What is soil ?? The uppermost layer of the earth is

known as soil. This layer consists of sand, mud, and rock

particles. What is humus?? Consists of dead and decayed plants and

animal remains called humus.

What Is weathering??• The breaking down of rocks is known as

Weathering

• Wind , water , frost helps in transporting of soil to places.

• There are two types of weathering :– Physical weathering– Chemical weathering

Physical weathering.

Physical weathering is the process of breaking of rocks into smaller pieces.

These change do not involve any characteristic change in the original rock .

These are caused by the-Temperature change,

-frost

Chemical weathering Chemical weathering is the process which

exists of mineral are broken down into mineral components.

Water is the main agents used in this Process.

soil What is weather??

The weather conditions prevailing in an area in general or over a long period.

Climate effects by the rain , wind , temperature of an place

Characteristic of the parent rock

• Characteristic of the parent rock also determines the kind of soil formed.

• Parent rock refers to the original rock from which something else was formed.

• It is mainly used in the context of soil formation where the parent rock normally has a large influence on the nature of the resulting soil.

What are the main factors affecting soil formation??

Climate Characteristic of the parent rock Slope of land

Climate : The weather conditions like the rain , wind ,etc plays an important role in loosing the soil. Increasing of pressure can also cause make the rocks to crack .Rocks are also worn down by wind.

Soil formation is faster in hot and slow in winter season.

Soil formation stagesstep 1: Weathering is the physical or

chemical process.Step 2: small rocks continue to undergo

weathering, causing large pieces of parential rocks.

Step 3: minerals and salts seep deeper into the ground along with water.

Humus and topsoil

Humus is the organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms.

is the uppermost layer of soil. this layer consists of humus and

fine particles of dust and sand.

Horizon Contains weathered rocks. It is very difficult to dig more than

this layer. the line at which the earth's surface

and the sky appear to meet. ___________________________________

Bedrock The lower most layer and consists of

parent rock. This layer is mainly consists of soil. _____________________________________

this layer is also soft and can hold water

O horizon lies just above this top soil which is rich in organic matter.

________________________________ Sub soil Subsoil is rich in minerals that

sweep down along with the water . It also consists of fine particles

of soil. ________________________________

Parental rock undergoing change

what is regolith : the layer of solid material covering the bedrock of a planet.

Humus

Top soil

Sub soil

Bedrock

Particles size of construction

Particles

Diameter

Clay Less than 0.002Slit 0.002 – 0.05Sand 0.05 – 2.00Fine bebbles 2.00 – 5.00Medium pebbles 5.00 – 20.00Coarse pebbles 20.00 - 75.00

Properties of soil The 3 properties of soil are :

Absorption of soil. Moister of soil. Percolation of water.

Percolation is the process of a liquid slowly passing through a filter.

Soil erosion

Soil compaction, low organic matter, loss of soil structure, poor internal drainage, salinisation and soil acidity problems are other serious  issues.

Surface water runoff occurs whenever there is excess water on a slope that cannot be absorbed into the soil or is trapped on the surface.

Sandy soil : Sand soils are often dry, nutrient

deficient and fast-draining. They have little ability to transport water from deeper layers through capillary transport.

tillage of sandy soils in the spring should be kept to a minimum in order to retain moisture in the seedbed.

meaning of tillage :the preparation of land for growing crops. the preparation of land for growing crops.

Clayey soil Clay is a fine-grained natural rock or

soil material that combines one or more clay minerals with traces of metal 

variable amounts of water trapped in the mineral structure. Depending on the content of the soil, clay can appear in various colours, from white to dull gray or brown to a deep orange-red.

Loamy soil Loam is soil composed mostly

of sand and a smaller amount of clay.

Use in farming !! Loam is considered ideal for

gardening and agricultural uses because it retains nutrients well and retains water while still allowing excess water to drain away

Pictures of 1.sandy soil , 2.clayey soil , 3.loamy soil.

1

2 3

How to prevent soil erosion

Deforestation Overgrazing Flood and heavy rainfall Improper farming

Plant more trees and cut less trees. Overgrazing in a same patch of land

should be avoided. Terrace farming should be adopted in hilly

areas.