Ecological Impacts of Modern Agriculture

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Closer Look

Read this 2013 OXFAM report “Behind the Brands” for economic data on global agriculture and the “Big 10” food and beverage companies.

For consumers who can afford it, today’s industrial agriculture, fishing, and food processing system offers an array of food items that would have been inconceivable even a short 25 years ago. A contemporary supermarket in the United States averages over 38,000 products, though many of these items are owned by only 10 global food and beverage companies: Associated British Foods (ABF), Coca-Cola, Danone, General Mills, Kellogg, Mars, Mondelez International (formerly Kraft), Nestlé, PepsiCo, and Unilever. These companies are part of the worldwide industrial food growing, transporting, processing, marketing, consuming, and disposing system that is valued at over 7 trillion dollars, representing approximately 10% of the global economy.

One might think that the 450 million men and women wage earning laborers in this system around the world would benefit from participation in this lucrative food industry. In fact, 60% of these workers live in poverty. And without taking his eyes off these poor workers for a moment, Pope Francis is quick to point out at the very start of his encyclical Laudato Sí that, “the earth herself, burdened and laid waste, is among the most abandoned and maltreated of our poor”.

Closer Look

One source for information on the environmental and health impacts of the industrial food system is this Missouri Coalition for the Environment website.

The cost of the industrial food system to the environmental is high. This cost is not reflected in the price of a food item on a supermarket shelf. Were it so, consumers would buy sparingly, waste little, and recycle. As it is, many people in 'developed' countries do not see the negative impacts of the industrial food system on the environment when they purchase food. There are many print and internet resources that describe the environmental impacts of industrial agriculture. Here, space permits only brief remarks on a few of the features of this system.

Ecological Impact of Intense Mechanization

Primitive and low intensity mechanization has historically been part of human agriculture. It is the dramatic leap in size and scale of mechanization during and after the Green Revolution that has come to degrade the environment at unsustainable levels. We have already touched on this development in the above discussion on the historical development of agriculture. What can be added here is a concrete example of this intensified mechanization and some of its environmental effects.

Figure 17: Today, the John Deere Corporation sells a seed drill that is 120 feet wide and can
plant 48 rows at a time.1

Looking Back:

To review fossil fuel effect on climate change, see the Energy Chapter

As one example, a seed drill is a farming device that plants seeds. When it operates, a seed drill meters out individual seeds, inserts the seeds into the ground, and covers them with soil. One of the earliest mechanized, horse-drawn seed drills was developed in 1701 by Englishman Jethro Tull. By mid-20th century, a typical seed drill was 9 feet wide, held 12 bushels of seed, and was pulled by a 3,400 lb., 38 horsepower tractor. Today, seed drills can be 80 to 120 feet wide, hold over 800 bushels of seed, and be pulled by a 33,000 lb., 400 horsepower tractor (Figure 17). Such a leap in magnitude over a short period of time has deeply altered the relationship between human agriculture and the natural world.

Figure 18: The result of 150 years of industrial
farming in Illinois, USA. Left side of photo shows
the loss of over 1m of top soil in comparison to
land on the right where the plow never touched.1

  • 1.

    Credit: Rev. Stephen Mitten, S.J.

Environmentally, this leap has meant an exponential increase in fossil fuel consumption and emission, which has contributed to global climate change. At the same time, the sheer size and weight of such equipment degrades the fertile porosity of soil through compaction. Efficient use of such large machinery also requires an increase in tillage area, thus contributing to deforestation and soil erosion as wind sweeps over larger tracts of open land. Soil erosion is now a worldwide problem. Every year more top-soil is lost to erosion due to the effects of intense mechanization (Figure 18).

Ecological Impact of Expansive Irrigation

Irrigation is the practice of artificially supplying water to land that does not naturally have enough water to sustain the production of crops. Like mechanization, primitive and low intensity irrigation has existed since the earliest days of human agriculture. But also like mechanization, the leap in size and scale of irrigation today threatens the existence of the very land it hydrates, as well as the source of the water that is being extracted.

Figure 19: Various irrigation sprinkler systems: (a) a pivot irrigation system, which uses
large-scale sprinklers that rain on crops from an elevated location; (b) center pivot
irrigation, also called waterwheel and circle irrigation, a method in which sprinklers
rotate around a pivot located at the center of crops that are watered in a circular
pattern; (c) a ground sprinkler system.1

Typically, irrigation systems are brought into areas where the soil is too infertile or shallow or where the climate is too cold or dry to naturally support plant growth. Irrigation is brought into these areas to compensate for these otherwise hostile growing conditions. These irrigation systems use large quantities of fossil fuels to move large mechanized sprinkler systems (Figure 19) and pump groundwater from aquifers deep underground. As explained in the Water Chapter, water is a universal solvent. This means that deep underground water is typically rich in dissolved mineral salts like chloride (Cl-) or sodium. As this irrigated water evaporates from fields, any dissolved salts in the soil are left behind and begin to accumulate. This process of salt accumulation in soils is called salinization (Figure 20). Over time, the concentration of these salts can reach levels that reduce and eventually inhibit plant growth. Today, salinization is severe in many parts of Asia and is beginning to take a toll on soil fertility in the Western United States.

Figure 20: Salinization - a ground view (left) and an aerial view (right).1

Ecological Impact of Monoculture Farming

Industrial agriculture has achieved a greater degree of economic efficiency than traditional forms of agriculture by cultivating only one variety of crop over a large area of land. This is called monoculture farming (Figure 21). From an ecological point of view, however, the short-term economic gain of monoculture farming is defeated by the long-term harm done to the environment, through soil erosion, soil compaction, fossil fuel consumption, water consumption, and high levels of pesticide and fertilizer application. We have already seen an example of this at the beginning of this chapter in the Guatemalan Palm Oil Case Study.

In order to plant thousands of rows of a species of crop quickly and without costly human laborers, heavy farm equipment is used for tilling and preparing soils, for seeding, applying fertilizers and pesticides, and harvesting. This equipment causes soil compaction, erosion, and requires large amounts of fossil fuels to operate. The soils are further degraded by the heavy use of herbicides and insecticides which deplete the important soil flora discussed previously in this chapter.

Figure 21: Monoculture of winter wheat. 1

Monocultures accelerate soil nutrient depletion. Every species of plant requires a slightly different proportion of micro and macro nutrients. Planting monocultures on the same ground year after year destroys soil nutrients, whereas planting different species together reduces the likelihood of depleting any one nutrient. Monocultures therefore require high inputs of chemical fertilizers to maintain a high crop yield.

Because monocultures lack diversity, they are especially prone to pest outbreaks (Figure 22). Pests can easily locate their host plants when grown in vast monocultures. This provides pests with a nearly unlimited food supply. As a result, it is usually necessary to use pesticides to prevent pest outbreaks in monoculture plantings, as compared with polyculture farms.

Figure 22: Extensive damage done to cabbage by cabbage moth larvae.1

Ecological Impact of CAFOs

Anatomical and archaeological evidence shows that humans and our ancestor hominids have been eating meat for over a million years. For most of human existence this meat has been obtained through either fishing and hunting, or pasturing domesticated animals, called livestock.

Closer Look

Read more here on Concentrated Animals Feeding operations (CAFOs).

Since the Green Revolution, livestock yield has been greatly enhanced by the development of biotechnological methods. For example, most cattle require four years to fully develop from newborns to adults that are fully grown and ready for slaughter. Today, the lifespan of cows can be shortened by 50% if animals are treated with growth hormones. To facilitate these treatments, industrial farms cage cows, pigs, chickens, and turkeys in confined, overcrowded spaces where they have little or no room to move and no ability to carry out their natural functions of mating, nest building, birthing, nursing, and browsing. The reason for the confinement is that it saves the animal's energy. The energy that would naturally be used for walking, nest-building, fighting, mating, and giving birth is now allocated solely to growth, basic metabolism, and weight-gain--the goal of the farmer. By conserving the animal's energy and giving it growth hormones to speed its natural rate of development, the process of raising livestock becomes much more economically efficient, while being inhumane and stressful for the animals, and extremely detrimental to the quality of the rivers and lakes that receive the fecal runoff from these operations. These animal production facilities are known as Concentrated Animal Feeding Operations (CAFOs) (Figure 23).

Figure 23: Concentrated Animal Feeding Operations (CAFOs) - hogs, cows, and chickens -
in the U.S. are designed for maximizing efficiency and yield, but provide little natural
functioning for the animals.1

In addition to growth hormones, animals confined to CAFO's must be injected with antibiotics to prevent the spread of disease due to over-crowding and the prevalence of fecal material. These growth hormones and antibiotics remain in the meat that we eat. The manure that was once considered a valuable nutrient for the pastures that animals grazed upon has become, in CAFOs, a waste product that typically runs off into nearby waterways causing pollution, eutrophication, and dead zones in lakes and oceans. For more information on dead zones, see this website by the US National Ocean and Atmospheric Administration (NOAA).

Ecological Impact of Pesticides, Insecticides, and Herbicides

Pesticides are chemicals that control insects, worms, fungi, and weed plants in cultivated fields that can present a significant challenge to farmers around the world, especially when planting large monocultures of single crop species. While some pesticides are derived from naturally occurring biological compounds, most are environmentally harsh, synthesized chemicals created in industrial facilities.

Closer Look

Read more here on genetically modified organisms (GMOs).

Insecticides are a subset of pesticides used specifically to control insects There are 9-10 major chemical groups of insecticides. The most commonly used today include organophosphates like diazinon, organochlorides like DDT, and neonicotinoids. Another form of insecticide used today is created by genetic modification biotechnology. This method extracts genes from naturally occurring soil bacteria such as Bacillus thuringiensis (Bt) that produce insecticidal proteins. These genes are then incorporated into various crop plants (like corn) to confer protection from insect herbivores. The genetically modified (GMO) corn, called Bt-corn, produces the insecticidal protein which is toxic to certain species of Lepidoptera (moth and butterfly) larvae that typically feed on corn.

Herbicides, also a subset of pesticides, are biological or chemical toxins developed to kill weeds that grow among crops and compete for crop resources. The world’s most widely used herbicide today is glyphosate. The most popular glyphosate-based herbicide today is a Monsanto Corporation product called Roundup. Roundup is highly toxic to all species of plants, most bacteria and Archaea, and is a known carcinogen in humans.

Because the high toxicity of Roundup kills both weeds and crops, Monsanto developed a plant gene resistant to glyphosate. Monsanto introduced this gene to many crops, creating a “Roundup Ready” GMO that is impervious to the toxins in Roundup. Today, Roundup can be broadcast from pesticide applicator planes to kill weeds, leaving the genetically modified crop plants unharmed.

While natural pesticides, insecticides, and herbicides are important tools for farmers, human-made chemical and genetic varieties like Roundup and Roundup Ready constitute serious threats to human and environmental health. For example, it is well-documented that pesticide exposure to human field laborers increases their risk of cancer. The general population also acquires this risk when consuming food that has pesticide residue on it.

Pesticide use can also lead to evolved resistance in both weed plants and pest insects. This means that the weeds or insects in a population that have become resistant to a given pesticide can successfully reproduce following pesticide application. These surviving pests pass the genes with resistance on to their offspring and, over several weed plant or insect generations, the pesticide is no longer effective. A common response to this phenomenon is to apply the pesticide in a higher concentration or produce an even more lethal pesticide, only to increase the risk to human and environmental health.

Figure 24: Bee pollination services play a critical
role in both crop and natural ecosystems, and
many plant species would rapidly go extinct
without pollination.1

Insecticides, especially neonicotinoids, have been linked to the decline of domestic honeybees and wild bee species, a condition known as colony collapse disorder. Bees are the most important group of pollinators, as their pollination is necessary for more than a third of the food plants on which humans rely for sustenance (Figure 24). Chemical herbicides also directly impact pollinators such as bees and butterflies. Many of the weeds that grow between crop rows are flowering plants that supply substantial amounts of nectar and pollen to pollinators, so adding herbicides to these 'weeds' further stresses the pollinators by eliminating and poisoning their forage.

Ecological Impact of Chemical Fertilizers

Closer Look

Read more about [INSERT HYPERLINK TO HONEYBEE CL] and the central role they play in food production through pollination. You can also watch What Happens When All The Bees Die

Soil amendments (or additives), such as animal dung, human excrement or decaying plant material, have long been a part of human crop cultivation because they confer necessary nutrients and increase soil fertility. Today, conventional farming uses synthetically-produced nutrient blends, called chemical fertilizers, to enhance plant growth.

Nitrogen (N), phosphorus (P), and potassium (K) tend to be the elements that limit plant growth, so most synthetic fertilizers contain N, P and K in the ratio of 15:1:5, the same ratio that these elements are found in typical plant tissues. Phosphorous and potassium come from the lithosphere and have historically been relatively easy to obtain through surface mining. However, most of the nitrogen on Earth that is not already incorporated into plant or animal bodies is contained in the atmosphere in the form of dinitrogen gas (N2). Although dinitrogen gas comprises 78% of the air we breathe, it is not biologically available to plants for uptake in this form. The nitrogen must therefore be “fixed” into a form that makes it nutritionally available to plants, including ammonia (NH3+) and nitrate NO3=.

Looking Back:

To review the Planetary Boundaries chart, turn back to the Science section of the Biodiversity Chapter

One of the most important technological developments in human history is the ability to synthetically convert nitrogen gas into ammonia. This process was invented by the German chemist, Fritz Haber in 1910, and was expanded to an industrial scale by Carl Bosch over the following decade. Both chemists were awarded Nobel Prizes at the time for the enormous boost to crop yield that cheap nitrogen fertilizer produced. Today Earth's nitrogen cycle is so far out of balance due to the Haber-Bosch process that many waterways are polluted with excess nitrogen fertilizer, which causes harmful algal blooms and dead zones world-wide. This is but one example of the unanticipated and unintended consequences of technological advances in the food system.

Looking Back:

To review more detailed information about the Haber-Bosch process of nitrogen fixing, turn back to the Science section of the Natural Resources Chapter

The Haber-Bosch process is still used extensively for fertilizers, producing about 450 million tonnes of ammonia annually, which greatly exceeds the amount produced through natural nitrogen fixation. While the additional nitrogen availability has undoubtedly allowed for significant crop yield increases, our overuse of nitrogen fertilizers has led to a serious over-shooting of the planetary boundary for nitrogen.

Scientists have also recently discovered widespread evidence of increased atmospheric nitrogen deposition in areas of the world that are not using synthetic fertilizers locally and seem otherwise uninfluenced by human impact. This 'foreign' nitrogen originates from dust in fertilized fields that is blown into the atmosphere and later settles in continents far from its original source. The deposition of bio-available forms of nitrogen in regions that were once nitrogen-limited significantly changes the native plant community dynamics. This can lead to the loss of important native plant species that had a competitive advantage in low nitrogen regions, along with the loss of insects and other animals that have evolved within low-nutrient areas and are dependent upon these native plant communities.

Questions to Consider

  • Can you think of any method that could be used to prevent, or at least reduce, the unintended negative impacts of new agriculture technology on the environment?
  • If you had the power to change one negative environmental impact of industrial agriculture, which would you choose and why?