• Agricultural Pollution – Types, Causes and Effects

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Agricultural Pollution – Types, Causes and Effects

Nov 10 2022

Over recent centuries, the global population has increased almost exponentially and is projected to reach almost 10 billion by 2050. Clearly, cultivating enough food to sustain that ever-increasing number of mouths is a gargantuan task but, thanks to the advances of science and technology, one of which the human race has proven capable thus far.

The development of fertilisers has helped to boost growth rates and maximise crop yields, squeezing the most amount of produce possible from the land. Meanwhile, pesticides, herbicides and fungicides have protected these crops from flora and fauna which may encroach on their growth, ensuring that humans access as many of the fruits of their own labour as possible.

While these developments and techniques have certainly been beneficial in increasing the amount of food we are capable of producing, they have not been without their unintended negative impacts. Indeed, modern agricultural methods are responsible for a significant amount of pollution, which comes in a variety of types, has a multitude of causes and incurs a number of undesirable effects. This article will delve into those particulars in more detail, as well as investigating how they may be overcome in the future.

What are the different types of agricultural pollution?

There are a wide range of ways in which farming and livestock rearing pollutes the natural world. However, for simplicity’s sake, we have narrowed things down to three broad categories of agricultural contamination: air pollution, soil pollution and water pollution.

Air pollution contaminates the quality of the air in the immediate vicinity of a farm or other agricultural location, while it can even infiltrate environments further afield if carried there by the wind. It can also contribute towards global warming and climate change, which are two of the biggest issues facing the planet today.

Soil pollution can negatively impact the biodiversity of the soil, reducing the number of lifeforms which can thrive in it and making it less fertile for cultivation in the future. It can also become eroded due to over-tilling and excessive irrigation, while it can be swept into nearby bodies of water in times of heavy precipitation.

Which leads us on to water pollution caused by agriculture. Rivers, lakes, streams and coastal waters in the vicinity of a farm can be negatively impacted by run-off and sedimentation of soil or chemicals displaced by industrialized agriculture. Contaminants can also seep into groundwater beneath the soil and potentially jeopardise drinking water supplies.

What causes agricultural pollution?

The factors contributing to agricultural pollution are as manifold and diverse as they are damaging. Indeed, many of the scientific and technological innovations intended to help safeguard the future survival of the human race could end up jeopardising it through the unforeseen consequences that they have engendered.

For example, fertilisers may have optimized crop yields, but they are often used wantonly and recklessly, resulting in oversaturation of the soil. This can imbalance nutrient levels underground and contribute to fertility and groundwater quality problems in the future, while there are even more serious repercussions if excessive precipitation is allowed to wash the chemicals (such as ammonia, nitrates and phosphorus) contained within the fertilisers into surrounding bodies of water.

Pesticides are perhaps even more harmful. While chemicals like carbonates, organochlorines and organophosphates may effectively target insects and other unwanted creepy-crawlies which can reduce crop yields, they are indiscriminate in their efficacy. That means that other animals (such as birds and small mammals) may ingest plants or bugs containing the chemicals and suffer adverse reactions of their own. Meanwhile, beneficial pollinators, such as butterflies and bees, are also vulnerable to poisoning from pesticides. Their decline has far wider ramifications for the ecosystem.

Aside from chemical additives, modern methods of farming are also contributing to pollution in other ways. For example, the intensity with which crops are produced, especially in monoculture environments, is wreaking significant damage on soil quality. Over-tilling of the land and improper irrigation techniques not only consume vast amounts of resources, but actively damage the health of the soil, thus negatively impacting the biodiversity within it. In many parts of the world, forested areas are being felled to make way for more arable land, while the practice of stubble burning – which is outlawed in most countries but remains prevalent nonetheless – produces vast amounts of air pollution.

Meanwhile, the global preoccupation with a meat-based diet means that more and more livestock are being reared around the world. Much of the crops produced today go towards feeding cows, sheep, goats, pigs and other animals bred for slaughter, thus creating an outsized footprint of the resources consumed. What’s more, ruminant animals are responsible for significant emissions of methane, which pollutes the air and contributes to global warming. That’s not only through emissions caused by flatulence, but also the inadequate storage, disposal or application of the manure they produce.

Elsewhere, manually tilling, sowing and reaping the land has become a thing of the past, as machinery, vehicles and electrical equipment have made farming more efficient. The downside of these technological breakthroughs, however, is that they produce various greenhouse gases, airborne chemicals and other pollutants that impinge on ambient air quality.

What are the effects of agricultural pollution?

The real-world effects of this agricultural pollution are concerning indeed. For example, the rampant use of pesticides and fertilisers can be devastating for soil quality, meaning that the ground is gradually becoming less fertile over time. It can also be eroded and end up as sediment in nearby bodies of water, which makes the habitat murkier and allows less sunlight to infiltrate it. This, in turn, inhibits photosynthesis, meaning aquatic plant life suffers.

It's not just the soil that has a negative impact on water quality and the health of the ecosystems within it, either. Agricultural run-off sweeps excess chemicals into rivers, streams, lakes and coastal areas, leading to an abundance of certain substances such as ammonia, nitrates and phosphate. This encourages the rapid proliferation of certain species – such as algae – to the detriment of others. That’s because the process of eutrophication means algal blooms block out sunlight and consume more than their fair share of oxygen, making it more difficult for other flora and fauna beneath the surface of the water to survive.

As well as negatively impacting soil and water quality, fertilisers and pesticides can also create air pollution. In strong winds, they can become airborne before they even land on their intended target, or else evaporate into the air over time. They can then be blown long distances and serve as damaging contaminants in their own right, or else mix with other elements in the air, like volatile organic compounds (VOCs) and polyaromatic hydrocarbons (PAHs) to create even more damaging types of pollution, such as particulate matter (PM) and ozone (O3). These are known to have potentially disastrous repercussions for human health when exposure occurs over an extended period of time.

Finally, it’s not just the health of the humans, animals and plants in the vicinity of a farm which can be compromised by agricultural activity, but that of the planet itself. The aforementioned emissions associated with using agriculture machinery and rearing livestock are a leading contributor to the greenhouse gases in our atmosphere; indeed, the EPA estimates that the industry is responsible for almost a quarter (24%) of all greenhouse gas emissions worldwide.

Carbon dioxide produced as a by-product of many agricultural processes persists in the atmosphere for centuries or even millennia, trapping heat from the rays of the sun and raising ambient, oceanic and ground-level temperatures and contributing to more intense and more frequent extreme weather events. Meanwhile, the methane produced by livestock cultivation is maybe even more concerning; although it persists in the environment for a far shorter time period, it has a global warming potential (GWP) over 80 times that of CO2 over a 20-year period.

What can be done to address agricultural pollution?

While all of the above might make for grim reading, the good news is that it is eminently possible to substantially curb the pollution produced by agriculture. It will, however, require collaboration and a concerted effort from farmers, governments and consumers to effect that change.

Concrete methods by which the negative environmental impacts of farming can be addressed include better optimisation of resources. This includes only consuming the volume of water and the amount of chemical additives that are absolutely needed; thankfully Big Data and artificial intelligence (AI) can help to achieve this goal through precision farming. If fewer products are being used, fewer contaminants can infiltrate the environment. Organic farming is another eco-friendly means of growing crops, though it is more expensive and less productive than other methods.

Elsewhere, agricultural run-off and all of its attendant outcomes can be mitigated by better use of the land in question. Planting grasses, reeds, shrubs and trees at the periphery of farmlands can act as natural filters so that in the event of flooding, contaminants are caught and retained onsite instead of being allowed to pollute the surrounding air, soil and water. Rotating crops and avoid overworking of the land can also help to boost soil health and prevent negative impacts associated with intensive farming.

As for livestock, a global shift towards a diet that focuses less on meat and more on plant-based alternatives is perhaps the biggest single thing that we can do to address agricultural pollution. However, farming is of course a demand-based industry and as long as people continue to buy animal produce, farmers will continue to supply it. Aside from this grassroots change, livestock farmers can also better manage manure on their property and investigate ways to harness the methane emissions that their animals produce.


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International Environmental Technology 32.6 - Nov/Dec 2022

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