Soil Resources Flashcards

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1
Q

Define Soil

A

The thin layer of loose mixture of rock particles and rotting organic matter that covers much of the land

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2
Q

What are the constituents of soil?

A

Decomposed vegetal and animal remain (humus), silica, clay and sand

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3
Q

Define soil fertility

A

The ability of soil to sustain plant life

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4
Q

How is alluvial soil formed?

A

Alluvial soil is formed by the deposition of river load as the river flows from upper course to lower course.

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5
Q

Why is alluvial soil known as riverine soil?

A

Because it is mainly found in river basins

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6
Q

What is bhangar? What is its composition?

A

Bhangar is older alluvium. It is composed of lime nodules (kanker) and has a clayey composition. It is above the flood levels of rivers.

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7
Q

What is khadar?

A

Khadar is newer alluvium and is more fertile as newer layers are deposited year after year during monsoon floods. It is composed of fine silt and clay and is lighter in colour.

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8
Q

Where is inland alluvium found?

A

Plains of the Ganga, Indus, and Brahmaputra

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9
Q

Where is deltaic alluvium found?

A

In deltas of Ganga-Brahmaputra, Mahanadi, Krishna and Kaveri

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10
Q

Where is coastal alluvium found?

A

Coastal strips of peninsular India and the plains of Gujarat

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11
Q

What is the texture of alluvial soil in upper reaches of river valleys? In the lower reaches?

A

Upper Reaches - soil is coarse, large and non-uniform

Lower reaches - smaller particles, more uniform

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12
Q

Which states is alluvial soil found in?

A

Punjab, Haryana, Assam

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13
Q

How does the alluvial soil of the Upper Ganga Valley differ from that of the Lower Ganga Valley

A

Upper Ganga Valley - dry, porous, sandy, faint yellow, consisting of clay and organic matter
WB (lower Ganga Valley) - more compact, less coarse and more moist

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14
Q

Why is alluvial soil easily tillable?

A

It is light and porous

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15
Q

Is alluvial soil fertile? What minerals does it contain? What minerals is it deficient in?

A

Yes. rich in minerals - (especially) potash and lime

Deficient in nitrogen and humus

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16
Q

What crops is alluvial soil suitable for growing?

A

Rice, wheat, sugarcane, tobacco

Jute(lower Ganga-Brahmaputra Valley)

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17
Q

Why is Black soil said to be a residual soil?

A

It is formed at the place of its origin over the underlying rocks.

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18
Q

Why is black soil also known as lava soil?

A

As it is formed by the denudation of igneous or volcanic rocks

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19
Q

What are the different names for black soil?

A

Black cotton soil, Regur Soil, Lava Soil

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20
Q

Where is Regur Soil found?

A

Deccan Lava Tract - Maharashtra, Madhya Pradesh, Gujarat, Karnataka

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21
Q

What is the texture of Black Soil?

A

Fine textured and clayey in nature

22
Q

What minerals is black soil rich and deficient in?

A

Rich in - lime, iron, magnesium

Poor percentage of - phosphorous, organic matter and nitrogen

23
Q

Why is Black soil black?

A

As it is formed from weathered lava rocks

24
Q

Why does black soil develop cracks during the dry season? What happens when it Is wet?

A

It is clayey and highly retentive of water. It expands and becomes difficult to plough.

25
Q

Is black soil fertile?

A

It is very fertile in most places.

26
Q

What crops is black soil suitable for?

A

Cotton, wheat, jowar, sugarcane, cereals, oilseeds

27
Q

Why is black soil suitable for dry farming

A

Because of its moisture retentiveness

28
Q

How is red soil formed?

A

It develops on old crystalline rocks. Under prolonged weathering by rainfall, ancient crystalline and metamorphic rocks of the peninsular plateau break up to form this soil.

29
Q

Why is red soil red in colour?

A

Due to the high amounts of iron oxide

30
Q

Where is red soil found?

A
  • Plateau region

- Tamil Nadu, Karnataka, Andhra Pradesh and Maharashtra

31
Q

What is the pH, depth and texture of red soil?

A

It has a pH of around 6.6 to 8, is usually shallow, and is loose, aerated and porous.

32
Q

What is red soil deficient in? What does it contain?

A

Nitrogen, organic matter, phosphorous and potassium. It contains soluble salts in small quantities.

33
Q

Why is red soil ideal for dry farming?

A

It is formed in low rainfall areas

34
Q

Is red soil fertile?

A

It is not fertile but it responds to fertilisers and needs irrigation support for cultivation

35
Q

What crops is red soil suitable for?

A

Vegetables, rice, ragi, tobacco

36
Q

How is Laterite soil formed?

A

It is formed as a result of atmospheric weathering under high rainfall and temperature with alternate wet and dry periods. It is the residual soil formed by leaching due to tropical rains

37
Q

Define Leaching (AKA Desilication)

A

The process by which nutrients get percolated down below the soil due to heavy rainfall, thus leaving the top soil infertile

38
Q

Why is laterite soil poor in humus?

A

It is removed by bacteria that survives well in high temperatures

39
Q

Where is Laterite soil found?

A

Summits of Sahyadris, Eastern Ghats, Rajmahal Hills
Highland areas of Peninsular plateau
Odisha, Madhya Pradesh, Maharashtra, West Bengal

40
Q

What is the texture of Laterite soil?

A

It is coarse, soft, porous and friable

41
Q

Why is Laterite soil red?

A

Due to the presence of iron oxide formed by leaching. Potash, lime and silica are removed, leaving iron oxide and alumina.

42
Q

What are the minerals deficient in Laterite soil?

A

Silica is removed from it. It is poor in lime, magnesium and nitrogen.

43
Q

Why is Laterite soil not fertile?

A

It does not retain moisture

44
Q

What is the pH of Laterite Soil?

A

It is acidic in nature as alkalis are leached

45
Q

What can laterite soil be used for?

A

Building purposes

46
Q

Why is manuring required to make laterite soil suitable for agriculture?

A

It has low fertility, high acidity and low moisture retention

47
Q

What are the crops grown on laterite soil?

A

Paddy, rubber, tea, cinchona and coffee

48
Q

Define soil erosion

A

The removal of top soil cover by wind, water and human activities.

49
Q

What is sheet erosion? Where does it occur?

A

It is the slow removal of a thin layer of soil, washed away by rainwater, when vegetation is destroyed. On gentle slopes in hilly areas of Uttarakhand, HP, etc.

50
Q

What is rill erosion? Where does it occur?

A

When sheet erosion happens for a long time and the silt-laden run-off forms finger shaped rills or grooves over a large area