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NABARD Agri 2025 > Soil Science > Flashcards

Soil Science Flashcards

1
Q

Father of soil science?

A

Vasily Dakuchaiev

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2
Q

A natural body composed of minerals and organic content having a definite genesis and a distinct nature of its own is?

A

Soil

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3
Q

A pedon is?

A

The smallest unit or volume of soil

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4
Q

The study of soils in relation to crop growth, nutrition and yield is called as?

A

Edaphology

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5
Q

A study of soils, it’s classification, pedogenesis and morphology is?

A

Pedology

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6
Q

Different types of weathering of rocks?

A

Physical, Chemical, Biological

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7
Q

Physical and chemical weathering occurs due to?

A

Physical - disintegration
Chemical - decomposition

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8
Q

Biological weathering occurs due to?

A

Disintegration + Decomposition

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9
Q

Ultimate result of soil formation is?

A

Profile development

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10
Q

Rocks formed from the consolidation of sediments accumulated due to wind and water action on Earth is?

A

Sedimentary rock’s

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11
Q

Limestone, sandstone, shale, peat and Fuller’s earth are examples of?

A

Sedimentary rocks

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12
Q

Sedimentary rocks composed of coarse grained, sand like particles are ?

A

Arenaceous
Eg: sandstone breccia

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13
Q

Sedimentary rocks composed of clay-sized particles?

A

Argillaceous
Eg: Mudstone, shale, Fuller’s earth

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14
Q

Sedimentary Rocks composed of carbonate of lime, magnesia and bases?

A

Calcareous.
Eg: limestone, challk

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15
Q

Sedimentary rocks composed of decomposing vegetation under anaerobic processes?

A

Carbonaceous
Eg: peat, coal

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16
Q

Sedimentary rocks composed of minute plants and animals like diatoms?

A

Silicious rocks
(Rocks from ciliated animals)

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17
Q

The strongly deformed type of rock, short of metamorphic conditions?

A

Anthracite (from bituminous)

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18
Q

Primary rocks or massive rocks are?

A

Igneous rocks

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19
Q

Granite, Diorite and Gabbro are examples of what kind of rocks?

A

Intrusive (plutonic) igneous rocks

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20
Q

Basalt, Pumice, Obsidian are examples of what kind of rocks?

A

Igneous extrusive

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21
Q

Igneous rocks with more than 65% silica content is called as?

A

Acidic rocks
Eg: Granite, pegmatite, rholite

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22
Q

Igneous rocks with 55-65% silica are called?

A

Intermediate
Eg: Andesite, Diorite, Syenite

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23
Q

What is the range for sub-acidic and sub-basic igneous rocks?

A

Sub-acidic: 60-65 -> Diorite
Sub basic: 56-60 -> Syenite

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24
Q

Igneous rocks with 40-55% silica ?

A

Basic
Eg: Basalt, Gabbro, dolerite

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25
Q

Granite classifications are? (Acidic, basic, intrusive, extrusive, etc)

A

G=Ai -> acidic, intrusive

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26
Q

Basalt rock classification

A

B=Be -> basic, extrusive
Popular in deccan lands

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27
Q

Diorite classification

A

D=ii -> intermediate, intrusive

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28
Q

Rocks formed due to the solidification of molten magma

A

Primary Rocks/ Igneous rocks

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29
Q

Rocks formed due to heat, pressure, chemically active liquids, has or a combination of them, on previously formed rocks is?

A

Metamorphic rocks

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30
Q

Quartzite and marble is formed from?

A

Q= Sandstone
M= limestone

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31
Q

Poorly sorted material near the base of strong slopes transported by the action of gravity?

A

Colluvium

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32
Q

Material that is transported and deposited by water, found along major streams courses at the bottom of slopes of mountains and along small streams flowing out of drainage basins

A

Alluvium

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33
Q

Materials that have settled due to the quiet water of lakes?

A

Lacustrine

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34
Q

Materials picked up, mixed, disintegrated and transported through action of Glacial ice - primary due to melting of glaciers

A

Moraine

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35
Q

Wind blown material of silty texture

A

Loess

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36
Q

Wind blown material of sandy texture

A

Aeolian

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37
Q

Soils that bear the name of their parent material

A

Eolian

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38
Q

A process of mixing of soils causing differentiation due to humification, eluviation and illuviation

A

Pedoturbation
Eg: black soil

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39
Q

Processes by which the soil materials are differentiated into several horizons in a profile?

A

Soil Horizonation

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40
Q

Illuviation of Na+ ions

A

Solonisation
Or Alkalisation

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41
Q

Eluviation of Na+ ions
Increasing Mg or Ca conc

A

Solodisation or Dealkalization

42
Q

Specific Eluviation of salts

A

Desalinisation
Due to improved drainage in soil

43
Q

Specific illuviation of salts (sulphates, chlorides, magnesium, sodium, potassium)

A

Salinization
Common in arid and semi arid regions with impeded drainage

44
Q

Illuviation of Ca
Accumulation CaCO3

A

Calcification

45
Q

A process of soil formation resulting in the development of glei - a bluish grey horizon with mottling of yellow or reddish-brown colours

A

Gleization

46
Q

Specific illuviation of Silica
Iron and alumina stay in upper layers (Sesquioxides)
Soluble substances are depleted

A

Laterisation

47
Q

Specific Eluviation of Sesquioxides and humus

A

Podsolisation

48
Q

% of clay in clayey soil?

49
Q

Soils formed under the supreme influence of parent material which show advanced development and excessive leaching

A

Endodynamomorphic soils

(Endo = still inside parents house)

50
Q

Soils formed under the predominant influence of climate, where effects of parent materials are obliterated

A

Ectodynamomorphic

Ecto..= climate

51
Q

Organic matter in O horizon?

52
Q

Soil forming processes are of 2 types…?

A

Active - CVO
Passive - PRT

53
Q

Passive soil forming processes include?

A
  • Parent Material
  • Relief
  • Topography

PRT

54
Q

Active soil forming processes?

A

CVO
Climate Vegetation Organism

55
Q

The process of soil formation is known as

A

Pedogenesis
- Fundamental: HEI
- Specific

56
Q

A complex process where first simple compounds like sugars and starches are attacked, followed by proteins and cellulose and finally resistant compounds like tannins are decomposed forming a dark coloured substance

A

Humification
- A fundamental soil forming process
- Decomposition of OM to Humus

57
Q

Soil with abundant montmorillonite clay, and is the 2nd largest soil group in india, aka a self ploughing soil

A

Black soil

58
Q

Which soil has high clay content, Iron, Lime , Calcium and Potassium but is deficient in Nitrogen, Phosphorus, and OM

A

Black soil

59
Q

Why is black soil best for cotton?

A

Best water retention capacity and high calcium and potassium in soil

60
Q

Expansive nature of black soil is due to

A

High presence of montmorillonite clay

61
Q

Area covered by Alluvial soil

A

43% of land -> 143 km2
Largest soil group in India

62
Q

Which soil is rich in potash, lime & phosphoric acid?

63
Q

Which soil is formed due to leaching effect and is rich in iron and aluminium

A

Laterite Soil

64
Q

Major secondary minerals in soils

A

Kaoline, Smectite, Vermiculite, Illite. All 1:1 and 2:1 structured clays

65
Q

Amongst sandy, silty, clayey and loamy soil, which has highest pore space?

66
Q

Amongst Sandy, silty, clayey and loamy, which has the highest permeability?

67
Q

Diameter of macro-pores

A

0.06mm
Common in sandy soils

68
Q

What is the diameter of micro capillary pores?

A

<0.06 mm
More in clayey soils

69
Q

Which soil formation stage has unweathered parent material?

A

Initial Stage

70
Q

In which soil formation stage has weathering just started but much of the original material is still there?

A

Juvenile Stage

71
Q

In which soil formation stage is easily weatherable material completely decomposed and not seen, while clay content starts to increase

A

Virile Stage

72
Q

In which soil formation stage only the most resistant minerals like quartz survive

A

Senile Stage

73
Q

In which soil formation stage is soil development completed under prevailing conditions?

A

Final Stage

74
Q
  1. It is the relative Proportion of sand, silt and clay particles.
  2. The basic property of soil
  3. It cannot be changed unless considerable mechanical and financial inputs are used
A

Soil Texture
(T = P)

75
Q
  1. It is the Arrangement of primary & secondary particles in a soil mass
  2. It is the study of pore space and their interaction
A

Soil Structure
(S = A)

76
Q

Soil Structure is dependent on?

A

TCG
Type (shape)
Class (size)
Grade (strength/weakness)

77
Q

Which is the best type of soil structure for agricultural purposes?

A

Spheroidal/Crumbly

78
Q

Which type of soil structure is mostly seen in forest top soil or in virgin soil?

A

Platy Soil
(Mostly Horizontal Development)

79
Q

Which type of soil structure is mostly seen in arid or semi-arid sub-soils?

A

Prism Soil
(Mostly Vertical Development)

80
Q

Primary soil material like sand, silt and clay, when grouped together are called?

A

Soil Aggregates

81
Q

Natually formed soil aggregates are called?

82
Q

Artificially formed soil aggregates are called?

83
Q

As per International Society of Soil Science (ISSS), what is the particle density of Clay, silt and sandy soil?

A

Clay: 0-0.002mm
silt: 0.002-0.02mm
sand: 0.02-0.2mm

84
Q

Which is the best kind of soil for agri?

  1. Sandy
  2. Loam
  3. Silt Loam
  4. Clayey
  5. OM
85
Q

Soil with what Bulk Density is best for agriculture?

A

1.3 g/cc
(Silt Loam)

86
Q

How many soil textural classes are there, as per the USDA?

87
Q

Will sandy soil have lower bulk density or clayey soil?

A

Clayey soil
Because of higher organic matter content

88
Q

% of clay and % of OM in the best agricultural soils?

A

10-20% clay
5-10% OM

More clay than OM

89
Q

This kind of soil is:
1. Low in nitrogen
2. Adequate Potash, Phosphoric acid and alkalis present
3. Iron oxide and lime vary within a wide range

A

Alluvial soil

90
Q

This kind of soil:
1. Varies from loamy to sandy-loam in drier regions and clayey loam towards the delta
2. They have immature and weak profiles
3. They are common in Dooars, Chos and Terai

A

Alluvial Soil

91
Q

This type of soil is formed due to leaching, high temp & heavy rainfall
It is best for growing of tea, coffee
It is Rich in Iron and aluminium

92
Q

How many essential elements are there, necessary for plant growth and of what types?

A

17
divided into 3 types:
1. Micro (7+1)
2. Macro (6): N,P,K (Pri); Ca, Mg, S (Sec)
3. Non-mineral (3): CHO

93
Q

Nutrient that is: Imp part of Chlorophyll. Helps in absorption of phosphorus, nitrogen and sulphur by plants, ripen fruit, reinforce cell wall

94
Q

Basic component of proteins and chlorophyll. Essential role in plant growth, feeds microorganisms in soil

95
Q

Important for overall structure and cell wall of the plant - holds it together. Promotes development of root system

96
Q

Moves through plant, promotes movement of sugars, tugor and stem rigidity, hardening of woody plants, formation of flowering buds. Also increases the plant’s overall resistance to cold, diseases, insects, pests, etc. Regulates stomatal movement

97
Q

A component of several proteins, enzymes and vitamins. Imp role in oil formation in oil crops (Soyabean)

98
Q

Overall plant health and tissue growth - formation of fruit, absorption of water and translocation of sugar

A

Boron
(movement of sugar is K but in options always go for Boron)

99
Q

Synthesis of proteins, enzymes and growth hormone

100
Q

Plays an important role in root growth and establishment of young flowering plants and fruits, ripening, photosynthesis. Increased activity of Rhizobium, cell division, energy storage and transfer.

A

Phosphorus

101
Q

Acc to ICRIER, every rupee invested on agriculture will yield?

NABARD Agri 2025 (26 decks)

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