This document discusses the origin and formation of soil. It explains that soil is formed through the processes of degradation, transportation, and deposition of rocks and minerals. Degradation occurs through weathering processes like physical, chemical and biological weathering which break down rocks. Transportation involves the movement of eroded rock fragments by agents like wind and water. Finally, deposition results in the accumulation of sediments in lower elevations over time, which eventually form soil through pedogenesis.

1. ORIGIN OF SOIL
MICROBIAL ECOLOGY
SANDEEP YADAV
BSC.CMBT-5TH SEM
JAIN UNIVERSITY, BANGALORE

2. SOIL:
Soil is a most outer soft layer of earth, formed by different process which is generally called soil
forming forces.
The topmost layer of the earth's crust contains soil, a porous biologically active medium. Soil is an
accumulation of unconsolidated sediments and deposits of solid particles as a result of rock
breakdown. Rocks are a naturally occurring collection of minerals that are bound together by strong
attraction forces and are regarded as consolidated materials.

3. ORIGIN OF SOIL:
Soil Is A Naturally Occurring Unconsolidated Particle Material. The Process Of Formation Of Soil
Is Called Pedogenesis. Vasily Dokuchaev, A Russian Geologist, popularly Regarded As The Father
Of Soil Pedology.
PROCESS OF FORMATION OF SOIL:
1. Degradation
2. Transportation
3. Deposition

5. 1) DEGRADATION:
Degradation can be divided into 3 processes. The process are:
a) Weathering
b) Mass wasting
c) Erosion

6. a) WEATHERING:
The breakdown or dissolution of rocks and minerals on the earth's surface into soils is referred to as
weathering.
The disintegration of bulk rock is the result of a complex of processes involving physical, chemical,
and biological activities. Rock formations are weathered into soil. There are 3 types of weathering:
physical, chemical and biological weathering.

7. i) PHYSICAL WEATHERING:
The likes of wind, water, freeze-thaw cycles, landslides, and earthquakes are the agents behind its
occurrence. It is responsible for the fracturing of the bedrock fragments. The forms that these
particles take are always changing because of the natural forces that cause them to shrink in size.
Granular materials are those that have been worn down by the effects of physical weathering.

8. ii) CHEMICAL WEATHERING:
Chemical processes like oxidation, hydration, carbonation, solution, leaching, hydrolysis, and others
are to blame. The source material's chemical and physical characteristics are completely altered. Silt
and clay are the two types of soil produced by this method.

9. iii) BIOLOGICAL WEATHERING:
It occurs when plants break up rock with roots or root exudates. It is a combination of physical and
chemical breakdown. Physical deterioration is primarily caused by root of vegetation, animal
activity etc. Chemical change is caused by organic acids and carbon dioxide supplied by plants.

10. b) MASS WASTING:
The movement of rock and soil downslope under the effect of gravity is known as mass wasting.
Water may be present to perform the functions of a lubricant and a minor carrier, but its presence is
not required for the process. There are many different types of mass wasting, including rock falls,
slumps, and debris flows.

11. c) EROSION:
The geological process of erosion is the wearing away and transfer of earthen materials by natural
forces such as wind and water. Erosion can be caused by a variety of natural processes. Rock
fragments usually suffer a slow but steady deterioration that causes them to break up into ever
smaller pieces. A significant part of the deterioration process is played by the grinding, banging, and
bouncing that occurs while the item is in transit.

12. 2) TRANSPORTATION:
Rock fragments and materials that dissolve in water are the products of the process of degradation.
In most cases, the resulting fragment is carried away by physical agents and transformed into clastic
sediments. As a result of rock breaking up and fragmenting over time due to natural processes,
smaller particles become easier for nature to move around. Working and reworking under the
influence of wind, water, ice, and gravity is what makes the transportation effort possible.

13. 3) DEPOSITION:
The remains of mass rock are deposited in the lower areas of the earth's crust resulting in
the elevation of those area behind raised. This process of deposition, in addition to
diastrophism (mountain building and volcanism (volcanic activity), prevents degradation and
transportation from ultimately reducing the earth's land areas to base level where they
would be covered with water.
These deposit are the materials that, given the proper conditions and time, become what is
commonly called soil.
Soil is the result of natural actions on these masses of rock. These actions result in a
heterogeneous mix of mineral fragments; organic matter, air and water.