Soil

It is needed for:-
 Holding the roots firmly
 Supplying water and nutrients

 Temperature changes
 Frost
 Water
 Wind
 Living organisms
WEATHERING
Factors responsible for weathering

 Rocks expand when heated and
contract when cooled.

 Rainwater may become trapped in small
crevices of the parent rock. In winter this
water freezes to ice. The ice expands
producing a lateral pressure,causing the
crevices in the rock to further open up.

 Continual movement of rain and river
water, in liquid form,causes breaking
down of rock particles into finer particles.

 A rock has energy in several ways. Assuming it's
sitting still, a rock may have gravitational
potential energy because of gravity pulling on
it. It has energy stored in the chemical bonds in
the molecules of the rock. Also, if the rock has
some charge on it(its a possibility), it could
have electrical potential energy if it was in an
electric field. Then of course there is the rest
energy of the rock. According to
relativity(E=mc^2), the rock has some energy
just by being massive.

 rocks do have potential energy. Potential
energy is defined as energy stored within a
physical system. It is called potential
because it has the potential to be
converted into other forms of energy, such
as kinetic energy which can do work in the
process.
 This means that a rock can have potential
energy as simple as, a rock held at an
elevation. If dropped it's potential energy is
then being converted to kinetic energy.

 Wind blowing across a rock surface has
an abrassive affect on the rocks.

Weathering by living organisms is
called biological weathering

 The term used for the vertical section of
soil to show the different layers or
horizons of soil.

 Darkest in colour
 Rich in humus
 Very fertile
 Soft,porous
 Roots of plants are present
 Living organisms are present

 Lighter in colour
 Harder and more compact than the A-
horizon
 Rich in soluble minerals and iron oxides
 Remains of plants and animals are not
found
 Roots of tall plants reach
 Little organic matter found

 Beneath c-horizon is the bed rock

 Rock or different types of soil
 Humus
 Soil water
 Soil air
 Soil organisms

 Soil particles-gravel ,sand and clay
 Soil types-loamy, clayey and sandy

 Highly porous
 Large particles
 Well aerated
 Holds less water
 Dry

 Very little air
 Particles are smaller and tightly packed
 Holds enough water
 Contains humus.

 Different sized particles
 Contain humus
 Hold sufficient water
 Contain enough air

 For the respiration of roots and soil
organisms

 Earthworms burrow the soil
 Micro-organisms release the minerals
back to the soil
 Some bacteria fixes nitrogen

 White
 Grey
 Yellow
 Red
 Black

 Clayey soil -wheat ,gram and paddy
 Loamy soil -Lentils and other pulses
 Sandy soil -cotton

 Destroys vegetation
 Results in barren land

 After fire soil is exposed to wind and
water

 Afforestation
 Plant trees along the boundaries of the
field
 Crop rotation
 Proper drainage and irrigation

 To reduce the effect of winds

 Reduces the steepness
 Checks the soil erosion

Soil

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Soil