3. Agrochemicals
โข Agrochemicals (pesticides and fertilizers) are looked upon as a vehicle for
improved crop production technology though it is a costly input. Balance use,
optimum doses, correct method and right time of application of agrochemicals
ensures increased crop production.
โข Agrochemicals are the result of modern technology that depends on inorganic
fertilizers and pesticides. Over use of these chemicals have severe effects on
environment that may lead to an immediate and long term effects.
5. Agrochemicals
โข The current industrial agriculture system promotes the reliance on
agrochemicals, both synthetic fertilizers and pesticides, while neglecting to
consider their negative effects on local communities, human health and the
environment.
โข The use of agrochemicals, has contributed enormously to the success of Green
Revolution program globally, but with some noticeable pollution effects on
ecosystem and human health (FAO, 1993).
7. Fertilizers
โข Not all the nutrient ions in a fertilizer applied to a field soil are taken up by
the growing crop, and the fate of the remainder is very important in any
discussion on the effects of their long-term intensive use.
โข Three things can happen to these residues in the soil
โ They may remain in the soil
โ They may be removed in the water leaching through the soil or
running off the surface of the soil
โ They may be lost to the atmosphere by volatilization.
โข This loss of the nutrients from the soil can negatively affect
the environment in many ways.
โข The most commonly cited hazards are the
8. Crop damage
Fertilizer use at excessive rates has been known to have deleterious effects on
crop growth.
Examples are
โข The lodging of small grains and the low sugar content of sugar beets from
excessive N.
โข Nutritional disorders involving such trace elements as Zn and Fe incurred by
excessive P fertilizer and lime.
โข Damaging salt effects on seed germination and seedling injury from too
much soluble fertilizer salt adjacent to the seed row.
โข Acidifying action of excessive fertilizer N on soil and induced Al and Mn
toxicities.
โข Increased incidence of plant disease and pest attacks with excessive N, etc.
โข Too high level of N fertilizer is likely to lower the storage and cooking quality
of potatoes.
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10. Damage to soil macro and micro organisms
โข It is possible to demonstrate the lethal effects of fertilizers and anhydrous
ammonia when applied in contact with a living worm. Of far greater significance
to the earthworm is the greater supply or fresh organic material for its
sustenance afforded through fertilization.
โข Heavy use of N fertilizer is known to be inimical to the activity of symbiotic N
fixing organisms. The legume plant well supplied with soil and fertilizer N is not a
very efficient N fixer.
โข Contention has also been made that fertilizer use, most particularly N, will inhibit
soilโs capacity to nitrify N from the native organic matter source.
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11. Eutrophication
โข The term eutrophication describes the enrichment of surface waters with plant
nutrients. It is an unsightly process that degrades the aesthetic qualities of surface
water bodies. Degradation may be in respect of excessive algal scum and aquatic
weeds as well as undesirable color, taste and odor of the water.
โข Agriculture is considered to be the major factor in the eutrophication of surface
waters. Factors that trigger eutrophication process are Nutrients (N & P), a carbon
source of CO2, favorable temperature and non-turbid water. If the latter three are
favorable and nutrient concentrationยฐ reach 0.3 ppm N and 10 ppb P the algal and
various water plant growths are likely to increased.
โข A number of environmental scientists have claimed that the use of fertilizers on farm
land has seriously increased the liability of inland water to become eutrophic, causing
pollution in lakes and reservoirs both by the algal pigments becoming distributed in
the water and by creating anaerobic conditions in the subsurface waters.
โข Additional phosphorus may stimulate large blooms of algae, which do not naturally
occur in abundance. Dense filamentous algal mats may form, changing the
environment, excluding species and diminishing biodiversity.
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12. Harmful effects of Nutrients in water and food
โข Many factors of chemical, physical and biological character contribute to water
quality.
โข WHO recommended standards for drinking water in Europe are: 0-11.3 ppm NO3
โ N recommended, 11.3 - 22.6 ppm acceptable, and above 22.6 ppm not
recommended.
โข NO3 is being reduced to NO2 after ingestion, which combine with hemoglobin in
the blood and produces methaemoglobin, reducing the capacity of the blood to
transport oxygen (Methaemoglobinaemia).
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13. Harmful effects of Nutrients in water and food
โข Nitrate levels have similarly been established for various fresh vegetables and for
canned baby foods from natural sources as well as NO3 + NO2 in preserved fish
and meats.
โข The vegetables spinach, celery, lettuce and kale have a substantial capacity to
accumulate nitrate as do such forages as sudan grass, annual grasses, immature
cereals and maize cut for silage.
โข Deficiency of Mg has been recognized as a major problem in the nutrition of
cattle in many different regions of the world. Due to access of K.
โข Excessive rates of P fertilizer have been known to cause substantial reduction in
the above-ground concentration of such elements as Fe and Zn in plants.
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14. ๏ต A pesticide is any substance or mixture of substances
intended for preventing, destroying, repelling, or mitigating
any pest.
๏ต โPesticideโ includes herbicides, fungicides, insecticides, or any
other substance used to control pests.
Pesticides
16. Pesticides
โข Worldwide, about 3 billion kg of pesticides is applied each year with a purchase
price of nearly $40 billion year-1 (Pan-UK, 2003).
โข Although pesticides are generally profitable in agriculture, their use does not
always decrease crop losses.
โข Most benefits of pesticides are based on the direct crop returns. Such
assessments do not include the indirect environment and economic costs
associated with the recommended application of pesticides in crops.
โข To facilitate the development and implementation of a scientifically sound policy
of pesticide use, these environmental and economic costs must be examined
19. Harmful effect of Pesticides
1 Public Health
โข Acute Poisoning
โ Worldwide, the application of 3 million metric tons of
pesticides results in more than 26 million cases of pesticide
poisonings (Richter, 2002).
โ Of all the pesticide poisonings, about 3 million cases are
hospitalized and there are approximately 220, 000 fatalities
and about 750 000 chronic illnesses every year (Hart and
Pimentel, 2002).
20. CANCER AND OTHER CHRONIC EFFECTS
โข Pesticides are carcinogenic and can cause chronic disorders. These major types of chronic health
effects of pesticides include
โ neurological effects
โ respiratory
โ reproductive effects
โ cancer.
โข There is some evidence that pesticides can cause sensory disturbances as well as cognitive effects
such as memory loss, etc (Hart and Pimentel, 2002).
โข In addition to neurological effects, pesticides can have adverse effects on the respiratory and
reproductive systems. For example, 15%of a group of professional pesticide applicators suffered
asthma, chronic bronchitis (Weiner and Worth, 1972).
21. โข Studies have also linked pesticides with reproductive effects. For example, some
pesticides have been found to cause testicular dysfunction or sterility (Colborn et
al., 1996).
โข US data indicate that 18% of all insecticides and 90% of all fungicides are
carcinogenic (NAS, 1987).
โข Several studies have shown that the risks of certain types of cancers are higher in
some people, such as farm workers and pesticide applicators, who are often
exposed to pesticides (Pimentel and Hart, 2001).
22. โข Many pesticides are also estrogenic โ they mimic or interact with the hormone
estrogen โ linking them to increase in breast cancer among some women. The
breast cancer rate rose from 1 in 20 in 1960 to 1 in 8 in 1995 (Colborn et al.,
1996).
โข Pesticides that interfere with the bodyโs endocrineโhormonal system can also
have reproductive, immunological, or developmental effects (McCarthy, 1993).
โข The negative health effects of pesticides can be far more significant in children
than adults, for several reasons.
โ Higher metabolic rates in children
โ Children consume more foods
23. PESTICIDE RESIDUES IN FOOD
โข The majority of foods purchased in supermarkets have detectable levels of
pesticide residues.
โข For instance, of several thousand samples of food, the overall assessment in 8
fruits and 12 vegetables is that 73%have pesticide residues (Baker et al., 2003).
โข In five crops (apples, peaches, pears, strawberries, and celery) pesticide residues
were found in 90%of the crops. Of interest is the fact that 37 different pesticides
were detected in apples (Groth et al., 1999).
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24. ENVIRONMENTAL COSTS OF PESTICIDES
Domestic animal poisonings and contaminated products
โข In addition to pesticide problems that affect humans, several thousand domestic
animals are accidentally poisoned by pesticides each year, with dogs and cats
representing the largest number
โข For example, of 250 000 poison cases involving animals, a large percentage of
the cases were related to pesticides (National Animal Poison Control Center,
2003).
โข It is reported that 0.5%of animal illnesses and 0.04%of all animal deaths
reported to a veterinary diagnostic laboratory were due to pesticide toxicities.
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25. โข Pesticide residues are not only found in animal tissues but also in their products.
โข For example, in Oahu, Hawaii, in 1982, 80%of the milk supply, was condemned
by the public health officials because it had been contaminated with the
insecticide heptachlor (Baker et al., 2003).
26. Destruction of beneficial natural predators and
parasites
โข In both natural and agricultural ecosystems, many species, especially predators and
parasites, control or help control plant feeding arthropod populations. Indeed, these
natural beneficial species make it possible for ecosystems to remain โโgreen.โโ
โข Like pest populations, beneficial natural enemies and biodiversity (predators and
parasites) are adversely affected by pesticides (Pimentel et al., 1993).
โข For example, the following pests have reached outbreak levels in cotton and apple crops
after the natural enemies were destroyed by pesticides.
โ Cotton bollworm
โ Tobacco budworm
โ Cotton aphid
โ Spider mites
โ Cotton loppers
โ European red mite
โ Red-banded leaf roller
โ Rosy apple aphid
โ Apple rust mite.
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27. โข Fungicides also can contribute to pest outbreaks when they reduce fungal pathogens that are
naturally parasitic on many insects.
โข For example, the use of benomyl reduces populations of entomopathogenic fungi, resulting in
increased survival of velvet bean caterpillars and cabbage loopers in soybeans.
โข For example, from 1980 to 1985 insecticide use in rice production in Indonesia drastically
increased the brown plant hopper due to the destruction of natural enemies (Oka, 1991). The
estimated cost of rice loss in just a 2-year period was $1.5 billion (FAO, 1988).
28. Pesticide resistance in pests
โข The extensive use of pesticides has often resulted in the development
and evolution of pesticide resistance in insect pests, plant pathogens, and
weeds.
โข An early report by the United Nations Environmental Program (UNEP,
1979) suggested that pesticide resistance ranked as one of the top 4
environmental problems of the world.
โข About 520 insect and mite species, a total of nearly 150 plant pathogen
species, and about 273 weeds species are now resistant to pesticides
(Stuart, 2003).
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29. Honeybee and wild bee poisonings and
reduced pollination
โข Honeybees and wild bees are vital for pollination of fruits, vegetable, and other
crops. Bees are essential to the production of about one-third of US and world
crops.
โข Most insecticides used in agriculture are toxic to bees, pesticides have a major
impact on both honeybee and wild bee populations.
โข Mussen (1990) emphasizes that poor pollination will not only reduce crop yields,
but also equally important, it will reduce the quality of some crops, such as
melon and fruits.
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30. Crop and crop product losses
โข Basically, pesticides are applied to protect crops from pests in order to increase yields, but
sometimes the crops are damaged by the pesticide treatments.
โข This occurs when
(1) The recommended dosages suppress crop growth, development, and yield
(2) Pesticides drift from the targeted crop to damage adjacent crops
(3) Residual herbicides either prevent chemical sensitive crops from being planted
(4) Excessive pesticide residue accumulates on crops, necessitating the destruction of the harvest.
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31. โข When weather and soil conditions are inappropriate for pesticide application,
herbicide treatments may cause yield reductions ranging from 2 to 50%
(Pimentel et al., 1993).
โข When residues of some herbicides persist in the soil, crops planted in rotation
are sometimes injured.
โข Crop injury and subsequent loss due to drift are particularly common in areas
planted with diverse crops.
32. Ground and surface water contamination
โข Certain pesticides applied at recommended dosages to crops eventually
end up in ground and surface water as well as in rain water.
โข The three most common pesticides found in groundwater are aldicarb,
alachlor, and atrazine (Cornell, 2003).
โข The main routes through which pesticides reach the water are:
1. It may drift outside of the intended area when it is sprayed.
2. It may percolate, or leach, through the soil.
3. It may be carried to the water as runoff.
(States of Jersey, 2007).
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33. Fishery losses
โข Pesticides are washed into aquatic ecosystems by water runoff and soil erosion.
โข Pesticides cause fishery losses in several ways.
These include
โ High pesticide concentrations in water that directly kill fish
โ The elimination of essential fish foods, like insects and other invertebrates.
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34. 10 Wild birds and mammals
โข Wild birds and mammals are damaged and destroyed by pesticides and these animals make excellent
โโindicator species.โโ
โข Deleterious effects on wildlife include
โ Death from the direct exposure to pesticides
โ Secondary poisonings from consuming contaminated food which reduced survival, growth, and
reproductive rates from exposure to sub-lethal dosages
โ Habitat reduction through the elimination of food resources and refuges.
36. Microbes and invertebrates
โข Pesticides easily find their way into soils, where they may be toxic to arthropods,
earthworms, fungi, bacteria, and protozoa.
โข Small organisms are vital to ecosystems because they dominate both the structure and
function of ecosystems (Pimentel et al., 1992).
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37. โข Agrochemicals as a management tool for optimum production practices had been a
reality to increased yield and quality of Agriculture product.
โข But a number of environmental pollution and health hazards have been associated
with application of pesticides and fertilizers.
โข The following recommendation and suggestion will decrease the detrimental effect
and safeguard the use of agro-chemicals.
39. Recommendation
i. Sales and use of pesticides must be legible to read the hazard and precaution for handling.
ii. Pesticides should be registered and recommended for use.
iii. All chemical should store away from food stuff to prevent accidental ingestion and
contamination.
iv. Washing of sprayers and empty containers should be avoided in rivers, streams and
near source of drinking water.
v. Use of personal protective equipment should be encouraged, reduce rate of inhaling fumes,
gas dust and spray vapor.