|| A note on soil || || Introduction/Profile of soil || || Characteristics &Types of soil || || Production & Formation of soil || || Properties & classification of soil ||

1. The most important natural resource around the earth!

2. CHAPTER:- 1
Introduction/Profile of soil............................ 3 to 9
CHAPTER:- 2
Production & Formation of soil……………19 to 25
CHAPTER:- 3
Characteristics &Types of soil.......................10 to 18
CHAPTER:- 4
Properties & classification of soil.................26 to 38
.2
Page no.

3. Soil..
Major part of the natural
environment,
Vital to the existence of life on the
planet.
Soil is the result of the process of the
gradual breakdown of rock, such as
weathering and erosion
Soil is made up from four
constituents:
mineral material,
organic material,
air and
water.
.3

4.  Provides air, water and nutrients to plants
 Soil provides mechanical support to plants
 Consists of weathered materials, decaying organic matter, air
and water
 Decomposing animals and plants
 Fungi and bacteria feed on the material to break it down until it is released
into the soil
.4

5.  Rocks and minerals break down through weathering
(freezing, thawing) and mechanical forces to create soil
texture.
Soil Profile
The soil profile is one of the most
important concepts in
soil science.
The soil profile is defined as a vertical
section of the
soil that is exposed when a soil pit, or
hole, is dug from
the surface of the soil to the underlying
bedrock .5

6. Soil profile .6

7. Soil Structure
Combination or arrangement of
primary soil particles.
Soil particles are:
Sand
Silt
Clay
Cont,,
Sand: Natural occurring rough
material,
The size of sand particles range
between 2.0 mm and 0.05 mm.
Silt: Small particles, and size is
between sand and clay.
Silt size as 0.05 mm and 0.002 mm.
Clay: very fine particles
And clay, less than 0.002 mm.
Notice that clay particles may be
over one thousand times smaller than
sand particles.
.7

8. Soil Composition
Soil composition is an important
aspect of nutrient management.
The basic components of soil are:
Minerals/Nutrients 45%,
Organic matter 5%,
Water 25% and
Air 25%.
Soil Texture
 Different sized mineral
particles give soil its
texture
 Sand
 Silt
 Clay
.8

9.  Sand is largest particle size, allowing for more air and water to
movement
 Clay soils are heavy and hold a lot of water
 Loamy soils are intermediate between sand and clay – both water
holding capacity and fertility
.9

10. .10
CHAPTER:- 2
Characteristics &Types of soil
BLACK SOIL
BLACK SOIL Also known as Regur or Black Cotton
soil. Dark grey to Black in colour. High clay
content. Highly moist retentive. Develops cracks
in summer. Covers 5.4 lakh sq. km. Highly suitable
for cotton. Rich in iron, lime,
calcium, Magnesium, carbonates, and alumina

11. .11
RED SOIL Formed due
to weathering of old
crystalline rocks.
More sandy and less
clayey. Rich in iron,
small amount of
Humus. Poor in
phosphorus, nitrogen
and lime. Slightly
acidic and do not
retain moisture. 3.5
lakhs sq.km area.
Porous and Friable.
RED SOIL
LATERITE SOIL Latin word
meaning brick. Formed
under high temperature
and rainfall with wet and
dry spell. Silica is
leached due to high
rainfall.
Remnants of iron and aluminium oxides left
behind is
know as Late rite. Brown to Yellowish colour.
Becomes
hard when exposed to atmosphere. Used as
building
material.
LATERITE SOIL

12. DESERT SOIL Contains soluble salts.
Originated by
Mechanical disintegration & wind deposit.
Porous
and coarse. 90% sand & 5% clay. Rich in
Nitrates &
Phosphates. Poor in Nitrogen & Humus.
Friable,
sandy & low moist content. 1.4 Lakh sqkm
DESERT SOIL
MOUNTAIN SOIL Found in hill
slopes. Formed by
deposition of organic matter from
forest. Rich in
humus. Poor in Potash and Lime.
Areas: Assam,
Kashmir, Sikkim & Arunachal
Pradesh. Crops: Tea,
Coffee, Spices & Tropical Fruits.
MOUNTAIN SOIL .12

13. SALINE & ALKALINE SOIL Contains
salts
like Sodium, Magnesium, Calcium.
Infertile, unfit for cultivation. Sandy to
loamy in texture. Areas: Parts of
Gujarat, Rajasthan, Punjab, Haryana, U.P
& Maharashtra.
SALINE & ALKALINE SOIL
PEATY AND MARSHY SOIL
Occur in Humid region.
Formed by accumulation of organic matter.
Black in colour. Highly acidic and heavy.
Areas:
Kottayam & Alleppey in Kerala, Coastal
Orissa,
Sundarbans of W.B
PEATY AND MARSHY SOIL .13

14. A sticky soil, such as
clay or silt; its shear
strength equals about
half its unconfined
compressive
strength. Soil in which the
absorbed water and
practical attraction act
such that it deforms
plastically at different
water Contents are
known as Cohesive soils
or clays. These soils
possess higher plasticity
. e.g. clays & plastic silt.
COHESIVE SOIL
Residual soils are those that remain at
the place of
their formation as result of the weathering of
the
parent rocks. The depth of residual soils
depends
primarily on climatic conditions and the time
of
espouser. In temperate zones residual soils are
commonly stiff and stable. An important
characteristics of residual soil is that the sizes
of
grains are indefinite.
COHESIVE SOIL
Residual soils
.14

15. ALLUVIAL soil is formed when a soil
carrying
stream gradually loses its carrying
capacity with decreasing velocity. In
slowing
down, a river does not have sufficient
power to keep the large
particles of soil suspended; these
particles settle to the riverbed. Further
decrease in velocity causes smaller
particles to settle. These particles
are deposited, finally, at the mouth of the
river, where they form DELTAS
of fine-grained soil.
ALLUVIAL soil
MARINE soil is formed from materials
carried into the
seas by streams and by material eroded
from the
beaches by the tidal action of the
waves. Part of the material is carried out
and
deposited in deep water; part is heaped
upon the
beaches along the coast MARINE soil
.15

16. A type of soil
that is
transported
from one place
to another by
the wind.e.g
sand
dunes, loess.
AEOLIAN SOIL
Loam is soil composed
of sand, silt, and c
lay in relatively even
concentration
(about 40-40-20% concentration respectively).[1]
Loam soils generally
contain more and humus than sandy soils, have
benttuetrri einnfitlstration and drainage than
silty soils, and are easier to till than clay soils.
Loams are gritty, moist, and retain water
LOAM .16

17. Clay is a naturally
occurring aluminium
silicate composed
primarily of fine-grained
minerals.
Clay deposits are mostly
composed of clay
minerals, a subtype
Of phyllosilicate minerals,
which
impart plasticity and
harden when fired or dried; they also may
contain
variable amounts of water trapped in the
mineral
structure bipolar attraction. Organic
materials which
do not impart plasticity may also be a part of
clay
deposits.
Clay
.17

18. Glaciers carry with them soils varying
in
size from fine grained to huge boulder.
Soil
get mixed with the ice and are
transported far away from their original
position. Drift is a general term used
for the
deposits made by glaciers
GLACIAL SOIL
GLACIAL SOIL
.18

19. .19
CHAPTER:- 3
Production & Formation of soil
Soil: Definition
• Solid earth material that has been altered by physical,
chemical and organic processes so that it can support
rooted plant life.
• Engineering definition: Anything that can be removed
without blasting
SOIL PRODUCTION

20. .20
Soil Production: inputs
Conversion of rock to soil

21. Soil Production: Outputs
Downslope movement of soil
.21

22. Soil Thickness: Storage
Soil thickness reflects the balance between rates of
soil production and rates of downslope soil movement.
• Slope
• Weathering Rate
Factors of Soil Formation
•Climate
• Organisms
• Parental Material
• Topography
• Time .22

23. Climate
• Temperature and precipitation
• Indirect controls (e.g., types of
plants)
• Weathering rates
The greater the rainfall
amount, the more rapid the rate of
both weathering and erosion.
Organisms
• Types of native vegetation
• Weathering is dependent of plant
growth
• Plant and animal activity produces
humic acids that are powerful
weathering agents.
• Plants can physically as well as
chemically break down rocks.
• Plants stabilize soil profiles,
Animals (including humans) tend to
increase erosion
Parent Material:
• Chemistry
• Mineralogy
• Grain size
.23

24. Topography:
• Ground slope
• Elevation
• Aspect (e.g., north facing
vs. south facing slopes)
Time
• Development and destruction of
soil profiles
• Typical reaction rates are slow,
the longer a rock unit has been
exposed, the more likely it is to be
weathered.
.24

25. Soil Development
.25

26. CHAPTER:- 4
Properties & classification of soil
SOIL PROPERTIES
The various properties of soil include-
1. Colour
2. Humus
3. Texture
4. Soil structures
1.COLOUR
Colour is the foremost physical
property that can be seen with naked
eye and is useful in interpretation of
valuable insight into the soil
environment, thus it can be very
important in assessment and
classification of soil.
.26

27. DIFFERENT SOIL COLOURS
The most influential colours in a
well
drained soil are white, red, brown
and black.
White indicates the predominance
of
silica (quartz), or the presence of
salts.
Red indicates the accumulation of
iron oxides.
Brown and black indicate the level
and type of organic matter. A colour
triangle can be used to show the
names and relationships between
the influential colours
.27

28. FACTORS DETERMINING SOIL COLOUR
Four main factors influence the colour of
a soil:
1. Mineral matter derived from the
constituents of the parent material
2. Organic matter
3. The nature and abundance of iron
4. Moisture content
DETERMINING SOIL COLOUR
Soil colour should be determined on moist
surfaces
of freshly broken (not sliced) soil samples.
Like any other soil property, colour must
always be
observed throughout soil profile, paying special
attention to the differences between soil
horizons.
Colour characteristics such as mottle
size, percentage and contrast should be observed
and recorded. .28

29. A system that uses specially printed
colour charts
(Munsell Soil Colour Charts) gives an
international
standard. It divides colour into
wavelength, lightness, and colour
saturation.
Where a Munsell Chart is not
available, simple
names as listed in the triangle can be
used.
Munsell Colour Charts
Hue = dominant spectral or
“rainbow” colour
Red, Yellow, Blue, Green
Number increases and the
colour is more
brilliant as greyness decreases0
Colour Determination in the field
ALWAYS USE MOIST SOIL
Mussel's colour charts values:-
1. Absolute black = 0
2. Absolute white = 10
3. Light soils hue value = 7 or more
4. Medium soils hue value = 5 – 6
5. Dark soils hue value = 4 or less
.29

30. •In agriculture, humus is sometimes also
used to describe
mature compost, or natural compost
extracted from a forest
or other spontaneous source for use to
amend soil. It is also
used to describe a topsoil horizon that
contains organic
Matter
HUMUS
The term was coined in1790–1800;
(< Latin: earth, ground)
Dark brown or black organic
substance
made up of decayed plant or animal
organic matter, that provides nutrients
for plants and increases ability of soil to
retain water
•In soil science, humus refers to any
organic matter that has
reached a point of stability, where it
will break down no
further and might, if conditions do not
change, remain as it is
for centuries. Humus significantly
improves the structure of
soil and contributes to moisture and
nutrient retention.
Humus also
controls
the colour of soil
higher the humus
content darker is
the
soil colour.
.30

31. TEXTURE
Refers to the size of particles.
Three types are….
Sand (Large)
Silt (Medium)
Clay (Small)
TEXTURE = % of sand, silt
and clay.
SOIL STRUCTURE
The soil structures
commonly
seen are-
1. Blocky
2. Platy
3. Massive
4. Prismatic
5. Granular
.31

32. 1. BLOCKY
Particles cling
together in angular
aggregates.
Typical of soils with
high clay content.
Typical of B
horizons.
beds are large
about 5 to 50
millimetres.
2. PLATY
Large, thin
beds.
Plate-like &
arranged in
overlapping
horizontal
layers.
.32

33. 3. MASSIVE
Soil has no
visible
structure.
Hard to break
apart & appears in
very large clods.
4. PRISMATIC
Prismatic structure are
bounded by flat to
rounded vertical
faces. Units are longer
vertically and top of
the prisms are
normally flat.
It is commonly found
in B horizons. .33

34. 5. GRANULAR
Is the best for most
plants.
Particles cling
together to form
rounded aggregates.
It is commonly found
in A horizons.
Beds are small
usually between 1 to
10 millimetres.
.34

35. .35

36. CLAY
< 0.002 mm
Flat plates or tiny
flakes
Small clay particles
are colloids
If suspended in
water will not settle
Wet clay is
very sticky and
is plastic or it
can be molded
readily into a
shape or rod.
Easily formed
into long
ribbons
Pores spaces are very
small and convoluted
Movement of water
and air very slow
Water holding capacity
Tremendous capacity
to adsorb water- not
all available for plants.
Chemical adsorption is
large .36

37. SILT
< 0.05 mm to >
0.002 mm
Not visible without
microscope
Quartz often
dominant mineral in
silt since other
minerals have
weathered away.
Does not
feel gritty
Floury feel–
smooth
like silly putty
Smaller particles –
retains more water
for plants and have
slower drainage
than sand.
Easily washed
away by flowing
water – highly
erosive.
Holds more plant
nutrients than
sand.
.37

38. SAND
Feels gritty
Considered non-cohesive – does not
stick together in a mass unless it is
very wet.
Sand has less nutrients for plants
than smaller particles
Voids between sand particles
promote free drainage and entry of air
Holds little water and prone to
drought
.38