poor in phosphorus.

Laterite soils of the North Kanara district are coarse, poor in lime and phosphorus but fairly high in humus, nitrogen and potash. Laterite soils of Mangalore are fairly fertile but strongly acidic in reaction. The Laterite soils of Pattukkottai are also fairly fertile, but are almost neutral in reaction.

Alluvial soils which occur along the West coast in the north and south Kanara districts are reddish or greyish sand and are well drained. But poorly drained heavy-textured alluvial soils occur along the banks of the rivers Netravati and Gurpur.

11. Soils of Kerala:

Laterite soils of Malabar have developed from basalt and gneiss under hot humid conditions. In laterite, the process of Laterisation i.e. decomposition of the mineral colloid to release iron and aluminum hydrous oxide or hydroxide and silicic acid resulting in base unsaturation is complete, whereas in lateritic soil, this process is considered incomplete.

Lateritic soils are generally loamy in texture, without the gravelly vesicular nodules which characterize true laterite. Laterite soils are usually very deep and red in colour. The red colour at the surface gradually changes to reddish yellowish and finally yellow in the deeper layers.

Ferruginous gravel is found both in laterite soil and lateritic soil. Hydrous oxides of iron and aluminum dominate the clay, so the cation exchange capacity of the clay is even lower than the soil, as the soil contains a considerable amount of humus.

Lateritic soils contain 50 per cent or more exchangeable calcium. Magnesium is the next important exchangeable cation. The surface soil contains less than 25 per cent exchangeable calcium 25 per cent of the metallic cations 50 of the exchangeable hydrogen. Hence the soil is distinctly acidic in reaction.

Laterite and lateritic soils are usually poor in nitrogen, available phosphorus and lime. They may contain adequate amounts of total phosphorus and potash. Water soluble phosphorus when added to these soils is converted to water insoluble phosphorus.

In Kerala, there are two types of alluvium; coastal alluvium and inland alluvium indepressional lands. In central Kerala, the widths of coastal alluvium tracts increase, whereas in the north and south, they are comparatively narrow.

Alluvial soils of Kuttanad occur at low lying areas which were once a part of the sea. These low lying areas were later filled up by silt carried by Pampa and other rivers and deposited in these low lying areas. The coastal alluvium is coarse sand to loamy sand to sandy loam of a light grey colour, low in moisture and nutrient retention capacity, and acidic in reaction. The alluvium is usually fertile on the banks of rivers.

Excessive amounts of organic matter accumulated in the low lying areas, and decomposed in the humid climate of Kerala to form Peaty soils, which are locally known as Kari soils.

They have been found in taluks of Ambalapuzha, Vaikom and Shertallai rivers. They remain submerged in water during the rainy season after which they are puddled, and paddy is transplanted on these heavy black coloured highly acidic soils, containing 10-40 per cent organic matter.

The Soil pH may be as low as 4.0 which are due to anaerobic decomposition of organic matter. Sometimes soil contain ferrous and aluminum sulphate. Soluble salts accumulate in Kari areas. They are relatively poor in phosphorus.

12. Soils of Tamil Nadu:

Major portion of Tamil Nadu is covered by red sandy soil and red loam soils. Red sandy soils have developed from acidic parent material like granite, gneiss, quartzite, sandstone etc. Sand particles are coated with red coloured haematite or yellow coloured limonite which is responsible for the various shades of red and yellow of these soils, which usually contain ferruginous gravel containing iron, aluminum and silica.

These sandy, loamy sand and sandy loam soils are heavily leached and therefore poor in basic elements and plant nutrients. Their pH ranges from 6.6 to 8.0. Majority of red loam soils are loamy is texture. The red color of soils is due to the coating of ferric oxides on soil particles. Calcium is the important exchangeable cation. They are neutral to slightly alkaline in reaction.

Black soils of Tamil Nadu which are either shallow (3 to 4 ft. deep) or deeper, are of very heavy texture, have a high moisture retention capacity are rich in lime and alkaline in reaction. They contain low amounts of nitrogen but sufficient amounts of phosphoric acid and potash.

Mixed red and black soils occur in Coimbatore, Madurai, Ramanathapuram and Tirunelveli districts. Black soils are dominated by beidellite, while red soils are dominated by kaolinite. So the cation exchange capacity of the black soils is much higher than that of the red soils but the cation exchange capacity of red soils is maximum at an intermediate depth. Black soils contain almost the same amount of nitrogen.

Laterite soils occur in the Chinglepet and Thanjavur districts. These were formed from varieties of parent materials in humid climate. Paddy is grown in lower elevation and tea, cinchona, rubber and coffee are grown at the higher elevation. They are rich in humus and plant nutrients and strongly acidic in reaction. Soil acidity increases with elevation.

Delatic alluvium occurs in the Thanjavur district and a belt of coastal alluvium covers Tamil Nadu from Madras to Kanyakumari. Alluvial soils are most extensive and most fertile. They are usually up to several feet deep at higher elevations. These soils consist of alternate layers of silt, clay and sand of varying thickness. The texture of the surface soil is usually loamy.

The Cauvery alluvium is poor in humus, nitrogen and phosphorus, but rich in potash Slid lime. These soils possess a low cation exchange capacity and are alkaline in reaction.

Soils developed from Cuddalore sandstone are loamy in texture and deep to light red, yellow and light yellow and even greyish white in colour and deficient in humus, nitrogen, phosphorus and lime. These soils are of a low cation exchange capacity and neutral to moderately alkaline in reaction.

The soils which have developed from Archaean schist are found only in a small area to the west of Budalur. The profile show brownish grey loam or clay at the top one foot surface soil and brown sub soil. Soils are usually sandy below three feet. Surface and sub soils are usually very hard. They are poor in humus, nitrogen, phosphorus and lime but rich in potash. These slightly alkaline soils are free from soluble salts and are of low cation exchange capacity.

The profile characteristics of coastal alluvial soils formed from recent marine deposits are similar to Cauvery alluvium in their alternate layers of clay, silt and sand but exhibit influence of sea as indicated by the presence of shells and bleached sand.

They are poor in nitrogen and available phosphorus but rich in potash and lime. Some of them also contain salts. Peaty soils which occur mainly on the south east coast of Tamil Nadu are usually coloured blue due to the presence of ferrous iron. They contain varying amounts of organic matter.

13. Soils of Andhra Pradesh:

Black soils occur in the districts of Aeilabad, Nizamabad, Medak, Karimnagar, Warangal, Khammam, Guntur, Mehboobnagar and Hyderabad. Mixed red and black soils occur mainly at Kurnool, Ananthapur, Cuddapah, and Krishna districts. Flue cured tobacco is grown on black soil. These are deep (120cms) highly clayey soils of high moisture retention capacity but of poor structure and permeability.

They have been tentatively grouped as follows:

(i) Dry black soils which include most of the area under tobacco.

(ii) Wet land black soils where tobacco is grown in rotation with paddy.

(iii) Tank bed soils of low lying area which remain in inundated during the monsoon and are cultivated late in the season.

(iv) Saline land black soils.

(v) High land black soils of the Deltaic regions which are comparatively lighter in texture and more fertile.

Soils of the Central Tobacco Research Institute, Rajahmundri and the Farm of Cigarette Tobacco Research Sub-Station, Guntur are uniformly clayey in texture down the profile where calcium carbonate increases with depth.

These soils are low in organic carbon and medium in total nitrogen, contain soluble salts and are alkaline in reaction. Calcium and magnesium are the important exchangeable cations. These highly clayey soils have a high moisture retention capacity. The Soils of Nizamabad district are sandy clay loam to clay loam and alkaline in reaction.

Soil of Ananthapur and Kurnool are mostly black clays which enclose small areas of red and mixed black soil.

Red sandy soils occur in Chittoor, Ananthapur, Cuddapah, Nellore, Kurnool, Mehboobnagar, Guntur, Hyderabad, and Warangal, Khammam, east and west

Godavari, Visakhapatnam and Krishna districts. The important clay minerals are kaolinite and illite which are coated with red haematite or yellow limonite.

A horizon is pale reddish brown to red coloured coarse sand, fine sand of loamy sand. B horizon is dark reddish brown loam or sandy clay.

Deltaic alluvium occurs in the east and west Godavari, Krishna and Guntur districts. It represents the heterogeneous sediments brought by rivers Godavari and Krishna and deposited by them near their mouths, where they join the Bay of Bengal.

These rivers drain the black soils which have developed from basaltic traps, so the delta soils are largely composed of dark silty clay; the soils are usually well drained.

Godavari and Krishna deltaic alluvium contain black fertile mud of a high moisture and nutrient retention capacity. A variety of crops like paddy, sugarcane, banana and tobacco are grown on these soils.

14. Soils of Orissa:

Major parts of Orissa are covered by red and yellow soils. They are usually well drained and deep soils of sandy loam texture at the surface and clay loam at the sub surface. Their colour is pale brown to reddish brown. These acidic soils contain a moderate amount of humus. Laterites of Orissa have been found capping hills and in Plateau.

Large areas in Khurda and Balasore are occupied by laterite. They are granular clay loam soils that contain gravels. Deltaic Alluvium occurs in Cuttack, Balasore, and Mayurbhanj districts. Mahanadi delta alluvium is light brown and light yellow sandy loam, loam, and silty loam.

They contain enough potash but a low amount of Phosphorus. Marshy soils occur in the coastal areas. These soils contain varying amounts of organic matter. They are generally blue due to the presence of ferrous iron.

15. Soils of West Bengal:

Alluvial soils of the Coochbehar district have developed from sediment laid down by Tista, Mahananda and Jaldhaka rivers. These new alluvial soils have no genetic profile.

They are greyish brown to dark brown in colour, loam to silt loam in texture and are of a low cation exchange capacity. Illite in the important clay mineral.

The river Ganga brought the products of weathering of rocks constituting the Himalayas and deposited them in the districts of West Dinajpur, Murshidabad, Nadia, Hooghly and 24-Parganas.

The Damodar and Ajoy rivers have brought the products of weathering of rocks in Chota Nagpur and Santhal Parganas of Bihar and deposited these in the Burdwan, Bankura, Midnapore and Hooghly districts. Alluvial soils have developed from silt laid down by these rivers.

Alluvial soils of West Bengal have been grouped into two broad families called Ganga alluvium, which has originated from the material deposited by the river Ganges and Vindhyan alluvium, which has originated from the material deposited by the river Damodar.

The Ganga alluvium comprises of the following soils:

(i) Ganga riverine lands that have an immature profile. These soils contain plenty of greyish white fine sand and lime.

(ii) Ganga flat lands that have a slightly mature profile. The soil texture varies from sand to clay, sub-soil contain more clay than the Surface soil. Sub-soil contains lime at many places.

(iii) Ganga low lands that have flat clayey surface soil and lighter textured sub-soil which often contains lime concretions at many places.

(iv) Ganga Uplands occur over older alluvial fans, alluvial plains and terraces. They have better developed profiles. A moderate amount of clay and high amount of lime have accumulated.

Vindhyan Alluvium includes the following soils:

(i) Riverine lands that have a stratified, immature soil profile. These soils contain yellowish brown sand.

(ii) Flat land soils that are usually poorly drained, as indicated by mottling in the lower horizon. They contain brown coarse sand. Some clay has been illuviated in the lower horizons.

(iii) Upland have a mature soil profile. Some clay, sesquioxide has been illuviated in the B horizon.

These alluvial lands are fairly fertile and support the growth of many varieties of crops. The Southern parts of 24-Parganas and Midnapore districts have been covered by deltaic alluvium which is usually poorly drained lighter coloured silty clay.

The Lower horizons are mottled. Swampy vegetation of mangroves occur at the mouth of the river Ganges, which is responsible for a large accumulation of organic matter in the soil, which has been formed from the deposit brought by tidal currents.

The original deltaic branches of the Ganges have been choked up because the head water has been cut off. Consequently these lands were converted into numerous tidal flats. These lands have been bonded to prevent the ingress of the sea water, while sluice gates have been provided in order to allow the accumulated rain water to drain off.

Coastal alluvial soils which occur in canning are saline and contain a high amount of neutral salts like sodium chloride and are thus almost neutral in reaction. They are usually medium to heavy textured and occur in depressions.

In the Sundarbans and other places in West Bengal, peaty soils usually bluish in colour due to the presence of ferrous iron are found. They contain large amounts of organic matter.

Red and yellow soils of the Bardhhaman district are pale brown to dark brown loamy sand at the surface and brownish yellow and yellowish brown sandy loam to clay loam at the sub surface. These soils are slightly acidic in reaction and contain low amounts of humus and nitrogen.

Red soils of the Bardhhaman district have a moderately deep A horizon of pale reddish brown to red coloured coarse sand, fine sand or loamy and a B horizon of dark reddish brown loam or sandy clay loam of varying depth. These soils are acidic in reaction and low in humus.

Laterite soils also occur in the Midnapore, Bankura, Burdhaman and Birbhum districts. These soils have been heavily leached and are consequently acidic, and of a poor fertility. The Darjeeling district is mainly covered by Brown Hill soils is usually highly acidic in reaction and of a high exchange capacity due to their high humus content.

The surface soil is a mixture of well decomposed humus and inorganic material. Its colour gradually turns to the colour of the parent rock. Tarai soils of the Jalpaiguri district have originated from the material brought from elevations of more than 3000 metres above sea level at the Himalayas by hilly rivers like Tista, Mahananda, Torsa and Jaldhaka and deposited by them at an elevation of 50 to 150 metres above sea level along the foothills. They are naturally fertile but poorly drained soils.

16. Soils of Assam:

Alluvial soils of Assam have developed from the deposition of the products of weathering of rocks constituting the Himalayas by the river Brahmaputra. They are acidic in reaction. Generally those on the hills and old alluvium are more acidic than the new alluvial soils along the river bank.

Soil acidity increases with the increase in rainfall and fineness of the soil texture. Soils on the northern bank of the Brahmaputra are less acidic than those on the southern bank. In the Surma valley, soils on Tillas and Bheel are markedly acidic in reaction.

Soils of low lying inundated areas are less acidic. The new alluvial soils are often neutral in reaction. Soils of the Brahmaputra valley are of a coarser texture, while soils of the Surma valley are of finer texture.

Alluvial soils of Assam contain moderate amounts of organic matter and nitrogen and high amounts of phosphorus and potash. Soils of the Surma valley contain more humus than those of Brahmaputra valley. The soils of Brahmaputra valley are richer in total magnesium.

The five following local soil types have been recognized in the Assam valley:

(i) A layer of micaceous sand skirting the base of the Himalayas in Kamrup and Mangaldai.

(ii) The silt of the plateau rising suddenly out of the lower plains in Tezpur, Bishnath, Sibsagar and Golaghat, sandy soils of Nowgong and Jorhat.

(iii) Heavy soils, chiefly of very fine silt, comprising north Lakhimpur and Dibrugarh.

(iv) A series of sand ridges running more or less across the lime of the valley of Jorhat, extending east and west particularly from Titabar to Jhamzie river and

(v) A series of low hills skirting the base of the Naga Hills and separated by rolling land.

Red soils occur in Karbianglong and north Cachar Hill districts. These soils contain high amounts of organic matter and nitrogen and are of a finer texture.

17. Soils of North Eastern Hill Regions of India:

Farmers of the North Eastern Hill regions of India have been practicing shifting cultivation. They clear jungles by burning them and grow crops there for a few years.

Thereafter they abandon the land and burn forests, and grow crops in a new area. Burning causes severe loss of nutrients especially nitrogen and sulphur. They do not follow any soil conservation practices.

Consequently fertile top soil is being eroded at an increasing rate. These soils have been tentatively classified by Govinda Rajan and Gopal Rao (1978) as discussed below:

Most of the land area of Nagaland is covered by red loam soil except for a very small area bordering the Sibsagar and Lakhimpur districts of Assam covered by Laterite soil.

The soils of the Twensang district are low in organic carbon and therefore in available nitrogen, available phosphoric acid and available potash. Soils of Kohima, Mokokchung, Phek and Wokha districts have a high organic carbon and content therefore a high available nitrogen and low available phosphoric acid content.

Soils of Mon and Zunheboto district are medium in nitrogen. Soils of all the districts contain medium amounts of organic carbon and therefore, available nitrogen soils of all the districts except those of organic carbon and therefore Soils of the Zunheboto district have a medium quality available phosphoric acid.

Soils of Kohima, Phek, Wokha and Zunheboto district have medium amounts of available potash and those of the rest of the districts are low in available potash.

Almost the whole of Manipur is covered by red and yellow soils except for a small area on the Assam border that is covered by laterite soil.

Manipur soils are moderately rich in organic carbon and therefore in available nitrogen, low in phosphoric acid content and medium in potash content.

Practically the whole of Mizoram is covered by red and yellow soil, Mizoram soils contain a high amount of organic carbon and are therefore high in available nitrogen, have a low to medium amount of available phosphoric acid and a medium amount of available potash.

Tripura is covered by red and yellow soils. Soils of Tripura contain medium to high amounts of organic carbon and therefore the same amounts of available nitrogen, low to medium amounts of available phosphoric acid and low amounts of available potash.

The Garo Hills are covered by laterite soils and alluvial soils, Jaintia Hills are covered by red and yellow soils.

Laterite, red and yellow soils and alluvial soils cover the Khasi Hills. Almost the entire soils of Meghalaya contain low amounts of available phosphoric acid and a medium of potash.

The soils of Khasi and Jaintia Hills contain high amounts of organic carbon and hence a high amount of available nitrogen.

The whole of Lohit district, two-thirds of the Siang and Tirap district and half of Kameng district is covered by red loam soil.

The rest of the areas in the Siang, Subansiri and Kamang districts are covered by brown hill soils. Laterite soils have been found in the Tirap district.

Soils of all the districts contain a high amount of organic Carbon and hence of available nitrogen. Soils of the Kameng district contain medium amounts of available phosphoric acid, and the soils of the remaining districts contain low amounts of available phosphoric acid. Soils of the entire district except those of Siang district contain low amounts of available potash. Soils of Siang district contain medium amounts of available potash.