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Chapter 7: Soil Resources

By the end of April, a cotton field on the Deccan lava tract looks broken. The black earth has pulled apart into cracks so wide that a farmer can push a hand down into them, and the field is crossed by them like a dried riverbed. To a visitor it looks like ruined land. To the farmer who has grown cotton there all his life, it is the field doing exactly what it should. This soil is almost half clay. Clay swells when it takes in water and shrinks when it loses it, so the drying of one hot season opens the ground from the inside. Air travels down the cracks to the roots. Loose crumbs fall in and turn the topsoil over without a plough, which is why the soil is said to plough itself. Then the first heavy rain closes the cracks, the clay swells shut, and the water that has gone in is held. Months later, with no canal and no well, the crop draws on that stored moisture and survives the dry season. The cracks were never damage. They were the soil getting ready.

Diagram

Fig. 7.A1 Caption: Deep cracks open across a black soil field at the end of the dry season. Brief: Photograph or realistic drawing of a cracked black cotton soil field on the Deccan lava tract; show the wide polygonal cracks in the dark surface, a few cotton plants for scale, and label one crack with an arrow going downwards to indicate air and loose crumbs moving into it.

NoteCuriosity Corner

Q1. Why does black soil crack open in the dry season, and how do those cracks help the farmer? Q2. Why is the soil of the northern plains made new again almost every year, while the soil of the Deccan is not? Q3. How does a shallow wash of water across a bare field turn, over time, into a gully deep enough to swallow farmland? This chapter will answer all three, by looking at how soil is made, how it differs from place to place, how it is lost and how it can be held.

7.1 Constituents Of Soil

What Soil Is

Soil is the thin layer of loose mixture of small rock particles and rotting organic matter that covers the surface of the earth. It is thin, and it is loose, and both of those words matter — this is not solid rock but a covering that can be moved, washed or blown away.

Everything that grows on land grows in it. Soil supports forests, grasslands and crops, and from these all living creatures on earth draw their energy. A layer only a few centimetres deep therefore stands between rock and the entire food supply of a country.

How Soil Came To Be There

Soil is not made in a season. Various forces of nature act on rock and break it into ever smaller pieces, and three of them do most of this work. (a) Changing temperature loosens rock, because rock heats and expands by day and cools and contracts by night, and this repeated straining opens cracks in it. (b) Running water carries broken material away, grinding the pieces smaller as they are rolled and knocked against one another. (c) Wind moves the finest particles and rubs them against exposed rock surfaces.

These forces of nature, together with the chemical and organic changes that take place within the soil itself, contribute to the evolution of soil. Chemical change alters what the particles are made of, and organic change adds the remains of plants and animals to them. Thus soil itself has evolved over millions of years.

Soil Is Millions Of Years Old Evidence: Temperature change, running water and wind break rock grain by grain, and no one has ever watched a soil finish forming. Reasoning: A layer deep enough to root forests must represent an enormous number of such small steps. Limit: This tells us soil is very old; it does not date any one soil.

Because soil takes so long to make, what happens to it in a single human lifetime matters. Faulty agricultural practices, overgrazing and deforestation lead to soil erosion. Improved agricultural practices, reduced pressure of grazing and afforestation can help in the conservation of soil. Both of those chains are taken up in detail later in this chapter.

What Soil Is Made Of

Soils are derived from parent rock — the rock lying beneath, from which the mineral part of the soil has come — through a process of breakdown or wear and tear. To this mineral material, life adds a second ingredient. Decomposed vegetal and animal remains, called humus, are an important constituent of soil and add to the fertility of the soil.

The chapter names four constituents in all. (a) Humus is the dark, decayed remains of plants and animals, and it is the part of the soil that raises its fertility. (b) Silica comes from the parent rock and forms the hard mineral framework of the soil. (c) Clay is made of the finest mineral particles, and it is the part of the soil that holds water. (d) Sand is made of coarser rock particles, and it lets water pass through easily.

Q. If soil is mostly broken rock, why does humus matter so much?

A. Broken rock gives the soil its body; humus is what makes it fertile enough to grow a crop.

The proportions of these four decide almost everything about a soil — its colour, how it feels, how much water it holds and what will grow in it. That is why the same four ingredients, mixed differently, give India the very different soils studied in this chapter.

Flowchart

Fig. 7.A2 Caption: Soil is the meeting point of broken rock and decayed life. Nodes: parent rock → breakdown by changing temperature, running water and wind → small rock particles (silica, clay, sand) → decomposed plant and animal remains added → humus mixed through → chemical and organic changes within the layer → soil

The flowchart shows why soil differs from place to place. Change the parent rock at the top of the chain, or change the climate that drives the breakdown, and the soil that comes out at the bottom is a different soil.

7.2 Soil Fertility

Soil fertility refers to the strength of the soil to support plant life. It is not the same thing as the presence of soil. A field can be covered in soil and still grow almost nothing, because fertility depends on what that soil holds and how deep it lies.

What Makes A Soil Fertile

A fertile soil has four characteristics, and a soil that is short of any one of them will hold a crop back. (a) It contains an adequate amount of moisture to supply essential nutrients to the plants, because a root does not take up dry powder — nutrients reach the plant dissolved in soil water. (b) It has sufficient depth to enable the plants to grow their roots as per their requirement, so a thin soil over hard rock cannot support a deep-rooted crop however rich its surface may be. (c) It is rich in nutrients such as nitrogen, phosphorus and potassium, which are the mineral foods necessary for basic plant nourishment and are drawn up through the roots. (d) It contains organic matter, which improves the structure of the soil — that is, the way its particles clump together, leaving spaces for air and water to move.

Q. A soil is deep and moist but grows a poor crop. What is likely missing?

A. The nutrients. Depth and moisture only deliver plant food; they cannot supply it.

Fertility Can Be Restored

Fertility is not fixed for ever. Soil fertility can be improved by adding the missing nutrients in the form of fertilizers to the soil. A soil short of nitrogen, phosphorus or potassium can be brought back into use by supplying what it lacks.

This is worth holding on to as you read the rest of the chapter. Some of what a soil lacks can be added by a farmer, but depth cannot be — and depth is exactly what erosion takes away.

7.3 Soil Classification

Before the soils of India are taken one by one, they can be sorted in a simple way. According to its location, soil can be categorised into two groups, and the question that separates them is whether the soil is still lying where it was made.

Soil Made In Place, And Soil Brought In

Residual or sedimentary soil is soil formed ‘in situ’, that is, formed in its original position by the breaking down of the parent rocks beneath it. Almost all soils are formed in this way. Because such a soil has been sitting still while it formed, its layers have had time to sort themselves out, and it has a well defined soil profile — the arrangement of layers you would see in the side of a freshly dug pit, from the loose surface down to the rock below. Black soil, red soil, laterite soil and desert soil are all residual soils.

Transported soil is the opposite case. These soils are ‘ex situ’, which means they have been carried away from where they formed. They are transported by various agents of erosion and consist of sediments carried and deposited by rivers and winds. Since fresh material keeps arriving and is dropped in whatever order the river or the wind delivers it, these soils do not have a well defined soil profile. Alluvial soils are transported soils.

The two groups therefore share their raw material and differ in their history. Both begin as broken parent rock; one stayed at home and settled into layers, while the other travelled and was dumped.

Q. You cut into a soil and find clear layers. In situ or ex situ?

A. In situ. A well defined profile means the soil formed where it lies.

Flowchart

Fig. 7.A3 Caption: Soils are first sorted by whether they stayed where they formed or were carried there. Nodes: soil of India → formed in situ? yes → residual or sedimentary soil, with a well defined profile → black soil / red soil / laterite soil / desert soil; no, carried by agents of erosion → transported soil, ex situ, no well defined profile → alluvial soil

This split explains something you will meet again and again in the next section. A residual soil tells you about the rock underneath it, so it changes where the rock changes. A transported soil tells you about the river that brought it, so it can lie hundreds of kilometres from the rock it came from.

7.4 Types Of Soil

India is a vast region with a varied natural environment. We find several physiographic regions and different types of climate within it, and since soil is made by rock and climate working together, a number of soil types have developed here. On the basis of their origin, colour, composition and location, the soils of India have been classified into the types studied below.

The map of soil distribution shows how these types are laid out across the country, and it is worth keeping in front of you through the whole of this section.

Map

Map 7.1 Caption: Soil distribution across India. Brief: Political outline map of India showing the full extent of India as officially defined, with international boundaries; shade four classes with the key given in the book — alluvial soil, black soil, red and yellow soil, laterite soil; mark the Arabian Sea, Bay of Bengal, Indian Ocean, Andaman Sea, Lakshadweep (India) and Andaman and Nicobar Islands (India); show the Tropic of Cancer; print the scale 1:20,000,000 with the kilometre bar; no district names or city names.

Map 7.1 The key gives four classes by colour, not by fertility. Read the pattern: alluvium along the northern plains and coasts, black over the Deccan, red around it, laterite in narrow highland strips. At 1:20,000,000 one centimetre stands for 200 km, so any patch smaller than a district disappears. The map cannot tell you how deep a soil is, or how much of it is left.

7.4.1 Alluvial Soil

How It Forms

This soil is formed by the sediments brought down by rivers, and it is rich in chemical ingredients. As a river travels, it carries a load of broken rock, and over the course of that long journey it deposits very fine particles of soil, called alluvium, across its plains. The resultant alluvial soil is also known as riverine soil, because it is mainly found in the river basins. It is a mixture of sand, clay and silt, called loam.

In India, alluvial soils have been deposited by three important river systems — the Indus, the Ganga and the Brahmaputra, which together drain the whole of the northern plains. This soil occupies 40 per cent of the land area. The entire Northern Plains are made up of it. It is also predominant in coastal plains and deltas, particularly in the deltas of the Mahanadi, the Godavari, the Krishna and the Kaveri rivers, all of which reach the sea on the eastern side of the peninsula.

On the basis of its age, the alluvial soil is of two types, bhangar and khadar, and the difference between them is simply how recently the river last added to them. The bhangar, or the older alluvium, is composed of lime nodules or kanker and has a clayey composition. The khadar is light in colour and is composed of newer deposits. Khadar is more fertile than bhangar, as new layers are deposited year after year during the monsoon floods, while crops can be grown on old alluvial soil by using manure.

Table 7.1 Caption: The old and the new alluvium of the northern plains compared. | Bhangar Soil | Khadar Soil | |—|—| | Old alluvium soils, known as Bhangar, occupy the largest part of northern plains. | The area in northern plains that lies below flood levels is made up of Khadar. | | Bhangar is found above the flood levels of rivers and presents a terrace like structure. | Khadar is younger alluvium as flood waters deposit new layers every year. | | Bhangar is full of kankars (lime nodules). | It is formed of fine silt and clay. | | Bhangar is not very fertile. | Khadar is very fertile and ideal for intensive cultivation. |

Q2. Why is the soil of the northern plains made new again almost every year, while the soil of the Deccan is not?

A. Alluvium is transported soil. Every monsoon flood spreads a fresh layer of khadar over the low ground. Black soil is residual — it weathers in place from the rock below, so no new material arrives.

Alluvial soil forms the largest and most important soil group in the country, as it contributes the largest share to the agricultural wealth of India.

7.4.1.1 Distribution

The chapter divides the distribution of alluvial soil into three, by the way the sediment was delivered. (a) Inland alluvium is found on the plains of the Indus, the Ganga and the Brahmaputra rivers, extending from Punjab and Sindh (Pakistan) to Bangladesh and Assam (India). Punjab, Haryana, Uttarakhand, Uttar Pradesh, Bihar and West Bengal have alluvial soil, and this soil type also covers a part of Gujarat and a few patches in Rajasthan. (b) Deltaic alluvium is found in the deltas of the Ganga-Brahmaputra, Mahanadi, Godavari, Krishna and Kaveri, where each river drops the last of its load as it enters the sea. (c) Coastal alluvium is of tidal origin, and it is found in the coastal strips of Peninsular India and also in the plains of Gujarat.

7.4.1.2 Characteristics Of Alluvial Soil

The colour of the alluvial soil varies from light grey to deep black. Its shades depend on the depth of deposition, the texture of the materials and the time taken for maturity, so the same soil type can look quite different in two districts.

Its texture changes along the length of a river, because alluvial soil is formed by the deposition of the river load as it flows from its upper to its lower course. In the upper reaches of the river valleys, near the place of their origin, the soil is dry, coarse, porous and sandy, and it consists of clay and organic matter. Soil particles there are large and non-uniform. Such soil is predominant in piedmont plains, which are the plains lying near the foot of mountains.

As we move further down a river valley, the soil particles become smaller and more uniform. They are more compact, less coarse and more moist. Alluvial soil is found up to a depth of 500 metres — deeper than a fifty-storey building is tall, which is why the plains can carry crops that root far below the surface.

Diagram

Fig. 7.A4 Caption: The river sorts its load, so the soil gets finer and moister towards the sea. Brief: Long cross-section from mountain foot to sea; label piedmont plain on the left with large, non-uniform, coarse, sandy and porous particles, the middle plain with smaller and more uniform particles, and the delta on the right with fine, compact and moist material; arrow along the base pointing from mountain to sea marked direction of flow; mark soil depth up to 500 metres.

The minerals in alluvial soil are set out below. (a) Alluvial soil varies in nature from sandy loam to clay, and it is a fertile soil, as it is rich in minerals, especially iron, magnesia, alumina, potash and lime, but poor in phosphorous, nitrogen and organic matter. (b) It is deficient in nitrogen and humus, except the alluvium of the Ganga deltaic region, which is rich in humus. (c) In the drier areas, it is more alkaline.

Alluvial soil is light and porous and therefore easily tillable, which matters a great deal to a farmer working with a small plough. It is suitable for the growth of a large variety of rabi and kharif crops. It is fertile and suitable for the cultivation of rice, wheat, sugarcane, cotton, tobacco, gram and oilseeds, and in the lower Ganga-Brahmaputra Valley it is useful for jute cultivation.

7.4.2 Black Soil

How It Forms

This soil is black in colour and is also known as the Black Cotton Soil or Regur soil. It is dark in colour and is suitable for cotton cultivation. This soil is the residual soil, that is, it is formed at the place of its origin over the underlying rocks. Since it is formed by the denudation of volcanic rocks — the wearing down and stripping away of the old lava flows that lie beneath it — it is also known as lava soil.

7.4.2.1 Distribution

The Regur soils are concentrated over the Deccan lava tract, the great sheet of old lava rock in the western and central peninsula. This tract includes parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, Karnataka and some parts of Tamil Nadu.

7.4.2.2 Characteristics Of Regur (Black) Soil

It is black in colour, as it is formed from weathered lava rocks. The colour is inherited from the parent rock rather than from anything the soil has gained since.

It is fine textured and clayey in nature, with up to 50 per cent clay content, and is therefore highly retentive of water. Because of the high clay content, this soil expands when wet and becomes difficult to plough. During the dry season it shrinks and develops big cracks, which help in air circulation. This characteristic causes a kind of ‘self-ploughing’.

Q1. Why does black soil crack open in the dry season, and how do those cracks help the farmer?

A. It is up to half clay, and clay shrinks as it dries, so the ground splits apart. The cracks let air reach the roots and let loose crumbs fall in, turning the topsoil without a plough.

Due to slow absorption and loss of moisture, the black soil retains moisture for a very long time, which helps the crops — especially the rain fed ones — to sustain even during the dry season.

It has high quantities of lime, iron and magnesium, and generally a poor percentage of phosphorous, nitrogen and organic matter.

The soil is very fertile in most of the places. It is suitable for the cultivation of cotton, jowar, wheat, linseed, gram, citrus fruits and vegetables, tobacco and sugarcane. In any season it has moisture stored in its subsoil, and this moisture retentiveness of black soil makes it suitable for dry farming. Dry farming refers to crop cultivation without irrigation during the dry season, as the crops would utilise the moisture stored in the soil during the rains.

7.4.3 Red Soil

How It Forms

Red soil is a category of soil which develops on old crystalline rocks. Under prolonged weathering by rainfall, the ancient crystalline and metamorphic rocks of the Peninsular plateau break up to form this soil. Because the parent rock varies from place to place across the plateau, this soil differs from place to place on the basis of the parental rock material and climatic conditions.

7.4.3.1 Distribution

Red soil forms the second largest soil group in India and is found mainly on the plateau region of Peninsular India, from Tamil Nadu in the south to Bundelkhand in the north, and from the Rajmahal Hills in the east to Kutch in the west. Red soil covers almost the whole of Tamil Nadu, Karnataka, Andhra Pradesh, south-eastern Maharashtra, parts of Odisha, Chhattisgarh, Jharkhand, Bundelkhand, Meghalaya, Mizoram, Manipur, Telangana and Nagaland.

Scattered patches of red soil are also found in Birbhum (West Bengal), Mirzapur, Jhansi, Banda and Hamirpur (Uttar Pradesh), and Udaipur, Chittorgarh, Dungarpur, Banswara and Bhilwara districts (Rajasthan). It practically encircles the entire black soil region on all sides, and it extends northwards in the west along the Konkan Coast of Maharashtra.

7.4.3.2 Characteristics Of Red Soil

It is red in colour, as it contains large amounts of iron oxide. At several places its colour slightly changes and it appears brown or grey, and it looks yellow when it occurs in a hydrated form, that is, when the iron in it has taken up water.

It is porous, loose and aerated, and it is generally shallow. Its pH value ranges from 6.6 to 8.0. The pH scale measures how acidic or alkaline a soil is, with 7 as neutral, lower values acidic and higher values alkaline, so red soil sits close to neutral.

It is poor in nitrogen, phosphorus, potassium and organic matter, and it contains soluble salts in small quantities.

Its porous nature makes red soil ideal for dry farming. The limited rainfall can percolate and be stored in the subsoil, from where it can be utilised by the roots of plants. It needs irrigation and fertilizer support for crop cultivation. It is suitable for cultivating almost all crop types, and it is most suitable for growing vegetables, rice, ragi and tobacco. Groundnut and potatoes can be grown on coarse soils at higher levels, and sugarcane on heavy clays at lower levels.

7.4.4 Laterite Soil

How It Forms

This soil type is formed as a result of atmospheric weathering of rocks under conditions of high rainfall and temperature with alternate wet and dry periods. It is the residual soil formed by leaching due to tropical rains. Leaching is the process in which the nutrients get percolated down below the soil due to heavy rainfall, thus leaving the topsoil infertile. This is also called desilication.

Due to heavy rains, lime and silica are leached away and aluminium compounds are left behind. The humus content of the soil is removed by bacteria that survive well in high temperature. The soil is therefore stripped from two directions at once — the rain takes the soluble material downwards, and the heat lets bacteria destroy the organic matter at the top.

Flowchart

Fig. 7.A5 Caption: Heavy rain and high heat together strip a soil of almost everything a plant needs. Nodes: rocks under high rainfall and high temperature → alternate wet and dry periods → heavy tropical rain percolates through the soil → lime and silica leached away (desilication) → aluminium compounds and iron oxide left behind → high temperature lets bacteria remove the humus → infertile red topsoil, acidic and low in moisture → laterite soil

There are two types of laterite soils, Upland Laterites and Lowland Laterites. Upland laterites are formed over hills and uplands. From there they are transported by streams towards lowlands, and such transported soils are known as Lowland Laterites.

7.4.4.1 Distribution

Laterite soil mainly occurs in the highland areas of the Peninsular Plateau, especially on the summits of the Sahyadris, the Eastern Ghats, the Rajmahal Hills and many other hills in the eastern parts of the peninsula. Patches of laterite soil are found in Madhya Pradesh, Odisha, Maharashtra, West Bengal, Andhra Pradesh, Telangana, Karnataka, Kerala and Tamil Nadu, and along the top slopes of the peninsular mountains, the Western and Eastern Ghats.

7.4.4.2 Characteristics Of Laterite Soil

It is red in colour due to the presence of iron oxide, which is formed by leaching. The soluble plant foods like potash are removed from the topsoil, leaving alumina and iron oxide behind. It is of a coarse texture, soft and friable, which means it crumbles easily between the fingers.

Its mineral condition follows directly from leaching. (a) It is a porous soil, and silica is removed from it by chemical action. (b) It is poor in lime and magnesium and deficient in nitrogen. (c) It is acidic in nature, as the alkalis are leached out of it. (d) It is rich in iron oxide, which is left behind when the soluble material has gone.

Laterite is widely cut as bricks and is considered suitable for construction materials — one of the few soils in India that is used as a building material rather than only as a growing medium.

Being infertile, it suits only special crops like tapioca, cashew nuts, tea and coffee. It has low fertility because of high acidity and low moisture retention, so manuring and other activities are required to make it 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.

The Four Soils Side By Side

The chapter’s summary table sets the four soils against one another on the same five points, and it is the quickest way to check that you have not confused two of them.

Table 7.2 Caption: The four soils of India compared by formation, area, characteristics and crops. | Soil | Formation | Areas | Characteristics | Crops | |—|—|—|—|—| | Alluvial Soil | Deposition of sediments by rivers. | Inland alluvium in Punjab, Haryana, U.P., Bihar, West Bengal, parts of Gujarat and Rajasthan. Deltaic alluvium in the deltas of Ganga-Brahmaputra, Mahanadi, Godavari, Krishna and Kaveri. Coastal alluvium along the coastal strips of the Peninsula. | Loamy. Coarse and dry in upper reaches of the river and gets finer and moist as the river flows. Rich in minerals especially potash and lime. Poor in nitrogen and humus. | Large variety of Rabi and Kharif crops; rice, wheat, sugarcane, cotton, gram and oilseeds; jute in Ganga-Brahmaputra delta. | | Black Soil | Residual soil formed by weathering of lava rocks. | Deccan lava tract. Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, Karnataka and parts of Tamil Nadu. | Clayey. Black in colour. Rich in lime, Magnesium. Poor in phosphorous, nitrogen and organic matter. Very fertile. | Cotton, cereals, citrus fruits and vegetables, tobacco, and sugarcane. | | Red Soil | Prolonged weathering of crystalline rocks. Differs on the basis of parent rock material and climatic conditions. | Plateau region of Peninsular India extending northwards along Konkan coast. Tamil Nadu, Karnataka, Andhra Pradesh, South-East Maharashtra, Chhattisgarh, parts of Odisha, Jharkhand, Bundelkhand, Meghalaya, Mizoram, Manipur, Telangana and Nagaland. | Ranges from Sandy to Clayey. Red in colour due to large amounts of iron-oxides. Deep and fertile in lowlands; thin and poor in highlands. Poor in nitrogen, phosphorus and organic matter. | Vegetables, rice, ragi, tobacco, groundnut and potatoes. | | Laterite Soil | Due to leaching in areas of heavy rain. | Highland areas of Peninsular plateau. Patches in Madhya Pradesh, Odisha, Maharashtra, West Bengal, Andhra Pradesh, Telangana, Karnataka, Kerala, and Tamil Nadu. | Coarse and porous. Red due to Iron Oxide. Poor in lime, nitrogen and magnesium. High acidity and low moisture retention. | Tapioca, cashew nuts. With manure ragi, rice, sugarcane, tea, rubber and coffee. |

Read the table down the Formation column rather than across the rows, and the logic of the four soils appears. One is delivered by rivers, one is weathered from lava, one is weathered from crystalline rock, and one is what heavy rain leaves behind after it has washed the goodness out.

7.5 Soil Erosion

The removal of the topsoil cover by water, wind and human activities is called soil erosion. The word to hold on to is topsoil, because it is the uppermost layer that carries the humus and the nutrients, and it is exactly the layer that moves first.

Man is responsible for soil conditioning either through agriculture or through pollution like the dumping of chemical wastes in water bodies as well as underground. Besides human activity, soils are degraded by nature during drought or floods.

7.5.1 Soil Erosion By Water

Water removes soil in six ways, and the first three of them are stages of one process rather than three separate events. (a) Sheet erosion occurs on gentle slopes and is the slow removal of a thin layer of soil when vegetation is destroyed, as rainwater washes away the thin layer of bare soils. (b) Rill erosion follows when sheet erosion continues for long, and the silt-laden run-off forms many finger-shaped rills or grooves over a large area. It is the intermediate stage between sheet erosion and gully erosion. (c) Gully erosion happens during a heavy downpour, when deep gullies are made on bare soils on account of water run-off. Gully erosion removes nutrients and a heavy load of loose soils, making the soil unproductive, and it makes water very muddy. This is seen in the Chambal Valley region. (d) Leaching takes place after harvesting, when farmers leave the soils bare for some time, and during rainfall the nutrients in the soil are leached or percolated below the top layer. (e) Sea or shore erosion is caused by the tidal waters of the sea, which do considerable damage to the soil along the coast. The powerful waves dash against the coast and break hanging cliff rocks, and the broken material is then removed by the retreating sea waves. This type of sea erosion is seen throughout the eastern and western coasts of India. (f) Stream bank erosion occurs as streams and rivers change their courses by cutting one bank and depositing the silt loads on the other, and during flash floods the damage is accelerated.

Flowchart

Fig. 7.A6 Caption: The same run-off, left unchecked, cuts deeper each season. Nodes: vegetation destroyed → bare soil on a slope → rainwater washes off a thin layer evenly (sheet erosion) → run-off gathers into finger-shaped grooves (rill erosion) → heavy downpour deepens the grooves (gully erosion) → nutrients and loose soil carried away → land unproductive and water muddy

Stream bank erosion is prevalent in the flood plains of the Ganga, the Yamuna and other rivers. As a result of stream bank erosion, large areas of agricultural land in the States of Uttar Pradesh, Madhya Pradesh and Rajasthan are getting transformed into ravines — networks of deep, steep-sided channels in which no crop can be grown.

Diagram

Fig. 7.1 Caption: Ravines cut into the land of the Chambal Valley. Brief: Photograph of the Chambal ravines; show the maze of bare, steep-sided gullies and sharp ridges with almost no vegetation cover, taken from a raised viewpoint so the depth and extent of the cutting is visible.

Q3. How does a shallow wash of water across a bare field turn, over time, into a gully deep enough to swallow farmland?

A. Once vegetation goes, run-off first strips a thin sheet. The water then gathers into finger-shaped rills, and a heavy downpour deepens the same grooves into gullies.

The Poverty Cycle Behind The Damage

Erosion is not only a physical process. Where land degradation and poverty meet, each one worsens the other, and the chapter sets this out as a closed loop.

Flowchart

Fig. 7.2 Caption: The cycle of poverty and soil erosion. Nodes: poverty → increasing population → small landholding → low production per person → non-sustainable land management practices (deforestation, overgrazing, unbalanced fertilizer application) → land degradation (soil erosion) → reduced productivity → back to poverty

Fig. 7.2 Follow the arrows one full turn: every box is both a result of the one before it and a cause of the one after. A cycle has no starting point, so it can be broken at any box. It does not tell you how fast the loop turns, how many households are caught in it, or which box is easiest to break.

To counter this vicious cycle of poverty and soil erosion, government agencies need to encourage four things. (a) The use of technology for soil conservation. (b) The use of high yielding crop varieties. (c) Alternative avenues of livelihood. (d) A limit on the increase in population.

7.5.2 Soil Erosion Due To Human Action

The loss of vegetation cover 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 with the absorbent topsoil washed off, 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 Shiwaliks, and the Western and Eastern Ghats are subjected to deforestation by man. These areas also receive heavy monsoon rains, so the two conditions that erosion needs — bare ground and falling water — arrive together.

Clearing A Steep Slope In The Shiwaliks Vegetation removed for a road, a railway line, a building or a field → rain no longer sinks in and runs off the bare slope → sheet erosion, then rills, then gullies → topsoil from the slope reaches the valley below → the slope loses its productive soil and the valley receives it as a load of loose material.

The removal of vegetation cover for different land uses like railway lines, roads, buildings or even agriculture has caused sheet, rill and gully erosion. In these areas the local population practise shifting cultivation, and the heavy rains then wash away the bare soil from the slopes to the valleys below. Another important cause of sheet, rill and gully erosion is the uncontrolled grazing of domestic animals in the valleys and the upper slopes.

7.5.3 Erosion By Wind

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, which is why it is a problem of dry, bare and open country rather than of wet slopes.

What the wind does with a particle depends on how heavy that particle is, and the chapter separates three cases. (a) Particles greater than 0.5 mm are moved by rolling along the ground, and this is known as soil creep. (b) Particles 0.1 mm to 0.5 mm in size are moved in a bouncing or hopping fashion, and this is known as saltation. (c) Particles less than 0.1 mm, the finest of all, detach into suspension and are carried in the air itself.

Flowchart

Fig. 7.A7 Caption: Particle size decides whether the soil rolls, hops or flies. Nodes: bare soil exposed to high-velocity wind → particle greater than 0.5 mm? yes → rolled along the ground → soil creep; 0.1 mm to 0.5 mm? yes → bounced or hopped along → saltation; less than 0.1 mm? yes → detached into the air → suspension → visible as dust storms → deposited along fence lines and across roads

In fact, wind erosion is most visible in the suspension stage, as dust storms, or subsequently as deposition along fence lines and across roads. A drift of fine soil banked against a fence is not a curiosity; it is a field that has been moved.

Wind erosion reduces the productive capacity of soil, as most of the nutrients required by the plants are carried away by the wind. The particles that travel first are the finest ones, and those are the particles that carry the nutrients.

7.6 Causes Of Soil Erosion

Erosion needs bare ground and a moving agent. Almost every cause listed below works by supplying one of those two, and several supply both at once.

Six Causes

The chapter names six causes of soil erosion in India. (a) Heavy population pressure on land is the main cause. India’s forest cover continues to be very low, just 21.54 per cent of the total area, while the population continues to rise at a rapid rate and has already crossed the one billion mark in the year 2000. More forests are being destroyed to house and feed the increasing population, and the heavy pressure on land follows from that. (b) The nature of rainfall matters, because India receives 80 to 90 per cent of its rainfall in the monsoon season. Heavy downpour during the monsoon months causes floods, and in the remaining months droughts are frequent, so the soil is either being struck by concentrated rain or drying out. (c) Overgrazing exposes the ground, since the number of domestic animals, particularly cattle, in India is the highest in the world. Cattle freely graze in open lands, making them bare of vegetation, and winds then carry away dry soil particles from the bare landscape. (d) Bad farming techniques increase the loss, as fields are ploughed in traditional ways and holdings are small, which together lead to soil erosion on a large scale. The absence of terracing, contour cultivation and crop rotation, and the improper use of manure, have caused serious problems of soil erosion. (e) Topography decides where the damage is worst. The northeastern parts of India, the Shiwaliks and the hilly regions in South India are affected by soil erosion because of steep slopes and heavy rainfall, and during heavy rainfall the soils are washed away by running water down the slope. (f) Deforestation strips the protection off the soil, because forests are destroyed so that more land can be used for cultivation, and cutting trees exposes the soil to both water and wind.

The figure for forest cover in cause (a) is drawn from the Forest Survey of India Report 2017.

India’s Forest Cover Is Low Evidence: The Forest Survey of India Report 2017, a national survey of how much of the country is under forest. Reasoning: Forest area set against total area gives the share — 21.54 per cent. Limit: One survey year gives a share, not a trend, and it says nothing about where that forest stands or how healthy it is.

In many parts of Rajasthan, excessive grazing by cattle has resulted in the exposure of the topsoil to the elements of denudation, that is, to the wearing away and stripping off of the surface layer by wind and water.

Diagram

Fig. 7.3 Caption: Terraced fields cut a steep hillside into level steps. Brief: Photograph of terrace farming on a steep hillside; show the stepped fields following the contour of the slope, with water standing or crops growing on the level surfaces, and enough of the hill visible for the reader to see how steep the original slope is.

The terraced hillside in Fig. 7.3 shows what the absence of terracing costs. Where the slope has been cut into level steps, run-off has nowhere to gather speed, and where it has not, the same rain runs straight down the bare slope.

Why Erosion Must Be Stopped

There is an acute need to prevent soil erosion, because of its adverse effects, which include the following. (a) The loss of fertile topsoil together with its mineral nutrients from the upper surface leads to a gradual loss of soil fertility and agricultural productivity. (b) The lowering of the water table and decreasing soil moisture leave less water within reach of roots and wells. (c) The drying of vegetation and the extension of arid lands lead to an increase in the frequency of droughts and floods. (d) The silting of river and canal beds occurs as the eroded material is dropped downstream. (e) Landslides recur where slopes have lost the cover that held them. (f) There is an adverse effect on economic prosperity and cultural development.

Flowchart

Fig. 7.A8 Caption: One loss at the surface spreads outwards into water, land and livelihood. Nodes: topsoil and its mineral nutrients removed → soil fertility and agricultural productivity fall; water table lowered and soil moisture decreased → vegetation dries and arid lands extend → droughts and floods become more frequent; eroded material carried downstream → river and canal beds silted; slopes stripped of cover → landslides recur; all of these together → adverse effect on economic prosperity and cultural development

Notice that only the first of these effects is felt on the field where the soil was lost. The rest are felt somewhere else — in the well, in the riverbed, on the road below the slope — which is why soil erosion is treated as a national problem and not a private one.

7.6.1 Regions Of Soil Erosion

In India, soil erosion is one of the great enemies of Indian agriculture and is responsible for low agricultural productivity. According to an estimate, every year rainwater alone washes out 1.25 mm of thick fertile topsoil.

WC 7.A1 — What 1.25 mm A Year Adds Up To The situation: The chapter’s estimate that rainwater alone washes out 1.25 mm of fertile topsoil every year, applied over the working life of one farm. The working: Loss in one year \(= 1.25 \text{ mm}\). Loss in ten years \(= 1.25 \times 10 = 12.5 \text{ mm}\). Loss in forty years \(= 1.25 \times 40 = 50 \text{ mm}\), and since \(10 \text{ mm} = 1 \text{ cm}\), this is \(50 \div 10 = 5 \text{ cm}\). Loss in eighty years \(= 1.25 \times 80 = 100 \text{ mm} = 10 \text{ cm}\).

Ten centimetres in eighty years sounds small until you set it against how soil is made. The layer taken in a single lifetime took, as section 7.1 explained, an enormous span of time to form, and nothing in the field replaces it at the same speed. That is the whole case for conservation: the loss is slow enough to ignore each year and far too fast to repair.

Among the States, Rajasthan comes on top of the soil eroded regions, followed by Madhya Pradesh, Maharashtra, Uttar Pradesh, Gujarat, Andhra Pradesh and Karnataka.

Rajasthan At The Top Of The List Factors: Dry areas with little vegetation, the highest numbers of grazing cattle, rainfall concentrated into a short monsoon, and high-velocity wind over bare ground. The decisive one: Bare ground. Every other factor only matters because there is no vegetation holding the surface. Move it: Restore a cover of vegetation and the same wind and the same rain would carry far less away.

The worst affected areas include the following. (a) The badlands of the Chambal and Yamuna rivers, where gullying has already destroyed the farmland. (b) The piedmont zone of the western Himalayas, at the foot of the mountains. (c) The Chota Nagpur plateau region, in eastern India across Jharkhand and parts of the neighbouring States. (d) The Tapi-Sabarmati valley region in Gujarat. (e) The regur soil area of Maharashtra. (f) The dry areas of Rajasthan, Gujarat and Haryana.

Read that list against the causes above and it explains itself. Every one of these places is either steep, or dry and open, or already stripped of its vegetation — and most of them are more than one of the three.

7.7 Soil Conservation

Soil conservation means the prevention of soil loss from erosion, or the prevention of reduced fertility of soil caused by over usage, acidification, salinisation or other types of soil contamination. Acidification is a fall in the soil’s pH, and salinisation is the building up of salts in it, and both leave a soil that is still in place but no longer able to grow much.

Thus soil conservation refers to practices that protect soil from degradation to ensure its health and productivity. The key aspects involve preventing erosion, maintaining fertility, improving soil structure, managing soil moisture and minimising contamination by pollutants. Notice that only the first of those is about holding the soil down; the other four are about keeping it worth holding.

7.7.1 Methods

Soil conservation can be achieved through physical, biological (or agronomic) or chemical methods. The three groups attack the problem in different ways — the first changes the shape of the land, the second changes what is grown on it, and the third changes what is in it.

Flowchart

Fig. 7.A9 Caption: The three families of conservation method, and what belongs in each. Nodes: soil conservation → physical or mechanical methods → terrace farming / contour ploughing / plugging gullies / shelter belts / planting trees / construction of dams; agronomic or biological methods → cover cropping / crop rotation / strip cropping / mulching / zero tillage / agroforestry; chemical methods → soil amendments / pH adjustments

7.7.1.1 Physical/Mechanical Methods

Terrace farming is used on hilly slopes, where terraces act as bunds and prevent the soil from being washed away by running water. A bund is a low earth wall that holds water back instead of letting it run on. Terrace farming is practised with successful results in Japan, South-East Asia and the USA, and Fig. 7.3 shows what a terraced hillside looks like.

Contour ploughing means ploughing along the contours on a slope, which prevents soil being washed away by rainwater or by surface run off. A contour is a line joining points of equal height, so ploughing along one means ploughing across the slope rather than up and down it. The contours act like bunds. Terraces are levelled into step-like small fields with an even slope. Contour ploughing is common in Japan, China and some South-East Asian countries.

Q. Why does the direction of the furrow matter so much on a slope?

A. A furrow running downhill becomes a channel for run-off. A furrow along the contour stops it, like a small bund.

Plugging gullies is a direct repair: the gullies made in the soil are plugged with the deposition of silt during heavy rains, so the channel is filled instead of being deepened further.

Shelter belts are rows of trees planted by farmers, several rows deep, to check wind erosion, and they are known as wind breaks. Planting trees works in the same way as shelter belts — trees are planted along the edges of the fields, on waste land and on steep slopes, both to prevent soil erosion and to enhance the capacity of the soil to retain water.

A Shelter Belt Across A Dry Field Rows of trees planted across the wind → wind speed at ground level is cut → fewer dry soil particles are lifted from the bare surface → the fine, nutrient-carrying particles stay in the field → the soil keeps both its depth and its fertility.

The construction of dams is the last of the mechanical methods. Rivers cause soil erosion, and dams are built in the upper course of rivers to control the erosion of soil by water.

7.7.1.2 Agronomic/Biological Methods

These methods work by keeping living roots in the ground, because roots are what hold soil particles together.

Cover cropping means growing grasses or legumes on a field even when there are no crops. This prevents soil erosion, improves the field’s fertility and maintains its moisture. Crop rotation means planting different types of crops together to maintain soil health.

Strip cropping means growing crops in alternate strips of land to check soil erosion by water or wind. Crops like hay and wheat are alternated with strips of crops such as corn, soya beans and cotton. This method helps to prevent soil erosion by having the roots of the crops hold on to the soil and prevent it from being washed away by water or wind.

Diagram

Fig. 7.4 Caption: Alternate strips of different crops follow the curve of the land. Brief: Photograph of strip cropping on gently rolling farmland; show the contrasting bands of two different crops running as alternate strips along the curve of the slope, with enough of the landscape visible to show that the strips follow the contour.

Mulching means covering the soil with organic material to retain moisture. Zero tillage means avoiding tilling, so as to minimise soil disturbance and erosion. Agroforestry means planting trees along with crops, which reduces wind erosion and maintains soil health, and it is taken up in detail in the next chapter.

7.7.1.3 Chemical Methods

Soil amendments involve the use of nano fertilizers and bio fertilizers. pH adjustments involve the addition of lime or sulphur to correct the soil pH, so as to ensure optimal plant growth through better nutrient availability — because a soil that is too acidic or too alkaline locks up nutrients that are physically present.

Practices such as checking indiscriminate tree felling, afforestation, contour ploughing and reclaiming ravines, as well as saline and alluvial soils, go a long way to ensure soil conservation. These need to be supported by various schemes to educate the public and encourage farmers to adopt techniques of sustainable agriculture.

7.7.2 Advantages Of Soil Conservation

Conservation pays back in five ways. (a) It improves soil quality. (b) It increases water retention. (c) It increases crop yield. (d) It reduces soil erosion. (e) It supports biodiversity.

7.7.3 Challenges To Soil Conservation

Three difficulties stand in the way. (a) Population pressure on land leads to overuse, so land gets no rest. (b) Climate change induced unpredictable rainfall makes it harder to plan for either flood or drought. (c) Low awareness amongst farmers limits how widely the methods are taken up.

Government Initiatives

Six government programmes support soil conservation in India. (a) The Soil Health Card Scheme (2015) provides soil testing and nutrient recommendations to farmers, and it encourages balanced fertilizer use and reduces nutrient depletion. (b) Watershed Development Programmes include the Integrated Watershed Management Programme (IWMP) under the Pradhan Mantri Krishi Sinchayee Yojana (PMKSY), which promotes a ridge-to-valley approach to conserve soil and water and transforms dry lands through community-led watershed management. (c) The National Mission for Sustainable Agriculture (NMSA) focuses on conservation agriculture, water use efficiency and soil health management. (d) The Paramparagat Krishi Vikas Yojana (PKVY) promotes organic farming and minimal soil disturbance. (e) The ‘Catch the Rain’ Campaign aims to recharge groundwater and reduce erosion during the monsoons. (f) The Compensatory Afforestation Fund Management and Planning Authority (CAMPA) supports forest regeneration and the restoration of degraded lands.

The ridge-to-valley approach named in point (b) is worth pausing on, because it follows the same logic as this whole chapter. Water starts at the ridge, so the treatment starts there too — hold the water where it falls, and the valley below is spared what it would otherwise have carried away.

7.8 Summary

  1. Soil is the thin layer of loose mixture of small rock particles and rotting organic matter that covers the surface of the earth, and it supports the forests, grasslands and crops from which all living creatures draw their energy.
  2. Soil is made by changing temperature, running water and wind breaking down parent rock, together with the chemical and organic changes within the layer itself, and it has evolved over millions of years.
  3. Besides humus, which is decomposed vegetal and animal remains and adds to fertility, the constituents of soil are silica, clay and sand.
  4. Soil fertility is the strength of the soil to support plant life, and a fertile soil shows four characteristics.
    1. It has adequate moisture to supply nutrients to the plants.
    2. It has sufficient depth for roots to grow as required.
    3. It is rich in nitrogen, phosphorus and potassium.
    4. It contains organic matter that improves soil structure.
  5. Fertility can be improved by adding the missing nutrients as fertilizers, but lost depth cannot be added back.
  6. By location, soils are of two kinds.
    1. Residual or sedimentary soils form ‘in situ’ from the parent rock below and have a well defined soil profile; black, red, laterite and desert soils belong here.
    2. Transported soils are ‘ex situ’, carried and deposited by rivers and winds, and have no well defined profile; alluvial soil belongs here.
  7. Alluvial soil is formed from sediments brought down by rivers, occupies 40 per cent of the land area, makes up the entire Northern Plains, and contributes the largest share to the agricultural wealth of India.
    1. Bhangar is the older alluvium, lies above flood level, is full of kankar or lime nodules and is not very fertile.
    2. Khadar is the newer alluvium, lies below flood level, is renewed by flood deposits every year and is very fertile.
    3. It occurs as inland, deltaic and coastal alluvium, and grows rice, wheat, sugarcane, cotton, tobacco, gram and oilseeds, with jute in the lower Ganga-Brahmaputra Valley.
  8. Black or regur soil is a residual soil formed by the denudation of volcanic rocks over the Deccan lava tract, and is also called lava soil or black cotton soil.
    1. It is clayey, with up to 50 per cent clay, so it swells when wet and cracks when dry, giving a kind of ‘self-ploughing’.
    2. It holds moisture for a very long time, which makes it suitable for dry farming, and it grows cotton, jowar, wheat, linseed, gram, citrus fruits, vegetables, tobacco and sugarcane.
  9. Red soil is formed by the prolonged weathering of ancient crystalline and metamorphic rocks of the Peninsular plateau, and forms the second largest soil group in India.
    1. It is red because of its iron oxide content, is porous, loose and generally shallow, with a pH of 6.6 to 8.0.
    2. It is poor in nitrogen, phosphorus, potassium and organic matter, and suits dry farming, vegetables, rice, ragi and tobacco.
  10. Laterite soil is formed by leaching under high rainfall and high temperature with alternate wet and dry periods, which washes lime and silica down and leaves aluminium compounds and iron oxide behind.
  1. It is acidic, coarse, friable and infertile, and occurs as Upland and Lowland Laterites in the highland areas of the Peninsular Plateau.
  2. It is cut as bricks for construction, and with manuring grows tapioca, cashew nuts, ragi, rice, sugarcane, tea, rubber and coffee.
  1. Soil erosion is the removal of the topsoil cover by water, wind and human activities.
  2. Water erodes soil in six ways — sheet, rill and gully erosion, which are successive stages of one process, together with leaching, sea or shore erosion and stream bank erosion.
  3. Wind erosion moves particles greater than 0.5 mm by rolling, called soil creep, particles of 0.1 mm to 0.5 mm by hopping, called saltation, and the finest particles in suspension as dust storms.
  4. The six causes of soil erosion are heavy population pressure on land, the nature of India’s rainfall, overgrazing, bad farming techniques, steep topography and deforestation.
  5. Poverty and soil erosion form a closed cycle, in which small holdings and low production per person drive non-sustainable land management, land degradation and reduced productivity, which returns to poverty.
  6. Erosion causes loss of fertility, a lower water table, drying vegetation and extension of arid lands, silting of river and canal beds, landslides, and harm to economic prosperity, and rainwater alone is estimated to wash out 1.25 mm of fertile topsoil every year.
  7. Rajasthan is the worst eroded State, followed by Madhya Pradesh, Maharashtra, Uttar Pradesh, Gujarat, Andhra Pradesh and Karnataka.
  8. Soil conservation prevents both the loss of soil and the loss of its fertility, and is achieved by three families of method.
  1. Physical or mechanical — terrace farming, contour ploughing, plugging gullies, shelter belts, planting trees and the construction of dams.
  2. Agronomic or biological — cover cropping, crop rotation, strip cropping, mulching, zero tillage and agroforestry.
  3. Chemical — soil amendments and pH adjustments.
  1. Conservation improves soil quality, water retention and crop yield, reduces erosion and supports biodiversity, but is held back by population pressure, unpredictable rainfall and low awareness amongst farmers.
  2. Government initiatives supporting soil conservation include the Soil Health Card Scheme, Watershed Development Programmes, the National Mission for Sustainable Agriculture, the Paramparagat Krishi Vikas Yojana, the ‘Catch the Rain’ Campaign and CAMPA.

Flowchart

Fig. 7.A10 Caption: The whole chapter in one chain — how soil is made, sorted, lost and held. Nodes: parent rock + climate → breakdown and humus added → soil → sorted by location → residual (black, red, laterite) or transported (alluvial) → vegetation removed or land overused → erosion by water, wind and human action → topsoil, fertility and depth lost → conservation by physical, agronomic and chemical methods → vegetation and structure restored → back to soil held in place

What This Chapter Cannot Tell You

The four soil types are broad classes drawn at the scale of a country, and Map 7.1 is printed at 1:20,000,000. Inside any one shaded belt a farmer may be working soil that is deeper, stonier or more alkaline than the class suggests, and the map cannot show it.

The chapter gives no year for its soil distribution, and its erosion figures are estimates and rankings rather than measurements of any single field. An average loss of 1.25 mm a year tells you nothing about which fields lost ten times that and which lost none.

Nor does the chapter say what conservation costs, or who pays for it. It lists the methods and the schemes; whether a farmer with a small holding can afford to leave land under a cover crop is a question the data here cannot reach. ## 7.9 Check Your Concepts

  1. Look at Map 7.1. Name the soil that practically encircles the black soil belt on all sides, and use what the chapter says about how each of the two soils is formed to explain why they lie next to each other.
  2. Wind moves soil particles in three different ways.
    1. Arrange soil creep, saltation and suspension in order of the particle size involved, smallest first, and give the size range for each.
    2. Explain why wind erosion is most visible at the suspension stage, and why this stage does the greatest damage to soil fertility.
  3. The chapter estimates that rainwater alone washes out 1.25 mm of fertile topsoil every year. Calculate the depth of topsoil that would be lost from a field in 25 years at this rate, and give your answer in centimetres. Show every step of your working.
  4. The chapter gives India’s forest cover as 21.54 per cent of the total area, from the Forest Survey of India Report 2017. State two things this single figure cannot tell you about the link between forest cover and soil erosion in India.
  5. Give a geographical reason for each of the following.
    1. Deltaic alluvium is more fertile than coastal alluvium.
    2. Black soil is largely found in the Deccan Trap region.
    3. Black soil is often referred to as Cotton soil or Regur soil.
  6. Give a geographical reason for each of the following.
    1. You have gone to Rishikesh and notice that the soil is dry, coarse, porous and sandy.
    2. The soil in your ancestral village at the outskirts of Agra has fine, smooth and moist particles.
    3. You have gone to Jhansi for an excursion and notice that the colour of the soil is a shade of red.
  7. What is soil erosion? Name the areas of soil erosion in India for wind erosion and for running water erosion.
  8. How are poverty and land degradation linked through a vicious cycle?

7.10 Case-Based Questions

  1. Pawan and Akash have been friends since childhood, and both are farmers in a village near Prayagraj. They often compare their inputs so as to increase their yields. Pawan, whose farm is along the Ganges, gets better yields with lower inputs of fertilizer and irrigation than Akash, whose fields are twenty kilometres away. Identify their soils, which are sub-categories of one major soil type. Which one of them is superior to the other, and why?
  2. Study the picture of the Chambal Valley in Fig. 7.1. What is responsible for erosion here? Briefly describe how the soil is eroded in this case.