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 20 years ago. A contemporary supermarket in the United States averages over 38,000 products. 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 production, processing, distribution, consumption, and disposing system.

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, up to 60 percent of agriculture and food workers in many countries live in poverty. It is estimated that globally the industrial food system 'employs' nearly 130 million child laborers between the ages of 5 and 171. Without taking his eyes off this human situation, Pope Francis adds another member to the ranks of the poor. "The Earth herself, burdened and laid waste," says the Pope in Laudato Sí, "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 Union of Concerned Scientists website.

From an environmental science perspective, the ecological cost of the industrial food is high. This cost is not included in the price of a food item on a supermarket shelf. Without this inclusion in price, many if not most food-purchasers in high-tech, industrially developed countries are not aware of the negative effects of the industrial food system on the environment. Were ecological costs included in food prices, most consumers would likely begin buying less non-nutritious food, wasting less food, and (where possible) planting gardens and composting food scraps.

What are some of the ecological costs of the industrial food system? Space permits only brief remarks on a few of these impacts. We will cite places to go for more information on this topic in the Additional Resources section of this chapter.

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 threaten the environment. We have already touched on this issue in the above discussion exploring the historical development of agriculture. What can be added here is a few concrete examples of this intensified mechanization and some of its environmental effects.

Figure 15: Today, the John Deere Corporation sells a seed drill that is 120 feet wide and can
plant 48 rows at a time.1

One example can be found in the seed drill. 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 15). Such a leap in magnitude over a short period of time has deeply altered the relationship between human agriculture and the natural world.

Figure 16: 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, a topic we discussed in the soil section above. To efficiently use such large machinery it is best to increase as much as possible the area being tilled. Yet, scientists estimate that nearly all of Earth's tillable land (3.7 billion acres) is now under cultivation. The deforestation that has accompanied this scale of has promoted soil erosion as wind sweeps over larger tracts of open land. Today, such soil erosion is major global problem (Figure 16). And as Daniel Botkin and Edward Keller note in their book Environmental Science, "[m]ore soil is lost each year to eroision (about 26 metric tons) than is formed."2

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. Primitive and low intensity irrigation has existed since the earliest days of human agriculture. Today, mechanization has created a quantum leap in the size and scale of irrigation (Figure 17). In many areas, this leap has created problems for the land being hydrated and the water being used.

Figure 17: 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

Irrigation systems are often brought into areas where the soil is too infertile or shallow or where the climate is too cold or dry to support natural plant growth. 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 18). 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 18: Salinization - a ground view (left) and an aerial view (right).1

The Ogallala Aquifer under the Great Plains in the United States is one of the largest sources of fresh water on Earth. At some places, the aquifer's water depth exceeds 1000 feet. Since World War II, large-scale center pivot irrigation has caused the rate of water extraction from the aquifer to far exceed the rate of recharge. The Ogallala Aquifer is recharged by Great Plains rainfall. The average yearly rainfall recharge rate is one inch. When compared to the current yearly extraction rate of approximately two feet per year, there may come a time when the Ogallala runs dry. Today, the aquifer water level in many areas is down 300 feet from its pre-irrigation level. Over 30% of that depletion has occurred in the last 20 years. Some scientists estimate that at current extraction rates, the Ogallala could be emptied within the next 50 years. In some areas this could happen sooner, in other areas possibly later (Figure 19).3 The total depletion of the Ogallala Aquifer would have a devastating environmental impact, not to mention the impact on people living in the Great Plains, 82% of whom rely on the aquifer as their water source.

Figure 19: Ogallala Aquifer Water-Levels in Decline.1

Ecological Impact of Monoculture Farming

In many areas of the world, 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 20). From an ecological point of view, the short-term economic gain of monoculture farming is ultimately defeated by the long-term harm it does 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 these effects in the Guatemalan Palm Oil Case Study that began this chapter.

Figure 20: Monoculture of winter wheat. 1

What may be added to the environmental problems of monoculture farming is the accelerated depletion of soil nutrients. Every plant species requires a slightly different proportion of micro and macro nutrients. Planting monocultures on the same ground year after year destroys soil nutrients. This then calls for high inputs of chemical fertilizers to maintain a high crop yield.

Because monocultures lack diversity, they are especially prone to pest outbreaks (Figure 21). 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 farms that grow a diverse array of crops.

Figure 21: Extensive damage done to cabbage by cabbage moth larvae.1

Ecological Impact of CAFOs

Anatomical and archaeological evidence shows that our ancestor hominids and we homo sapiens have been eating meat for over a million years. For most of that time, meat was obtained through fishing, hunting or pasturing domesticated animals.

Since the Green Revolution, livestock yield has been greatly enhanced by the development of biotechnology. For example, most cattle require four years to fully develop from newborns to adults ready for slaughter. Today, the lifespan of cows can be shortened by 50% if animals are treated with growth hormones. To facilitate these treatments, cows, pigs, chickens, and turkeys are caged 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. These industrial-scale animal production facilities are known as CAFOs, Concentrated Animal Feeding Operations (Figure 22).

Figure 22: 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

The reasoning behind CAFOs is to direct as much of an animal's energy as possible to the production of food commodities such as meat, milk, and eggs. The energy that would normally be used for walking, nest-building, fighting, mating, and giving birth is redirected in a CAFO to growth, basic metabolism, and weight-gain. By conserving the animal's energy and giving it growth hormones to speed its rate of development, the process of raising livestock increases quantity and economic efficiency.

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. Consider also the manure genenerated in CAFOs. This once valuable nutrient for animal pastures is now a waste product held in CAFO pools and a runoff that causes pollution, eutrophication, and dead zones in lakes and oceans.

Ecological Impact of Pesticides, Insecticides, and Herbicides

Pesticides are used to control insects, worms, fungi, and weed plants in cultivated fields. While some pesticides are derived from naturally occurring biological compounds, most are environmentally harsh, synthesized chemicals. Many of these chemicals were the direct result of developments in chemical weaponry during World War II. As Josh Tickell writes in his book Kiss the Ground, “In the first seven years after the war some ten thousand new pesticides were registered with the USDA [United States Department of Agriculture].”4

Insecticides are a subset of pesticides used specifically to control insects. There are ten major chemical groups of insecticides. The most commonly used today include organophosphates like diazinon, organochlorides like DDT, and neonicotinoids like dinotefuran. 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.

Looking Ahead

An invasive pest from the Americas is now threatening India's food security. You will read about this in the upcoming Action Section.

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 seed 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. 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 contains pesticide residue.

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.

Closer Look

Read more about honeybees and the central role they play in food production through pollination. You can also watch What Happens When All The Bees Die

Figure 23: 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 vitally important pollinators. There pollinating activity is necessary to more than a third of the food plants on which we rely (Figure 23). 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

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, the industrial food system 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-.

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 another 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 tons 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 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

  • If you had the power to change one negative environmental impact of industrial agriculture, which would you choose and why?
  • There is significant disagreement between people over the purpose of industrial agriculture. Why do you think that is the case?