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PART
Ι:
AGRICULTURE AND THE ENVIRONMENT
A.
The Development of Agriculture
1
Historical Overview
Early people depended for their survival on hunting, fishing and
food gathering. It is thought that the first modification of
the environment started with human-managed fire and was further
intensified with the transition from hunter-gatherer to farmer and
stockbreeder. After that various groups of people passed from
the stage of living as nomads to the stage of living in stake farm
communities, some which grew to the town and city states. By
the deliberate cultivation of wild plants and domestication of wild
animals, human societies transformed the “natural” ecosystems into
rural ecosystems. In these types of ecosystems, humans
establish and favor the development of desired plant varieties and
spread the breeding of certain animal species, thus transforming the
composition of flora and fauna in the areas where agriculture is
practiced (Giourga,
1990).
With the passing of time and under the demographic pressure, a
growing number of inventions and technological innovations led to
the development of agriculture and contributed to the creation of a
framework within which the so called industrial revolution took
place. Then came the vast outflow of the rural population
towards the towns in the
19th
and 20th
centuries and the transformation of consumer habits (Fowerland &
Mooney, 1990).
Whilst population was growing and technology was progressing, vast
areas of bush and forest were turned into cultivated land, with the
purpose of expanding production and satisfying the constantly
increasing nutritional needs of an ever increasing population.
Large tracks of land were changing form. However, at the same
time there were early signs of adverse consiequences resulting from
the practice of agricultural activities. Regions where high
cultures were flourishing were being turned into deserts and
historical evidence indicates that those early cultures destroyed
their environment. Around the Mediterranean basin and in parts
of
Asia, agriculture transformed rich land into exhausted and dry,
rocky ground.
Human impact on ecosystems continue to occur. The movement of
population leads to the transformation and development of animal
species away from their origins. The peak in the expansion of
plant species occurs with the expansion of Europeans worldwide
during the
16th
century. Among vegetative species we see mainly promoted ones
which production better serves basic nutritional needs, and which
easy storage facilitates commerce. These species finally set
the basis for the creation of what was later called “plantation
economy” (Croal, 1981).
From the
18th
century onwards human relation with nature changes, radically
following the industrial revolution. The development of
industry and colonialism, commerce and means of transportation
resulted in profound changes in the way agriculture as practiced.
A way of life was transferred into a commercial act and later into a
business act with the ultimate aim of feeding the ever-increasing
urban population. Finally, the development of industry allows
the mechanization and the modernization of agriculture, thus setting
strict new rhythms for the production and exploitation of land,
resulting in the appearance of adverse effects on the environment.
2.
The Intensification of Agriculture
The modernization of agriculture after the Second World War, the so
called “Green Revolution” was based (technologically) on the
production of improved corn hybrids and short-stemmed varieties of
rice and wheat that resulted in high performances which combined
with improved irrigation and the growing use of fertilizers and
pesticides. This type of agriculture was based on political
achievements and the production/influx of supporting prices (Tietenberg,
1996), the support of agriculture research – education and the big
investments especially in the sector of irrigation
Hhuang et al.,
2002).
The application of new cultivation techniques increased the
productivity of cultivated soil creating, however, at the same time
serious problems such as the inability to feed an increasing
proportion of the world population, due to the uneven distribution
of resources and of food. We can see the appearance of
countries with overabundance in production of agricultural products
and relatively low population, whilst at the same time
over-populated countries have reduced production.
Whilst the production of food products is increased, without the
demand following the same tendency, developed countries are often
led to the destruction of produced products, when at the same time,
hunger torments Third-World countries.
3.
Agriculture: The problems in three
dimensions
After the Second World War, the effort of the European countries for
rebuilding and restructuring their economies was based on the
availability of sufficient quantity and quality of food at low
costs. This type of growth requires an increase in
agricultural production through the improvement of soil
productivity, of work and of capital. It was under those
circumstances that gradually the substitution of work by capital
came about. Most manual procedures are replaced by machines
(weeding, cutting, harvesting, milking, etc.) and the usage of
immediate inflows is increased (seeds, fertilizers, pesticides and
fuels). Agricultural exploitation tends to turn into industrial
expertise, organized in huge collectively controlled land
ownerships, with extremely specified forms of monocultures.
This stage of agricultural production enlargement had profound
economic, social and environmental impacts.
Firstly, an economic problem
is created by the search for maximum production, which, in the frame
of an ever-spreading model results in over production. Over
production initially only affected a few products sporadically, but
this phenomenon slowly became more generalized. The policy
that was applied, in order to correct the imbalance and which
involved the reduction of the number farming and the “freezing” of
farm expansions, did not actually solve any of the problems of
over-production. On the contrary, the concentration of the
means of production in the hands of few producers and the continuous
rise on levels of production at work due to the technological
progress, more than made up for the reduction in production
resulting from the disappearance of thousands of farms.
The
second problem is a social
one. Poorer farmers were forced to abandon agriculture settling in
areas away from consuming centers with low productivity capacities,
like for example in mountainous and island zones, or other
disadvantageous areas. At the same time, in
Third World areas, where the necessary means for the application of
new methods of cultivation were owned by a small minority only, that
minority’s economic and social strength against farmers with small
properties was increased.
Finally, the third problem is an
environmental one.
Agricultural production was concentrated mainly in those areas that
were suitable for mechanization and intensification. In many
cases, this concentration and intensification led to the destruction
of the environment in those areas, and in difficulties for managing
environmental problems. At the same time socio-economic and
environmental problems appeared in areas which were already
disadvantaged, resulting from the practice of agriculture under new
terms such as reduction of income, abandonment of agriculture,
population shrinking, changes in land use, degradation of land
productivity (Giourga,
1991).
1
Cultivated Plants
The production of nutritional products of high-energy value, for the
satisfaction of the basic nutritional needs of humans and animals,
is today the focus of agricultural production. Covering
specific nutritional needs of contemporary times is of secondary
importance, although on a local level this might not be the case.
Therefore, big cultivations are the ones that shape the agricultural
scenery in every area and also those that have the biggest impact on
the appearance of the environmental problems.
The most important cultivation are cereals, which makes up
50%
of the total area cultivated worldwide, an area of over seven
billion.
The three basic cereals are wheat, rice and corn, which are relied
upon to cover the whole of the world’s population needs in energy.
They are used in the nutrition of humans and animals, either in the
form of fruit, or after special processing as various nutrition
kinds. The vegative mass and their crop remnant are used
mainly for animal feeding. More recently, cereal biomass has
also been used for the production of energy and bioethanol (Papacosta,
1997).
Wheat is the plant occupying the biggest area in the world (15% of
the total cultivated land) and is also the basis of nutrition in
most of the world. Rice comes next in importance, since it is the
basic food of 2 billion people. Corn takes the third place in
cultivation worldwide and has some peculiarities in its use, since
its fruit is primarily used for the feeding of animals, and
secondary as food for humans. Barley, finally, is mainly
cultivated to cover the energy needs of animals and partly of
humans. This variety is of special importance because it is
also used in industry for the production of drinks (beer, whisky).
The rest of the cereals such as rye, oats, etc. are cultivated in
smaller areas and for the cover of specific needs.
Legumes or pulses, which have been known since ancient times, are
foods of high nutritional value for both humans and animals.
In the past, they were the main source of proteins in human diet.
Nowadays, the wider availability of animal proteins has reduced
their importance and cultivation. In the Mediterranean and the
Middle East, the most prevailing legumes were chickpeas, lentils,
peas, faba beans, in America, beans and in China, soya. Today,
the first place in the cultivation of legumes is taken by soya,
which is used in the developed countries for the production of oil
and animal feeds, and in the developing countries for the production
of oil and animal feeds, and in the developing countries for the
production of proteins in human nutrition.
Also, belonging to the legumes is the Alfa alfa (a kind of perennial
clover), which is one of the most important livestock plants and is
widely cultivated. Alfa alfa has been extensively used since
the
13th
Century B.C. in animal feeding and is regarded to be the species
that changed the way animals are bred. Further livestock
development is deemed impossible without the existence of Alfa alfa.
One of the most important advantages of legumes is their capability
of binding nitrogen from the atmosphere through nitrogen-binding
bacteria (Rhizobium,
Bradyrhizobium) which
are present in their roots. Through this, they contribute to
sustainability and to improvement in soil productivity.
Using their nitrogen-binding property, legumes satisfy their needs
in nitrogen, and furthermore, via decomposition of vegetative
debris, they enrich the soil with nitrogen, which is then available
for the next cultivation. Therefore, their cultivation
contributes to reducing the use of nitrogen-containing fertilizers.
The cultivation of plants for the production of specialized products
is of limited economic importance on a world scale, but is often
very important at the local level. The importance of the olive
and the vine for the Mediterranean countries is not the same as for
other countries cultivating the same products, although for the
Mediterranean region, they were, together with wheat, the basis for
the cultural development of the area.
Tree growing for the production of fruits and garden cultivations
are usually of great economic importance at the local level.
Even though these products are only supplementary in the diet, they
often have a commercial value which is many times higher than their
nutritional value. The demand for those products is observed
in high-income societies, although Mediterranean types of climate
have a comparative advantage for their cultivation, if the water
supply is sufficient.
In recent times, the trend for consumers with high incomes to
consume off-season products has increased the development of
cultivations under glass which are today the most intensive form of
agriculture of big investment in variable and stable income.
Glasshouses have transformed the rural landscape dramatically, and
“covered agriculture” is continously expanding worldwide.
1.4
Industrial Plants
Amongst cultivated species of substantial economic importance are
also those, which are produced mainly for industrial use.
Amongst those, the most important are cotton, sunflower, canola,
sugar cane and tobacco.
Special reference must be made to the cultivation of corn and
potato, since their products after industrial processing end up in
the market as nutritional goods for wide consumption (potato crisps,
shrimp crisps, etc.). They have replaced in our diets other
products of traditional cultivations (dried nuts), which have seen
their other economic importance diminish.
1.5
Specialized Cultivations in Tropical Countries
Developing countries in tropical areas have specialized cultivations
such as coffee, cocoa, bananas and sugar cane, which do not,
however, make up basic nutritional goods for the local people.
The spread of their cultivation occurred during the colonial period
mainly to serve nutritional needs of the people of Europe and North
America. These cultivations are called “subsidized” or
“exporting”, since they make up the main source of income for the
farmers of those areas, and at the same time, the main source of
currency for the producing countries. In contrast,
cultivations of basic nutritional goods are called “vital” and in
most of those countries are not subsidizes, but are based on local
production for local consumption.
It is noted that “subsidized” cultivations are competing with the
“vital ones” and have resulted in the dependence of many
Third World countries on the import for basic nutritional goods.
The second largest part of food production for man is livestock
farming. Today, livestock farming in developing countries, has
become intensive with full control of the direction for the
production animals bred.
Modern livestock is substantially different from that of the past.
In traditional farming systems, agriculture and livestock are
connected and mutually supportive (Giourga,
1991). Livestock in the past, was using mainly byproducts and
products of secondary importance in agriculture for animal feeding,
whilst at the same time it provided the necessary force for soil
cultivation, and animal manure was used to enrich cultivated lands.
Animal manure was very important in enriching the soil with vital
elements and acted as a soil improving its high organic value
content, which improves the structure and physical qualities of the
soil, increases microbe activity and protects the cultivations from
the abundance of salts and toxic substances.
In contemporary times, the important changes that have taken place
in the practice of agriculture and the consumption patterns (major
increase of animal proteins in human nutrition) have led to an
important increase in livestock breeding and the ultimate dependence
of stock breeding from agriculture. At the same time, the
importance of animals for the cultivation of soil and manure plays a
main role for the sustainability of fertility that has dramatically
been cut down.
As a
result of human intrusion, places and ways of nutritional goods’
production have been shaped and set. However, the soil used in
agriculture is a natural resource that needs extremely special care
in order to sustain its productive qualities.
Contemporary agriculture has a technological megasystem that is more
and more liable to the dangers deriving from technology. The
problems caused derive mainly from the exhaustion of natural
resources, pollution and the downgrading of the environment, as well
as from the production of products that do not safeguard public
health. The pollution of waters, the degradation of soil fertility,
the alteration of agricultural landscapes, the reduction of
biodiversity and the presence of toxic substances in nutritional
goods are an everyday reality.
The soil
is often regarded as an inactive way for sustaining human
activities. However, it is a dynamic, lively system in which
important bio-geo-chemical processes take place. The course of soil
formation process is so slow that it can be considered as
none-renewable natural resource.
The
intensification of agriculture, aiming at increasing productivity,
pushes the cultivators to the over-use or even to the abuse of the
means of production, like agricultural machinery, irrigation, usage
of agrochemicals etc. Basic problems of soil degradation are the
soil’s compression and the destruction of its structure, the
lowering of its fertility, the increase of soil salts and acids, the
pollution from chemicals and pesticides and erosion.
Cultivation of soil sometimes aims at improving its structure;
however, quiet often, the prerequisites for its degradation are
produced instead. The import of big, heavy, specialized agricultural
machinery, mainly for the needs of ploughed cultivations, results in
the destruction of the soil structure due to compression. The use of
those machines, sometimes aids the formation in the subsoil of an
impenetrable layer of ground, with the consequence of
limiting airing, water permeability
and the filtration of the soil
(Polizopoulos,
1970) as well as that of the
active root-layering of plants. Furthermore, the continuous
processing of the soil speeds up the oxidization of organic
substance, which results in the degradiation of its productivity.
The
aforementioned transformations in the soil’s natural properties,
apart from the effect they have in crop yield, further intensify its
erosion. Special
problems arise due to the use of agricultural machinery, like lifts,
for soil processing in hilly areas. The inability of machinery to
follow a ploughing course in contour lines increases erosion in
these areas, because circumstances for the fast removal of the
surface soil are created.
The
continuous expansion of irrigated areas and the great demands of
cultivations for water, use up water supplies. As a result of this
practice the level of underground waters is decreasing,
approximately by
0,5 to 1 meter yearly (Georgopoulos,
1998). At the same time above-ground water bodies are eligible for
reduction in the amount of water they can store during summer
months, a fact that in the case of rivers can be seen in their
reduction in supply and has impacts all the way to their estuaries.
So, the need for finding more water arises, therefore water is
either transported from other areas, or the depth of pumping is
increased. The deficiency of surface water in coastal areas and the
excessive pumping of the underground waters, leads to the phenomenon
of salting of underground waters
and the destruction of water
springs.
Another
phenomenon that has its roots in the abuse of water, and its usage
in paces much faster than those of its natural rhythms of
substitution, is the subsidence of soils. At the Mississipi Delta
subsidence of soil in connection with the rise of water level
results in the flooding of many square kilometers of land (Jacobson,
1990).
Even the
mildest form of irrigation, the drop by drop type, often causes
saltation (soil
salinity) problems on its application, because with this system the
existing salts in the water are concentrated and are a weight to the
soil in themselves, as well as around the plant’s own root system.
The substitution of soils that have not been under saltation demands
the application of increased quantities of water to be washed off, a
fact that, when it happens, intensifies the exhaustion of water
supplies on the semi arid areas.
The usage
of vast quantities of water in the cultivated areas causes problems
in the soil structure.
The soil’s thin-grain elements are washed deep into the ground and
form the impenetrable horizon that has as a consequence the limited
development of the root structure of plants and the limitation of
their performance. At the same time the filtering quality of grounds
is limited, and that results in weakness in enriching underground
waters and in cutting down of available soil wetness necessary for
plants for next season cultivation.
The usage
of high-pressure irrigation systems also destroys soil structure, so
does extreme irrigation. High mechanical pressures that are
exercised during the release of water destroy the colloid aggregates
of the soil and divide it into big thin-grained constituents. Their
application has to be designed having taken into account the
mechanic composition of the soil, so as to avoid intensifying the
phenomena of erosion and the degradation of soil.
The
choice of the right irrigation system and the definition of the
prescribed quantity of water (irrigation quantity) is of very high
importance, especially in the case of sloping soils.
Chemical
fertilizers constitute the basic contributor for the increase of
yields. The continuous and increased quantity, application of
fertilizers, causes reduction to
the soil fertility and stability of soil structure and
possibly its pollution
as well. Among soil chemical fertilizers the most commonly used are,
nitrogen and sodium, sulphuric ammonium and urae, and among
phosphorus ones, hyperphosphoric compounds.
The
application of fertilizers that include in their compositions
ammonium forms (sulphuric and nitrogenic ammonium) in high
quantities for many years, can cause several serious problems of
soil acidification.
Fertilizers are not clear combinations contain, however, traces of
toxic substances, usually of metals that are usually difficult to
move from the ground. Barrows (1966)
claims that the addition of phosphorus fertilizers in soil includes
increased dangers of “poisoning” of the cultivated areas. These are
elements with small mobility that are concentrated in the upper
soil, where the root part of plants is developed. Therefore, many
problems may occur
in the production of vegetables,
are manifested with the appearance of toxic symptoms (chlorosis,
deadly spots on leaves), with the downgrading of quality of produced
products (change in organoleptic characteristics) and the reduction
of the total production (Macrides, 1989).
The soils
that have been polluted with inorganic toxic elements and are
withdrawn from production, many times with the financial support of
the owners, so that the danger of transforming those elements to
humans through the food chain, is avoided. The withdrawal of soils
from cultivation is regarded to be the safest way for protecting
consumers and restoring soils. However, the restoration of polluted
soils is difficult, because heavy metals are bound to the soil’s
colloids and are difficult to wash off (Furrer,
1983). It is estimated that over 100 years are demanded until they
are “cleansed” and given back to the productive procedure. The
withdrawal of agricultural soils from cultivation has as a
consequence the intensification of production in the rest of
cultivated areas - which results in a vicious circle.
Another
form of negative consequence of soil pollution and fertility is
related to the inefficient
supply of organic substances of soils. Chemical
fertilizers provide the possibility of direct use of land after
harvest. In this case, it is necessary to withdraw vegetables, or
use fire for their destruction so that they do not enter the animal
food chain, leading to the quick diminishing of organic substances
and the result being the reduction of the humus that guarantees the
fertility of soil.
The use
of pesticides in agriculture causes problems to all ecosystems and
consequently affects the wider environment and soil as well.
Many
researchers, like
Ηeitefths,
realized that there appears to be a
reduction in biological activity
in soil microorganisms, resulting in the reduction of soil fertility
(Macrides, 1989). Long-term use of triazine derivatives for fighting
weeds in corn cultivations, affects soil stability in ground’s
aggregates and the action of micro-organisms (Mailard, 1981). The
inhibitive action of microorganisms, undermines the fertility of
soils and reduces their productive properties.
Degradation of soil can also be the result of the use of pesticides
that contain heavy metals, like arsenic, copper and zinc, or various
other inorganic toxic elements. Those elements are very hard to move
and are mainly concentrated in the area of the root system; they are
transferred through the roots to the main plants, and then into the
food chain, finally reaching humans.
3.1.5
Effects from Various Farming Practices
Soil
structure is negatively affected from the development monoculture.
For example, the continuous cultivation of cereals results in the
diminishing of porouses, the restriction of filtering and the
diminishing of the quality of drinking water that the soil can
sustain, which would also be available for the next crop.
Furthermore, in those surfaces where crops rotation techniques are
not applied, certain bio-communities develop in which pathogenic
clones of high resistance to standard pesticides are often obeserved,
often hard to eradicate.
The
abandonment of fallow practices has restricted the possibilities for
the replacement of the productive possibilities of the soil and at
the same time it has burdened the soil with a continuous flow of
fertilizers, pesticides etc.
Finally,
the unification of cultivated areas, the disappearance of
plant-fencing and the drainage of marshes resulted in a reduction of
the animal species depending for food on that soil and as a
consequence it has diminished the biodiversity of ecosystems.
3.1.6
Effects from the Use of Improved Plants
The
introduction in cultivation of new kinds of plants and hybrids
intensifies the import of inflows, due to their demands in order to
yield the maximum of their productive capabilities. The result is
the continuous increase of used quantities in fertilizers,
pesticides and energy and the burdening of the environment, with
consequences mentioned above.
3.2
Water
Water, as
already mentioned, was used by humans so as to increase cultivation
yields. Like soil, water too was used at the beginning as an
inexhaustible source and was used without thrift. However, during
the last decades and in light of constantly increasing needs, water
has come to be regarded as an insufficient source. Agriculture has
the biggest consumption of water. In areas with uneven distribution
of rainfalls, in big geographical areas, very costly constructions
are built for water irrigation, a fact that leads to the increase of
costs in agricultural productions. The extensive drawing of
underground waters in coastal areas results, as already mentioned,
in degradation of water quality.
Contemporary agricultural practices, applied in intensive
agriculture, often lead to the pollution of surface and underground
waters; these are bacterial, farming wastes, or chemical type
wastes, agrochemicals and stock-breeding waste (Yerakis,
1995).
3.2.1
Effects from Livestock Wastes
Infections of bacterial type in agricultural practices are often
caused by bacteria coming from animal waste, produced in large
quantities at industrial type stock breeding establishments. The
contamination may be the result of an immediate dumping of wastes,
or from silo waters, or directly from rain waters that flow through
dirty channels to end up in huge water tanks. The problem becomes
worse due to the large size of units and their tendency to be
located in clusters aiming at lower production costs.
3.2.2
Effects from Agrochemicals
Chemical
pollution can be observed equally in surface and ground waters. As a
result of the washing out of chemical fertilizers and pesticides,
the presence of sodium in water is observed. These agrochemicals,
which are extensively used in conventional agriculture to achieve
high yields, can be transferred through rain waters, or rivers, or
outflows from reserves and be filtered into ground waters. Pollution
hazard is increased in areas with high rainfalls during the period
of plant growing (Central European Countries). However, possible
water pollution appears in areas where erosion is liable, because
agrochemicals are transferred from polluted surface soils to surface
water. Finally, accidents of pollution, should be mentioned, that
happened due to the violation of application rules (Louloudis &
Beopoulos,
1993).
Νitrogen
presence in surface waters has immediate effects to aquatic
organisms and at the same time reduces the possibility for urban
use. During recent years, there has been an unsettling increase in
nitrogen contents in surface waters and this fact caused great
worries as to whether this water is drinkable or not. This
responsibility is allocated to agriculture. Therefore, the European
Union issued the Directive of 1980 that set the allowed nitrogen
content in drinking water to 50 mg/lt.
Moreover,
environmental problems are created by the high concentration of
nitrogenic and phosphorus salts in the water ecosystems, due to
eutrophication. The high concentration of these elements in water
pose a threat for animal and human health (cancer hazards through
the formation of nitrosamines). Over-fertilization, applied by
farmers who are not aware of the cultivation needs and the soil
nutrient content, enhanced water pollution. For example, during the
Fall, the use of nitrogen fertilizers in cereals crops has been
generalized. However, as it is well known, this application is not
justified since the accumulation of nitrogenic elements in the soil
increased and consequently the winter rains multiply the danger of
draining of nitrogen in groundwater (Ηenin,
1980; Machet, 1987).
3.3
Agricultural Landscapes
The
intensification of agriculture contributed to the undermining, or
even worse, to the destruction of important habitats and rural
landscapes. Some agricultural practices that led to this phenomenon
and are still used, are, the destruction of plant fences, the
exploitation of margin lands, the abandonment of rotation and fallow
and, the replacement of natural pastures with artificial
cultivations, the straining works and the reduction of water
ecosystems areas (Louloudis et
al.,
1993).
Ιn
the United Kingdom, the changes in cultivated areas, and in rural
landscapes are substantial (Βlunden,
1988). Researches indicate that during the 1960s, the rate of
plant-fencing removal rose to 10.000 miles annually (Countryside
Commission, 1977). The size of the damage caused can be understood
if one also takes into account the fact that the margin lands and
plant-fencings were a habitats for at least 20 species of mammals,
37 kinds of birds and 17 types of lepidopteran
etc.
The
drainage of water-ecosystems for agricultural use, using purely
agro-economic criteria, was a common practise until the
1960s. The value of those
ecosystems lies not only in the fact that they are a habitat for
important and rare flora and fauna species, but also act as water
tanks and regulators of water and climate. The absorption of carbon
dioxide and the emission of oxygen are among their most important
functions. Therefore, their destruction affects a series of factors
from the extinction of species to the climate change of those areas.
It is
likely that the extensive use of pesticides causes atmospheric
pollution by the release of steams, or the spread of spraying
substances and their transfer through the wind in wider and more
remote areas. For example, this is observed at the cultivation
places (store-houses, glass-houses etc), during periods of insects
and rodents control, so that substances in the form of gas or steam
are used. These chemical substances are very toxic. (Tsiouris,
1999).
At the
Organisation for Economic Co-operation and Development (OECD)
countries, agriculture contributes approximately
7%
of the total anthropogenic emission of glass-house gases (Brouwer,
2002). In the EU, agriculture contributes approximately 11% of the
anthropogenic glass-house gasses, which can be analyzed as less than
2% of the
CO2,
but more than 50% of the total nitrogenic oxids and almost 45% of
the emissions of
CH4
(Baldock et al.,
2002).
3.5
Biodiversity – Genetic Diversification
The ability of ecosystems to resist the destabilizations and to
fulfill their functions is analogous to their complicated structure.
In other words the more diversified the ecosystem is in flora and
fauna, the bigger chances it has to absorb the internal and external
vibrations and recover its initial form (Georgopoulos,
1998). Stability then, is
the coherence of diversity and differentation. If the environment is
simplified then the diversity of animal and plant species is
diminished, the fluctuation in populations become increasingly
apparent and tend to become uncontrolled.
Agriculture, as is practiced nowadays, is totally depended on the
complete replacement of compound natural ecosystems, from other
simpler ones, that include much fewer species. Agroecosystems,
therefore are the most advanced productive systems but at the same
time the most vulnerable and sensitive to climate changes, to animal
and plant parasites etc. (Divigneaud,
1980).
Additionally, plant diversity changes in grass pastures and in
margins of cultivated lands due to over-pasturing, the loss of
crucial habitats due to eutrophication or their conversion to
agricultural land, the loss of species diversity within the
agrosystems due to the changes in management (Hails,
2002), the push of species to the limits of their natural habitats
with the danger of their disappearance (Chapin
et al., 2000), are
important reasons for the loss of biodiversity. It is thought that
there are serious consequences in processes such as the drainage of
water ecosystems, the loss of plant fences, ditches and other
elements of landscape, due to the increase of agricultural land
size, as well as the loss of common weeds and insects due to the use
of pesticides and veterinary products (Baldock
et al., 2002).
The
spread in the cultivation of hybrids has laso resulted in the
substantial loss of genetic diversity and the disappearance of
traditional species, especially during the 60s. The plants being
used by man today are based on older varieties that were cultivated
and improved. It is typically mentioned that in India during the
last 50 years, approximately 30.000 varieties of rice were being
cultivated (Ryan, 1992). Contrarily, in the USA today only 4
varieties of cotton are being cultivated. This fact indicates a loss
of genetic material that is substantial for the creation of new
varieties and consequently the loss of future substances, needed for
the cultivation of plants, that are not available in science.
Similar
phenomena of reduction in the biodiversity are observed in the
transmission of high quality systematic animal breeding and the
disappearance of indigenous animal species.
3.6
Livestock Effect on Environment
The pursuit of “High Standards of Living” in the food sector is
associated with the effort for continuously increasing the
consumption of animal protein. The energy consumed for meat
production created some problems related to soil pollution and
degradation, the health of people that consume excessive quantities
of meat and the increasing dependence of some countries on cereal
imports in order to increase the quantities of the meat produced.
The most important change that meat production brought about to the
profile of the cultivations in the planet, is the domination of
cultivations aiming at forage production, with simultaneous
supplantation of the cultivations aiming at food production for
people.
The
following are problems related to meat production (Georgakopoulos,
1998):
1.
Around 38% of the global
corn, barley, sorgo and oat production is consumed by animals. The
agricultural methods implemented by machines and used for the
cultivation of forage production are energy consuming. For example,
a kilo of pork needs indirectly 30.000 kcal for its production; that
means the equivalent in energy of 4 litres of petrol. In the USA
half of the energy consumed in the agricultural sector is for meat
production. It is estimated that 3.000 litres of water are required
for cereal cultivation corresponding to one kilo of beef meat (Durning
and Brough, 1992).
2.
The Low Countries are
characterized by the European Union as regions with manure surplus.
The millions of breeding animals in these countries produce more
manure that the soil can absorb, resulting to nitrites passing into
the groundwater, threatening the health of users (e.g. cancer) since
this water is used for water supply.
3.
The over grazing of the soil
leads to soil degradation and devastation.
4.
Huge forest areas are
cleared in order to be used as grazing fields, resulting to
biodiversity reduction and possible degradations due to wrong
administrative practices.
5.
The global meat production
contributes to the increase of the greenhouse gases, since 15-20% of
the global methane quantity is coming from gases from the stomach of
ruminants and the anaerobic biodegradation of their manure.
6.
The “nutritional legend”
indicating that increased quantities of proteins are contributing to
better health, led today’s population of the industrial countries to
the consumption of double the proteins needed. Saturated fats that
accompany protein are associated with some of the diseases of
“abundance” such as heart diseases, strokes and breast and large
intestine cancer.
7.
The cultivations of forage
plants, displace those of the plants for direct consumption by
people, especially in the Third World. Corn displaced wheat, rice
and sorghum (Sorghum vulgare).
It must
be underlined that cows along with the rest of the ruminants, use
for graze half the planet’s surface, while the forage they consume
together with poultry and pigs are produced from ¼ of the cultivated
land globally.
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