2. Environmental Science: Natural Resources part 5
FERTILIZER PROBLEM
Fertilizer is very essential for increasing productivity in agriculture. It has been estimated
that about 70 per cent of growth in agriculture can be attributed to increased fertilizers
application. Increase in yearly consumption of fertilizers would thus be a good indication of
the country’s progress in agriculture.
Total consumption of fertilizers went up from 69,000 tonnes of nutrients in 1950-51 to
estimated level of 115.68 lakh tones during 1989-90. During 1990-91, the consumption of
fertilizers was around 126 lakh tones.
Fertilizer is very essential for increasing productivity in agriculture. It has been estimated
that about 70 per cent of growth in agriculture can be attributed to increased fertilizers
application. Increase in yearly consumption of fertilizers would thus be a good indication of
the country’s progress in agriculture.
Total consumption of fertilizers went up from 69,000 tonnes of nutrients in 1950-51 to
estimated level of 115.68 lakh tones during 1989-90. During 1990-91, the consumption of
fertilizers was around 126 lakh tones.
Soil-testing is an important tool to advise farmers on judicious, balanced and efficient
use of fertilizers for economic returns. There are 461 soil-testing laboratories with analysis
capacity of 64.75-lakh-soil sample per annum. It is intended to expand the soils, twenty-five
sets of Atomic Absorption Spectro Photometers had been provided to the state governments
under the India-United Kingdom Bilateral Programme. Besides, the state government/
agriculture universities have installed a number of such equipments.
Balanced and Integrated use of Fertilizers and Organic Manures
Appreciable progress has been made in crop production by the increased use of ‘NPK
Fertilizers’. However, lately the intensification of agriculture coupled with the use of his
analysis chemical fertilizers has resulted in soil micronutrient deficiencies in large areas. To
ensure optimum benefit from ‘NPK Fertilizers’, it is necessary that they are applied on the
basis of soil-testing results and, where necessary, in combination with micronutrients farmers
are being encouraged through extension training to do this. Organic Manures are essential
for maintaining proper soil health. The Country has a potential of 650 million of rural and
160 lakh tones of Urban Compost. Presently, the potential is not fully utilized.
Fertilizers Quality Control
Quality, price and trade in fertilizers are regulated so that farmers get good quality
fertilizers at the right time and at reasonable prices. The Government has issued the
Fertilizers (Control) Order, 1985, under the Essential Commodities Act, 1955. This order
sampling analysis and provision for appointment of enforcement agencies for regulating the
trade and distribution of fertilizers. There are 43 fertilizers Quality Control and Training
Institute at Faridabad with its One Central Fertilizers Quality Control and Madras. Total
analyzing capacity of these laboratories in the Country is 87,400 fertilizers samples per
annum. The institute organizes training programmes for state enforcement officers, state
fertilizers analysts and for foreigner’s developing countries. Besides, training courses for
fertilizers dealers are also organized in collaboration with the state governments and the
fertilizers industry.
Development of Bio-Fertilizers
Decreasing non-renewable petroleum reserves all over the World and increasing cost of
chemical fertilizers have necessitated search, for alternative renewable sources to meet the
increasing demand, for chemical fertilizers, Emphasis is being laid on integrated nutrient
supply through combined use of fertilizers, organic manures and bio-fertilizers. Scientists
have proved that bio-fertilizers are an effective, cheap and renewable supplement to chemical
fertilizers. Rhizobium inoculants have been found to be effective for pulses, Legume Fodder,
Legume Oilseeds like Soyabean, Groundnut and Blue Green Algae (BGA) for lowland Paddy.
Considering the prospect of bio-fertilizers, the government is implementing the National
Project on Development and Use of Bio-fertilizers with a view to produce, distribute and
promote bio-fertilizers used by organizing training and demonstration programmes and also
quality testing of bio-fertilizers. Under the scheme, one National Centre at Ghaziabad in
Uttar Pradesh and Six Regional Centres Bangalore (Karnataka), Bhubaneshwar (Orissa),
Hissar (Haryana), Imphal (Manipur), Jabalpur (M.P.) and Nagpur (Maharasthra) have been
use of fertilizers for economic returns. There are 461 soil-testing laboratories with analysis
capacity of 64.75-lakh-soil sample per annum. It is intended to expand the soils, twenty-five
sets of Atomic Absorption Spectro Photometers had been provided to the state governments
under the India-United Kingdom Bilateral Programme. Besides, the state government/
agriculture universities have installed a number of such equipments.
Balanced and Integrated use of Fertilizers and Organic Manures
Appreciable progress has been made in crop production by the increased use of ‘NPK
Fertilizers’. However, lately the intensification of agriculture coupled with the use of his
analysis chemical fertilizers has resulted in soil micronutrient deficiencies in large areas. To
ensure optimum benefit from ‘NPK Fertilizers’, it is necessary that they are applied on the
basis of soil-testing results and, where necessary, in combination with micronutrients farmers
are being encouraged through extension training to do this. Organic Manures are essential
for maintaining proper soil health. The Country has a potential of 650 million of rural and
160 lakh tones of Urban Compost. Presently, the potential is not fully utilized.
Fertilizers Quality Control
Quality, price and trade in fertilizers are regulated so that farmers get good quality
fertilizers at the right time and at reasonable prices. The Government has issued the
Fertilizers (Control) Order, 1985, under the Essential Commodities Act, 1955. This order
sampling analysis and provision for appointment of enforcement agencies for regulating the
trade and distribution of fertilizers. There are 43 fertilizers Quality Control and Training
Institute at Faridabad with its One Central Fertilizers Quality Control and Madras. Total
analyzing capacity of these laboratories in the Country is 87,400 fertilizers samples per
annum. The institute organizes training programmes for state enforcement officers, state
fertilizers analysts and for foreigner’s developing countries. Besides, training courses for
fertilizers dealers are also organized in collaboration with the state governments and the
fertilizers industry.
Development of Bio-Fertilizers
Decreasing non-renewable petroleum reserves all over the World and increasing cost of
chemical fertilizers have necessitated search, for alternative renewable sources to meet the
increasing demand, for chemical fertilizers, Emphasis is being laid on integrated nutrient
supply through combined use of fertilizers, organic manures and bio-fertilizers. Scientists
have proved that bio-fertilizers are an effective, cheap and renewable supplement to chemical
fertilizers. Rhizobium inoculants have been found to be effective for pulses, Legume Fodder,
Legume Oilseeds like Soyabean, Groundnut and Blue Green Algae (BGA) for lowland Paddy.
Considering the prospect of bio-fertilizers, the government is implementing the National
Project on Development and Use of Bio-fertilizers with a view to produce, distribute and
promote bio-fertilizers used by organizing training and demonstration programmes and also
quality testing of bio-fertilizers. Under the scheme, one National Centre at Ghaziabad in
Uttar Pradesh and Six Regional Centres Bangalore (Karnataka), Bhubaneshwar (Orissa),
Hissar (Haryana), Imphal (Manipur), Jabalpur (M.P.) and Nagpur (Maharasthra) have been
established. The anticipated production from these Centres during 1990-91 is 85 tonnes of
Rhizobium Inocculant. In addition to production, these Centres have “Culture Collection
Bank” with a good number of effective and promising starting. Quality-testing for biofertilizers have also been taken up at these centers. During 1988-89, Sixty Blue Green Algae
(BGA) Centres have produced 110 tonnes and during 1989-90, it was 200 tonnes. It is
expected that during 1990-91 also the production will be maintained at the same level.
Fertilizers and Pollution
Some of the fertilizers have washed off the lands through irrigation, rainfall and drainage,
into rivers and streams. There they can seriously disturb the aquatic ecosystem. Depletion
of dissolved oxygen caused by excessive algae growths can bring disaste or death to fish and
other aquatic biota. Excessive and indiscriminate application of inorganic fertilizers often
leads to accumulation of nitrates in water. When such waters are drunk by living beings,
these nitrates are reduced to the toxic nitrites by intestinal bacteria. Nitrites can cause a
serious disease known as nethnohlobinemia. The disease can inflict serious damage to
respiratory and vascular systems and may even cause suffocation.
The indiscriminate and excessive use of fertilizers can have serious and adverse ecological
consequences, especially in aquatic ecosystems and ground water resources. The world’s
ecosystems form a sort of continuous and interlinked network. As such, the materials lost
by one ecosystem may spell a gain for its neighbours. Hence fertilizers when applied in
excess, leach from crop fields into water bodies, affecting the down-stream aquatic life.
Beneficial Affects of Fertilizers
Known beneficial effects of fertilizers use in ecosystems include the following:
(1) Increase in food production,
(2) Improvement of soils in temperature areas,
(3) Checking of soil erosion
(4) Conservation of soil and water;
(5) Enhancement in water and efficiency of crops.
Adverse Effects of Fertilizers
Some adverse effects of fertilizers used are as under:
(1) Changes in mobility status of nutrients in soils.
(2) Deterioratory of water resources caused by eutrophication.
(3) Stimulation of weed growth in crop fields.
(4) Disturbance in the ionic balance and equilibrium in soils, often leading to high
acidity, nutritional imbalance, shortages of certain trace elements, and molybdenum
or selenium toxicity.
(5) The Excessive applications of nitrogenous fertilizers to soils can lead to its
accumulation to such a stage that the plants begin to absorb excess amounts and
even then some of the excess amounts present in the soil get leaked off through the
soil into groundwater or into streams and springs.
Rhizobium Inocculant. In addition to production, these Centres have “Culture Collection
Bank” with a good number of effective and promising starting. Quality-testing for biofertilizers have also been taken up at these centers. During 1988-89, Sixty Blue Green Algae
(BGA) Centres have produced 110 tonnes and during 1989-90, it was 200 tonnes. It is
expected that during 1990-91 also the production will be maintained at the same level.
Fertilizers and Pollution
Some of the fertilizers have washed off the lands through irrigation, rainfall and drainage,
into rivers and streams. There they can seriously disturb the aquatic ecosystem. Depletion
of dissolved oxygen caused by excessive algae growths can bring disaste or death to fish and
other aquatic biota. Excessive and indiscriminate application of inorganic fertilizers often
leads to accumulation of nitrates in water. When such waters are drunk by living beings,
these nitrates are reduced to the toxic nitrites by intestinal bacteria. Nitrites can cause a
serious disease known as nethnohlobinemia. The disease can inflict serious damage to
respiratory and vascular systems and may even cause suffocation.
The indiscriminate and excessive use of fertilizers can have serious and adverse ecological
consequences, especially in aquatic ecosystems and ground water resources. The world’s
ecosystems form a sort of continuous and interlinked network. As such, the materials lost
by one ecosystem may spell a gain for its neighbours. Hence fertilizers when applied in
excess, leach from crop fields into water bodies, affecting the down-stream aquatic life.
Beneficial Affects of Fertilizers
Known beneficial effects of fertilizers use in ecosystems include the following:
(1) Increase in food production,
(2) Improvement of soils in temperature areas,
(3) Checking of soil erosion
(4) Conservation of soil and water;
(5) Enhancement in water and efficiency of crops.
Adverse Effects of Fertilizers
Some adverse effects of fertilizers used are as under:
(1) Changes in mobility status of nutrients in soils.
(2) Deterioratory of water resources caused by eutrophication.
(3) Stimulation of weed growth in crop fields.
(4) Disturbance in the ionic balance and equilibrium in soils, often leading to high
acidity, nutritional imbalance, shortages of certain trace elements, and molybdenum
or selenium toxicity.
(5) The Excessive applications of nitrogenous fertilizers to soils can lead to its
accumulation to such a stage that the plants begin to absorb excess amounts and
even then some of the excess amounts present in the soil get leaked off through the
soil into groundwater or into streams and springs.
PESTICIDES: ENVIRONMENTAL PROBLEM
Use of Pesticides
Until 1940’s the following chemicals were used to control pests:
(1) Elements fungicides (S, Cu, Hg, organomercury) against fungal diseases.
(2) Copper sulphate, sodium aresenite and ferrous sulphate against weeds.
(3) Nature insecticides e.g. pyrethrum and nicotine, against beetles and aphids.
(4) Tar oil, petroleum, etc., against and red spider mite eggs.
(5) Lead arsenate against caterpillars.
Even these chemicals were sparingly used. The applications to cereals used to be confined
to seed treatment with organomercury to kill-borne pathogens.
The organochlorine insecticides and herbicides became quite widespread in the mid and
late 1950s and a large variety of these dangerous compounds were being used in the 1960s
in USA, UK, and other developed countries. The British Govt. approved over 150 chemicals
for use as pesticides/herbicides by 1970.
THE HAZARDOUS METHODS OF PESTICIDE APPLICATION
The main method of pesticide application on a large scale is the ‘Aerial Drift Spray”. It is
a highly inefficient and wasteful, capital-intensive technique. A close study shows its nature:
(1) More than 40 per cent of applied pesticide is normally out of the target area.
(2) 15 per cent is out of the target crops.
(3) 40 per cent near the target insect.
(4) 75 per cent is not in contact with it.
(5) It is estimated that the insect through contact, inhalation and ignition absorbs less
than one of the total applied pesticide.
(6) Only about 0.3 per cent of the applied insecticides appear to be absorbed by aphids
on bean contours and 0.02 per cent by myriads on cocoa. The wasteful use is
magnified by the practice followed by farmers who apply pesticide according to the
pre-set schedules prepared by manufacturers. Indeed the actual use of pesticides
by many advanced country farmers may safely be cut by 30 to 50 per cent with no
adverse effect on crop production in case pesticides are applied only when necessary
and in relation to specific pests.
The following are some general properties of pesticides or their residues:
(1) They often strike the intended pests as well as several off.
(2) Many of them continue to persist and cannot be disposed off.
(3) They may cause unintended effects like resistance, faunal displacement and other
population changes.
(4) They may be carried to places fare removed from the points of application or origin.
(5) Their concentration and magnification in biological systems may lead to certain
unexpected or untoward result.
Use of Pesticides
Until 1940’s the following chemicals were used to control pests:
(1) Elements fungicides (S, Cu, Hg, organomercury) against fungal diseases.
(2) Copper sulphate, sodium aresenite and ferrous sulphate against weeds.
(3) Nature insecticides e.g. pyrethrum and nicotine, against beetles and aphids.
(4) Tar oil, petroleum, etc., against and red spider mite eggs.
(5) Lead arsenate against caterpillars.
Even these chemicals were sparingly used. The applications to cereals used to be confined
to seed treatment with organomercury to kill-borne pathogens.
The organochlorine insecticides and herbicides became quite widespread in the mid and
late 1950s and a large variety of these dangerous compounds were being used in the 1960s
in USA, UK, and other developed countries. The British Govt. approved over 150 chemicals
for use as pesticides/herbicides by 1970.
THE HAZARDOUS METHODS OF PESTICIDE APPLICATION
The main method of pesticide application on a large scale is the ‘Aerial Drift Spray”. It is
a highly inefficient and wasteful, capital-intensive technique. A close study shows its nature:
(1) More than 40 per cent of applied pesticide is normally out of the target area.
(2) 15 per cent is out of the target crops.
(3) 40 per cent near the target insect.
(4) 75 per cent is not in contact with it.
(5) It is estimated that the insect through contact, inhalation and ignition absorbs less
than one of the total applied pesticide.
(6) Only about 0.3 per cent of the applied insecticides appear to be absorbed by aphids
on bean contours and 0.02 per cent by myriads on cocoa. The wasteful use is
magnified by the practice followed by farmers who apply pesticide according to the
pre-set schedules prepared by manufacturers. Indeed the actual use of pesticides
by many advanced country farmers may safely be cut by 30 to 50 per cent with no
adverse effect on crop production in case pesticides are applied only when necessary
and in relation to specific pests.
The following are some general properties of pesticides or their residues:
(1) They often strike the intended pests as well as several off.
(2) Many of them continue to persist and cannot be disposed off.
(3) They may cause unintended effects like resistance, faunal displacement and other
population changes.
(4) They may be carried to places fare removed from the points of application or origin.
(5) Their concentration and magnification in biological systems may lead to certain
unexpected or untoward result.
PESTICIDES: ENVIRONMENTAL PROBLEM
Use of Pesticides
Until 1940’s the following chemicals were used to control pests:
(1) Elements fungicides (S, Cu, Hg, organomercury) against fungal diseases.
(2) Copper sulphate, sodium aresenite and ferrous sulphate against weeds.
(3) Nature insecticides e.g. pyrethrum and nicotine, against beetles and aphids.
(4) Tar oil, petroleum, etc., against and red spider mite eggs.
(5) Lead arsenate against caterpillars.
Even these chemicals were sparingly used. The applications to cereals used to be confined
to seed treatment with organomercury to kill-borne pathogens.
The organochlorine insecticides and herbicides became quite widespread in the mid and
late 1950s and a large variety of these dangerous compounds were being used in the 1960s
in USA, UK, and other developed countries. The British Govt. approved over 150 chemicals
for use as pesticides/herbicides by 1970.
THE HAZARDOUS METHODS OF PESTICIDE APPLICATION
The main method of pesticide application on a large scale is the ‘Aerial Drift Spray”. It is
a highly inefficient and wasteful, capital-intensive technique. A close study shows its nature:
(1) More than 40 per cent of applied pesticide is normally out of the target area.
(2) 15 per cent is out of the target crops.
(3) 40 per cent near the target insect.
(4) 75 per cent is not in contact with it.
(5) It is estimated that the insect through contact, inhalation and ignition absorbs less
than one of the total applied pesticide.
(6) Only about 0.3 per cent of the applied insecticides appear to be absorbed by aphids
on bean contours and 0.02 per cent by myriads on cocoa. The wasteful use is
magnified by the practice followed by farmers who apply pesticide according to the
pre-set schedules prepared by manufacturers. Indeed the actual use of pesticides
by many advanced country farmers may safely be cut by 30 to 50 per cent with no
adverse effect on crop production in case pesticides are applied only when necessary
and in relation to specific pests.
The following are some general properties of pesticides or their residues:
(1) They often strike the intended pests as well as several off.
(2) Many of them continue to persist and cannot be disposed off.
(3) They may cause unintended effects like resistance, faunal displacement and other
population changes.
(4) They may be carried to places fare removed from the points of application or origin.
(5) Their concentration and magnification in biological systems may lead to certain
unexpected or untoward result.
Use of Pesticides
Until 1940’s the following chemicals were used to control pests:
(1) Elements fungicides (S, Cu, Hg, organomercury) against fungal diseases.
(2) Copper sulphate, sodium aresenite and ferrous sulphate against weeds.
(3) Nature insecticides e.g. pyrethrum and nicotine, against beetles and aphids.
(4) Tar oil, petroleum, etc., against and red spider mite eggs.
(5) Lead arsenate against caterpillars.
Even these chemicals were sparingly used. The applications to cereals used to be confined
to seed treatment with organomercury to kill-borne pathogens.
The organochlorine insecticides and herbicides became quite widespread in the mid and
late 1950s and a large variety of these dangerous compounds were being used in the 1960s
in USA, UK, and other developed countries. The British Govt. approved over 150 chemicals
for use as pesticides/herbicides by 1970.
THE HAZARDOUS METHODS OF PESTICIDE APPLICATION
The main method of pesticide application on a large scale is the ‘Aerial Drift Spray”. It is
a highly inefficient and wasteful, capital-intensive technique. A close study shows its nature:
(1) More than 40 per cent of applied pesticide is normally out of the target area.
(2) 15 per cent is out of the target crops.
(3) 40 per cent near the target insect.
(4) 75 per cent is not in contact with it.
(5) It is estimated that the insect through contact, inhalation and ignition absorbs less
than one of the total applied pesticide.
(6) Only about 0.3 per cent of the applied insecticides appear to be absorbed by aphids
on bean contours and 0.02 per cent by myriads on cocoa. The wasteful use is
magnified by the practice followed by farmers who apply pesticide according to the
pre-set schedules prepared by manufacturers. Indeed the actual use of pesticides
by many advanced country farmers may safely be cut by 30 to 50 per cent with no
adverse effect on crop production in case pesticides are applied only when necessary
and in relation to specific pests.
The following are some general properties of pesticides or their residues:
(1) They often strike the intended pests as well as several off.
(2) Many of them continue to persist and cannot be disposed off.
(3) They may cause unintended effects like resistance, faunal displacement and other
population changes.
(4) They may be carried to places fare removed from the points of application or origin.
(5) Their concentration and magnification in biological systems may lead to certain
unexpected or untoward result.
DEHP
Dehp 0.00034 18.32 7.30 36.61 0.044
Phthalic anhydride 0.0036 0.18 5.77 0.113
Phthalic acid 0.00077 0.094 2.72 0.018
Polar metabolites 0.00016 0.1555 1.218 0.010
Ecological magnification 53890 24480 107670 130
Source: Metcalf R.L.A laboratory model ecosystem for evaluating the chemical and biological
behaviours of radiolabelled micropollution. IAEA Wien ST/PUB/348. pp, 49-63 (1974).
(4) Findings of the Researches
Extensive researches in the USA found widespread distribution of DDT residues through
food grains in several lakes. Residues were detected in shallow and deep-water mud samples,
crustaceans, whitefish, duck ring-billed and herring gulls and other fauna. Both DDT and
Dieldrin are found passing from mother off spring through the placenta in mice and certain
other animals, possible including man.
(5) Adverse Consequence of Pesticides like DDT
Most pesticides tend to accentuate the problems of both production and pollution instead
of containing them. The consequence of pesticides is almost invariably adverse and harmful.
In the Ninteenth century, the ladybird beetle was brought from Australia to California to
control a scale insect pest of oranges. It is reported that the beetle successfully kept the pest
under check for more than five decades until about 1946 when DDT began to be used in the
citrus orchards. The beetle was susceptible to DDT and hence its population declined.
However, a subsequent withdrawal of DDT again restored the natural balance of biological
control within a few years.
In fact, DDT is one of the most effective pesticides known. This is the reason why it was
banned in the USA in 1972. its remarked insecticidal properties were first discovered in
1939. it became a ubiquitous contaminant of fish, penguins, birds and human being. Hence
a popular public movement started in the USA that asked the Government to protect the
public from the general toxification of the environment by DDT and persistent poisons.
(6) Harm to Human Beings
Human beings are exposed to pesticides mainly through the intake of food and war but
also by inhaling contaminated air. Several pesticides are teratogenic, mutagenic, or
carcinogenic.
(7) Harm to Bees
Bees vitally aid the pollination of several plants. Pesticides have adversely affected
some honey bees and other useful insects whose populations have declined. According to
Pimental, annual agriculture losses due to poor pollination from pesticides can be as high
as US$ 4000 million in the USA.
Dehp 0.00034 18.32 7.30 36.61 0.044
Phthalic anhydride 0.0036 0.18 5.77 0.113
Phthalic acid 0.00077 0.094 2.72 0.018
Polar metabolites 0.00016 0.1555 1.218 0.010
Ecological magnification 53890 24480 107670 130
Source: Metcalf R.L.A laboratory model ecosystem for evaluating the chemical and biological
behaviours of radiolabelled micropollution. IAEA Wien ST/PUB/348. pp, 49-63 (1974).
(4) Findings of the Researches
Extensive researches in the USA found widespread distribution of DDT residues through
food grains in several lakes. Residues were detected in shallow and deep-water mud samples,
crustaceans, whitefish, duck ring-billed and herring gulls and other fauna. Both DDT and
Dieldrin are found passing from mother off spring through the placenta in mice and certain
other animals, possible including man.
(5) Adverse Consequence of Pesticides like DDT
Most pesticides tend to accentuate the problems of both production and pollution instead
of containing them. The consequence of pesticides is almost invariably adverse and harmful.
In the Ninteenth century, the ladybird beetle was brought from Australia to California to
control a scale insect pest of oranges. It is reported that the beetle successfully kept the pest
under check for more than five decades until about 1946 when DDT began to be used in the
citrus orchards. The beetle was susceptible to DDT and hence its population declined.
However, a subsequent withdrawal of DDT again restored the natural balance of biological
control within a few years.
In fact, DDT is one of the most effective pesticides known. This is the reason why it was
banned in the USA in 1972. its remarked insecticidal properties were first discovered in
1939. it became a ubiquitous contaminant of fish, penguins, birds and human being. Hence
a popular public movement started in the USA that asked the Government to protect the
public from the general toxification of the environment by DDT and persistent poisons.
(6) Harm to Human Beings
Human beings are exposed to pesticides mainly through the intake of food and war but
also by inhaling contaminated air. Several pesticides are teratogenic, mutagenic, or
carcinogenic.
(7) Harm to Bees
Bees vitally aid the pollination of several plants. Pesticides have adversely affected
some honey bees and other useful insects whose populations have declined. According to
Pimental, annual agriculture losses due to poor pollination from pesticides can be as high
as US$ 4000 million in the USA.
(8) Damage to Crops
(i) Sometimes crops are damaged by pesticide applications, e.g. application of improper
dosage under unfavourable conditions.
(ii) Herbicides that drift from a treated crop to a nearby crop also cause serious
environmental problems. Persistent herbicides also can injure crops planted in
rotation.
(9) Harm Caused to Fishery and Wildlife
Drifting or leaching pesticides drain into nearly water bodies causes fishery and wildlife
losses. Wild birds and mammals exposed to pesticides suffer by death from direct
exposure to high doses and reduced survival growth and reproduction from exposure to
subtle dosages.
(10) Harmful Effect on Decomposers
Pesticides have harmful effects on insects, earthworms, invertebrates, protozoa, and
microbes found in soils, especially the decomposers. It is reported that human pesticide
poisonings, reeducation in insects and mites, and honeybee poisonings account for about 70
per cent of the calculated socio-environmental costs for pesticides in the USA.
(11) Development of Secondary Pests
The use of pesticides kills natural enemies and creates such problems as the development
of secondary pests eg. Red spider mites. Resurgence of primary pests can also occur. To
illustrate, caterpillars of the small cabbage white butterfly in Brussels sprouts reappeared
after DDT has killed their natural enemies. Resistance to pesticides is a cause for serious
concern. Other hazards include those to the operator or worker who sprays pesticide, those
to the consumer of the crop and those to wildlife.
(12) Elimination of Birds
Some species of Eagles and top carnivors are known to be eliminated by DDT because
contaminated adults failed to lay viable eggs. Populations of peregrine falcons and some
pelicans have disappeard from some areas from some areas where excessive use of DDT
interfered with the bird’s ability to transport calcium to growing eggs, leading to marked
thinning of the eggs shells. Such weak eggs fail to reach the hatching stage. It is discovered
that in ringdoves, DDT greatly reduced the activity of carbonic anhydrase. This enzyme is
critical in providing calcium for eggshell growth. When the pesticide inhibits this enzyme,
eggshell grows thinner.
(13) Growth of New Pests
Artificial introduction of pesticides in the environment upsets natural biological controls.
This is the reason why new pests are created in this way because their natural predators,
which previously checked their populations, are eliminated. In this way mites have become
a pest as a consequence of the emergence of the pesticide industry. Indiscriminate and
excessive use of DDT killed some insect predictors of these mites, enabling the mites to
multiply to pest status.
(i) Sometimes crops are damaged by pesticide applications, e.g. application of improper
dosage under unfavourable conditions.
(ii) Herbicides that drift from a treated crop to a nearby crop also cause serious
environmental problems. Persistent herbicides also can injure crops planted in
rotation.
(9) Harm Caused to Fishery and Wildlife
Drifting or leaching pesticides drain into nearly water bodies causes fishery and wildlife
losses. Wild birds and mammals exposed to pesticides suffer by death from direct
exposure to high doses and reduced survival growth and reproduction from exposure to
subtle dosages.
(10) Harmful Effect on Decomposers
Pesticides have harmful effects on insects, earthworms, invertebrates, protozoa, and
microbes found in soils, especially the decomposers. It is reported that human pesticide
poisonings, reeducation in insects and mites, and honeybee poisonings account for about 70
per cent of the calculated socio-environmental costs for pesticides in the USA.
(11) Development of Secondary Pests
The use of pesticides kills natural enemies and creates such problems as the development
of secondary pests eg. Red spider mites. Resurgence of primary pests can also occur. To
illustrate, caterpillars of the small cabbage white butterfly in Brussels sprouts reappeared
after DDT has killed their natural enemies. Resistance to pesticides is a cause for serious
concern. Other hazards include those to the operator or worker who sprays pesticide, those
to the consumer of the crop and those to wildlife.
(12) Elimination of Birds
Some species of Eagles and top carnivors are known to be eliminated by DDT because
contaminated adults failed to lay viable eggs. Populations of peregrine falcons and some
pelicans have disappeard from some areas from some areas where excessive use of DDT
interfered with the bird’s ability to transport calcium to growing eggs, leading to marked
thinning of the eggs shells. Such weak eggs fail to reach the hatching stage. It is discovered
that in ringdoves, DDT greatly reduced the activity of carbonic anhydrase. This enzyme is
critical in providing calcium for eggshell growth. When the pesticide inhibits this enzyme,
eggshell grows thinner.
(13) Growth of New Pests
Artificial introduction of pesticides in the environment upsets natural biological controls.
This is the reason why new pests are created in this way because their natural predators,
which previously checked their populations, are eliminated. In this way mites have become
a pest as a consequence of the emergence of the pesticide industry. Indiscriminate and
excessive use of DDT killed some insect predictors of these mites, enabling the mites to
multiply to pest status.
Some of the pesticides inhibit division in aquatic algae. They may decrease their rates
of photosynthesis. In this way they almost produce changes in the species composition and/
or diversity of algal communities. The algae-grazing animals are more affected by the level
of blooms.
(15) Flora And Fauna
Pesticides have adverse effects on the flora and fauna of soils. Effects on mycorrhizal
fungi or decomposer bacteria in forests would almost certainly alter plant community structure
in forests. Some soil animals consume plant debris and contribute to soil fertility. Use of
insecticides changes the populations of some of these animals. It leads to reduction in soil
fertility especially in woodlands.
of photosynthesis. In this way they almost produce changes in the species composition and/
or diversity of algal communities. The algae-grazing animals are more affected by the level
of blooms.
(15) Flora And Fauna
Pesticides have adverse effects on the flora and fauna of soils. Effects on mycorrhizal
fungi or decomposer bacteria in forests would almost certainly alter plant community structure
in forests. Some soil animals consume plant debris and contribute to soil fertility. Use of
insecticides changes the populations of some of these animals. It leads to reduction in soil
fertility especially in woodlands.
Comments
Post a Comment