IB ESS Topic 3 Human population

HUMAN
POPULATION
4/6/2014 Guru IB ESS TOPIC 3

World's 7th Billion Baby to be Born
in Lucknow
• Lucknow, the capital of Uttar Pradesh will
welcome the seventh billion baby of planet
earth at 12 noon on October 31. The
recognition has been granted following a letter
from General Secretary, United Nations Ban
Ki Moon that the seven billionth baby will be
probably born in India or China, the two of the
world's fastest growing population

• 3.1.-Population Dynamics
• 3.1.1-Describe the nature and explain the
implications of exponential growth in human
populations.

This question is difficult to answer.
• Estimates are usually based on
food, but human agriculture limits
assumptions on available
amounts.
• Human population growth rate
has been growing more than
exponentially.
What is the carrying capacity of Earth
for humans?

HUMAN POPULATION GROWTH
1999
1975
domestication of plants,
animals 9000 B.C. (about
11,000 years ago)
agriculturally based
urban societies
beginning of industrial,
scientific revolutions

What is HUMAN POPULATION?
• The total number of persons inhabiting a co
untry, city, or any district or area.

What is Exponential growth?
• Exponential population growth is when
the birth rate is constant over a period of
time and isn't limited by food or disease

Measures of population changes are
1. Crude Birth Rate
2. Crude Death Rate
3. Rate of Natural Increase

What is CRUDE BIRTH RATE?
• Crude birth rate is the childbirths per
1,000 people per year. This is a common
measure of fertility for a given
population.

• Therefore, the formula for crude birth rate is
The crude birth rate = number of births per year x 1000
Total population
Example.
In 2007, there were 3,250 births in a city with
population of 223,000. Therefore:
CBR = 3,250 x1000
223,000
CBR =14.57
So, there were 14.57 births for every 1,000 people in
the city.

• The crude birth rate could be of concern for
particular countries who may be experiencing
population decline, or for national
governments who are worried about
population growth rates that are higher than
their country can sustain

• The birth rate is usually the dominant
factor in determining the rate of
population growth. It depends on both the
level of fertility and the age structure of
the population.

CRUDE DEATH RATE
• The death rate, while only a rough indicator of the
mortality situation in a country, accurately
indicates the current mortality impact on
population growth.
• This indicator is significantly affected by age
distribution, and most countries will eventually
show a rise in the overall death rate, in spite of
continued decline in mortality at all ages, as
declining fertility results in an aging population.

How to calculate Crude Death Rate?
The crude death rate = number of death per year x 1000
Total population
Example.
In 2007, there were 4,000 death in a city with population of
2,000,000. Therefore:
CBR = 4,000 x1000
2,000,000
CDR =2
So, there were 2 death for every 1,000 people in the city.

Rates of Global Pop. Change
• CBR (crude birth rate) = number of births per 1000
population
– 1990: 24 Today: 21.3
• CDR (crude death rate) = number of deaths per 1000
population
– 1990: 9 Today: 8.93
• Growth rate = birth rate - death rate (often in %)
– 1990: 1.5% Today: 1.3%
– growth rates have come down

Special Kinds of Fertility and
Mortality Rates
• TFR (total fertility rate) =
– number of children born to a woman during her
reproductive years (or life time)
– 1990: 3.1 2000: 2.8
• IMR (infant mortality rate) =
– infant deaths per 1000 live births (infant < 1 yr)
– 1990: 62 2000: 56 (1900: 200)

RECAP
What is Human population?
What is Crude Birth Rate? Formula
What is Crude Death Rate? Formula
What is Exponential growth?

Population, population change, growth
rates
• Population: number of persons
• Population change: increase in the number of
persons (per year)
• Growth rates: rate of change (per year)

Doubling Time
Doubling time (T) = 70 .
annual percentage rate
Doubling time (T) = 70 . = 50 years
1.4
Doubling time = the number of years it
would take a population to double its size
at its current growth rate.

Doubling Time
• Number of years in which a population reaches
twice its size
• Doubling time can be approximated using growth
rates
• doubling time = 70 : growth rate
– rate: 1.4 doubling time: 49
– rate: 2.0 doubling time: 34.5
– rate: 0.5 doubling time: 138
– rate: -0.5 doubling time: ????

How to calculate Rate of Natural Increase?
• The rate of natural increase shows the
rate at which people are added to a given
population by births and deaths (ignoring
migration). It is usually represented as
follows:
• Rate of Natural Increase
Crude Birth Rate - Crude Death Rate
10

For example,
Madagascar's crude birth rate 37.89
The crude death rate 7.97
37.89 -7.97
10
29.92 =2.992%
10
divide that by 10 and the result is 2.992%,
Madagascar's rate of natural increase

Why has the world’s population
grown at such different rates
throughout history?
Natural increase = births – deaths
Net migration = immigrants – emigrants
• Births
• Deaths
• Migration

What is mortality?
• Mortality rate is a measure of the number of
deaths (in general, or due to a specific cause)
in a population, scaled to the size of that
population, per unit of time

What is fertility rate ?
• The total fertility rate (TFR), sometimes also
called the fertility rate, period total fertility
rate (PTFR) or total period fertility rate (TPFR)
of a population is the average number of children
that would be born to a woman over her lifetime
• The number, which ranges from more than 7
children per woman in developing countries in
Africa to around 1 child per woman in Eastern
European and highly-developed Asian countries.

Births per woman
< 2
2-2.9
3-3.9
4-4.9
5+
No
Data
Fertility Rates

What affects fertility rates?
• Importance of children to labor force
• Urbanization
• Cost of raising and educating children
• Education and employment options for women
• Average age of marriage
• Availability of pension plans
• Availability of legal abortions
• Availability of birth control
• Religious beliefs, traditions and culture

What affects death rates?
• Higher food supplies
• Better nutrition
• Improved medical and health technology
• Improved sanitation
• Safer water supplies

Indicators of overall health
Growth = natural increase – net migration
• Life expectancy
• Infant mortality

Infant deaths
per 1,000 live births
<10
<10-35
<36-70
<71-100
<100+
Data not
available

Population
(2002)
Population
projected
(2025)
Infant
mortality
rate
Life
expectancy
Fertility
rate (TFR)
%Population
under
age 15
% Population
over
age 65
Per capita
GNI PPP
(2000)
288 million
174 million
130 million
346 million
219 million
205 million
6.8
33
75
77 years
69 years
52 years
2.1
2.2
5.8
21%
33%
44%
13%
5%
3%
$34,100
$7,300
$800
United States (highly developed)
Brazil (moderately developed)
Nigeria (less developed)
© 2004 Brooks/Cole – Thomson Learning

Developed Countries
50
40
30
20
10
0
1775 1800 1850 1900 1950 2000 2050
Rateper1,000people
Year
Rate of
natural increase
Crude
birth rate
Crude
death rate
Rate of natural increase = crude birth rate – crude death rate
©2004Brooks/Cole–ThomsonLearning

Developing Countries
50
40
30
20
10
0
1775 1800 1850 1900 1950 2000 2050
Rateper1,000people
Crude
birth rate
Rate of
natural
increase
Crude
death rate
Year
©2004Brooks/Cole–ThomsonLearning

• A population pyramid, also called an age
structure diagram, is a graphical illustration
that shows the distribution of various age
groups in a population which forms the shape
of a pyramid when the population is growing.
What is Population Pyramid?

Population Pyramids
• Graphic device: bar graph
• Shows the age and gender composition of a
region
• Horizontal axis: gender
– male: left-hand female: right-hand
– absolute number of people or %
• Vertical axis: age
– 5-year or 10-year age groups

• It typically consists of two back-to-back bar
graphs, with the population plotted on the X-
axis and age on the Y-axis, one showing the
number of males and one showing females in a
particular population in five-year age groups
• Males are conventionally shown on the left
and females on the right, and they may be
measured by raw number or as a percentage of
the total population.

• It show how many individuals are alive in
different age groups in a country for a given year.
• They also show how many are male and female.
• Population numbers are always on the x-axis and
age groups on the y-axis.
• The overall stage can depict the stage of
development of the country at a particular time.
• LEDC’s tend to have expanding populations so
they are wide at the bottom, whereas MEDC’s
tend to have stationary or contracting
pyramids as birth rates fall and individuals live
longer.

Age Structure
• Age structure—the proportion of the
population in each age class.
• Age structure influences whether a population
will increase or decrease in size.

Age Structure
• Countries that have high rates of growth
usually have more young people than older
people.
• In contrast, countries that have slow growth or
no growth usually have an even distribution of
ages in the population.

Age Structure
• Age structure can be graphed in a
population pyramid, a type of double
sided bar graph.

Age-Structure Diagrams

Age/Sex Pyramids
Show the
proportion of
the population
(or of each sex)
at each age
level.

Demographer usually plot % or # of male
and females in the total population in
each of three categories:
1. Pre-reproductive (0-14)
2. Reproductive (15-44)
3. Post-reproductive (45 and up)
Male Female
Ages 0-14 Ages 15-44 Ages 45-85+

How does Age Structure Affect Population
Growth?
• Age/Sex Pyramids help demographers determine the
potential for future growth of a specific age group as
well as that of the total population .
• The overall shape of the pyramid indicates potential
growth.
• Age structure diagrams not only reveal a population’s
growth trends, but can point to future social
conditions.

Male Female
U.S.
Male Female
Congo
Male Female
Germany

• Why would a country’s leaders want to know
the proportion of the population in different
age groups?
• What difference does the age of the people in a
country make?
• What kinds of products do young people use?
• Is it important for a government leader or
planner to know the age of population they are
serving?

Male Female
Rapid Growth
Guatemala
Nigeria
Saudi Arabia
Ages 0-14 Ages 15-44 Ages 45-85+
Slow Growth
United States
Australia
Canada
Male Female

Zero Growth
Spain
Austria
Greece
Male Female
Negative Growth
Germany
Bulgaria
Sweden
Male Female
Ages 0-14 Ages 15-44 Ages 45-85+

300 200 100 0 100 200 300
85+
80-85
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
Male Female
Population (millions)
Age
Developing Countries

300 200 100 0 100 200 300
85+
80-85
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
Male Female
Population (millions)
Age
Developed Countries

Fig. 46.15, p. 827
CANADA UNITED STATES
INDIA AUSTRALIA
MEXICO CHINA

Age Structure Diagram
U.S.

Stage 1: High birth rate; rapid fall in each upward age group due high death rates; short life
expectancy.
Stage 2: High birth rate; fall in death rate as more living to middle age; slightly longer life
expectancy.
Stage 3: Declining birth rate; low death rate; more people living to old age.
Stage 4: Low birth rate; low death rate; higher dependency ratio; longer life expectancy.

Describe and explain the main features of the population pyramid below
This population pyramid has a very wide base showing that there are a lot of babies born
every year.
This shows that there is a good medical service within the country. The different sectors from
5 - 9 up to 25 - 29 decreases very quickly and decreases even more quickly on the male side.
This is good for the country, as there are fewer people to feed and educate. As the ages
increase up through the pyramid, it gets narrower and narrower.
This might be because as people get older they leave the country in search of a job or a better
standard of living

3.1.3-
• Analyse age/sex pyramids and diagrams
showing demographic transition model

How can economic development help
reduce birth rates?
• Demographers have developed a hypothesis
known as the DEMOGRAPHIC
TRANSITION.
• It states that as countries become
industrialized, first death rates go down and
then their birth rates decline.

Demographic Transition

• The "Demographic Transition" is a model that
describes population change over time.
• The demographic transition model (DTM) is
the transition from high birth and death rates to
low birth and death rates as a country develops
from a pre-industrial to an
industrialized economic system.
What is Demographic Transition?

Stage 1 - High Fluctuating
Stage 2 - Early Expanding
Stage 3 - Late Expanding
Stage 4 - Low Fluctuating
Stage 5- Only Possible in some countries
FIVE STAGES IN DTM

Birth Rate is high as a result
of:
1. Lack of family planning
2. Need for workers in
agriculture
3. Religious beliefs
Death Rate is high
because of:
1. High levels of disease
2. Famine
3. Lack of health care
4. War
5. Lack of education
Stage One-DTM
Both high birth rates and death rates fluctuate in the first stage of the
population model giving a small population growth. There are many
reasons for this:
Typical of Britain in the 18th century and the Least
Economically Developed Countries4/6/2014 Guru IB ESS TOPIC 3

• Birth Rate remains high. Death Rate is falling.
Population begins to rise steadily.
• Reasons
Death Rate is falling as a result of:
1. Improved health care (e.g. Smallpox Vaccine)
2. Improved Hygiene (Water for drinking boiled)
3. Improved sanitation
4. Improved food production and storage
• Typical of Britain in 19th century; Bangladesh;
Nigeria
STAGE TWO-DTM

Birth Rate starts to fall. Death Rate continues to
fall slowly. Population rising.
Reasons:
1. Family planning available
2. Lower Infant Mortality Rate
3. Increased standard of living
4. Changing status of women
• Typical of Britain in late 19th and early 20th
century; China; Brazil
STAGE THREE-DTM

• Both birth rates and death rates remain
low, fluctuating with 'baby booms' and
epidemics of illnesses and disease. This
results in a steady population.
Typical of USA; Sweden; Japan; Britain
STAGE FOUR-DTM

• A stage 5 was not originally thought of as part
of the DTM, but some northern countries are
now reaching the stage where total population
is declining where birth rates have dropped
below death rates.
• One such country is Germany, which has
taken in foreign workers to fill jobs.
STAGE FIVE-DTM

Area Birth Rate Reason Death Rate Reason
LEDCs High
No contraception
Couples have many babies
to compensate for the high
death rate caused by poor
health care
Large families need to
work on the land to
contribute to family
income
Children look after old
Religious reasons
High
Poor medical facilities
Disease
Poor nutrition
High Infant mortality
NICs
High/
Decreasing
People are used to having
many children. Takes time
for culture to change
Changing status of women
Decreasing
As an economy develops
money becomes available
for better health care
Housing improves
Better childcare
MEDCs Low
Children are expensive
People know their children
are going to survive so
they can keep their
families small
Widely available
contraceptives
Low
Better health care
Better standard of living

What are the main factors that affect
the growth of a population?
 The main factors that make populations
grow are births and immigration.(The
action of coming to live permanently)
 The main factors that make populations
decrease are deaths and
emigration.(moving from one place)

• Two types of population curve
• S Population Curve
• J Population Curve

TYPES OF POPULATION CURVE
• Two modes of population growth.
• J-Shape curve is also known as- Exponential
curve occurs when there is no limit to
population size.

• S-Shape curve is also known as - Logistic
curve shows the effect of a limiting factor
• S-Sigmoid

What is S-Shaped Curve?
• In S - shaped or sigmoid growth the population
show an initial gradual increase in population
size in an ecosystem, followed by an
exponential increase and then a gradual decline
to near constant level.

• In population of an ecosystem which
factors determining the S shape curve?

The curve obtained by plotting growth and
time is called a growth curve. It is a typical
sigmoid or S- shaped curve.4/6/2014 Guru IB ESS TOPIC 3

What is J shaped?
• A curve on a graph that records the situation in which, in a new
environment, the population density of an organism increases rapidly but
then stops abruptly as environmental resistance
• It may be summarized mathematically as:
I. dN/dt = rN (with a definite limit on N)
II. where N is the number of individuals in the population, t is time, and
III. r is a constant representing the rate of increase for the organism concerned.

• The growth of population is measured as increase in
its size over a period of time and populations show
characteristic patterns of growth with time.
• These patterns are known as population growth
forms.4/6/2014 Guru IB ESS TOPIC 3

3.2 RESOURCES-
NATURAL CAPITAL

What is Natural Capital ?
• Natural capital is the term used
for ‘natural resources’ which can
be exploited to produce natural
income of goods and services.
• e.g. trees as timber that can be
harvested and sold for money.

Natural Capital OF
EARTH
It includes the core and crust of
the earth, the biosphere itself -
teeming with forests, grasslands,
wetlands, tundra forests, deserts,
and other ecosystems - and the
upper layers of the atmosphere.

• The stock is the present accumulated quantity
of natural capital. It is a supply accumulated
for future use; a store.
• Natural capital is the term used for ‘natural
resources’ which can be exploited to produce
natural income of goods and services.
• e.g. trees as timber that can be harvested and
sold for money.
NATURAL CAPITAL & INCOME

• Natural capital provides a wide variety of valuable
ecosystem services including flood control, climate
stabilization, maintenance of soil fertility, and even
beauty and play.
• Globally, and within the bioregion, natural capital
is being depleted through over-harvesting,
development, poor agricultural practices, toxic
contamination, and other causes.
Human capture

3 TYPES OF NATURAL
CAPTIAL
oRenewable
oNon renewable
oReplenishable

Resources
oReplenishable Nonrenewable
Renewable
Fresh
air
Fresh
water
Fertile
soil
Plants and
animals
(biodiversity)
Direct
solar
energy
Winds,
tides,
flowing
water
Fossil
fuels
Metallic
minerals
Non-
metallic
minerals
(iron,
copper,
aluminum)
(clay,
sand,
phosphates)

RECAP
• What is Natural Resources?
• What is Natural Capital?
• Example of Natural Resources?
• Types of Natural resources

Values of Natural Capital:
• Economic value: can be determined from
the market price of the goods and services it
produces.
• Ecological value: have no formal market
price. Photosynthesis, nitrogen-fixation, soil
erosion control are essential for human
existance, but are taken for granted.

• Aesthetic value: have not market price and
may not provide identifiable commodities,
so they are unpriced or undervalued from
an economic viewpoint.

Natural Environment
SOURCES
Raw
Materials
production
Economy
Products
consumption
money
Waste
products
Natural Environment
SINKS

• Healthy ecosystems make very significant
economic contributions, but often in ways that
transcend conventional accounting.
• In order to maintain Natural Capital and the
services that it provides, the physical basis for the
productivity and diversity of nature must not be
systematically deteriorated.
Years of growth30
25 15
10
5
Clear cut
Weak trees
removed
Seedlings
planted

Natural Capital can be protected through
careful application of:
• Ecological Land-Use to maintain habitat
quality and connectivity for all species.
• A connected system of wild lands can coexist
with productive rural areas and towns and
cities, with each part of the landscape
contributing to the stability of natural capital.
• Sustainable Materials Cycles prevent the
systematic contamination of living systems.
• Social Capital contributes to a culture of
sufficiency easing consumption pressures on
natural capital.

What is Renewable energy &
Nonrenewable energy?
• Renewable energy is energy which
comes from natural resources such
as sunlight, wind, rain, tides,
and geothermal heat, which
are renewable
• Nonrenewable energy is energy that
comes from the ground and is not
replaced in a relatively short amount of
time.

RECAP
• What is Natural Resources?
• What is Natural Capital?
• Example of Natural Resources?
• Types of Natural resources
• Environmentalists have identified 5 basic
causes of environmental problems we
face.

What is Replenishable
energy?
• Replenishable energy is that energy
source that doesn’t reduce and gets
their replenishment of energies from
other natural sources like wind, sun,
trickling water, geothermal flows of
heat and biological processes
• Example:
• Water stores,Ground Water or surface
water

Difference between renewable &non
renewable energy
Renewable Energy
1. The resources that can be renewed
by reproduction are called
renewable resources.
2. Renewable resources are
inexhaustible.
3. Renewable resources are not
affected by the human activities.
4. All biotic resources are
renewable.
For example: air and water.
Non Renewable Energy
1. The resources that are present
in fixed quantities are called
non-renewable resources.
2. Non-renewable resources are
exhaustible.
3. Non renewable resources are
affected by human activities
4.
Some abiotic resources are
non-renewable.
For example- fossil fuels and
minerals.

What is Fossil fuels?
• Coal, oil and gas are called "fossil fuels"
becausethey have been formed from the
organic remains ofprehistoric plants and
animals.

FOSSIL FUELS
SOURCE OF ENERGY
• Coal ,oil and natural gas are the three fossil
fuels.
They have two common characteristic
1. They were formed from the decomposition of
the remains of plants and animals.
2. It has taken millions of years for them to
accumulate and form deposit which are large
enough to be mined for human use

Rank Company
1 Saudi Aramco
2 National Iranian Oil Company
3 Qatar Petroleum
4 Iraq National Oil Company
5 Petróleos de Venezuela
6 Abu Dhabi National Oil Company
7 Kuwait Petroleum Corporation
8 Nigerian National Petroleum Corporation
9 Libya NOC
10 Sonatrach
TOP 10 OILS COMPANIES

Advantage & Disadvantage of Fossil fuel
Advantages
1. Large amounts of
electricity can be
generated in one place
using coal, fairly cheaply.
2. Transporting oil and gas to
the power stations is easy.
3. Fossil fuels are very easy
to find.
4. Power stations that make
use of fossil fuel can be
constructed in almost any
location.
Disadvantages
1. Basically, the main drawback of
fossil fuels is pollution. Burning
any fossil fuel produces carbon
dioxide, which contributes to the
"greenhouse effect“.
2.
It also produces sulphur dioxide, a
gas that contributes to acid rain.
3. Mining coal can be difficult and
dangerous. Strip mining destroys
large areas of the landscape.
4. Coal-fired power stations need
huge amounts of fuel, which
means train-loads of coal almost
constantly.4/6/2014 Guru IB ESS TOPIC 3

• Nuclear energy originates from the splitting
of uranium atoms in a process called fission.
• At the power plant, the fission process is used
to generate heat for producing steam, which is
used by a turbine to generate electricity.
• Nuclear energy contributed only between 7 &
8 % of total world commercial energy
consumption .
What is Nuclear Energy?

Nuclear Power plants
• A nuclear power plant (NPP) is
a thermal power station in which the
heat source is one or more nuclear
reactors.

Nuclear Power plants in India
• Nuclear power is the fourth-largest source
of electricity in India after thermal, hydroelectr
ic and renewable sources of electricity.
• As of 2010, India has 20 nuclear reactors in
operation in six nuclear power plants,
generating 4,780 MW.

Is Nuclear Power plants is safe ?

SAFETY OF NUCLEAR
POWER PLANT
• Scientist have repeatedly emphasized how safe
nuclear power is ,but they have not been able
to convince most .
• Public confidence is nuclear power was
shattered by the great explosion in 1986,at
chernobl in the Ukraine

Advantage
1. Does not produce smoke or
carbon dioxide, so it does not
contribute to the greenhouse
effect.
2. Produces huge amounts of
energy from small amounts of
fuel.
3. Produces small amounts of
waste.
4. Nuclear power is reliable.
Disadvantage
1. Nuclear plants are more
expensive to build and
maintain.
2. Waste products are
dangerous and need to be
carefully stored for long
periods of time.
3. Nuclear power plants can
be dangerous to its
surroundings and
employees.
Advantage & Disadvantage of Nuclear Energy

FEBRUARY FORMATIVE
• Date :27.02.2014
• Topic :Human Population
• Total Marks :40
• Format :Paper 2-Essay Question
• Unit : 3.1 & 3.2
1. Human Population
2. Energy resources
3. Intrinsic value &Sustainable development.

FEBRUARY SUMMATIVE
• Date :28.02.2014
• Total Marks :45(IB Format)
• Time : 1 hour
• Syllabus :Human Population
• Unit : 3.1 & 3.2
1. Human Population
2. Energy resources
3. Intrinsic value &Sustainable
development

ALTERNATIVE ENERGY
SOURCES
AND
OTHER CONSERVATION
STRATEGIES

• An alternative source usually refers to an
energy source that can be used as a
replacement for fossil fuels.
• Most alternative sources are also renewable
sources of energy
• They are also SUSTAINABLE sources of
energy, which means that people will be able to
use long after fossil fuels run out.
What is alternative source of energy?

1. Solar energy is generating of electricity from the sun
2. Wind energy is generating of electricity from the
wind
3. Geothermal energy is using hot water or steam from
the Earth’s interior for heating buildings or electricity
generation.
4. Biofuel and ethanol are plant-derived substitutes of
gasoline for powering vehicles
5. Wave : force of the sea waves as they break against
the coastline
6. Biomass: using fuel wood, crop wastes and animal
dung as fuel
Most common types of alternative energy

What is biomass?
• Biomass, as a renewable energy source,
is biological material from living, or recently
living organisms.
• As an energy source, biomass can either be
used directly, or converted into other energy
products such as biofuel.

Advantages
1. Theoretically
inexhaustible fuel source
2. Minimal environmental
impact
3. Alcohols and other fuels
produced by biomass are
efficient, viable, and
relatively clean-burning
4. Available throughout the
world
Disadvantages
1. Still an expensive
source, both in terms of
producing the biomass
and converting it to
FUEL
Advantage & Disadvantage of Biomass

What is Solar Energy
• Solar energy refers primarily to the use
of solar radiation for various purposes.

Advantage
1. Solar energy is free - it needs
no fuel and produces no waste
or pollution.
2. Solar cells make absolutely no
noise at all.
3. Solar powered panels and
products are typically
extremely easy to install.
Disadvantage
1. The Solar Cells and Solar
Panels are very expensive
2. Solar power cannot be
harnessed during a storm,
on a cloudy day or at
night.
Advantage & Disadvantage of Solar Energy

What is Geothermal Energy?
• Geothermal means earth-heat. It is related to
the thermal energy of Earth’s interior.
• On a large scale, the intensity of this thermal
energy increases with depth, that is, the
temperature of the Earth increases as we travel
closer to its centre.

• Hot rocks underground heat water to produce
steam.
• We drill holes down to the hot region, steam
comes up, is purified and used to drive turbines,
which drive electric generators.
• There may be natural "groundwater" in the hot
rocks anyway, or we may need to drill more holes
and pump water down to them.
How it works?

1. Geothermal energy does not
produce any pollution,
2. The power stations do not take
up much room, so there is not
much impact on the
environment.
3. No fuel is needed.
4. Once you've built a geothermal
power station, the energy is
almost free.
1. Not universally available.
2. High Cost:
Advantage & Disadvantage of GeoThermal Energy
Advantage Disadvantage

• Hydropower or water power is power that is
derived from the force or energy of moving
water
• The production of electrical power through the
use of the gravitational force of falling or
flowing water
What is HYDRO POWER?

• Most hydroelectric power (HEP) comes from
the potential energy of dammed water driving
a water turbine and generator.
• The power extracted from the water depends on
the volume and on the difference in height
between the source and the water's outflow.
WORKING PROCESS

1. Once the dam is built, the energy
is virtually free.
2. No waste or pollution produced.
3. Much more reliable than wind,
solar or wave power.
4. Water can be stored above the
dam ready to cope with peaks in
demand.
5. Electricity can be generated
constantly.
1. The dams are very expensive to
build.
2. Building a large dam will flood a
very large area upstream, causing
problems for animals that used to
live there.
3. Finding a suitable site can be
difficult - the impact on residents
and the environment may be
unacceptable.
4. Water quality and quantity
downstream can be affected, which
can have an impact on plant life.

Name biggest dam in the world?
Hoover Dam

Name biggest dam in India
Bhakra Nagal Dam

• Bhakra Dam is a concrete gravity dam across
the Sutlej River, and is in Bilaspur, Himachal
Pradesh in northern India.

What is Wind Energy?
• Wind energy is energy that is created by using
the wind to generate power.
• It is a form of kinetic energy that can be
transformed into mechanical energy or
electricity.
How it works?
• Wind turbines transform the energy in the wind
into mechanical power, which can then be used
directly for grinding etc. or further converting to
electric power to generate electricity.

• On hill tops and other areas of open high
ground
• Along the coastline
• Offshore(in the sea) but close to the coast
Where you can see?

Top 10 countries by windpower capacity (2010) MW
China 44,733
United States 40,180
Germany 27,215
Spain 20,676
India 13,066
Italy 5,797
France 5,660
United Kingdom 5,204
Canada 4,008
Denmark 3,734

1. Wind is free, wind farms need
no fuel.
2. Produces no waste or
greenhouse gases.
3. The land beneath can usually
still be used for farming.
4. Wind farms can be tourist
attractions.
5. A good method of supplying
energy to remote areas.
1. The wind is not always predictable -
some days have no wind.
2. Suitable areas for wind farms are
often near the coast, where land is
expensive.
3. Some people feel that covering the
landscape with these towers is
unsightly.
4. Can kill birds - migrating flocks t
5. Can affect television reception if you
live nearby.

Discuss the factors that affect the choice
of energy sources adopted by different
societies.

• People in MEDCs need lots of resources to
sustain their high levels of consumption.
Whereas people in LEDCs sometimes have
limited access to basic resources such as food
and water.
• People in LEDCs also often have rich natural
resources, such as large forests and deep
deposits of valuable metals and minerals.
• To help them out of poverty, LEDCs can extract
and sell resources to MEDCs.

Demand - who is using the energy?

• The more resources that MEDCs buy from
LEDCs, the more money there is for LEDCs
to improve living standards, but the greater
the impact on the environment.

• There is an increasing demand for goods
and services from a growing global
population, especially those in MEDCs.
• The world's resources are being used up
more quickly. The consumption of resources
is spread unequally between MEDCs, who
use more resources, and LEDCs, who use
less.

Consequences of resource
exploitation

Socioeconomic consequences
• Higher energy prices as sources are depleted,
eg increase in petrol prices and domestic fuel
bills in the UK.
• This can have the result of leaving the elderly
and those on low incomes in fuel poverty.
• The gap between rich and poor becomes more
evident.
• Funding needed for research into alternative
energy, and increased costs for exploration and
extraction of existing energy sources.

Environmental consequences
• Increased carbon emissions cause global
warming with consequences including
climate change and sea levels rising due to
melting ice caps.
• Air pollution from factories as countries
industrialise and exploit resources. The
economic miracle in China is exploiting
resources at a rapid rate and making
Chinese cities, such as Beijing, some of the
most polluted in the world

What is Ecological footprint?
• The maximum number of a species or ”load”
that can be sustainably supported by a given
environment.

Ecological Footprint
• The ecological footprint is a measure of human
demand on the Earth's ecosystems.
• An ecological footprint measures the total amount
of land and resources used.
• It represents the amount of biologically
productive land and sea area necessary to supply
the resources a human population consumes, and
to assimilate associated waste.

Ecological footprint?
• Using this assessment, it is possible to estimate
how much of the Earth it would take to support
humanity if everybody followed a given
lifestyle.
• It is a standardized measure of demand
for natural capital that may be contrasted with
the planet's ecology

2007

Ecological footprints can be
increased by:
1. Greater reliance on fossil fuels
2. Increased use of technology and energy (but
technology can also reduce the footprint)
3. High levels of imported resources (which have
high transport costs)
4. Large per capita production of carbon waste
(high energy use, fossil fuel use)
5. Large per capita consumption of food
6. A meat-rich diet

Ecological footprints can be
reduced by:
1. reducing use of resources
2. recycling resources
3. reusing resources
4. improving efficiency of resource use
5. reducing amount of pollution produced
6. improving country to increase carrying capacity
7. reducing population to reduce resource use
8. using technology to increase carrying capacity
9. using technology to intensify land

3.8.3: Describe and explain the differences between the
ecological footprints of two human populations, one from an
LEDC and one from a MEDC
• LEDCs have small ecological footprints as MEDCs have
much greater rates of resource consumption.
• This is partly because MEDCs have higher incomes and the
demands for energy resources is high.
• MEDCs consume a lot of resources as they are wasteful, they
also have more waste and pollution.
• LEDCs are the opposite with lower consumption as people
do not have too much to spend.
• The economy of the country forces them to recycle many
resources, however they are developing and they’re
ecological footprint is increasing.

• Calculate from appropriate data the
ecological footprint of a given population,
stating the approximations and assumptions
involved.

• The ecological footprint calculation is very
complex, however approximations can be
obtained through the steps outlined in this
figure

• Factors used in a full ecological footprint calculation
would include those in the following list:
• bioproductive (currently used) land: land used for
food and materials such as farmland, gardens,
pasture and managed forest
• bioproductive sea: sea area used for human
consumption
• energy land: an amount of land that is required to
support renewable energy instead of non-renewable
energy.
• built land: land that is used for development such as
roads and buildings
• biodiversity land: land required to support all of the
non-human species

• There are factors ignored when calculating the
ecological footprint which influence the amount of
land a population needs to support itself:
• the land or water required to provide and aquatic
and atmospheric resources
• land or water needed to assimilate wastes other
than carbon dioxide
• land used to produce materials imported into the
country to subsidize arable land and increase yields
• replacement of productive land lost through
urbanization

• Discuss how national and international
development policies and cultural influences
can affect human population dynamics and
growth.

• Many policy factors influence human
population growth.
• Domestic and international development
policies which target the death rate through
agricultural development, improved public
health and sanitation.
• Some analysts believe that birth rates will
come down by themselves as economic
welfare improves and that the population
problem is therefore better solved through
policies to stimulate economic growth.

• Education and birth control encourages family
planning.
• Parents may be dependent on their children for
support when they get older and this may
create an incentive for more children.
• Urbanization may also be a factor in reducing
crude birth rates.
• Policies directed towards the education of
women, enabling women to have greater
personal and economic independence, may be
the most effective method for reducing
population pressure.

• Describe and explain the relationship
between population, resource consumption
and technological development, and their
influence on carrying capacity and material
economic growth.

• Because technology plays such a large role in
human life, many economists argue that human
carrying capacity can be
expanded continuously through technological
innovation.
• For example, if we learn to use energy and material
twice as efficiently,the use of energy
without necessarily increasing the impact imposed
on the environment.
• However, to compensate for foreseeable population
growth and the economic growth that is deemed
necessary, especially in developing countries, it is
suggested that efficiency would have to be raised by
a factor of 4 to 10 to remain within global carrying
capacity.

INTRINSIC VALUE

• Intrinsic values, in relation to ecosystems,
means those aspects of ecosystems and their
constituent parts which have value in their own
right, including:
• (a) Their biological and genetic diversity; and
• (b) The essential characteristics that determine
an ecosystem's integrity, functioning, and
resilience.
What is Intrinsic value?

Intrinsic value?
• Environmentalists argue that every part of
the ecosystem has intrinsic value.
• This means that although living things may have
no monetary value to human beings, they have
significant worth in other ways.

Resources can be valued in several ways:
1.Economic: having marketable goods or
services, e.g. timber and food.
2.Ecological: providing life-support services,
e.g. water storage and gas exchange by plants.
3.Scientific/technological: useful for
applications, e.g. genetic, medicinal use.
4.Intrinsic: having cultural, aesthetic,
spiritual or philosophical values.

DOES ENVIRONMENT HAVE
ITS OWN INTRINSIC VALUE?

Environment have its own Intrinsic value
In the modern world, many governments look
at the economic value of an aspect of the
environment when making policy decisions.
 Those who believe in intrinsic value would
say that though an endangered species or
a rainforest may not provide any use or value
for people, they have inherent worth to live in
this world.

There are then four positions occupied by
those who discuss value in nature.
• Only human beings have intrinsic value
• Only living things have intrinsic value
• Only humans can generate intrinsic values
• Intrinsic values can arise independent of
humans

3.2.6
Sustainable development

What is Sustainable development?
• Sustainable development is development that
meets the needs of the present without
compromising the ability of future generations
to meet their own needs. It contains within it
three key concepts:

• the concept of needs, in particular the essential
needs of the world's poor, to which overriding
priority should be given.
• the idea of limitations imposed by the state of
technology and social organization on the
environment's ability to meet present and
future needs."

• Sustainability is the extent to which a given
interaction with the environment exploits and uses the
NATURAL INCOME without causing long term
deterioration of NATURAL CAPITAL.
• Harvesting renewable or replenishable resources at a
rate that will be replaced by natural growth.
What is Sustainability?

Which one is Sustainable Yield?

Sustainable Yield
• Rate of increase in NATURAL CAPITAL.
• Amount which can be exploited without depleting
the original stock or its potential to be
replenished.
• Exploitation must not affect long term
productivity.

• Living standards that go beyond the basic
minimum are sustainable only if
consumption standards everywhere have
regard for long-term sustainability.
• Meeting essential needs depends in part on
achieving full growth potential, and
sustainable development clearly requires
economic growth in places where such
needs are not being met.

• Sustainable development is a process of
change in which the exploitation of
resources, the direction of investments, the
orientation of technological development;
and institutional change are all in harmony
and enhance both current and future
potential to meet human needs and
aspirations.

Calculation of SY
•Where t= the time of the original natural
capital
•t+1=the time of the original capital plus yield

REDUCE REUSE
RECYCLE

• Declaration of the United
Nations Conference on the
Human Environment

GOAL
• The United Nations Conference on the
Human Environment, having met at
Stockholm from 5 to 16 June 1972,having
considered the need for a common outlook
and for common principles to inspire and
guide the peoples of the world in the
preservation and enhancement of the
human environment,

RIO SUMMIT 1992
• The Stockholm and Rio Declarations are
outputs of the first and second global
environmental conferences, respectively,
namely the United Nations Conference on
the Human Environment in Stockholm, June
5-16, 1972, and the United Nations
Conference on Environment and
Development (UNCED) in Rio de Janeiro,
June 3-14, 1992.

Main Achievements
• The conference led to the Stockholm Declaration
,which played a pivotal role in setting targets and
shaping action at both international & national
level.
• The Earth summit changed attitudes to
sustainability on a global scale,and changed the
way in which people perceived the economic
growth.
• It encouraged people to think of the indirect
values of ecosystems rather than just the purely
economic values

• Soil is a natural body consisting of layers
of mineral constituents of variable thicknesses, which
differ physical, chemical, and
mineralogical characteristics
• Soil is composed of particles of broken rock that have
been altered by chemical and mechanical processes
that include weathering and erosion.
What is SOIL?

Soil formation is a slow process:
1. Weathering of rock
2. Deposition of sediments by erosion
3. Decomposition of organic matter in
dead organisms

Weathering of rock

Deposition of sediments by erosion

Decomposition of organic matter in dead organisms

These top two layers are most fertile, have the highest
concentration of organic matter, and contain large amounts of
living organisms.
Flatworm
Rove beetle
Ant
Centipede
Mite
Pseudoscorpion
Ground
beetle
Adult
fly
Millipede
Fly
larvae
Sowbug
Mite
Earthworm
Slug
Snail
Roundworms
Protozoa
Bacteria
Organic debris
Beetle Mite
Fungi
Springtail
Actinomycetes

• Soil has four basic constituents
1. Organic matter: living plants and
animals and their dead remains and
wastes
2. Mineral matter: mainly sand, silt and
clay
3. Water
4. Air

Soil Content
• Clay (very fine particles)
• Silt (fine particles)
• Sand
• Gravel (coarse to very coarse particles)
.

Silt (fine particles) Clay (very fine particles)

Sand (medium-size particles)

Gravel (coarse to very coarse particles)

Properties of Soils with Different Textures
Texture Nutrient
Capacity
Infiltration Water-
Holding
Capacity
Aeration Workability
Clay Good Poor Good Poor Poor
Silt Medium Medium Medium Medium Medium
Sand Poor Good Poor Good Good
Loam Medium Medium Medium Medium medium

Soil Horizons

Typical Horizons
• Surface litter = O horizon
– Fresh and partly
decomposed organics
• Topsoil layer = A horizon
– Humus mixed with
inorganics
– Most life in O & A
• Subsoil = B horizon
– Broken down Inorganics
• Parent material (bedrock)
= C horizon

Flatworm
Rove beetle
Ant
Centipede
Mite
Pseudoscorpion
Ground
beetle
Adult
fly
Millipede
Fly
larvae
Sowbug
Mite
Earthworm
Slug
Snail
Roundworms
Protozoa
Bacteria
Organic debris
Beetle
Mite
Fungi
Springtail
Actinomycetes
O & A horizon inhabitants

Living layers
• Organisms in the A & O layers are those that
break down the organics to form the soil
• A & O are where plant roots are, abosorbing
water and nutrients
• Humus = partly decomposed organics 
fertile and good for plant production
• Topsoil color indicates condition
– Dark brown good lots of nitrogen and organics
– Grey, yellow and red soils low in nutrients

SOIL PROFILE
• Soil Profile refers to the layers of soil;
• Horizon A, B, and C.
• Horizon A refers to the upper layer of soil,
nearest the surface. It is commonly known as
topsoil.
• Horizon A provides plants with nutrients they
need for a great life

• The subsoil is the horizon B
• This is where materials accumulates from
horizons above & below

• Horizon C consists mostly of weatherized big
rocks.
• This contains many loose pieces of rock,
broken off from the parent rock below
weathering

“B” (subsoil) and “C” (parent material)
HORIZON contain most of the soil’s
inorganic matter, broken-down rock.

Soil Minerals

• Soil minerals play a vital role in soil fertility
since mineral surfaces serve as potential sites
for nutrient storage.
• There are numerous types of minerals found in
the soil.
• These minerals vary greatly in size and
chemical composition.

Soil texture
• Soil texture is a qualitative classification tool
used in both the field and laboratory to
determine classes for agricultural soils based
on their physical texture.

What is Water Retention
• Soils can process and contain considerable
amounts of water.
• They can take in water, and will keep doing so
until they are full,
or
• the rate at which they can transmit water into,
and through, the pores is exceeded.
• Some of this water will steadily drain through the
soil and end up in the waterways and streams.
• But much of it will be retained, away from the
influence of gravity, for use of plants and other
organisms to contribute to land productivity and
soil health.

SOIL PERMEABILITY is the rate at which water and
air move from upper to lower soil layers.
Water Water
High permeability Low permeability

Soil Texture
• Soil Porosity: measure of the volume of
space in a volume of soil
• Fine particles = water retention
• Coarse particles = air retention
• More porous  more water and air
• Size of spaces in soil determines soil
permeability rate at which water and air
move from upper to lower soil levels

Texture continued
• Soil structure: the organization and
clumping of soil
• Loams are best for growing crops, hold
water but not too tightly that plants can’t
absorb it.
• Clay less porous, less permeable  lead to
water logged crops above

100%clay
Increasing
percentage silt
Increasing
percentage clay
0
20
40
60
80
80
60
40
20
0
100%sand 80 60 40 20 100%silt
Increasing percentage sand
sandy
clay
clay
silty
clay
silty clay
loam
clay
loam
loam silty
loam
silt
sandy clay
loam
sandy
loam
loamy
sandsand

Nitrogen fixing
by lightning
Commercial
inorganic
fertilizer
10-6-4
N-P-K
Organic fertilizers,
animal manure,
green manure, compost
Crop
plant
Dead
organic matter
Application
to land
Nitrogen fixing
by bacteria
Nitrogen fixing
Weathering
of rock
Nutrient removal
with harvest
Decomposition
Supply of
available plant
nutrients in soil
Nutrient loss
by bacterial
processes
such as
conversion
of nitrates to
nitrogen gas
Nutrient loss
from soil erosion
Absorption of nutrients
by roots
Pathway of
plant
nutrients in
soil.

Desertification is the enlargement of
deserts through human activities.
ConsequencesCauses
Worsening drought
Famine
Economic losses
Lower living
standards
Environmental
refugees
Overgrazing
Deforestation
Surface mining
Erosion
Salinization
Soil compaction

3.4.3
Soil Degradation

What is Soil Degradation?
• Soil degradation is the decline in quantity and
quality of soil.
• It includes erosion by wind and water,
biological degradation(e.g. the loss of humans
and plant or animal life)
• Physical degradation(loss of structure, changes
in permeability)
• Chemical degradatrion(acidification,declining
fertility,changes in ph & salinity)

What is Leaching?
• Leaching refers to the loss of water-
soluble plant nutrients from the soil,
due to rain and irrigation.

Soil gets degraded by human activities
1. Overgrazing – plants exposed to intensive grazing over
long periods of time or without sufficient recovery period
2. Deforestation - Removal of large sections of forest habitat
3. Unsustainable agriculture – Monoculture using high
chemical & fertilizer input and fossil fuels
4. Improper irrigation
5. Other factors- Lead to degradation by erosion,
toxification, salinization, desertification

Overgrazing Impacts
• Reduces Biodiversity
• Causes Desertification and Erosion
• Increases Erosion by loss of cover species
and loss of roots that held the soil in place
• Erosion leads to loss of organics and drop in
productivity

DO NOT POST TO INTERNET

DO NOT POST PHOTOS TO INTERNET

First year Second year Third year Fourth year Fifth year Sixth year
Pasture A
Pasture B
Pasture C
Deferred Grazed
last
Grazed
second
Grazed
first
Grazed
first
Grazed
second
Grazed
first
Grazed
second
Deferred Grazed
last
Grazed
second
Grazed
first
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second
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second
Deferred Grazed
last

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sending to me.

Types of Soil Degradation
• There are three main types of soil degradation:
1. Soil erosion,
2. Desertification, and
3. Salinization.

What is Soil erosion?
• Soil is naturally removed by the action of
water or wind
• Soil erosion is when the soil is blown away by
the wind or washed away by the rain.

Causes of soil erosion
• Water can cause soil erosion. Rainfall is an example of
water causing soil erosion.
• The lack of permanent vegetation cover in certain
locations can cause soil erosion due to the wind.
• Human activities such as farming, logging, and
constructions also cause soil erosion.
Consequences of soil erosion
• Soil erosion can lead to poor crop growth and yield
reductions in areas of fields.
• Loss of soil fertility through depletion of plant nutrients
in top soil.
• Soil quality, structure, stability and texture can be
affected by the loss of soil.
1.Soil Erosion

What is called this type of land?

• Desertification is the development of desert-like
conditions in regions that have experienced
human disturbance such as deforestation,
overgrazing, or poorly managed agriculture.
What is Soil Desertification?

Causes of desertification
• Natural climate change that causes prolonged
drought.
• Human activities that reduce or degrade top soil.
• Increased population and livestock pressure on
marginal lands accelerates desertification.
• Deforestation
Consequences of desertification
• Economic loses
• Lower living standards
• Major threat to biodiversity
• Prolonged droughts
2.Desertification

Lake Chad in a 2001 satellite image, with the actual lake in blue.
The lake has shrunk by 95% since the 1960s

Causes of Salinization
• High level of salt in the soils
• Over cultivation
• Irrigation mismanagement
• Climate trends that favor accumulation
Consequences of Salinization
• Stunts crop growth
• Lowers crop yields
• Destroys fertility and plants
• Damage to infrastructure (i.e. roads, bricks etc.)
• Reduction of water quality
3.Salinization

Salinization can result
• Irrigation increases productivity BUT
Irrigation water contains salts
• Evaporation leaves crust of salts on surface
• Accumulation of salts = salinization
– Stunts crop growth
– Lowers crop yields
– Kills plants and ruins land
• Reduced crop yield by 21% on irrigated land

Severe Salinization

Water logging
• Attempt to solve salinization
• Apply large amounts of water to leach salt
deeper into soil
• Water accumulates underground then raises
water table
• Saline water envelopes roots lowering
productivity  death
• 10% irrigated land is waterlogged

Evaporation
Evaporation
Transpiration
Evaporation
Waterlogging
Less permeable
clay layer

Prevention Cleanup
Reduce irrigation
Switch to salt-
tolerant crops
(such as barley,
cotton, sugar beet)
Flushing soil
(expensive and
wastes water)
Not growing crops
for 2-5 years
Installing under-
ground drainage
systems (expensive)
Solving the Salty Problem

Soil Conservation involves reducing
soil erosion and restoring soil fertility.

Tillage

Unsustainable Agriculture
• 1.Characteristics of Modern Agriculture
– High water input
– High pesticide use
– High inorganic fertilizer use
• 2.Traditional agriculture where soil is tilled at the end of a
growing season
• 3.Idea good in practice – add nutrients to the soil – but bare
soil exposed to erosion
• 4.Tillage also deteriorates soil structure
• 5.Can cause increased erosion, toxification and salinization

Unsustainable Agriculture Impacts
• Toxification of soil
– When non biodegradable pesticides and
inorganic fertilizers build up in the soil they
make it toxic
– Kills useful bacteria (N fixing) fungi, and
decreases productivity
• Soil erosion rates increase

Biodiversity Loss
Loss and degradation of habitat from
clearing grasslands and forests and
draining wetland
Fish kills from pesticide runoff
Killing of wild predators to protect
livestock
Loss of genetic diversity from
replacing thousands of wild crop
strains with a few monoculture strains
Soil
Erosion
Loss of fertility
Salinization
Waterlogging
Desertification

Air Pollution
Greenhouse gas emissions from fossil
Fuel issue
Other air pollutants from fossil fuel use
Pollution from pesticide sprays
Water
Aquifer depletion
Increased runoff and
flooding from land cleared
to grow crops
Sediment pollution from
erosion
Fish kills from pesticide
runoff
Surface and groundwater
pollution from pesticides
and fertilizers
Overfertilization of lakes
and slow-moving rivers
from runoff of nitrates and
phosphates from
fertilizers, livestock
wastes, and food
processing wastes

Human Health
Nitrates in drinking water
Pesticide residues in drinking water,
food, and air
Contamination of drinking and
swimming water with disease organisms
from livestock wastes
Bacterial contamination of meat

Improper irrigation
• Often results from unsustainable agriculture
in areas that are too arid
• Remember that water includes more than
just H2O
– Improper drainage or high evaporation leads to
salt deposition  crop damage, reduction of
productivity
– Unirrigated or underirrigated land can lead to
build up of toxic agricultural waste products

Unsustainable irrigation

Soil Restoration
• Organic fertilizer
• Manure
• Compost crop rotation
• No till farming
• Contour farming
• Terracing
• Nitrogen fixation-legumes

3.4.4
SOIL
CONSERVVATION

1.PLANTING TREES
• Roots of trees firmly hold on to the soil. As
trees grow tall, they also keep rooting deeper
into the soil.
• As the roots of trees spread deep into the
layers of soil, they hold it tightly, thus
preventing soil erosion.

2. No-till Farming
• Conventional Tillage Farming is bad To plow
land in the fall, bare & erodable all winter
• Conservation Tillage Farming disturb the
soil as little as possible while planting crops

3.Crop Rotation
• Some pathogens tend to build up in soil if the
same crops are cultivated again and again.
• To save the soil from these adverse effects,
crop rotation is practiced.
• It is a method of growing a series of dissimilar
crops in an area. Crop rotation also helps in
the improvement of soil structure and fertility.

• A terrace is a leveled section of a hilly
cultivated area.
• Owing to its unique structure, it prevents rapid
surface runoff of water.
• Terracing gives the landmass a stepped
appearance, thus slowing the washing down of
soil.
4. Build Terraces

5. Water the Soil
• Watering soil is a good measure of soil
conservation.
• Watering the soil along with plants growing in
it is a way to prevent soil erosion caused by
wind.

6. Salinity Management
• The salinity of soil increases due to excessive
accumulation of salts in the soil.
• The salinity of soil is detrimental to the
vegetative life in it.
• The death of vegetation leads to soil erosion.
Hence, salinity management is an indirect way
of conserving soil.

• 3.4.5 - Evaluate soil management strategies
in a named commercial farming system and
in a named subsistence farming system.

• What is Commercial Agriculture?
• (i) Farming practice in which goods
produced are mainly for the market to get
cash.
• (ii) Farms are larger and cash crops are
cultivated. Such as cotton, sugar-cane, jute.
• (iii) Better implements are used and there
are proper irrigation facilities.
• (iv) Less of manpower is used.

• The North American Prairies and commercial
farming
The problems occurred were increasing salinity, soil
erosion and loss of soil fertility.
• Farmers managed to reduce salinity and erosion, to
reduce salinity summer fallowing or leaving bare
soil for long periods were stopped or reduced.
•
And to reduce erosion is used Contour ploughing-
along the contour lines instead of up and down
slopes traps soil and water. Strip Cropping – growing
as flax and tall wheatgrass at right angles to the
wind.

What is Subsistence Agriculture?
• (i) Farming practices in which crops are
cultivated for local consumption.
• (ii) Farms are small and food crops are
cultivated such as rice and wheat.
• (iii) Old tools and implements are used by the
farmers.
• (iv) Depends on monsoon and there is greater
use of manpower.

Subsistence agriculture
• Subsistence agriculture is self-
sufficiency farming in which the farmers focus
on growing enough food to feed themselves
and their families. The typical subsistence
farm has a range of crops and animals needed
by the family to feed and clothe themselves
during the year. Planting decisions are made
principally with an eye toward what the family
will need during the coming year, and
secondarily toward market prices.

• Subsistence farming continues today in large
parts of rural Africa,[3] and parts of Asia and
Latin America.

Solutions: Soil Conservation
• Goal: Reduce soil erosion, restore fertility
• Conventional Tillage Farming is bad  plow land
in the fall, bare & erodable all winter
• Conservation Tillage Farming disturb the soil as
little as possible while planting crops
• Minimum tillage or No till farming
• Using conservation tillage on 80% of farmland
would reduce soil erosion by 50%

Advantages Disadvantages
Reduces erosion
Saves fuel
Cuts costs
Holds more soil water
Reduces soil compaction
Allows several crops
per season
Does not reduce crop
yields
Can increase herbicide
use for some crops
Leaves stalks that can
harbor crop pests and
fungal diseases and
increase pesticide use
Requires investment
in expensive equipment
Conservation Tillage Facts

Cultivation Techniques
• 1. Terracing
– Convert steep slopes into a series of broad, nearly level
terraces running across the land contour
– Retains water for crops controls runoff
– Marginal areas, Poor farmers, little time / manpower
• 2. Contour Plowing
– Plowing and planting crops in rows across the contour of
gently sloping land
– Each row holds soil and slows runoff

Terracing Contour planting and strip cropping

Reducing Wind Erosion
1. Strip cropping
- planting alternative strips of (1) row crop
like corn and (2) another crop like grass or
legumes that completely covers the soil
- Cover strips (1) trap soil that erodes from
row crop (2) catch & reduce runoff, (3)help
prevent spread of pests, (4) restore soil
fertility

Strip Cropping

Alley cropping
Windbreaks

Reducing Wind Erosion
2. Alley Cropping
-Crops planted in strips or alleys
between rows of trees and
shrubs which themselves are
harvestable for wood or fruit
-Trees & shrubs provide
1. Shade, reducing evaporation
water loss
2. Retain and slowly release
soil moisture
3. Provide fruit, fuelwood,
clippings for mulch (green
manure)
4. Livestock fodder
3. Shelter Belts / Wind breaks
Reduce wind effects
1. Less erosion
2. Retain soil moisture
3. Supply products
4. Habitat for animals
including birds and insects
that eat pests

Can we Maintain & Restore soil Fertility?
Soil Conditioners
• Fertilizers: compounds that partially restore
important soil nutrients lost by erosion,
leaching and harvesting crops
• Condition soils with
– Organic Fertilizers: made of plant and animal
materials that are biodegradable
– Lime: Increase alkalinity of the soil  improves
fertility

Organic Fertilizer Benefits
• Organic Fertilizers
1. Animal Manure: improves soil
structure, nutrients,
stimulates bacteria & fungus
growth
2. Green Manure: Vegetation
plowed into the soil increases
organic content
3. Compost: Brown humus
material, aerates soil,
improves water holding,
prevents erosion, recycles
nutrients
4. Fungus spores: moisture
control, disease resistance
• Inorganic Fertilizers
1. Nitrogen, Phosphorous,
Potassium
2. Easily available, transported,
stored and supplied
3. Help Produce crops in 3rd
world
BUT
1. Not adding humus or other
essential nutrients
2. Lower oxygen, organic matter
in soil
3. Raise N2O in atmosphere
(greenhouse gas)

Soil Management Strategies
• Differ depending on the agricultural system
you are observing
• Comparison of Florida sugar cane farming
(commercial farming) and slash and burn
(subsistence farming)

Florida sugar Cane
• Soils of everglades Agricultural area are rich in organics
formed from 4,400 years of sawgrass decomposition
• Soils are “muck soils” and must be drained for crop growth
• Even with high organic matter need inputs to keep soil fertile
– N, P, K all added on the order of 0-30 lbs per acre each year
depending on specific area differences
• Soil subsidence happening because of uptake of organics
• Water is seasonally available so may need suplementation

Big Sugar and Florida
An Uncertain Future

Slash and Burn Agriculture
• Mainly associated with Tropical Rainforest areas
• Madascar, Malasia, Central America
• Usually small scale subsistence
• Practiced in areas with poor soils
• Harvest wood, burn unusable portions
• Temporary pulse of nutrients from burning
• Ash also increases pH of soil
• Burning can drive off pests too

Slash and Burn II
• Land only fertile
for a few years
• Abandoned when
fertility declines
• Forces burning of
more land

What is Carrying Capacity ?
• Carrying Capacity is the maximum number of
a species or load that can be sustainably
supported by a given environment i.e without
destroying the stock
• Population remain stable when the death rate
and the birth rate are equal and so there is no
net gain or reduction in population size

IB ESS Topic 3 Human population

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