SOIL DEGRADATION

Impacting The Environment

Mr. Stewart

WHAT IS SOIL?

SOIL

S

oil is the earth’s fragile skin that anchors all life on Earth. It is

comprised of countless species that create a dynamic and complex

ecosystem and is among the most precious resources to humans.

S

oil is the end product of the influence of the climate, relief

(elevation, orientation, and slope of terrain) , biotic activities

(organisms), and parent materials (original minerals) acting over

periods of time.

SOIL PROFILE

IDENTIFY

WHAT IS SOIL DEGRADATION?

SOIL DEGRADATION

S

oil degradation may be viewed as any change or disturbance to the soil perceived

to be deleterious or undesirable.

S

oil Degradation are broken down to

O

ne (Physical)

T

wo (Chemical)

T

hree (Biological) subgroups

SOIL DEGRADATION

WHAT IS SOIL COMPACTION?

SOIL COMPACTION

Soil compaction is the process in which a stress

applied to a soil causes densification as air is

displaced from the pores between the soil grains.

When stress is applied that causes densification due

to water (or other liquid) being displaced from

between the soil grains then consolidation.

DENSIFICATION

SOIL COMPACTION

Soil compaction is usually a combination of both

engineering compaction and consolidation, so may

occur due to a lack of water in the soil, the applied

stress being internal suction due to water

evaporation as well as due to passage of animal feet

and other factors such as heavy machinery.

COMPACTING METHODSS

tatic - a large stress is slowly applied to the soil and then released.

I

mpact - the stress is applied by dropping a large mass onto the surface of the soil.

V

ibrating - a stress is applied repeatedly and rapidly via a mechanically driven plate or hammer. Often combined

with rolling compaction (see below).

G

yrating - a static stress is applied and maintained in one direction while the soil is a subjected to a gyratory motion

about the axis of static loading. Limited to laboratory applications.

R

olling - a heavy cylinder is rolled over the surface of the soil. Commonly used on sports pitches. Roller-compactors

are often fitted with vibratory devices to enhance their ability.

K

neading - shear is applied by alternating movement in adjacent positions. An example, combined with rolling

compaction, is the 'sheepsfoot' roller used in waste compaction at landfills.

MEASURED

A

soil penetrometer can be used as a diagnostic tool to

measure the extent and depth of subsurface soil

compaction.

PENETROMETER

TIRE COMPACTION

COMPACTION

COMPACTION

ADVANTAGE

Roads

Housing

Lawns

DISADVANTAGES Causes soil pore spaces to become smaller

reduces water infiltration rate into soil

Decreases the rate that water will penetrate into the soil root zone and

subsoil

Increases the potential for surface water ponding, water runoff, surface

soil waterlogging and soil erosion

Reduces the ability of a soil to hold water and air, which are necessary for

plant root growth and function

Reduces crop emergence as a result of soil crusting

Impedes root growth and limits the volume of soil explored by roots

limits soil exploration by roots and decreases the ability of crops to take

up nutrients and water efficiently from soil

Reduces crop yield potential

MANAGEMENT

T

raffic control

-Reduce

overall soil compaction in a field

-Improve soil

structure

-Increase

water infiltration

-Increase soil

water storage

-Increase

moisture use efficiency

-Improve

nutrient use efficiency

MANAGEMENT

C

rop rotation

-

Promote plant roots to grow through and break up compacted soils

-

Increase soil organic matter

-

Improve soil structure, improve water infiltration and penetration into soil

-

Promote biological diversity

WHAT IS WATERLOGGING

WATER LOGGING

W

aterlogging refers to the saturation of soil with

water. Soil may be regarded as waterlogged when

the water table of the groundwater is too high to

conveniently permit an anticipated activity, like

agriculture.

WATER LOGGING

ADVANTAGES

P

lanting of WATER LOVING plants.

R

earing of aquaculture

I

rrigation method

DISADVANTAGE

I

nsect harboring

DISADVANTAGE

F

looding

ADVANTAGE

H

inder of Agriculture

DISADVANTAGE

LEACHING

Damaging of plant roots

MANAGEMENT

C

onsider a drainage

C

hoice of crop

F

ertilizer

W

eed control

P

roper farming planning

ACIDIFICATION

SOIL ACIDIFICATIONS

oil acidification is the buildup of hydrogen cations, also called

protons, reducing the soil pH. This happens when a proton donor

is added to the soil. The donor can be an acid, such as nitric acid

and sulfuric acid (these acids are common components of acid

rain). It can also be a compound such as aluminium sulfate, which

reacts in the soil to release protons. Many nitrogen compounds,

which are added as fertilizer, also acidify soil over the long term

because they produce nitrous and nitric acid when oxidized in the

process of nitrification.

SOIL ACIDIFICATION

SYMPTOMS

R

educing Yield

S

tunted root growth

A

bnormal leaf color

P

oor nodulation of legumes

BENEFITS

R

aises soil pH.

A

well balanced soil pH is important for: soil fertility

and nutrient availability plant species that can be

grown biological activity of the soil

BENEFITS

L

ivestock health

I

ncreased calcium and magnesium levels in the plant

helps to overcome problems such as grass tetany in

cattle.

BENEFITS

E

conomics

R

esearch data shows that responses to lime can be

profitable