Even when talking about different types of pollution, we were unaware of these kinds of pollution such as plastic pollution, soil pollution, agricultural pollution, smog etc. But when we study the particular topic, it is very familiar to us. Thus let us understand what agricultural pollution is, their cause, types, prevention methods and effects, elaborately.
Pollution by agricultural practices has come up ever since the demand for food has increased, proportional to the increase in population. To increase the yield of farms and fields the farmers have had to resort to additional chemical fertilizers, pesticides, weedicides, hormonal treatments for the animals, nutrient laden feed and many such practices which changed the way farming was done traditionally.
What is Agricultural Pollution?
Agricultural pollution is contamination of the environment and related surroundings as a result of using the natural and chemical products for farming. This contamination is actually injurious to all living organisms that depend on the food on cultivation.
Causes of Agricultural Pollution
- Chemical fertilizers
These are mostly nitrogen and phosphorus based chemicals like ammonia and nitrates that in correct amounts boost the fertility of the soil. But in most cases these are used in more quantity than required and hence tend to be retained in the soil not adding to its goodness.
- Chemical pesticides
When pests and insects cause losses on a large scale, this leads to economic fallout for the farmers. Pesticides and insecticides like organochlorines, organophosphates and carbonates are toxic to the pests. They also tend to bio accumulate i.e. they collect in the body of the organism and lead to chronic poisoning. This can be passed up the food chain. Some pesticides also are absorbed naturally by the plants themselves and stored their different parts. Pesticides are not discriminatory in nature as they also cause harm to beneficial insects such as bees and pollinators,
- Heavy metals
Cadmium, fluoride, radioactive elements like uranium are regularly found in the parent minerals from which the fertilisers are obtained. Dangerous metals such as Mercury, Lead, Arsenic, Chromium, and Nickel are seen in traces in Zinc rich wastes from the steel industries which are used as fertilizers. These are often not removed from the because of the high cost involved.
- Excessive tillage of the land
Overturning, digging or stirring leads to release of greenhouse gases produced in the ground such as nitrous oxide
- Soil erosion
Loss of soil material due to poor management causes soil to become infertile
- Soil sedimentation
The soil or sediments carried off into water bodies cause a lot of harm. Sedimentation reduces the transportation capability of navigation channels. It reduces the amount of sunlight reaching the water beds affecting the plants and animals living in it. The turbidity it causes interferes with the feeding patterns of the fishes and affects their population. Sedimentation also affects the transport and accumulation of water pollutants
- Introduction of foreign species
Many instances of foreign species of plants, animals and insects were introduced to control pests and weeds. But after a while these have taken over and become nuisances themselves. They cause harm to indigenous flora and fauna competing for the natural resources, and also cause changes in the bio diversity. There has been loss of many indigenous beneficial creatures due to this kind of biological pest control.
- Genetic Modification to increase resistance to pest and diseases
A raging topic of debate today, it is a cause of concern for many that these crops will lead to the loss of many original species and may become weeds themselves. If these will be toxic to consumers ranging from insects to humans is to be studied in depth.
- Animal management
Farms specializing in rearing cattle, sheep, goats, pigs, and poultry must have strict regulations concerning the disposal of manure and other associated waste material. These must not be indiscriminately disposed in the surrounding areas. They cause pollution of the air as well as the water. 18 per cent of Greenhouse gases are said to be generated by farm animals. The large amounts of manure created, carry pathogens that are harmful for humans too. Proper animal waste management can reduce the huge bulk of it, making it easier to use.
Mechanisms (Types) of Agricultural Pollution
Leaching and Ground Water Poisoning
When chemicals accumulate in the soil, depending on its water solubility and soil structure it percolates through reaching the ground water, causing its contamination. This also depends on the rainfall. For example after applying pesticides on crops in sandy areas, if excessive irrigation is done, the pesticide chemicals leach into ground. Leaching occurs not only in the fields, but also at the manufacturing, mixing and disposal sites.
Only a fraction of fertilisers and other chemical additives are utilised on the fields. The major bulk mixes in the runoff water and flows into the nearby watercourses. This is mainly in the form of nitrates and phosphates.
Eutrophication is also called water nutrient enrichment. When chemicals rich in nitrogen and phosphorus are flushed into water from farms, this increases the nutrient levels in the water. this encourages the growth of the plants.
Algae benefit greatly from this. When they flourish and bloom they use up most of the oxygen levels in the water body leaving very little for the other life forms in it. This leads to the death of the fish and other animals in the water that cannot swim away to safety.
Algae blooms restrict the penetration of sunlight into the water. This affects the photosynthesis in plants and does not allow the restoration of oxygen levels by this process. Ultimately the water becomes unfit to support any form of life.
Certain toxins are also released by the algae themselves which travel up the food chain and affect the higher life forms adversely.
Prevention of Agricultural pollution
The priority is to keep the nitrogen and phosphorus rich nutrients from running off into the water sources near fields and animal farms.
- Prevention can never be a solo effort. The state governments, farmers’ organisations, collectives and cooperatives, educational institutions and conservation groups need to work together for regulating and reducing farming related water pollution.
- Planning the application of fertilizer at the right time, in the right quantity with the correct methods can reduce the run off
- Planting certain grasses and clovers that can absorb and recycle the additional nutrients and prevent soil erosion. Planting rows of trees and shrubs around fields and along the borders of the stream or lake also help in the same way.
- Over tilling of the soil must be avoided to prevent soil erosion and soil compaction.
- Managing the correct disposal of animal wastes and keeping farm animals away from water will reduce the nitrogen pollution of the water.
- Composting, solid liquid separation, anaerobic digestion and lagoons are different ways of managing animal manure. Of these anaerobic digestion is the most effective. It involves the use of anaerobic bacteria and heat. The products of this process are nutrient rich liquid used as fertiliser and methane gas that can be burned to produce electricity and heat. Anaerobic digestion is a best method for controlling odour associated with manure management.
Effects of agricultural pollution
Since agricultural pollution is not a lone standing entity, its effects are carried over as water pollution and air pollution. It affects every aspect of the environment and every organism from the earthworm to humans. Some of the adverse effects are as follows:
Drinking or swimming in water with dangerous levels of algal bloom causes rashes, stomach and liver problems, respiratory illnesses and neurological effects.
Infants drinking water with high levels of nitrates get affected by the blue baby syndrome which is often fatal. Symptoms are shortness of breath and blue tinted skin.
Formation of dead zones or hypoxic areas where no aquatic life exists; Examples Chesapeake Bay and Gulf of Mexico
Entry of toxins from algal blooms into the food chain hurts larger animals like dolphin’s seals and turtles etc.
Air pollution with nitrogen oxides leads to occurrences of smog because of the formation of ozone. Ozone pollution damages trees and forests.
Agricultural pollution also causes heavy economic losses. Cleaning up contaminated waters is costly. Tourism is affected by decrease in fishing and boating activities. Visibility at tourist locations and scenic spots are reduced by air pollution. Marble and limestone buildings are damaged by ozone pollution. Fishing and shellfish industries are also losing money to contamination. Real estate value that always rises when ground water and nearby water sources are in good condition suffer when the opposite happens.
Safe drinking water and clean water habitats are the rights of every living being. Let’s become more responsible in our agricultural practices in order to preserve this and make this available to all.