Different Properties Of Soil | Chemistry | Enviromental Chemistry

1. 1

2. SOIL PROPERTIES
The various properties of soil include
1. Color
2. Texture
3. Humus
4. Soil structures
2

3.  Color 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.
3

4. DIFFERENT SOIL COLORS
 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.
4

5. 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
5

6. INTERPRETATION USING
SOIL COLOUR
 If we understand what determines soil colour,
then we can use colour to make some
inferences about, history, chemistry and
hydrology.
 For example, an obvious change in colour
between horizons is a real indication of
changes in soil properties which are the result
of biological activity, water movement and
weathering.
6

7. 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.
 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.
7

8. Munsell Color Charts
Hue = dominant spectral or “rainbow” color Red,
Yellow, Blue, Green
 Number increases and the color is more brilliant as
grayness decreases
8

9. Color Determination in the
field
 ALWAYS USE MOIST SOIL
 Munsell’s color 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
9

10. MOTTLES
 Spots of different colors in the soil
 Generally indicate that the soil has periods
of inadequate aeration each year
 Usually rust colored
 Bluish, grayish, & greenish subsoils – with or
w/o mottles = indicate longer periods each
year of waterlogged conditions &
inadequate aeration.
10

11. Hums
 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
11

12.  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.
 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 also controls the colour of soil higher the humus
content darker is the soil colour
12

13. 13

14. TEXTURE
Refers to the size of
particles.
Three types are:
Sand (Large)
Silt (Medium)
Clay (Small)
14

15. SOIL STRUCTURE
The soil structures commonly
seen are-
1. Blocky
2. Platy
3. Massive
4. Prismatic
5. Granular
15

16. 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
millimeters.
16

17. 2. PLATY
 Large, thin
beds.
 Plate-like &
arranged in
overlapping
horizontal
layers.
17

18. 3. MASSIVE
 Soil has no visible
structure.
 Hard to break
apart & appears
in very large
clods.
18

19. 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.
19

20. 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
millimeters.
20

21. 21