2. Magic Of Soil
“The Only Magic Material that Turns Death into Life.”
– SADHGURU
The Save Soil movement is about bringing humanity together to
keep the magic of soil alive.
3. Most of us are familiar with words and concepts such as Climate Change,
Carbon Emissions, Air Pollution and Water Scarcity, but very few have
focused attention on Soil. For millennia, life on earth has been sustained
by a thin layer of fertile soil on the earth's crust.
But...
What exactly is soil and
what does it do?
4. Soil is SAND + ORGANIC
MATTER
There is a common misconception that Soil is a bunch of minerals and rock
dust. So much so people use the words ‘dirt’, ‘sand’ and ‘soil’ interchangeably!
Soil is the foundation of almost all life on this planet. It is a complex symbiotic
system of organic matter, minerals, gases, liquids and living organisms that
together support life. Without organic content in the form of humus and
living organisms and microbes, soil is reduced to inert sand.
5. 87% percent of life on earth depends
on soil.
One teaspoon of soil contains more living organisms than there are
people on the planet.
In many ways, it is soil that supports the entire food chain and
ecosystem. It is the richness of organic content in soil that sustains all
other dependent life, including Human Life. In fact, the very word
‘Human’ comes from the Latin word ‘Humus’. Thriving, living soil is vital
to life.
6. Carbon Stored in Soil is 3 times that in living
plants.
After oceans, Soil is the largest carbon sink in the world. The soil which is rich
in organic content traps and stores CO2. On the flip side, land that is
ploughed & left to dry up and die releases the same CO2 into the
atmosphere.
We need soil rich in organic content that supports plant life, in order for the
excessive carbon emissions from the past century to be sequestered.
7. The water stored in soil represents about 65% of
fresh water.
Soil is the largest water soak on the planet. 90% of the water needed for
agriculture comes from soil.
Soil diversity plays a big role in purifying water that seeps into soil. Rich soils
not only ensure adequate levels of ground water but are also integral to the
health of tropical river systems – key to resolving the water crisis in several
parts of the world.
Healthy soil also averts the dangerous cycles of floods and drought that
afflict so many regions in the world
8. Soil also plays an important role in
keeping the AIR clean.
Soil microbes have a proven ability to absorb air pollutants. The trees,
plants, shrubs and grasses that soil hosts are the lungs of the earth,
which provide us with vital oxygen and absorb excess CO2. Green air is
clean air!
We don’t need a research paper to tell us this – a simple stroll in a rich
forest will convince us.
9. 95% of our food comes from
precious topsoil.
Healthy soils lead to healthy food production. It is the foundation for
agriculture and the medium in which nearly all food-producing plants grow.
Healthy soils supply the essential nutrients, water, oxygen and root support
that plants need to grow and flourish. Soils also serve as a buffer to protect
delicate plant roots from drastic fluctuations in temperature.
10. The Save Soil Movement will work toward
this by:
1 Turning the world attention to our dying soil.
2 Inspiring about 4 billion people (60% of the world’s electorate of
5.26 billion) to support policy redirections to safeguard, nurture and
sustain soils.
3 Driving national policy changes in 193 nations toward raising and
maintaining the organic content of soils to a minimum of 3-6%.
14. SOIL-STRUCTURE
The arrangement of soil
particles and their aggregate
into certain defined patterns
is called structure.
The primary soil particles sand,
silt and clay usually occur grouped
together in the form of aggregates.
Natural aggregates are called
peds, whereas clod is an
artificially formed soil mass.
15. Structure is studied in the field
under natural conditions and it is
described under three categories:
1.Type Shape or form and
arrangement pattern of peds.
2. Class Size of peds.
3. Grade Degree of distinctness
of peds.
17. TYPES OF SOIL STRUCTURE
There are four principal forms of soil structure:
(a) Plate-like:
(b) Prism-like:
(c) Block-like:
(d) Spheroidal (Sphere-like):
18.
19. PLATE-LIKE
In this structural type of aggregates are arranged in relatively thin
horizontal plates. The horizontal dimensions are much more
developed than the vertical. When the units are thick, they are
called platy, and when thin, laminar Platy structure is most
noticeable in the surface layers of virgin soils but may be present in
the sub-soil. Although most structural features are usually a
product of soil forming forces, the platy type is often inherited
from the parent material, especially those laid down by water.
20. PRISIM-LIKE
The vertical axis is more developed than horizontal, giving a pillar-
like shape. When the top of such a ped is rounded, the structure is
termed as columnar, and when flat, prismatic. They commonly
occur in sub-soil horizons in arid and semi-arid regions.
21. BLOCK-LIKE
All these dimensions are about the same size and the peds are
cube-like with flat or rounded faces. When the faces are flat and
the edges sharp angular, the structure is named as angular blocky.
When the faces and edges are mainly rounded it is called sub
angular blocky. These types usually are confined to the sub-soil
and characteristics have much to do with soil drainage, aeration
and root penetration.
22. SPHERIODAL-LIKE
All rounded aggregates (peds) may be placed in this
category, although the term more properly refers to
those not over 0.5 inch in diameter. Those rounded
complexes usually lie loosely and separately
When wetted, the intervening spaces generally are
not closed so readily by swelling as may be the case
with a blocky structural condition. Therefore in
sphere-like structure infiltration, percolation and
aeration are not affected by wetting of soil. The
aggregates of this group are usually termed as
granular which are relatively less porous; when the
granules are very porous, the term used is crumby.
24. CLASSES OF SOIL STRUCTURE
The terms commonly used for the size classes are:
1. Very fine or very thin
2. Fine or thin
3. Medium
4. Coarse or thick
5. Very coarse or very thick.
26. GRADES OF SOIL
1. Structure-less:
There are no noticeable peds, such as conditions exhibited by loose sand
or a cement-like condition of some clay soils.
2. Weak structure:
Indistinct formation of peds which are not durable.
3. Moderate structure:
Moderately well-developed peds which are fairly distinct.
27. 4. Strong structure:
Very well-formed peds which are quite durable and distinct. For naming a soil
structure the sequence followed is grade, class and type; for example, strong
coarse angular blocky (soil structure).
Examples of sphere-like soil structure:
29. FORMATION OF SOIL STRUCTURE
1. The mechanism of structure (aggregate) formation is quite complex. In
aggregate formation a number of primary particles such as sand, silt and
clay are brought together by the cementing or binding effect of soil
colloidal clay, iron and aluminium hydroxides and organic matter.
2. The mineral Colloids (colloidal clay) by virtue of their properties of
adhesion and cohesion, stick together to form aggregates. Sand and silt
particles cannot form aggregates as they do not possess the power of
adhesion and cohesion.
3. The amount and nature of colloidal clay influence the formation of
aggregates. The greater the amount of clay in a soil, the greater is the
tendency to form aggregates. Clay particles smaller than 0.001 mm
aggregate very readily. So also clay minerals that have high base exchange
capacity form aggregate more readily than those which have a low base
exchange capacity.
30. 4. Iron and aluminium hydroxides act as cementing agent is binding the soil
particles together. These are also responsible for forming aggregates by
cementing sand and silt particles.
5. Organic matter plays an important part in forming soil aggregates. During
decomposition of organic matter, humic acid and other sticky materials are
produced which helps to form aggregate. Some fungi and bacteria taking part
in the decomposition have also been found to have a cementing effect.
6. Another view of structure formation is that clay particles adsorbed by
humus forming a clay-humus complex. It seems that humus absorbs both
cations and anions. In normal soil, calcium is the predominant cation and
forms calcium humate in combination with humus.
32. FACTORS AFFECTING SOIL
STRUCTURE
1. Climate:
Climate has considerable influence on the degree of aggregation as well as 011 the
type of structure. In arid region, there is very little aggregation of primary particles.
In semi- arid regions, the degree of aggregation is greater than arid regions.
2. Organic matter:
Organic matter improves the structure of a sandy soil as well as of a clay soil. In a
case of sandy soil, the sticky and slimy material produced by the decomposing
organic matter and the associated microorganism cement the sand particles to form
aggregates. In the case of clayey soil, it modifies the properties of clay by reducing
its cohesive power. This helps making clay more crumby.
33. 3. Tillage:
Cultivation implements break down of large clods into smaller fragments and aggregates.
For obtaining good granular and crumby structure, an optimum moisture content in the
soil is necessary. If the moisture content is too high it will form large clods on drying. If it
is too low, some of the existing aggregates will be broken down.
4. Plant roots:
Large number of granules remain attached to roots and root hairs which help to develop
crumb structure. Plant root secretions may also act as cementing agents in binding the
soil particles. The plant roots, on decay, may also bring about granulation due to the
production of sticky substances.
5. Soil organism:
Among the soil fauna, small animals like earthworms, moles and insects etc., that burrow
in the soil are the chief agents that take part in the aggregation of finer particles.
34. 6. Fertilizers:
Fertilizer like Sodium nitrate destroys granulation by reducing the stability of
aggregates. Few fertilizers, for example, Calcium Ammonium nitrate, help in
development of good structures.
7. Wetting and drying:
Wren a dry soil is wetted, the soil colloids swell on absorbing water. On drying,
shrinkage produced strains in the soil mass give rise to cracks which break it
up into clods and granules of various sizes.
38. SANDY SOIL
The first type of soil is sand. It
consists of small particles of
weathered rock. Sandy soils are one
of the poorest types of soil for growing
plants because it has very low
nutrients and poor water holding
capacity, which makes it hard for the
plant’s roots to absorb water. This
type of soil is very good for the
drainage system. Sandy soil is usually
formed by the breakdown or
fragmentation of rocks like granite,
limestone and quartz.
39. CLAY SOIL
Clay is the smallest particle among the
other two types of soil. The particles in this
soil are tightly packed together with each
other with very little or no airspace. This
soil has very good water storage qualities
and makes it hard for moisture and air to
penetrate into it. It is very sticky to the
touch when wet but smooth when dried.
Clay is the densest and heaviest type of
soil which does not drain well or provide
space for plant roots to flourish.
40. SILT SOIL
Silt, which is known to have much smaller
particles compared to sandy soil and is
made up of rock and other mineral particles,
which are smaller than sand and larger than
clay. It is the smooth and fine quality of the
soil that holds water better than sand. Silt is
easily transported by moving currents and it
is mainly found near the river, lakes and
other water bodies. The silt soil is more
fertile compared to the other three types of
soil. Therefore, it is also used in agricultural
practices to improve soil fertility.
41. LOAMY SOIL
Loam is the fourth type of soil. It is a
combination of sand, silt and clay such that
the beneficial properties of each are included.
For instance, it has the ability to retain
moisture and nutrients; hence, it is more
suitable for farming. This soil is also referred
to as agricultural soil as it includes an
equilibrium of all three types of soil materials,
being sandy, clay, and silt, and it also
happens to have humus. Apart from these, it
also has higher calcium and pH levels
because of its inorganic origins.
42.
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