Soil is the mixture of minerals, organic matter, gases, liquids, and myriad organisms that together support plant life. Two general classes are topsoil and subsoil. Soil is a natural body that exists as part of the pedosphere and which performs four important functions: it is a medium for plant growth; it is a means of water storage, supply and purification; it is a modifier of the atmosphere of Earth; and it is a habitat for organisms all of which modify the soil. Soil is considered to be the "skin of the earth" with interfaces between the lithosphere, hydrosphere, atmosphere of Earth, and biosphere.[2] Soil consists of a solid phase (minerals and organic matter) as well as a porous phase that holds gases and water.[3][4][5] Accordingly, soils are often treated as a three-state system.[6]
2. WHAT IS SOIL?
Soil is the mixture of minerals, organic matter, gases, liquids, and
myriad organisms that together support plant life. Two general
classes are topsoil and subsoil. Soil is a natural body that exists as
part of the pedosphere and which performs four important
functions: it is a medium for plant growth; it is a means of water
storage, supply and purification; it is a modifier of the atmosphere of
Earth; and it is a habitat for organisms all of which modify the soil.
Soil is considered to be the "skin of the earth" with interfaces
between the lithosphere, hydrosphere, atmosphere of Earth, and
biosphere.[2] Soil consists of a solid phase (minerals and organic
matter) as well as a porous phase that holds gases and water.[3][4][5]
Accordingly, soils are often treated as a three-state system.[6]
3. HISTORY OF SOIL
The history of the study of soil is intimately tied to our urgent need to
provide food for ourselves and forage for our animals. Throughout
history, civilizations have prospered or declined as a function of the
availability and productivity of their soils.
The Greek historian Xenophon (450–355 B.C.) is credited with being
the first to expound upon the merits of green-manuring crops: "But
then whatever weeds are upon the ground, being turned into earth,
enrich the soil as much as dung."[20]
4. SOIL LAYERS
Soil is a major component of the Earth's ecosystem. The
world's ecosystems are impacted in far-reaching ways
by the processes carried out in the soil, from ozone
depletion and global warming, to rain forest destruction
and water pollution. Soil is the largest surficial global
carbon reservoir on Earth, and it is potentially one of the
most reactive to human disturbance and climate
change. As the planet warms, soils will add carbon
dioxide to the atmosphere due to its increased
biological activity at higher temperatures. Thus, soil
carbon losses likely have a large positive feedback
response to global warming.[14]
7. ABOUT
Red soil is any of a group of soils that develop in a warm, temperate,
moist climate under deciduous or mixed forests and that have thin
organic and organic-mineral layers overlying a yellowish-brown
leached layer resting on an illuvial (see illuviation) red layer. Red soils
generally derived from igneous rock. They are usually poor growing
soils, low in nutrients and humus and difficult to cultivate. Red soils
denote the second largest soil group of India covering an area of
about 6.1 lakhs sq. km (18.6% of India's area) over the Peninsula from
Tamil Nadu in the south to Bundelkhand in the north and Rajmahal
hills in the east to Kachchh in the west. They surround the black soils
on their south, east and north.
8. DISTRIBUTION
These soils are found in large tracts of
western Tamil Nadu, Karnataka, southern
Maharashtra, Chhattisgarh, Andhra
Pradesh, Orissa and Chotanagpur
plateau of Jharkhand. Scattered
patches are also seen in Birbhum (West
Bengal), Mirzapur, Jhansi, Banda,
Hamirpur (Uttar Pradesh), Udaipur,
Chittaurgarh, Dungarpur, Banswara and
Bhilwara districts (Rajasthan).
9. CONTENT
This soil, also known as the omnibus group, have been developed
over Archaean granite, gneiss and other crystalline rocks, the
sedimentaries of the Cuddapah and Vindhayan basins and mixed
Dharwarian group of rocks. Their colour is mainly due to ferric oxides
occurring as thin coatings on the soil particles while the iron oxide
occurs as haematite or as hydrous ferric oxide, the colour is red and
when it occurs in the hydrate form as limonite the soil gets a yellow
colour. Ordinarily the surface soils are red while the horizon below
gets yellowish colour.
10. CHARACTERSTICS
The texture of red soils varies from sand to clay, the majority being
loam. Their other characteristics include porous and friable structure,
absence of lime, kankar and free carbonates, and small quantity of
soluble salts. Their chemical composition include non-soluble
material 90.47%, iron 3.61%, aluminium 2.92%, organic matter 1.01%,
magnesium 0.70%, lime 0.56%, carbon-Di-oxide 0.30%, potash 0.24%,
soda 0.12%, phosphorus 0.09% and nitrogen 0.08%. However
significant regional differences are observed in the chemical
composition.
11. MORPHOLOGY
Ray Chaudhary (1941) has morphologically grouped red soils into
following two categories:
(a) Red Loam Soil-these soils have been formed by the
decomposition of granite, gneiss charnocite and diorite rocks. It is
cloddy porous and deficient in concretionary materials. It is poorer
in nitrogen, phosphorus and organic materials but rich in potash.
Leaching is dominant.
These soils have thin layers and are less fertile. These soils are mainly
found in Karnataka (Shimoga, Chikmaglur and Hassan districts),
Andhra Pradesh (Telangana), estern Tamil Nadu, Orissa, Jharkhand
(Chotanagpur), Uttar Pradesh (Bundelkhand), Madhya Pradesh
(Balaghat and Chhindwara), Rajasthan (Banswara, Bhilwara, Bundi,
Chittaurgarh, Kota and Ajmer districts), Meghalaya, Mizoram,
Manipur and Nagaland