| Jul 2012| © 2012 UPES

© 2012 UPESJul 2012Jul 2012

© 2012 UPESJul 2012Jul 2012

The lithosphere is the solid, rocky crust covering entire planet.

Also known as crust. This crust is inorganic and is composed

of minerals. It covers the entire surface of the earth from the

top of Mount Everest to the bottom of the Mariana Trench.

Silica and Aluminium dominate in this layer and hence it is

sometimes called „Sial‟.

Its average thickness is about 20 kms ( 8-40 kms)

It is thin below ocean beds and thick in continents.

Crust comprises 0.4 % of the total mass of earth.

© 2012 UPESJul 2012Jul 2012

Soil is the topmost layer of earth‟s surface which is composed of

mineral and organic matter and is capable of sustaining plant life.

Word soil has been derived from latin word „solum‟ which means

topmost layer of crust.

It is a dynamic layer of crust which goes on changing and

developing constantly.

Soil is formed by wear and tear of the crust, a process which has

been going on through the ages. This process is called

weathering ( discussed in previous unit)

© 2012 UPESJul 2012Jul 2012

The main components of soil are:

Inorganic material

It is parent material of soil. It is in the form of sand, silt, clay etc. which is

formed by wear and tear of rocks and minerals. The chemical

constituents of soil are nitrogen ( helps in growth of plants), phosphorus

(helps in the riping of grain and increases the yield), potassium

(determines the quality of grain), calcium ( helps in growth of leaves

which in turn provide food to plants) etc.

Organic Material

Organic matter is added to soil by dead animals and vegetation matter.

This matter is decomposed by microorganisms to form humus. Humus

helps in cementing the lose particles of sand, silt and clay; provides

food to plants; improves water retention power of soil.

© 2012 UPESJul 2012Jul 2012

Water

Air

Microorganisms

These decomposers decompose dead animals and plants. They

utilize the organic matter, derive energy and release inorganic

substances. They fix atmospheric nitrogen. Animals like

earthworms keep the soil porous.

© 2012 UPESJul 2012Jul 2012

Depending on their origin

Residual soils ( Diluvial).

This type of soil is found at its place of formation. Such soils are

common on hill slopes, foot hills or in the course of river

Transported Soil (Alluvial)

This type of soil is formed by deposition of material transported by

river, wind etc. Alluvial soil in gangetic planes is a good example.

© 2012 UPESJul 2012Jul 2012

For determining the quality of soil,

the surface features and

characteristics as well as the

characteristics in depth need to be

studied.

The depth of the soil can be studied

with the help of a soil profile.

A soil profile is a vertical section

through the soil downwards from

surface to the parent rock bed.

In a profile several characteristic

layers can be seen. These layers are

called horizons

The individual horizons are given

names, generally they are known as

O, A,B,C and R horizon

© 2012 UPESJul 2012Jul 2012

The 6 Soil Roles

A Soil’s role includes:

• Serving as a foundation

• Emitting and absorbing gases

• Providing habitat

• Interacting with water

• Recycling nutrients

• Supporting human settlements

© 2012 UPESJul 2012Jul 2012

The 5 Factors of Formation

Soil is formed by…

• Parent Material: the original “Mom & Pop” soil transported from

elsewhere, usually by wind or water, at different speeds

• Climate: the amount, intensity, timing, and kind of precipitation that

breaks down parts of ecosystem (i.e. rocks, trees) into soil

• Topography: Slope and Aspect affect the angle of the land and

position toward/away from the sun that soil will be exposed to

• Biological: Plants, animals, microscopic organisms, and humans

interact with soil in different ways

• Time: the amount of time it takes for the four factors (above) to

interact with each other

© 2012 UPESJul 2012Jul 2012

The “Organic Matter” Horizon

•Surface-layer, at depths of 0-2 feet

•Dark in color, soft in texture

•Humus - rich organic material of plant and

animal origin in a stage of decomposition

•Leaf litter – leaves, needles, twigs, moss,

lichens that are not decomposing

•Several O-layers can occur in some soils,

consisting only of O-horizons

-O1 : When the organic matter is in its

original vegetative form i.e. undecomposed

loose leaves and other organic matter

-O2: When organic matter is completely

decomposed

© 2012 UPESJul 2012Jul 2012

• Topmost layer of mineral soil, at depths

of 2-10 feet

• Some humus present, darker in color

than layers below

• Biomantle - most biological productive

layer; earthworms, fungi, and bacteria live

this layer

• Smallest and finest soil particles

• A1- It is dark colored layer composed of

organic matter and particles of minerals

and rocks. It has high content of organic

matter

• A2- It is light coloured layer composed of

mainly particles of rock and minerals

© 2012 UPESJul 2012Jul 2012

The “Subsoil” Horizon

• At depths of 10-30 feet

• Rich in sand, silt and clay and minerals

like Fe & Al

• Some organic material may reach here

through leaching

• Plant roots can extend into this layer

• Red/brown in color due to oxides of Fe &

clay

• Its sub divisions are B1, B2, B3 etc.

© 2012 UPESJul 2012Jul 2012

The “Regolith” Horizon

• At depths of 30-48 feet

• Made up of large rocks or lumps of

partially broken bedrock

• Least affected by weathering and

have changed the least since their

origin

• Devoid of organic matter due to it

being so far down in the soil profile.

• The material may be cemented by

calcium carbonate, alkali, silica etc.

© 2012 UPESJul 2012Jul 2012

The “Bedrock” Horizon

• At depths of 48+ feet

• Deepest soil horizon in the soil

profile

• No rocks or boulders, only a

continuous mass of bedrock

• It is underlying consolidated and

unweathered parent bed rock

such as granite limestone etc.

• Colors are those of the original

rock of the area

© 2012 UPESJul 2012Jul 2012

INGREDIENTS

• 3-4 copies of Master Soil Horizons Worksheet

• 30 sticky notes per group (7 per person)

• 3-4 pairs of gloves

• 1 large glass bowl

• 1 one-cup measuring cup

• 1 whisk

• 1 spatula

• 3.5 cups skim milk

• 2 packages vanilla Instant Jell-o pudding mix

• 1 tiny Ziploc bag Coconut w/green food

coloring + raisins

• 1 small Ziploc bag crushed chocolate graham

crackers & frosting

• 1 medium Ziploc bag Chocolate chip & Vanilla

wafers & gummy worms

• 1 small Ziploc bag crushed Vanilla wafers only

• 1 medium Ziploc bag crushed graham crackers

• 1 large Ziploc bag crushed Oreo cookies

• 1 large Ziploc bag crushed chocolate chips

DIRECTIONS

1. In large glass bowl, whisk 3.5 cups milk with 2

pkgs. vanilla Instant Jell-o pudding mix until

smooth. Let stand 5 minutes.

2. While waiting, refer to your version of “The Soil

Profile” powerpoint to review order that horizons

should be. You have A, E, B, R, O, C, and

vegetation as horizons. It‟s up to you to order it!

3. After 5 minutes, use spatula to scoop pudding in

middle of bowl, allowing for the “dry ingredients”

(the bags of various crushed up cookies) to

encircle the pudding along the sides of the glass

bowl. This creates a vertical cross-section of soil

layers visible to you.

4. Use sticky notes to label each horizon on outside

of bowl.

5. Fill out Master Soil Horizons Worksheet using

observations of Soil Profile Dessert.

6. Turn in worksheet to teacher. Only until you and

your team members turn in their worksheet can

you enjoy the delicious snack. You‟re finished!