Transcript Issues involved in the intensification and Extension of agriculture

Agricultural Systems and Food
Production
Issues involved in attempts to intensify production
e.g.
– replace slash and burn in Indonesia
– the Green Revolution
– small-scale self-help schemes
Issues involved in extending cultivation in LEDCs
e.g.
– irrigating oases
– draining swamplands
– fish farming
Issues involved in the intensification
and extension of agriculture
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Increases in agricultural production can
be achieved in two ways, by:
◦ increasing the land under cultivation through,
for example, irrigation, or extending farming
onto marginal land, or
◦ increasing the yield per hectare when
scientific advance allows such changes to
occur.
Issues involved in the intensification
and extension of agriculture
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Since the end of World War 2, there have
been huge advances in agricultural
production.
This was mainly due to:
◦ Increases in the use of mechanisation,
◦ Increased use of agro-chemicals - fertilisers,
pesticides and herbicides,
◦ Greater and more effective use of irrigation
methods, and
◦ The introduction of high-yielding varieties of
seeds (HYVs).
Issues involved in the intensification
and extension of agriculture
The result has been a substantial increase in
global food production over the last 60 years.
 However, intensification can alter ecosystems to
such an extent that serious local, regional and
global consequences result:

◦ local – increased soil erosion, lower soil fertility,
reduced biodiversity (removal of hedgerows and
monoculture)
◦ regional – pollution of groundwater, eutrophication
of rivers and lakes
◦ global – impacts on global atmospheric conditions
(climate change)
Soil Degradation
ISSUES INVOLVED IN THE
INTENSIFICATION AND
EXTENSION OF
AGRICULTURE
Soil Degradation
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Land degradation is the
temporary
or
permanent
lowering of the productive
capacity of land.
It thus covers the various forms
of soil degradation, adverse
human impacts on water
resources, deforestation, and
lowering of the productive
capacity of rangelands.
Soil degradation is a global
process.
It involves both the physical loss
(erosion) and the reduction in
quality of topsoil associated with
nutrient
decline
and
contamination.
It has a significant impact on
agriculture
and
also
has
implications for the urban
environment,
pollution
and
flooding.
The loss of the upper soil
horizons
containing
organic
matter and nutrients as well as
the thinning of soil profiles
reduces crop yields on degraded
soils.
 Soil degradation can cancel out
gains from improved crop yields.
 Degradation of soil and land in
already marginally productive
land is a significant issue for many
LICs, particularly in northern
Africa, the Sahara region and
parts of Asia, including China.
Many of these regions have
fragile ecosystems where any
human interventions can lead to
serious degradation.
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Effects of Land Degradation
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Land degradation has both on-site and offsite effects:
◦ On-site effects are the lowering of the productive
capacity of the land, causing either reduced
outputs (crop yields, livestock yields) or the need
for increased inputs.
◦ Off-site effects of water erosion occur through
changes in the water regime, including decline in
river water quality, and sedimentation of river
beds and reservoirs. The main off-site effect of
wind erosion is over-blowing, or sand deposition.
Types of Soil Degradation

This includes:
◦ soil erosion by water and wind,
◦ deterioration in soil physical, chemical and
biological properties,
◦ waterlogging, and
◦ the build-up of toxicities, particularly salts, in
the soil.
◦ Since soil productivity is intimately connected
with water availability, lowering of the
groundwater table is also noted.
Definitions
Desertification is land degradation in arid, semi-arid and
dry sub-humid areas resulting from adverse human impact.
 Water erosion covers all forms of soil erosion by water,
including sheet and rill erosion and gullying.
 Wind erosion refers to loss of soil by wind, occurring
primarily in dry regions.
 Waterlogging is the lowering in land productivity through
the rise in groundwater close to the soil surface. Also
included under this heading is the severe form, termed
ponding, where the water table rises above the surface.
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◦ Waterlogging is linked with salinisation, both being brought
about by incorrect irrigation management.
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Lowering of the water table is brought about through
tubewell pumping of groundwater for irrigation exceeding
the natural recharge capacity.
◦ This occurs in areas of non-saline ('sweet') groundwater.
Definitions
Soil fertility decline is used as short term to refer to what
is more precisely described as deterioration in soil physical,
chemical and biological properties.
 Whilst decline in fertility is indeed a major effect of erosion,
the term is used here of cover effects of processes other
than erosion.
 The main processes involved are:
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◦ lowering of soil organic master, with associated decline in soil
biological activity;
◦ degradation of soil physical properties (structure, aeration, water
holding capacity), as brought about by reduced organic master;
◦ adverse changes in soil nutrient resources, including reduction in
availability of the major nutrients (nitrogen, phosphorus,
potassium), onset of micronutrient deficiencies, and development
of nutrient imbalances.
◦ buildup of toxicities, primarily acidification through incorrect
fertilizer use.
Statistics on Soil Degradation
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Globally, it is estimated
that 2 billion hectares of
soil resources have been
degraded.
This
is
equivalent to about 15%
of the Earth’s land area.
Such a scale of soil
degradation has resulted
in the loss of 15% of
world agricultural supply
in the last 50 years.
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For three centuries
ending in 2000, topsoil
had been lost at the rate
of 300 million tonnes a
year.
Between 1950 and 2000,
topsoil was lost at the
much higher rate of 760
million tonnes a year.
During the last 40 years,
nearly one-third of the
world’s cropland has
been abandoned because
of soil erosion and
degradation.
Statistics on Soil Degradation
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In Sub-Saharan Africa,
nearly 2.6 million km² of
cropland has shown a
‘consistent
significant
decline’ according to a
March 2008 report by a
consortium of agricultural
institutions.
◦ Some scientists consider this
to be a ‘slow-motion
disaster’.
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In the UK, 2.2 million
tonnes of topsoil is eroded
annually and over 17% of
arable land shows signs of
erosion.
It takes natural processes
about 500 years to replace
25 mm of topsoil lost to
erosion.
 The minimum soil depth
for agricultural production
is 150 mm.
 From
this perspective,
therefore,
productive
fertile
soil
can
be
considered
a
nonrenewable,
endangered
ecosystem.
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GLOBAL ASSESSMENT OF HUMAN-INDUCED SOIL
DEGRADATION (GLASOD)
The Global Assessment of
Human-induced
Soil
Degradation (GLASOD) is
the only global survey of soil
degradation to have been
undertaken.
 The generalised map of the
findings of this survey shows
that substantial parts of all
continents have been affected
by various types of soil
degradation.
 The GLASOD calculation is
that damage has occurred on
15% of the world’s total land
area – 13% light and
moderate, with 2% severe and
very severe
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Degradation results from erosion, nutrient decline, salinization and physical
compaction. These frequently lead to reductions in yields. Land conservation and
rehabilitation are essential parts of sustainable agricultural development.
While severely degraded soil is found in most regions of the world, the negative
economic impact of degraded soil may be most severe in the countries most
dependent on agriculture for their incomes.
Causes of Soil Degradation
A major cause of soil degradation is heavy fertiliser use
Research has shown that the heavy and sustained use of artificial fertiliser can
result in serious soil degradation.
In this profile of an artificially fertilised soil, the
ability of the soil to infiltrate water has been
compromised by the breakdown of soil aggregates
to fine particles that have sealed the surface.
Pore spaces have been filled up by the fine soil
material from the broken crumbs. This can result in
ponding in surface depressions, followed by soil
erosion.
This profile shows a much healthier soil
treated with organic fertiliser.
Effects of Soil Degradation
A major effect of soil degradation is
climate change.
The International Forum of Soils, Society and Global Change
in September 2007 referred to ‘the massive degradation of
land and soil around the world which is contributing to
climate change and threatening food security’.
 The Forum noted that:
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◦ At least a quarter of the excess carbon dioxide in the
atmosphere has come from changes in land use, such as
deforestation, in the last century.
◦ Without the cover of vegetation, land becomes more reflective.
 It also loses fertility and the capacity to support vegetation and
agricultural crops.
◦ The Intergovernmental Panel on Climate Change should develop
a special report on the link between land degradation and
climate change. By addressing soils and protecting the land cover
and vegetation, it is possible to obtain high value in terms of
mitigating climate change.
◦ A better understanding of the capacity for carbon sequestration
in soil is needed.
Increased Greenhouse Gas Emissions
ISSUES INVOLVED IN THE
INTENSIFICATION AND
EXTENSION OF
AGRICULTURE
Increased Greenhouse Gas
Emissions
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It has been estimated that food
production and consumption accounts for
up to twice as many greenhouse
emissions as driving vehicles. The graph on
the following slide shows US data
published in the New Scientist:
◦ The average US household’s footprint for
food consumption is 8.1 tonnes of carbon
dioxide equivalent, compared with 4.4 tonnes
from driving.
A comparison of
greenhouse gas
emissions from food
and vehicle use in the
USA
Household greenhouse
gas emissions from
food
account
for
almost twice those
produced by vehicle
use.
Most of this comes
from
the
food
production
process
itself, rather than from
food miles, as is often
believed.
Loss of Biodiversity
ISSUES INVOLVED IN THE
INTENSIFICATION AND
EXTENSION OF
AGRICULTURE
Loss of Biodiversity
Mechanisation has resulted in farmers in the
UK having a strong incentive to remove
centuries-old hedgerows.
 By 1990 over half of UK hedgerows had
been removed and with them the habitats
and biodiversity that contributed to the
make-up of the traditional countryside.
 Agro-industrialisation led to the increased
use of monoculture.
 This also contributed to hedgerow removal
as well as the loss of biodiversity, increased
pests and habitat loss.
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Deforestation and Soil Erosion
ISSUES INVOLVED IN THE
INTENSIFICATION AND
EXTENSION OF
AGRICULTURE
Deforestation and Soil Erosion
This is a major cause of land degradation,
especially soil erosion, as well as climate change.
 Soil erosion usually occurs as a result of the
removal of the protective vegetation cover.
 In tropical forest areas removal (extension of
agriculture in LEDCs) can exacerbate erosion when
the surface is exposed to torrential tropical rain.
 In marginal areas (intensification of agriculture)
overgrazing can result in the scant vegetation
being stripped off, followed by the soil drying out
and being removed by wind erosion and surface
runoff.
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Deforestation and Soil Erosion
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Friable soil types are likely to be more at
risk.
◦ For example, in China, the loess soils in the
Yellow River Basin are lost at the rate of 100
tonnes per hectare per year.
◦ Soil erosion is a major problem in China. The
Yangtze River Basin loses 2.24 billion tonnes of
soil per year, which damages 67,000 ha of
farmland. The effects of soil erosion mean that
almost 100 million will lose the land they live on
within 35 years if erosion continues at the
current rate.
Salinisation
ISSUES INVOLVED IN THE
INTENSIFICATION AND
EXTENSION OF
AGRICULTURE
Salinisation - Definition
This refers to all types of soil degradation
brought about by the increase of salts in the soil.
 This covers both salinisation in its strict sense,
the buildup of free salts; and codification (also
called alkalization), the development of
dominance of the exchange complex by sodium.
 As human-induced processes, these occur mainly
through incorrect planning and management of
irrigation schemes.
 Also covered is saline intrusion, the incursion of
sea water into coastal soils arising from overabstraction of groundwater.
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Salinisation - Causes
This is a serious problem in arid and semi-arid
areas and affects 7% of the world’s land area.
 It occurs when transpiration from plants and
evaporation exceed the amount of incoming
precipitation in regions where the water-table is
close to the surface.
 The presence of salts is harmful to many plants
and, although the cause is natural, it can be made
worse by man’s intensification of agriculture –
irrigation without proper drainage can raise the
water table locally and by capillary action salty
water is drawn to the surface.
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Salinisation - Effects
Salinisation is a problem in dry areas like
South Australia with 3700km² affected.
 This is expected to increase by 60% by
2050 at currents rates.
 It is expected to cost the state around
US$37.3 million per year in lost
agricultural profit, and is expected to taint
more than 20% of groundwater to levels
above those safe for human consumption.
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Desertification
ISSUES INVOLVED IN THE
INTENSIFICATION AND
EXTENSION OF
AGRICULTURE
Desertification - Causes
Desertification is land degradation in arid,
semi-arid and sub-humid areas.
 It refers to the effects human activity and
climatic processes may have on a
landscape reducing it to desert-like
conditions.
 This often results from overgrazing of
semi-arid pastures (intensification) and its
results are often irreversible.
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Desertification - Effects
The process takes place in drylands and
some 15% of these (about 9 million km²)
may already be degraded.
 Over 250 million people in more than
100 countries are directly affected and
are more at risk.
 In Africa 66% of the total land area is
classified as arid
or semi arid and
therefore, at risk.
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The Green Revolution
ISSUES INVOLVED IN THE
INTENSIFICATION AND
EXTENSION OF
AGRICULTURE
What was the Green Revolution?
This refers to a series of research and development
and technology transfer initiatives occurring
between the 1940s and 1960s that increased
agricultural production, especially in the developing
world.
 Much of the global increase in food production in the
last 50 years can be attributed to the Green
Revolution, which took agro-industrialisation to LICs
on a large scale.
 The process involved:
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the development of high-yielding varieties of cereal grains,
supported by an expansion of irrigation infrastructure,
modernisation of management techniques, and
the distribution of hybridised seeds, synthetic fertilisers
and pesticides to farmers.
History of the Green Revolution
It was first trialled in Mexico and in 1961,
with India on the brink of famine, the
International Rice Research Institute
(IRRI) selected the Punjab region for trials
of a new variety of rice called IR8.
 This HYV produced more grains of rice
per plant when grown with certain
fertilisers and irrigation.
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◦ 5 tonnes per ha without fertiliser and 10
tonnes under optimal conditions.
Positive Effects of the Green
Revolution
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In the 1960s rice yields in India were about 2 tonnes per ha.
By the mid-1990s they had risen to 6 tonnes per ha.
India became one of the world’s most successful rice
producers and a major rice exporter, shipping nearly 5.4
million tonnes in 2013.
Today, India is the world’s largest exporter of rice – shipping
10.23 million tonnes in 2015, 30% of the world’s total.
In terms of production, the Green Revolution was a turning
point for Indian agriculture, which had virtually reached
stagnation.
The high-yielding variety seed programme (HVP) introduced
new hybrid varieties of five cereals: wheat, rice, maize,
sorghum and millet.
◦ All were drought-resistant with the exception of rice,
◦ were very responsive to the application of fertilisers and
◦ had a shorter growing season than the traditional varieties they
replaced.
Negative Effects of the Green
Revolution
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Serious criticisms have been made, many linked to
the impact on the environment:
◦ High inputs of fertiliser and pesticide have been
required to optimise production – this is costly in
both economic and environmental terms.
◦ The problems of salinisation and waterlogged soils
have increased, along with the expansion of the
irrigated area, leading to the abandonment of
significant areas of land.
◦ High chemical inputs have had a considerable negative
effect on biodiversity.
◦ People have suffered ill-health due to contaminated
water and other forms of agricultural pollution.
Negative Effects of the Green
Revolution
Areas like Punjab are now witnessing the serious health
consequences of intensive farming using chemicals and
pesticides.
 A study has underlined that there is a direct relationship
between the indiscriminate use of agro-chemicals and
increased incidence of cancer in this region.
 In 2009, a study indicated that 50 Punjabi villages had
widespread incidences of chemical, radiation and biological
toxicity.
 An environmental activist, Vandana Shiva has written about
these impacts in Punjab, claiming that the heavy use of and
reliance on agro-chemical inputs and monocultures has also
resulted in:
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◦ water scarcity
◦ vulnerability to pests,
◦ incidents of violent conflict and social marginalisation.
Negative Effects of the Green
Revolution
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There have also
environmental issues:
been
numerous
◦ In India’s Punjab, yield growth has flattened
since the mid-1990s.
◦ Over-irrigation has resulted in a steep fall in
the water table, now tapped by 1.3 million
tube wells.
◦ Since the beginning of the Green Revolution
in Asia, the amount of land under irrigation
has tripled.
Negative Effects of the Green
Revolution
In the early 1990s, nutritionists noticed that even
in countries where average food intake had risen,
incapacitating diseases associated with mineral
and vitamin deficiencies remained commonplace
and in some instances had actually increased.
 The problem is that the HYVs introduced during
the Green Revolution are usually low in minerals
and vitamins.
 Because the monocultures of new crops have
displaced the local fruits, vegetables and legumes
that traditionally supplied important vitamins and
minerals, the diet of many people in LICs is now
extremely low in zinc, iron, vitamin A and some
other micronutrients.
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Evaluation
The Green Revolution has been a major
factor in enabling global food supply to
keep pace with population growth (as per
Esther Boserup).
 However, with growing concerns about a
new food crisis, new technological
advances may well be required to improve
the global food-security situation.
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