DUE IN 16 HOURSFood Resilience Plan for Ashfordton [WLO: 2] [CLOs: 2, 3]Prior to beginning work on this discussion forum, read Chapter 4 in your course textbook.Imagine that you are a resident of Ashf
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Sustaining Our Agricultural Resources
Room crowded with white chickens inside a farming facility.
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Learning Outcomes
After reading this chapter, you should be able to
Describe the origins and history of agriculture.
Compare and contrast modern, industrialized agriculture with traditional agriculture.
Explain what constitutes healthy soil and how it affects plant life.
Describe the impact of chemical pesticides on the environment.
Describe the impact of synthetic fertilizers on the environment.
Describe the ways industrialized agriculture is dependent on water and fossil fuels.
Analyze how animal production and concentrated animal feeding operations create environmental problems.
Describe how sustainable farming strategies differ from unsustainable ones.
Evaluate the choices you can make to promote sustainable agriculture practices.
Outline some high-tech, sustainable farming techniques.
Describe the arguments for and against genetically modified organisms.
In October 2018 the scientific journal Nature published a major research report that presented a troubling picture of the future of food, agriculture, and the environment (Springmann et al., 2018). The authors of the report—including scientists from the United States, Europe, and Australia—argue that, based on current trends, we will see an increase of 50% to 90% in the negative environmental impacts of food production by the year 2050.
Their prediction is based on three key factors. First, as presented in Chapter 3, global population is expected to increase from roughly 7.7 billion people today to almost 10 billion by 2050. Second, the demand for food is actually growing faster than the population is, as rising incomes in countries like China result in more demand for meat and other animal proteins, which require more resources to produce. And third, current agricultural practices are already a significant contributor to major environmental problems like deforestation, air and water pollution, and global climate change.
The Nature report used the planetary boundaries concept described in Chapter 2 to argue that we need to change the way we produce, distribute, and consume food if we are to feed 10 billion people and not ravage the environment. We already use half of Earth’s ice-free land surface for grazing livestock and growing crops to feed animals, and 77% of the Earth’s land surface has already been developed or modified by human activities, up from just 15% a century ago. Every year, more and more forests, including biodiversity-rich tropical rain forests, are cleared for agriculture. Agriculture uses roughly 70% of global freshwater supplies. Meanwhile, roughly one third of global food production ends up being discarded as waste each year. This last fact is especially troubling, given that roughly 3 billion people are malnourished and that 1 billion suffer from outright food scarcity and shortages.
Given these trends, and given the fact that agriculture and food production are essential human activities, the Nature report focuses on the need to reduce the environmental impact of current agricultural practices. This chapter will contrast the unsustainable approaches to agriculture, which currently dominate, with sustainable approaches that we will need to adopt in the decades ahead. It starts with a brief review of the origins and history of agriculture and how it has shaped human history through time. This is followed by a review of the basics of soil, climate, and plant growth. We then examine how current agricultural practices are affecting the environment and why these practices are not sustainable. This is followed by a discussion of sustainable agricultural practices, including ideas presented in the Nature report, designed to help us stay within key planetary boundaries. Finally, the chapter will explore the somewhat controversial issue of genetic engineering and genetically modified organisms.
4.1 The Origins and History of Agriculture
As discussed in Chapter 3, most of human history occurred during what could be called the preagricultural period. Modern humans, or Homo sapiens, have been in existence for roughly 250,000 years, and for 95% of that period, they relied mainly on hunting and gathering to meet their needs for food and sustenance.
The Beginnings of Agriculture
Beginning about 10,000 years ago, however, human societies started to develop and rely on agriculture to meet their needs for food and sustenance. Agriculture is an approach to land management designed to grow domesticated plants and raise domesticated animals for food, fuel, and fiber. Anthropologists believe that this transition from hunter-gatherer to crop domestication and cultivation occurred for a couple of reasons. First, the climate was going through a natural warming cycle after a period of glaciation, and warmer and wetter conditions were more conducive to agriculture. Second, population growth among hunter–gatherer communities may have reached a point at which wild food sources were becoming scarce. Crop domestication and agriculture allowed these communities to grow more food on a given amount of land, and the first crops that were domesticated were easy to grow, dry, and store. Early agriculturists also began to settle in specific locations and to domesticate animals like dogs, goats, sheep, and pigs. Eventually, these more settled communities grew into small villages and even cities, and over the next 8,000 years, the human population of the planet grew from a few million to hundreds of millions of people.
Beyond crop selection and plant and animal domestication, other developments and technological advances helped increase agricultural productivity over time. The domestication of cattle was soon followed by the invention of the plow, allowing early farmers to cultivate more land using less human energy. Evidence of irrigation—the deliberate diversion of water to crops—dates back at least 5,000 years, and this helped expand the area under cultivation. Improvements in metal production, crop storage, and transportation also contributed to increased agricultural productivity over thousands of years.
Despite these developments, however, agriculture in the year 1500, 1600, or 1700 would have looked similar to what was being practiced 2,000 to 3,000 years before that. Increased land under cultivation allowed for more food production and population growth, but these increases occurred slowly over centuries and millennia.
The Modernization of Agriculture
Antique piece of farm equipment called a thresher sits on display at a farm.
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Early farming machines, such as the steam-driven thresher pictured here, changed agricultural practices during the Industrial Revolution.
That situation began to change around the beginning of the industrial period, roughly 200 years ago. The world population was hitting the 1 billion mark, and the Reverend Thomas Malthus argued that human population was growing faster than food production. The result, Malthus predicted, would be increasing starvation, famine, and disease, as well as social collapse, as human numbers outstripped food supply. However, despite some devastating famines in places like Ireland and India, food production was generally able to keep up with a growing population. New lands that had been colonized were put into agricultural production (especially in the Americas), and the invention of agricultural machinery made farming more efficient.
At the same time, scientific advances in fields like chemistry, plant genetics, and soil science boosted crop productivity per unit of land. In particular, breakthroughs in the production of synthetic fertilizer in the late 19th century, especially in the production of nitrogen fertilizer on an industrial scale, enabled continued increases in food production. Fertilizers are substances that add nutrients to the soil, thereby encouraging plant growth. While traditional farmers had long made use of available organic material for fertilizer, it’s estimated that without the development, mass production, and use of synthetic nitrogen fertilizers, the world’s population would never have exceeded 4 billion (Smil, 1997).
The Green Revolution
By the 1960s world population had reached 3 billion people, and another 1 billion were being added every 12 to 14 years. Massive famines in China, sub-Saharan Africa, and southern Asia claimed millions of lives and led to a return of Malthusian thinking about population and food security, whereby everyone has access to an adequate and reliable food supply. It was at this time that ecologist Paul Ehrlich published The Population Bomb, warning of mass starvation and upheaval due to human population growth. However, a series of advances in agricultural production that came to be known as the Green Revolution also occurred.
The Green Revolution was not the result of a single scientific breakthrough or technological development but rather the collective result of a number of changes in the way humans grew food. Plant breeders developed new, high-yielding varieties of wheat, rice, and corn that produced as much as four times the amount of grain per acre as conventional varieties. Expanded use of irrigation systems, synthetic fertilizer, and chemical herbicides and pesticides allowed farmers to grow even more crops on the same fields. The results of these changes were dramatic. From 1960 to 2014 global production of the five main cereal crops—corn, rice, wheat, barley, and sorghum—increased by an estimated 280% and yields by an estimated 175%, while the land area devoted to cereal production increased by only 16% (Ritchie, 2017).
The Challenges of Today
Today we may need another Green Revolution to keep up with continued population growth, changes in diet, and the environmental impacts of modern, industrialized approaches to agriculture. The impressive increases in yield achieved in the first few decades of the Green Revolution have begun to level off. At the same time, we continue to add roughly 75 million new people to the planet each year. Perhaps more importantly, many of the agricultural practices that emerged during the Green Revolution—including the heavy use of irrigation, synthetic fertilizers, and chemical pesticides—are taking a severe toll on the environment.
Rapid advances in science and technology have allowed us to feed a population that has grown from 1 billion to over 7.7 billion in just 200 years. However, there is overwhelming evidence that our current approaches to feeding the world are pushing us close to or beyond planetary boundaries and environmental limits. Clearly, feeding the world as human population reaches 8, 9, or 10 billion will require a change if we are to once again avoid the worst Malthusian predictions of the past.
4.2 Characteristics of Industrial Agriculture
The Green Revolution ushered in what is now known as industrial agriculture. These industrialized approaches have enabled food production to keep pace with population growth, but they differ in fundamental ways from the traditional farming practices that were in place for almost 10,000 years. To better understand the environmental impacts of industrialized agriculture and identify more sustainable alternatives to farming, it’s instructive to compare industrial agriculture with what is known as traditional agriculture. Agriculture is a necessary part of human civilization, and the challenge will be to combine the technological advances of industrialized agriculture with the sustainable practices of traditional agriculture to feed a growing human population.
Linear
First, whereas traditional agricultural practices are based on cyclical systems common in nature, industrial farming is highly linear and modeled on industrial systems. Industrial agriculture is sometimes referred to as “factory farming” because it is focused mainly on inputs (pesticides, fertilizers, seeds, water) and outputs (corn, wheat, soybeans, meat). The primary goals are to increase production and yield while decreasing costs of production.
Corn kernels pouring out onto a mountain of corn in a trailer.
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While traditional farms grow a variety of crops, industrial farms almost always raise one single crop.
A traditional farm will likely raise a variety of crops and be home to animals like horses, cows, pigs, chickens, goats, and so on. These animals’ waste products in the form of manure are used as fertilizer on crops, some of those crops are fed to animals, and the cycle begins again.
In contrast, an industrial farm will likely focus on raising a single crop. The farmers “import”—rather than generate on their own farms—seeds, fertilizers, pesticides, herbicides, water, and energy for equipment to grow that crop. In the United States and other developed countries, much of the production from these types of farms is soy and corn that is then fed to animals (mainly cows, chickens, and pigs). The animals are then fed to people, and waste products from both the animal production facilities and people are treated in sewage treatment facilities before finally ending up in water bodies (in the case of liquids) or landfills (in the case of solids). After that, the farmer goes back and “imports” a whole new set of inputs to start the process all over again.
Designed to Maximize Output
Second, whereas traditional agriculture focuses on the production of a wide variety of crops, animals, and other products, industrialized farming is designed to maximize the output of a narrow range of crops.
A diversity of crops and animals, sometimes referred to as polyculture farming, better assures the farm family of meeting its needs. At the same time, as will be discussed later in the chapter, this diversity mimics natural systems and is thus better for the environment. Traditional farming also generally includes the management of some trees, a practice known as agroforestry. Trees provide fuel, fruit, nuts, building material, and help with on-farm water retention and management.
In contrast, nearly all large-scale agriculture today is based on planting a single crop over large areas of land to maximize productivity. Whereas in the past a typical farm might produce as many as 10 different agricultural products for market, today a farm is more likely to grow a single crop like corn or soybeans. Agricultural mechanization combined with heavy inputs of agricultural chemicals allows a single farmer to grow the same crop on thousands of acres of land, something that would have been unimaginable just a few generations ago.
This kind of agriculture, known as monoculture farming, raises a number of concerns. The overreliance on a small number of genetically similar crop varieties increases the risk that a widespread insect infestation, crop disease, or fungal infection could wipe out a major global food source. In addition, large-scale monoculture farming tends to reduce the number of farmers and farm families living in rural areas. Some observers have associated this phenomenon with the loss of community and economic diversity in these areas (Union of Concerned Scientists, 2019).
Reliant on External Inputs
Finally, whereas traditional agriculture tends to be self-sustaining, industrialized farming is heavily reliant on external inputs to survive. Today’s industrial farmers depend on chemical pesticides and herbicides to control insects and weeds and must apply increasing amounts of synthetic fertilizers to maintain crop yields. Industrial farmers also require large amounts of water and fossil fuel energy resources. The environmental impact of these realities will be the focus of much of this chapter, and the chapter will also explore how ideas and practices from traditional agriculture can be incorporated into modern farming to make it more sustainable. Table 4.1 offers a brief comparison of industrial and traditional agriculture.
Table 4.1: Industrial vs. traditional agriculture
Industrial
Traditional
Focuses on maximizing yield (monoculture)
Focuses on a diversity of species and products (polyculture)
Results in higher rates of soil erosion and land degradation
Maintains soil quality and long-term soil health
Relies on synthetic fertilizers and chemical pesticides
Relies on organic fertilizers and natural approaches to pest management
Requires heavy use of irrigated water
Minimizes water use by matching crops to regional climate
Heavily uses fossil fuels
Uses minimal fossil fuels
4.3 The Importance of Soil
When most people think of the term soil, they automatically think dirt. And for most people, dirt is considered useless and something to be avoided whenever possible. In reality, soil is much more than dirt, and it is soil that forms the foundation of virtually all land-based food production around the world. Because soil health is so critical to agriculture, sustainable agriculture almost always implies sustainable management of soils. Traditional farming practices tend to carefully manage soil fertility to ensure the ability to grow crops year after year. However, industrialized farming tends to depend on inputs of synthetic fertilizers to compensate for declining soil quality.
What Is Soil?
Soil generally consists of five components:
mineral matter (sand, gravel, silt, and clay)
dead organic material (e.g., decaying leaves and plant matter)
soil fauna and flora (living bacteria, worms, fungi, and insects)
water
air
Variations in the levels of these components lead to many different types of soils and soil conditions. Soils that are sandy drain quickly, whereas soils with high clay content hold water and become sticky. Soils with high levels of organic matter tend to be soft and good for plants, whereas compacted soils with few air spaces are less conducive to plant growth. High levels of soil fauna and flora are also generally better able to support plant growth, since these living organisms help decompose dead organic matter and make nutrients available to plants.
Most people are surprised that there can be so many living organisms in soil. Far from being lifeless dirt, a small handful of soil can contain millions of bacteria and thousands of fungi and algae (Ingham, 2019). Soils are also habitat for earthworms, ants, mites, sow bugs, centipedes, and other decomposers that make nutrients available to plants.
Because soils consist of both living organisms and nonliving material that interact to form a more complex whole, they meet the definition of an ecosystem. When we think of soils as ecosystems in and of themselves, we can begin to see why many of the agricultural practices discussed later in the chapter are not sustainable. Soil compaction from heavy farm machinery, regular plowing and manipulation of soils, heavy applications of synthetic fertilizers and chemical herbicides and pesticides, and overuse of irrigation all undermine long-term soil health and threaten the future of agriculture.
How Is Soil Made?
New soils can form over time and thus might be considered a renewable resource. However, because soil formation is such a slow process, it might be better to think of soils as a finite, limited resource. Soil formation occurs primarily as a result of two basic processes: weathering and the deposition and decomposition of organic matter such as leaves.
Weathering is the process of larger rocks being worn away or broken down into smaller particles by physical, chemical, and biological forces. Physical weathering occurs through wind, rain, and the expansion and contraction of rocks due to changes in temperature. Chemical weathering is caused when water, gases, or other substances chemically interact with larger rocks and break them apart. Biological weathering is caused by living organisms, such as when tree roots grow and grind against rocks.
The deposition and decomposition of organic matter occurs when living organisms drop waste or debris or die. When animals deposit waste or when plants shed leaves and branches, this organic material gets added to the soil. Likewise, when plants, animals, and other living organisms die and drop to the ground, decomposers and detritivores break them down and incorporate that organic material into the soil.
The processes of weathering and deposition and decomposition are influenced mainly by climate, topography, and time, allowing soils to form faster in some locations than in others. For example, an inch of new soil can take 50 to 100 years to develop in a healthy grassland ecosystem, whereas the same inch of soil might take 100,000 years to develop in a desert or tundra ecosystem.
Soil scientists recognize that soil develops into distinct layers, and they refer to each of these layers as a soil horizon. For our purposes, we can consider five different soil horizons: O, A, B, C, and D. The O (organic) horizon is at the very top and is made up of decomposing plant matter and animal waste that is sometimes referred to as humus. Below this is the A horizon, which is made up of organic matter and mineral particles.
The A horizon is where most of the living soil organisms reside, and the upper portions of the A horizon are generally referred to as topsoil. Most plant roots are established in the A horizon, which is why soil health is often based on the condition of topsoil.
Below the A horizon is the B horizon, also known as subsoil, and below that is the C horizon, which consists of weathered rock. Finally, the D horizon is known as bedrock (see Figure 4.1).
Figure 4.1: Soil horizons
Farmers are most concerned with the fertility of the topsoil, or A horizon.
Illustration of soil horizons. From top to bottom: humus, or the O horizon; topsoil, or the A horizon; subsoil, or the B horizon; weathered rock, or the C horizon; and bedrock, or the D horizon.
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Soil and Plant Life
Soil conditions have a lot to do with their ability to support plant life and agriculture, and the term soil fertility defines those conditions. Among the most important factors influencing soil fertility are nutrient levels, soil pH (a measure of the acidity or alkalinity of soil), and soil structure.
We know from Chapter 2 that nutrients like phosphorous and nitrogen can be limiting factors in plant growth. The amount of these and other nutrients in soils is dependent in part on the amount of organic material that is deposited and decomposed in that area. This is why the living organisms (e.g., bacteria, fungi, worms) that are found in soil—and act as decomposers—are so important to soil fertility.
Soil pH is determined by many factors, including the amount of organic material added to soils, the mineral composition of soil particles, and temperature and precipitation levels in that area. Some plants thrive in more acidic soils, whereas others do better in soils that are less acidic or even alkaline. Farmers utilize different soil additives to make soils more or less acidic, depending on the type of crops they want to grow.
Lastly, soil structure refers to how much air is in the soil or how compact it is. Plant roots and the living soil fauna and flora that improve soil fertility need oxygen and other gases to survive, so well-aerated soils tend to be better for plant growth. In contrast, when soils are compacted or compressed, such as through repeated pressure from tractors and heavy farm equipment, they tend to become less aerated and less conducive to plant growth. Highly compacted soils also decrease the ability of water to infiltrate and enter the ground, and as this water runs off the surface, it can carry soil with it. The displacement of this valuable resource—often caused by water or wind—is known as soil erosion.
4.4 The Problem of Chemical Pesticides
For as long as humans have farmed, they have had to contend with crop damage and competition from insects, fungus, and weeds. Early agriculturists made some use of chemicals like sulfur—as well as salt, smoke, and other deterrents—to ward off pests, but for the most part, traditional farming relied on more passive approaches to minimize crop loss. For example, by growing a variety of crops and rotating where those crops are grown on the farm, traditional agriculturists created conditions that were not as favorable for the outbreak and growth of pest populations. Likewise, traditional polyculture farming tends to promote and provide habitat for pest predators like spiders, beetles, predatory mites, and mantids like the praying mantis that feed on pests that can damage crops.
On the other hand, monoculture farming creates ideal conditions for pest and weed infestations. Because most insect pests are crop specific, and because monoculture farming grows the same crop season after season over large areas of land, insect pests are able to establish and spread in large numbers.
Agricultural pests are organisms that damage or consume crops intended for human use. Agricultural weeds are plants that compete with crops. Of course, weeds and pests don’t necessarily see it this way, because they are living organisms attempting to survive. Nevertheless, weeds compete with agricultural crops for sunlight, water, and nutrients, and pests can damage or destroy plant roots, stems, leaves, flowers, and fruit. As a result, industrialized agriculture makes use of a wide variety and a large quantity of chemicals to control weeds and pests. Insecticides kill insects, and herbicides kill weeds. There are also fungicides that kill fungus, as well as rodenticides that kill rodents. These chemicals are collectively known as pesticides.
Tractor spraying pesticides on vegetable field.
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Industrial agriculture relies heavily on pesticides to ward off pests.
The agricultural chemical industry has developed thousands of pesticides in the past 50 to 60 years, and it’s estimated that we apply close to 454 million kilograms (1 billion pounds) of pesticides in the United States each year (Alavanja, 2009). Roughly 80% of this pesticide is applied to farm fields, with the other 20% applied to backyard lawns, gardens, golf courses, and parks. It’s also estimated that over 95% of all corn and soybean crops planted in the United States are treated with herbicides each year (Wechsler & Fernandez-Cornejo, 2016), whereas cotton is probably the most intensive user of chemical insecticides (Cubie, 2006).
Biomagnification
One of the earliest chemical pesticides to come into widespread use was a compound known as dichloro-diphenyl-trichloroethane, or DDT. First developed in the late 1930s, DDT was seen to be an inexpensive, stable, and highly effective insecticide that was also relatively nontoxic to humans and other mammals. Because DDT was a broad-spectrum insecticide, meaning it could kill a wide variety of insects, it quickly became popular among farmers for controlling crop pests, as well as mosquitoes and household insect pests.
After more than a decade of widespread use, however, in the 1950s it began to become apparent that DDT might be causing unintended environmental consequences. Because DDT is a long-lived and stable compound, it gradually built up in soils and water bodies. Because DDT is fat soluble and attaches itself to body fats when ingested, it was also building up in populations of wild fish, birds, reptiles, and other organisms.
This poses a particular problem for animals near the top of the food chain. For example, DDT sprayed on agricultural fields will eventually flow into streams or lakes, where it could be ingested by tiny zooplankton. These organisms are then eaten by small fish, thereby accumulating all the DDT in the zooplankton. Small fish are then eaten by larger fish that are then eaten by birds of prey, like falcons, bald eagles, and pelicans.
Recall from Chapter 2 that only about 10% of the energy consumed at one trophic level is available to the next level. This means that birds of prey, like the bald eagle, have to eat a lot of fish to have sufficient energy. As birds eat, the DDT in fish becomes more and more concentrated in the birds.
The increasing concentration of a chemical pesticide at higher levels of the food chain is known as biomagnification. By the late 1950s and early 1960s, populations of birds of prey were declining dramatically, and the cause was linked to high concentrations of DDT. It turns out that DDT was not killing the birds outright but rather altering the way calcium was metabolized in their bodies. This resulted in a thinning of bird eggshells and low survival rates for chicks. The 1962 publication of the book Silent Spring by ecologist Rachel Carson drew attention to this unfolding disaster and eventually helped lead to the banning of DDT in most developed countries.
Resistance
Today the agricultural chemical industry has learned some lessons from the experience with DDT. Newer varieties of pesticides are designed to be short lived and less stable in the environment so that they break down quickly after use. They are also designed to be more targeted at specific species and applied at specific times when target pests are most vulnerable. Nevertheless, a number of other environmental problems still remain with widespread pesticide use.
First, because insects breed rapidly, they can develop genetic resistance to insecticides within a relatively short time. In other words, the insecticide will wipe out most of the pests initially—but the ones that survived will multiply, and the insecticide will become less effective with each successive generation (see Figure 4.2). Likewise, weeds can also develop resistance to herbicides over time. Heavy applications of chemical pesticides will initially help control insects and weeds, but over time they prove less and less effective as these organisms develop a resistance.
Figure 4.2: Pesticide resistance
Pests can develop resistance to pesticides over time. In this figure, the red bugs are the resistant individuals. Notice how, with each subsequent generation, the number of resistant pests increase. Eventually, the entire population will be resistant.
Flowchart and line graph illustrating the increase in resistant pests and the overall pest population over time, as resistant pests survive after each pesticide application and reproduce.
Based on “Managing the Community of Pests and Beneficials,” by L.Gut, A. Schilder, R. Isaacs, and P. McManus, in J. Landis and J. Sanchez (Eds.), Fruit Crop Ecology and Management, 2002, East Lansing, MI: Michigan State University.
It’s estimated that since the start of widespread chemical pesticide use in the late 1940s, over 500 species of insects (Gut, Schilder, Isaacs, & McManus, 2015) and 500 species of weeds (Heap, 2019) have developed chemical resistance, prompting what is known as pest resurgence. Farmers are then forced into what some call a “pesticide treadmill” or a “pesticide arms race” and must spend money on either larger doses of pesticides or new varieties of the chemicals. And despite the fact that synthetic pesticide use has seen a 50-fold increase since 1950 and that today’s pesticides are 10 to 100 times more toxic to pests than those used in the past (Roser & Ritchie, n.d.; Gross, 2019), it’s estimated that we still lose over 40% of major crops to pests and crop diseases each year—a higher proportion than in 1950 (Elliott, 2015; Fernandez-Cornejo et al., 2014).
Threat to Biodiversity
Praying mantis blending in with nearby vegetation.
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Pesticides can harm nontarget species, such as the praying mantis, reducing their numbers and creating unforeseen environmental consequences.
Another major environmental problem associated with the widespread use of chemical pesticides in agriculture is the impact these chemicals have on nontarget species and biodiversity. The case of DDT and its impact on birds like the bald eagle was an early and high-profile example of this problem. Today there continue to be concerns over the impact of pesticides on natural predators, other wildlife, and biodiversity generally, even if it doesn’t involve a species as well known as the bald eagle. Some of the nontarget species whose populations are reduced or eliminated by chemical insecticides include the spiders, beetles, and mantids that help control insect pests in traditional agricultural systems.
One particular area of concern involves the impacts that some pesticides appear to be having on bee colonies around the world. A newer class of chemical compounds developed in the 1990s known as neonicotinoid pesticides are now the most widely used form of insecticides globally. These chemicals appear to be responsible for significant declines in honeybee populations in agricultural regions and for the complete collapse of honeybee colonies through a process known as “colony collapse disorder.” This development is a significant concern because honeybees provide a critical ecosystem function by pollinating many major vegetable and fruit crops, including tomatoes, peppers, apples, and almonds. In addition to impacting honeybees, neonicotinoid pesticides appear to be negatively affecting a variety of bird and fish species as well.
Threat to Human Health
Lastly, chemical pesticides can pose a threat to human health. The World Health Organization (WHO) estimates that every year, at least 3 million agricultural workers are directly poisoned through improper handling of and exposure to chemical pesticides, which results in over 250,000 deaths a year (WHO, n.d.a). Every year, the Environmental Working Group (EWG) publishes a Shopper’s Guide to Pesticides in Produce, which estimates levels of pesticide residues found on fruits and vegetables sold in grocery stores around the United States. The 2019 EWG list ranked strawberries, spinach, kale, nectarines, apples, grapes, peaches, cherries, pears, tomatoes, celery, and potatoes as the “dirty dozen” in terms of levels of pesticide residues (EWG, 2019a). While the link between exposure to pesticide residues from food and cancer or other health problems is complicated, a number of studies suggest that people with less exposure have fewer of these problems (Baudry et al., 2018; Chiu et al., 2018).
It’s also estimated that well over 90% of chemical pesticides sprayed on crops never reach the target insects they were intended for (Duke, 2017). Instead, they drift through the air, run off into streams and lakes, or seep into groundwater—water found underground in soil or in the pores and crevices of rock. These chemicals can then be inhaled by people or ingested through drinking water. Agricultural chemicals like glyphosate (trade name Roundup), malathion, and atrazine have been found in municipal water supplies and in private wells, especially in heavily agricultural areas. These and other chemicals have been linked to human health problems such as infertility, low sperm count, and prostate and testicular cancers.
Overall, chemical pesticides have become a virtual necessity in industrialized agriculture because of the perfect conditions created for pests and weeds in monoculture farming. However, the heavy use of these chemicals is proving less effective over time as insect pests and weeds develop greater resistance to them. Furthermore, herbicides and pesticides are having negative impacts on nontarget species of animals and are also implicated in a variety of negative human health impacts.
Learn More: Shopping for Produce
You can learn more about the EWG’s Shopper’s Guide to Pesticides in Produce, and what you can do to reduce pesticide exposure in your own life, here.
https://www.ewg.org/foodnews
4.5 The Problem of Synthetic Fertilizers and Poor Soil Management
Just as industrialized, monoculture farming requires chemical pesticides, it also relies on synthetic fertilizers. Raising the same crop year after year quickly depletes soils of specific nutrients and requires the application of synthetic fertilizers to maintain crop yields. Traditional farmers use substances already produced on their farms, applying animal manure or compost or plowing under old crops to enhance soil fertility. In contrast, industrialized farmers apply over 109 million metric tons of synthetic nitrogen fertilizer alone to crop fields each year (Pearce, 2018b). This dependence on synthetic fertilizers is a symptom of the linear approach to agriculture, which views soil as simply one input to the production process, rather than the complex, living ecosystem that it actually represents. Heavy fertilizer use and poor soil management can result in serious environmental problems, including pollution of groundwater supplies, nutrient runoff and eutrophication, and soil erosion and land degradation.
Water Pollution
Industrialized farming operations tend to spray more chemical pesticides than needed and also tend to apply more fertilizer than plants can make use of. This excess nitrogen fertilizer in the form of nitrate can make its way through soils and into groundwater deposits. This nitrate pollution can persist in the water supply and build up over time as more and more nitrogen fertilizer gets applied to farm fields. While nitrate pollution in groundwater is not a major health threat for adults, it can cause low oxygen levels in the blood of infants and children and result in a potentially fatal condition known as “blue baby syndrome.” Large areas of the agricultural Midwest, including much of Iowa, Nebraska, and Kansas, have both high levels of nitrogen fertilizer application and vulnerable aquifers that provide drinking water to the general population. As a result, many of these areas are at high risk of groundwater contamination by nitrate.
In addition to groundwater pollution, excess fertilizer from farms can contribute to the pollution problem known as eutrophication (recall the case study in Section 2.4). Excess nitrogen and phosphorous fertilizers run off of farm fields (as well as residential lawns, golf courses, and parks) into bodies of water, where they fertilize aquatic plant growth and create algae blooms. This aquatic plant life, or phytoplankton, builds up and eventually sinks to the bottom, where it is decomposed by bacteria that use up the dissolved oxygen in the water. This results in low oxygen or hypoxic conditions that can lead to the death and displacement of fish and other aquatic life and eventually to the formation of low oxygen areas known as dead zones. As we learned in Section 2.4, the Gulf of Mexico dead zone is the largest such area in the United States, and the formation of this dead zone is linked directly to the large quantities of nitrogen and phosphorous flowing from the agricultural Midwest into the Gulf.
Topsoil Erosion
While some soil erosion occurs naturally, industrialized agricultural practices greatly speed up this process.
Water is the primary cause of soil erosion from most farm fields. Because most forms of industrialized agriculture involve plowing and clearing the land of vegetation, even small amounts of rain can move soil particles off a field, since there are no roots or organic material to hold them in place. Mechanization and the use of heavy farm equipment compacts soils and requires more frequent plowing and manipulation of soils, which can worsen erosion and further deplete the soil of nutrients. This type of gradual, almost imperceptible loss of topsoil is known as sheet erosion. Heavier rains can create small streams of water or rivulets that wash even greater amounts of soil off fields in a process known as rill erosion. In more extreme cases these small streams of water can merge to form large streams that can gouge out large channels from fields in a process known as gully erosion. Soil erosion not only reduces soil fertility and crop productivity, it also creates water pollution and sedimentation problems in rivers, streams, and lakes.
Erosion in a field, where rainfall created shallow cracks in the soil.
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Erosion in a field, where the cracks left in the soil after rainfall are deeper.
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Erosion in a field, where rainfall created large gullies in the soil.
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There are different types of soil erosion: sheet (left), rill (center), and gully (right).
In addition to water, heavy winds can loosen and blow topsoil off farm fields, especially in places that are dry and flat. The 1930s Dust Bowl in prairie areas of the United States and Canada was a result of drought conditions and removal of trees and other ground cover to expand farm area. While not as dramatic as images from the 1930s, windblown soil erosion continues to be a major problem in the United States today, and scientists cannot rule out the return of dust bowl conditions in periods of severe drought. In drier regions of Asia and Africa, overgrazing of livestock and clearance of vegetation is allowing desert areas to expand in a process known as desertification. Over the past 3 decades, China has lost a land area the size of Indiana to desertification as the Gobi Desert encroaches into areas that were previously suitable for some forms of agriculture.
Air Pollution and Climate Change
Excessive use of nitrogen fertilizer can also contribute to air pollution. Ammonia gas from nitrogen fertilizer application can contribute to haze great distances from where the fertilizer is being applied. Nitrous oxide gas can also form in soils fertilized with nitrogen fertilizer. Nitrous oxide is a local/regional air pollutant and also contributes to global climate change and even ozone depletion (discussed in Chapter 8). It’s estimated that two thirds of global nitrous oxide emissions from human activities are a result of agriculture. Ammonia and nitrous oxide can react with other compounds in the atmosphere to form fine particulate pollution. These particulates are responsible for haze and are also a public health risk when inhaled into the lungs. Wind erosion of farmlands can carry soil particles into the air and also contribute to particulate pollution.
Overall, heavy application of agricultural fertilizers and poor soil management practices are resulting in the degradation of two key forms of natural capital: water and soil. Excess fertilizer can seep into groundwater or run off into surface water and result in drinking water pollution, eutrophication, and aquatic dead zones. Soil erosion by water and wind can reduce soil quality and contribute directly to water pollution.
4.6 The Dependence on Water and Nonrenewable Energy
Unlike traditional agricultural systems that make relatively limited use of external inputs and are powered primarily by energy from the sun (photosynthesis), modern industrialized agriculture is heavily reliant on external inputs of water and fossil fuel energy resources. Traditional agricultural systems and approaches are generally tailored to local conditions. For example, farmers in regions with less precipitation and more frequent droughts know to depend to a greater extent on crops that require less water and that are drought resistant. Likewise, the cyclical approaches used in traditional agriculture—including the use of animal manure, composting, and crop rotation—are designed to make the most of resources that are already on the farm, rather than importing them.
In contrast, the highly linear approach to industrialized agriculture enables farmers to ignore local climate conditions and essentially import large amounts of water and fossil fuel energy to produce a monoculture crop.
Impact of Water Consumption
Large commercial-size irrigation pivot watering a field of turnips.
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Agriculture accounts for as much as 90% of all water use in some western states of the United States.
Agriculture is the single largest user of water globally, accounting for roughly 80% of all water use in the United States and over 90% in most western states (USDA, 2019). Large-scale irrigation systems allow modern farmers to grow crops in certain regions where it would otherwise not be possible to do so, such as rice production in desert regions of Arizona. Roughly 40% of world food production comes from land that is artificially irrigated (Food and Agriculture Organization of the United Nations, 2014), and demand for irrigation water is projected to continue to increase in the future.
One area of concern associated with agriculture’s heavy dependence on water is the overextraction of groundwater. Overextraction occurs when water is pumped out of an underground aquifer (an underground layer of water-bearing rock) at a rate that exceeds natural recharge or replenishment of that supply. If you think of an underground aquifer as a bathtub or basin filled with water, the rate of extraction would be water going down the drain, while the rate of recharge would be water coming out of the tap and into the basin. Obviously, if more water is going down the drain than coming from the tap, the water level in the basin will go down. That is exactly what is happening in many key agricultural areas around the world today, especially in parts of North Africa, southern Asia, China, and the United States. Many aquifers in these regions contain “fossil water” that was deposited there over geological timescales. Heavy extraction of water from these deposits is not offset by new water recharge, and as a result water levels are dropping dramatically. As water levels drop, the land above it can sink or subside. Overextraction of groundwater in coastal areas can also allow salt water from the sea to intrude into freshwater aquifers, making them unsuitable for residential or agricultural uses.
Another environmental problem associated with overuse of irrigation water in agriculture is soil salinization. Most irrigation water contains small or trace amounts of salts from the rocks in underground aquifers. When irrigation water is applied to farm fields, some of the water evaporates, leaving a tiny residue of salt behind. Over time, as more and more water gets added to a field and evaporates, more of the salt particles can build up in the soil. Soil salinization can lower crop yields and damage or even kill some crop plants. It’s estimated that over 20% of all irrigated cropland, mostly in dry areas, is impacted by soil salinization and that the damage to crop productivity is over $25 billion each year (United Nations University, 2014).
Impact of Fossil Fuel Consumption
Energy use in agriculture is both direct and indirect. Direct energy consumption includes the diesel fuel, propane, electricity, and other forms of energy used to power tractors, harvesters, pumps, lights, driers, and other forms of farm equipment. Indirect energy consumption includes the energy used to transport crops, process foods, and produce the fertilizers and other agricultural chemicals used in farming. It’s estimated that direct and indirect forms of energy consumption in agriculture account for 19% of all energy use in the United States each year (Pimentel, 2006).
Agriculture’s contribution to global climate change results from emissions of greenhouse gases like carbon dioxide, methane, and nitrous oxide. Carbon dioxide emissions from agriculture happen directly as a result of burning diesel, propane, and other fossil fuels to power farm machinery and equipment. Carbon dioxide is also released when forests are cut and burned to make way for agricultural production. Agriculture is also a major producer of methane from livestock operations and rice farming, as well as nitrous oxide from fertilizer use. Overall, it’s estimated that the global food system—including growing, processing, and transporting crops—is responsible for up to one third of human-caused greenhouse gas emissions (Gilbert, 2012).
4.7 The Issues With Animal and Meat Production
The global meat and dairy industry is massive and growing. Worldwide, the livestock sector produces roughly 120 million metric tons of poultry, 120 million metric tons of pork, 72 million metric tons of beef and veal, 15 million metric tons of meat from sheep and goats, and 827 million metric tons of milk and milk products each year (Food and Agriculture Organization of the United Nations, 2018a). If divided equally among all of the people around the world, this would result in an average global consumption of roughly 42 kilograms (92 pounds) of meat per person and 107 kilograms (237 pounds) of milk and milk products per person per year. In reality, levels of meat and milk consumption are highly uneven. For example, the average American or Australian eats over 90 kilograms (200 pounds) of meat per year, the average person in China or Vietnam eats about 50 kilograms (110 pounds) a year, and the average Ethiopian, Indian, or Bangladeshi eats less than 4 kilograms (9 pounds) per year (Organisation for Economic Co-operation and Development & Food and Agriculture Organization of the United Nations, 2018a). Producing meat and dairy products has a large environmental footprint, and as developing countries become wealthier, it’s expected that their citizens will incorporate more of these foods into their diets. This will likely aggravate some of the major environmental issues associated with meat and dairy production, including managing animal waste, preventing pollution, and dealing with antibiotic resistance.
Feeding Our Food
Before we discuss the direct environmental impact of the meat and dairy industries, it’s important to understand the basic inefficiencies in our current system. To start, a significant portion of the commercial crops grown on industrialized farms around the world is fed directly to animals rather than to humans. In the United States, after excluding corn grown for ethanol production, 50% of corn is fed to cattle, pigs, and chickens (USDA, 2015b). Over 70% of the soybeans grown in the United States are for animal feed, mostly for chicken production (USDA, 2015c).
When looked at this way, we can link virtually all of the environmental problems associated with agriculture to animal and meat production. Heavy use of chemical pesticides, overapplication of fertilizers, soil erosion and land degradation, water pollution and aquatic dead zones, air pollution, and global climate change can all be linked to the agricultural production of crops like corn and soy that are fed to animals.
In addition, feeding grains to animals that are then fed to humans is an inefficient way to feed the world. Farm animals are fed well over 1 billion metric tons of grain a year, and roughly 80% of all farmland is utilized for raising animals or growing crops to feed animals (Food and Agriculture Organization of the United Nations, 2019). And yet meat and dairy account for just 18% of calories and 37% of protein consumed by humans each year. For example, it takes as much as 24 kilograms (53 pounds) of grain in the form of animal feed to produce 1 kilogram (2.2 pounds) of beef. For pork, that figure is roughly 4 to 1, and for chicken about 3 to 1, as illustrated in Figure 4.3 (Wirsenius, Azar, & Berndes, 2010). This basic inefficiency associated with meat production and consumption lies at the heart of debates over how to feed a global population on track to hit 10 billion in the next few decades.
Figure 4.3: Feeding our food
Feeding grains to animals to then be fed to humans is an inefficient way to feed the world.
Infographic showing how much feed it takes to produce a food item: 1.1 kg to produce 1 kg milk, 2.3 kg to produce 1 kg eggs, 2.7 kg to produce 1 kg chicken, 3.5 kg to produce 1 kg pork, 24.0 kg to produce 1 kg beef.
Data from “How Much Land Is Needed for Global Food Production Under Scenarios of Dietary Changes and Livestock Productivity Increases in 2030?” by S. Wirsenius, C. Azar, C., and G. Berndes, 2010, Agricultural Systems, 103 (https://www.sciencedirect.com/science/article/pii/S0308521X1000096X).
Waste Management Problems
Many of the environmental and health issues associated with large-scale, industrialized approaches to meat production have to do with how these animals are raised. Today most of the chicken, pork, and beef consumed in developed countries like the United States originates from what are known as concentrated animal feeding operations (CAFOs). The USDA defines a CAFO as an animal feeding operation with at least 1,000 “animal units” confined for at least 45 days a year. Because an “animal unit” equates to 454 kilograms (1,000 pounds) of live animal weight, the USDA definition of a CAFO describes an animal feeding operation that has at least 1,000 cattle, 2,500 pigs, 55,000 turkeys, or 125,000 chickens. In 2016 it was estimated that there were just under 20,000 CAFOs in the United States (USDA, n.d.).
Dozens of pigs standing in wire cages inside an indoor farm facility.
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Modern meat production has many negative environmental effects, from fertilizer use to water pollution and waste management.
One benefit of CAFOs is that they bring many animals together in one concentrated location instead of requiring a larger land area for grazing. This has the potential to cut down on overgrazing and soil erosion. However, concentrating so many animals together in a small space can create serious problems with waste management. For example, an average cow can produce about 30 kilograms (66 pounds) of manure per day, or 11 metric tons each year. A CAFO with 1,000 cows (most CAFOs are much larger than this) produces as much waste as a city of 10,000 people. Nationwide, annual production of animal waste from the meat industry is as much as 20 times greater than waste produced by humans (Hribar, 2010).
Environmental and health problems stem from both the sheer volume of waste and how this waste is handled. Typically, animal waste from CAFOs is mixed with water to form a liquid slurry and simply stored in open pits or lagoons to decompose over time. In traditional approaches to agriculture, this waste could potentially serve as valuable fertilizer for crops. However, in the case of CAFOs, there is often simply too much waste in one location to be utilized on local farm fields. Also, because animals in CAFOs are often fed antibiotics and grain treated with pesticides, their waste is often so contaminated that it is dangerous to apply it to the soil. Nevertheless, it’s estimated that about half of the animal waste collected from CAFOs is applied to nearby farm fields.
Some of this manure slurry runs off of fields and into nearby rivers, streams, and other waterways, where it can cause eutrophication and also contaminate drinking water supplies with bacteria and pathogens. Some manure slurry stored in open pits and lagoons can seep through the soil and into groundwater deposits. In other cases heavy rains and flooding can cause these waste lagoons to overflow or even break open, dumping massive amounts of concentrated animal waste into nearby rivers and streams. When Hurricane Florence hit North Carolina in September 2018, hundreds of hog farm manure lagoons either overflowed or failed completely, severely contaminating nearby drinking water supplies (Pierre-Louis, 2018).
In addition to water pollution, CAFO waste management practices contribute to air pollution. Manure lagoons and open pits found in CAFOs emit many different types of gases, including some—like ammonia and hydrogen sulfide—that can be hazardous to human health in the immediate area. Many of these gaseous emissions from CAFOs are also foul smelling, and they can reduce quality of life and property values for nearby residents.
CAFOs are also a major source of greenhouse gas emissions (especially methane) that contribute to global climate change. These methane emissions come both from the digestive systems of cows being raised for meat and from the breakdown of organic wastes in the manure lagoons found in CAFOs. It’s estimated that raising livestock is responsible for about 36% of methane emissions worldwide and for about 18% of all greenhouse gas emissions (U.S. Environmental Protection Agency, 2019). As demand for meat and dairy increases worldwide, these greenhouse gas emissions are also expected to increase and further worsen rates of global climate change.
Antibiotic Resistance
Because CAFOs confine so many animals together in a relatively small space, they create ideal conditions for the spread of infections and diseases among the animals. As a result, CAFOs have historically made heavy use of antibiotics to try to prevent illness and to treat animals that are already sick. It’s estimated that roughly 70% of “medically important” antibiotics used in the United States each year are for animal production (Dall, 2016). However, recent changes in federal guidelines governing antibiotic use in animals, combined with growing public concern over the dangers of antibiotic resistance, appear to be resulting in declines in antibiotic use in animal feeding operations (Dall, 2018).
While in the short term this antibiotic use helps cut down on disease and increases productivity, it has a serious long-term consequence. Just as the overuse of pesticides and herbicides has led to the development of resistant insects and weeds, overuse of antibiotics results in the rise of antibiotic-resistant bacteria and disease organisms (see Figure 4.4). These antibiotic-resistant bacteria can contaminate human food supplies as the animals are slaughtered and can spread to drinking water supplies when manure lagoons overflow or seep into groundwater. The Centers for Disease Control and Prevention (CDC, 2018) has now established clear links between heavy antibiotic use in CAFOs and a rapid rise in antibiotic-resistant bacteria, including salmonella and E. coli. As a result, the CDC and other public health experts have been calling for a phase-out of routine antibiotic use in animal feeding operations, while the meat industry has resisted and pointed to the benefits of antibiotic use on productivity.
Figure 4.4: Antibiotic resistance from farm to table
Antibiotic resistance has serious repercussions for human health.
Text on infographic reads: Animals can carry harmful bacteria in their intestines. When antibiotics are given to animals, antibiotics kill most bacteria, but resistant bacteria can survive and multiply. Resistant bacteria can spread to animal products, produce through contaminated water or soil, prepared food through contaminated surfaces, and the environment when animals poop. People can get sick with resistant infections from contaminated food or the contaminated environment.
“Antibiotic Resistance and Food Safety,” by Centers for Disease Control and Prevention, 2018 (https://www.cdc.gov/foodsafety/challenges/antibiotic-resistance.html).
4.8 Moving Toward Sustainable Agriculture
Our modern, industrialized agriculture system produces a staggering amount of food at relatively low costs to consumers. On average, Americans spend less than 10% of their income on food, half of what we spent a generation ago and far less than what people in other countries spend to feed themselves (USDA, 2018a). Despite this success, it’s quite likely that no other human activity has as much of a destructive impact on the environment as agriculture. Whereas traditional approaches to agriculture were based on maintaining and enhancing natural capital, modern industrialized agriculture is designed around approaches that rely on exploitation and depletion of those resources. There are concerns that our food’s costs to society are not reflected in the prices we pay. Unless we fundamentally change the way we grow, distribute, and consume food, we can only expect that the negative environmental and health impacts of our food system will get worse as the population continues to increase.
The remainder of this chapter will examine how to meet the food and nutritional needs of a growing population in ways that are sustainable. But what does it mean for agriculture to be sustainable? Definitions of sustainable agriculture can be both simple and complex. At a basic level, sustainable agriculture is farming that meets our needs in ways that do not undermine critical natural capital systems and the ability of future generations to meet their own needs. Once we get beyond this basic definition, however, we see that sustainable agriculture involves issues of science, technology, the environment, economics, social equity, government policy, and personal choices and preferences. Researchers have concluded that no single approach or technological breakthrough will be enough to move us toward sustainable agriculture. Instead, we need an “all of the above” strategy that combines many different approaches and practices (Springmann et al., 2018; Searchinger, Waite, Hanson, & Ranganathan, 2018). The ideas in this chapter should not be considered in isolation or as “magic bullets” for solving the environmental and health impacts of industrialized agriculture. Rather, these practices and approaches should be viewed as being most effective when implemented in a synergistic or combined fashion.
Many of the on-farm practices that are promoted as “sustainable” are ones that were common in traditional agriculture and practiced for hundreds or thousands of years. These practices are designed to build and maintain healthy soil, manage water effectively, minimize air and water pollution, and promote a diversity of species and organisms on the farm and in surrounding areas. That being said, simply returning to traditional agricultural practices used before the Green Revolution might not be possible or practical at this stage. The key will be to take some of the wisdom and knowledge built up over thousands of years of practicing traditional agriculture and combine that with the scientific and technical knowledge that enabled the Green Revolution.
Crop Rotation and Intercropping
Crop rotation is the practice of planting different crops on the same piece of land every few years. A related method is intercropping, or strip cropping, wherein a mix of different crops are grown in the same area, as opposed to the monocropping of industrialized agriculture.
Crop rotation and intercropping help maintain soil fertility because different crops have different nutrient needs for growth. Some crops can even enhance soil fertility and reduce the need for fertilizers. For example, a farmer can grow corn—a nitrogen-intensive crop—in a field one year and the following year grow legumes, which add nitrogen to the soil.
Crop rotation and intercropping also help reduce pest outbreaks, since pests tend to be crop specific. By changing the crops grown in one field year to year or alternating the spacing of crops in a single year through intercropping, pests are not given an opportunity to establish themselves and spread over the area, which thereby reduces the need for pesticides.
Cover Crops
Common cover crops, such as alfalfa and clover, are planted on farm fields during the off-season. Letting a field lay bare can lead to soil erosion through wind and rain. Using cover crops can prevent erosion by helping hold the soil in place. Some cover crops can also enhance soil fertility and reduce the need for fertilizers by returning nitrogen to the soil. Cover crops prevent the influx of weeds and pests and reduce the need for pesticides.
Cover crops can simply be plowed into the soil at the start of the next growing season, where they continue to enhance soil quality and nutrient levels as they break down and decompose. Alternatively, these crops can be left on the field permanently and mowed like a lawn for animal feed. This latter approach is known as perennial agriculture because it involves leaving these crops in place year after year.
Contour and Terrace Farming
Rice fields grown using a terrace farming technique shown in the Vietnam countryside.
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Farmers who live in steep areas rely on techniques such as terracing, in which a series of platforms are cut into the hillside to allow crops to grow.
Traditional agriculturists have adapted to farming on hilly and steep land by practicing contour farming and terracing. Contour farming involves plowing sideways across a hillside, following the natural contour of the land. This creates small ridges or furrows that trap soil as it slides down the hill, preventing soil erosion and creating a series of contoured strips along the side of the hill.
Terracing is used on even steeper terrain and involves cutting into the hillside to create a series of steps or platforms that can hold soil and irrigation water in place to grow crops. Terracing is a common feature of rice cropping in mountainous regions of Southeast Asia, where this approach has been practiced for thousands of years.
Low-Till and No-Till Farming
Plowing, or tilling, fields for planting helps aerate the soil and cut down on weeds, but it also leaves the surface bare, thereby increasing soil erosion, water evaporation, and water demand. Low-till farming and no-till farming take a different approach, inserting seeds directly into undisturbed soil. Instead of plowing up a field after each harvest, farmers leave their fields covered in plants at all times. They use a device known as a no-till drill to make a shallow cut in the soil, drop in seeds, and cover them. Low-till and no-till farming minimize soil erosion, allow more organic material to accumulate on the surface, and help maintain soil moisture much better than plowed soils. These approaches are commonly referred to as conservation tillage.
Integrated Pest Management
Integrated pest management (IPM) is an approach to managing agricultural pests with few or zero chemical pesticides. Note IPM’s goal of managing agricultural pests rather than eliminating them. In IPM, tactics are tailored to the specific pest problem a farmer faces, as opposed to simply dousing a field in chemical pesticides and killing everything in it. IPM strategies might include the use of biological methods (introducing natural predators), altered planting practices (crop rotation, intercropping), and even mechanical devices to vacuum pests off of crops.
IPM has been used successfully in many different types of agricultural systems in every part of the world. Apple farmers in Massachusetts, soybean farmers in Brazil, vegetable farmers in Cuba, and banana farmers in Costa Rica have dramatically reduced pesticide use while maintaining or even improving crop productivity through the use of IPM.
One of the most dramatic IPM triumphs was with rice agriculture in Indonesia. Throughout the 1970s and 1980s, as more and more Indonesian farmers were adopting Green Revolution rice varieties, the government heavily subsidized the purchase and use of chemical pesticides to control outbreaks of brown planthoppers that threatened the rice crop.
However, over time, planthopper populations became resistant to many common forms of pesticide. As farmers applied increasing amounts of the chemicals to try to control this pest, they only succeeded in wiping out populations of beneficial insects (such as spiders) that naturally preyed on the planthoppers.
By the late 1980s the Indonesian government took drastic action, banning most pesticides, eliminating subsidies for others, and instituting a widespread IPM education program to teach farmers how to control the brown planthopper using biological methods. By all measures this change in approach was a success. Pesticide use dropped by as much as 75%, while rice yields actually increased slightly over time (Thorburn, 2015).
Integrating Crops and Livestock
A growing number of farmers are returning to the traditional integrated crop–livestock systems, in which a variety of crops and animals are raised on the same farm and animal wastes are used as fertilizer. Recall that industrialized agriculture is a linear process that tends to keep crop production and animal production separate, thereby removing a solution—using animal wastes as fertilizer—and instead creating two problems: a need for synthetic fertilizer and the disposal of massive amounts of waste.
Integrated crop–livestock systems are sometimes referred to as agroecology, permaculture, or low-input farming. These systems are often complex and cyclical and require careful planning and practice. However, when done well, integrated crop–livestock systems greatly enhance soil fertility, reduce the need for synthetic fertilizers, raise animals in more humane and less environmentally destructive ways, and help diversify local and regional farm economies. Many of these integrated crop–livestock farming systems have benefited from strong local consumer support, as discussed in the next section.
Each of these six traditional on-farm practices—crop rotation and intercropping, cover crops, contour and terrace farming, low-till and no-till farming, IPM, and integrated crop–livestock systems—has been demonstrated to reduce environmental impacts, increase crop yields, and save farmers money. However, all six also take careful planning, knowledge, and patience to implement. It’s also the case that many of the decisions that farmers make about what to grow and how to grow it are influenced by government policy, economic factors, and the preferences and personal choices that consumers make every time they purchase food. These issues are the subject of Section 4.9.
Explore the following slideshow to see examples of sustainable agriculture approaches.
4.9 Considering Farm Policy, Economics, and Personal Choices
Like any other business or enterprise, farmers make decisions about what to grow, how to grow it, and where to market it based in large part on the policy environment and market conditions in which they operate. In the United States and other developed countries, government policy has a significant impact on decisions that farmers make about what and how to farm. Likewise, farmers would be foolish not to consider or be influenced by consumer preferences, choices, and tastes. Therefore, in attempting to move toward more sustainable approaches to agriculture, it’s important to examine how we might influence policy, economic factors, and consumer choices in ways that encourage farmers and other actors in the food system to operate more sustainably.
Farm Policy
By its very nature, farming is a somewhat risky enterprise. Weather-related disasters like droughts, floods, tornadoes, and hurricanes can wipe out an entire season’s worth of labor and investment. For these reasons, governments in developed countries tend to be heavily involved in the farm economy. Some of this government spending goes to support agricultural research and development at universities and scientific institutes, food inspection and safety, infrastructure like rail and irrigation systems, and education and outreach programs for farmers. However, the bulk of this government spending—close to $500 billion a year from the top 21 food-producing countries worldwide—goes to direct and indirect subsidies to farmers and farm enterprises (Worldwatch Institute, 2014). Direct subsidies are payments made directly to farmers by the government, whereas indirect subsidies include things like crop insurance and price supports that are designed to help keep farming operations financially viable.
Proponents of these subsidy payments argue that they are necessary to help farmers manage the risk inherent in this line of work and that they benefit small family farms and local economies. Detractors point to a number of serious problems with this subsidized approach.
Issues With Subsidies
First, subsidies allow farmers to sell their crops overseas below the cost of production. When cheap exports of corn, wheat, or rice are sold in poorer, developing countries, they undercut local farmers and drive them out of business, since governments in these countries cannot afford to subsidize their own farmers. This creates a cycle of dependence in which local food production drops, more cheap food is imported, and local food production drops further.
Second, farm subsidies can be linked to some of the environmental problems described earlier. Subsidies tend to encourage farmers to overproduce, which brings more land than is needed into production, including lands prone to erosion (Edwards, 2018). As production increases, so does the use of fertilizers and pesticides, as well as the environmental problems associated with their application. In addition, since subsidies are usually targeted at a narrow range of “commodity crops” (like corn and soybeans), they tend to discourage crop rotation and intercropping since farmers are encouraged to maximize acreage planted with the subsidized crops (Edwards, 2018).
Lastly, there is little evidence that subsidies are important in protecting family farms and supporting local farm economies. Instead, the bulk of farm subsidies go to support some of the largest and most financially secure farm operations. The U.S. government spends over $20 billion a year on farm subsidies, and it’s estimated that over 70% of that amount goes to just 10% of America’s farm operations (Edwards, 2018; EWG, 2019b). In 2017 there were a total of 389 farm operations in the United States that each received at least $1 million in government subsidies, including 11 operations that received between $5 million and $9.9 million each (Andrzejewski, 2018). Likewise, millions of dollars in farm subsidy checks are mailed to addresses in Chicago, Houston, New York, and even Beverly Hills every year—not exactly locations that fit the definition of a local farm economy (Andrzejewski, 2018).
Learn More: Farm Subsidies in Your State
Research by the EWG and a group called Open the Books sheds light on how farm subsidy programs in the United States are mostly enriching financially secure farm operations and wealthy farmers while doing little to assist the vast majority of smaller, family farm operations. You can see how farm subsidies have been allocated in your state from 1995 to 2017 by visiting the EWG Farm Subsidy Database (https://farm.ewg.org) and clicking on your state. You can also see how many of the 389 farm operations that received over $1 million in 2017 are in your state by exploring the appendix of the Open the Books report Harvesting U.S. Farm Subsidies (https://issuu.com/openthebooks/docs/usfarmsubsidies_08072018?e=31597235/63670406).
Alternative Approaches
Instead of a farm subsidy program that undercuts farmers in poor countries, actually encourages farmers to practice unsustainable agriculture, and enriches farmers and farm operations that are already financially secure, these billions of tax dollars could be used in other ways.
Sustainable agriculture advocates argue that simply eliminating these subsidy programs could go a long way toward getting farmers to rethink what they grow and how they grow it. Alternatively, some of the billions of dollars spent annually on farm subsidy payments could be directed to programs that reward farmers for practicing conservation farming and sustainable agriculture.
Ultimately, such a change involves political decisions, since the beneficiaries of current subsidy programs have a lot of political influence. But there is strong evidence that such a change in policy can reduce government spending, bring environmental benefits, and actually support those farmers and farm communities most in need of help. Therefore, it’s possible to imagine a political alliance across the ideological left–right spectrum that could advocate for such a change.
Consumer Choices and Preferences
Perhaps more than any other factor, individual consumer preferences and decisions can have the biggest impact on how fast we move toward sustainable agriculture. What we choose to buy and eat, and where we choose to buy it, sends direct signals to farmers and other businesses in the food system.
Choosing Locally Sourced Foods
Currently, the U.S. commercial food system is dominated by large-scale, industrialized farming and food distribution enterprises. Food produced by these businesses often travels long distances before reaching its ultimate consumer. It’s estimated that a typical food item sold in a conventional American grocery store travels 2,400 to 4,000 kilometers (1,500 to 2,500 miles) before being purchased (Worldwatch Institute, n.d.). The environmental impact of all of those “food miles”—combined with the environmental impacts of industrialized agriculture discussed earlier in this chapter—is driving many consumers to reconsider their food purchases in terms of both what they buy and where they buy it. This trend has been described as the “local foods movement” and the “farm-to-table movement,” and people who buy and consume more locally produced foods are described as “locavores.” What these efforts have in common is an emphasis on purchasing locally produced foods that are in season.
Consumers can connect with local farmers in a few different ways. Farmers’ markets—where local farmers gather to sell their products directly to consumers—have become much more common in many areas of the United States in recent years. In the mid-1990s there were fewer than 1,800 farmers’ markets across the country. That number rose to almost 4,700 by 2008 and to well over 8,000 today (Farmers Market Coalition, 2019). Farmers’ markets help support small-scale local farms, involve much less transportation and packaging, and offer consumers fresh fruits, vegetables, and meats in place of many of the highly processed foods found in supermarkets.
Garden and planter boxes with apartment complex in the background.
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A shift toward local foods includes urban farming, which repurposes unused space in heavily populated areas.
Consumers can also connect with local farmers through a community-supported agriculture (CSA) program. In a typical CSA program, a consumer pays up front for a “share” of a local farmer’s crops or farm products (including meat and eggs). In return, the consumer receives a regular delivery of fruits, vegetables, and other products from that farm over the course of the growing season. CSA programs often offer consumers the opportunity to visit and even volunteer to work on the farm they are supporting. This helps bring people in closer contact with where their food comes from, how it’s grown, and what’s involved in bringing food from the farm to the table. While estimates of the number of CSA programs are harder to come by, a 2015 USDA report estimated that there were over 167,000 U.S. farms that produced and sold food for local markets through farmers’ markets, CSA programs, and other local food initiatives (USDA, 2015a).
One other example of the move toward local foods is the rise of urban farming. Urban farming repurposes unused space—such as rooftops, vacant lots, and even roadside medians—in heavily populated city areas. In the United States, urban farming programs often grow out of need, since many inner-city areas are food deserts—areas where it is difficult to purchase affordable, good-quality fresh food. Urban gardens and urban farming programs are now widespread in most major cities of the United States, including New York, Chicago, Detroit, Cleveland, Memphis, Baltimore, and Atlanta.
To find out more about local food options in your area, check out Close to Home: Developing a Local Diet.
Close to Home: Developing a Local Diet
There are a number of environmental benefits associated with eating local foods. Fruits, vegetables, and other perishables do not need to be transported very far or preserved for very long when they are produced close to consumers. As a result, local food options often result in less energy use and fewer greenhouse gas emissions. Crops that are well adapted to local climates also require fewer chemical inputs and less water management during production.
Assorted vegetables in a farmers’ market stall.
kasto80/iStock/Getty Images Plus
Buying food from local farmers helps local economies and fosters relationships within the community.
Local foods provide a number of social benefits as well. They build community by fostering relationships between growers and consumers. Some also argue that local food systems increase food security by diversifying food production. In our global food system, crops are often produced on a small number of very large farms. This means that diseases, natural disasters, and market disruptions that impact one region can have consequences for food availability all over the world. Local food systems, on the other hand, must rely on a large number of smaller food producers, so consumers have other options if a few farms have a bad year.
Purchasing local food can also help local economies generate wealth. Rather than sending money to a grower on the other side of the world, local foods support local farmers. These individuals can then use that wealth to support other community organizations and local businesses.
Local foods address several dimensions of sustainability, and arguments like these have convinced a lot of people to reconsider their eating habits and join the local food movement. Most just try to incorporate a few local options into their diet, but some try to survive mostly or entirely on locally produced foods—all the more impressive when you consider that very few fruits and vegetables are available year-round in most locations.
To explore what it would mean to eat a local diet in your location, take a look at the Seasonal Food Guide website that summarizes local produce availability. After selecting your location, scroll through the different harvesting seasons and note the foods that might be seasonally available. Do you think you could create a diet that incorporates more local produce? Are there certain times of the year when eating local becomes much more difficult? What are some strategies that you could use to continue eating the local foods you love even when they are not in season?
To get your hands on some local ingredients, explore Local Harvest, an online directory of local food growers and vendors. Many regions have one or more farmers’ markets that gather several growers in one convenient location. Individual farms in your region might also offer subscriptions to CSAs that provide you with an assortment of goods over the course of a growing season. Of course, the most local option of them all is to grow your own food around your home. If this sounds exciting to you, the USDA has a variety of home gardening resources that might help.
Choosing Organic
Yet another way individual consumers can push for sustainability in our food system is through organic foods. Organic food is produced through methods that comply with the federal standards of organic farming. Because organic farming requires that farmers forgo the use of synthetic pesticides and fertilizers, among other requirements, it is generally better for the environment than conventional approaches to agriculture. More and more Americans are choosing to purchase foods that are certified organic, with organic food sales now valued at over $35 billion annually in the United States alone (USDA, 2017).
However, organic farming is not always the most sustainable option. For example, should you buy organic apples shipped more than 4,000 kilometers (2,500 miles) across the country or locally grown but nonorganic apples? The more sustainable choice might be to go with the latter.
Choosing Less Meat
A final dietary decision consumers can make is how much meat to consume, which can have a significant effect on the sustainability of our food system. A typical Western diet is high in sugar, fats, refined carbohydrates, meat, and dairy. Not only is this diet a problem in terms of personal health, it also tends to have a greater environmental impact than other diet types.
The World Resources Institute (WRI) estimates that beef production accounts for almost half of U.S. agricultural land use and greenhouse gas emissions from farming while only providing for 3% of the calories consumed by Americans (Ranganathan et al., 2016). This is because of the basic inefficiency associated with converting grains to animal protein. A shift from beef to less intensive forms of meat like chicken or reducing meat consumption overall can bring significant environmental gains and help consumers reduce their environmental footprint. Much less agricultural land is required to support a more vegetarian diet, which translates into less energy and water use as well. Even small moves toward lowering meat consumption can have a big impact. One study estimated that if every American picked 1 day a week to avoid meat (such as a “meatless Monday”), it would reduce greenhouse gas emissions at a level equivalent to taking 30 million to 40 million cars off the road for 1 year (Center for Biological Diversity, 2019).
Explore the following interactive to consider the sustainability of your own grocery shopping. (To receive credit for this activity, complete the version that follows the reading quiz in your course.)
Food Loss and Waste
Trash bin filled with leftover food.
peder77/iStock/Getty Images Plus
Every year, one third of all food produced worldwide is wasted.
Food loss refers to food that is discarded before it even reaches the consumer; that is, during the production, processing, and distribution phases. Food waste refers to food that is discarded directly by consumers, restaurants, or other institutions like hospitals and schools. It’s estimated that worldwide approximately 1.6 billion metric tons of food—one third of all food produced—is lost or wasted every year. This wasted food is estimated to be worth $1.2 trillion annually; at the same time, close to 1 billion people around the world face food scarcity and shortages. In the United States the annual rate of food loss and waste is actually higher (40%) than the global rate, and it’s estimated that an average American family of four throws away 526 kilograms (1,160 pounds) of food every year (Lipinski et al., 2013).
Food loss and waste is challenging to address because the global food distribution system is complex, and waste occurs at every stage of that system. A 2013 WRI report found that food loss and waste differed significantly from country to country. In the poorer countries of Africa, Latin America, and Asia, between one half and three fourths of all food waste occurs at the production stage and the handling and storage stage of the food distribution system. This is due in large part to a lack of adequate infrastructure in the form of roads, refrigerated warehouses, and other modern food storage facilities. In contrast, in North America and Europe, well over half of all food loss and waste occurs at the consumption stage and can be tied directly to the behaviors of individual consumers and businesses like restaurants and caterers (Lipinski et al., 2013).
The WRI report recommends various programs and initiatives to help cut down on food loss and waste. These include
food redistribution programs that send food that would otherwise be wasted to food banks and shelters;
increased access for poor farmers to food storage facilities;
standardized and clear food date labeling (such as “use by,” “sell by,” and “best before” labels) to reduce unnecessary disposal of food that hasn’t spoiled;
consumer awareness campaigns to teach strategies for reducing food waste; and
reduced portion sizes in restaurants.
Two examples of these kinds of efforts come from the United Kingdom and New York City. From 2007 to 2010, the United Kingdom implemented the Waste and Resources Action Programme, which achieved a 13% reduction in household food waste and an additional 9% reduction in food waste at the retail stage. These savings came through simple and commonsense strategies that not only cut waste but also helped consumers and businesses save money. These efforts included education campaigns targeted at consumers on reducing food waste, as well as programs for businesses to channel food that might otherwise be discarded to charities or composting facilities (Waste and Resources Action Programme, n.d.). In New York City a program known as Rescuing Leftover Cuisine organizes hundreds of volunteers every day to collect food that would otherwise be thrown away by restaurants, grocery stores, and other businesses and distributes that food to shelters, soup kitchens, and social service agencies. The program estimates that since 2013 it has rescued close to 1.3 million kilograms (2.8 million pounds) of food and provided over 2.3 million meals to people in need (Rescuing Leftover Cuisine, 2019).
4.10 The Role of Science and Technology
This section will examine how science and technology are enabling agriculture to be more productive, efficient, and environmentally friendly—another option in our “all of the above” approach to meeting the food and nutritional needs of 10 billion people. The section will review a variety of approaches—including use of the Global Positioning System (GPS), drones, and robots in farming—that fall under the definition of “precision farming” or “site-specific crop management.” The section will also consider two approaches to growing food that do not require the use of soil: aquaponics and hydroponics. The section will conclude with a case study of how the tiny country of the Netherlands has become a world leader in sustainable agriculture and agricultural productivity, in part through the widespread adoption of a variety of precision farming approaches.
Precision Farming
Throughout the world, more and more farmers are adopting high-tech approaches to managing their crops. This includes using GPS, satellite imagery, soil moisture sensors, drones, and even robots to provide them with real-time data on crop and field conditions. Farmers use this data to make more precise decisions, like when and where to irrigate, whether pesticides or fertilizers are needed for certain crops, and when the ideal time is to harvest a crop. Thus, this type of high-tech farming is known as precision agriculture.
For example, almond farmers in water-scarce regions of California rely on networks of small moisture sensors buried in the soil throughout their orchards to determine when and where water is needed. The sensors feed data to an automated water pumping system that delivers just the right amount of water to just the right location.
Likewise, corn farmers can now make use of a device known as a Rowbot that applies precise amounts of fertilizers to the crop based on data provided by soil and crop sensors. Aerial drones can be mounted with sensors that can detect whether some plants are diseased or need nutrients, and that data can be used to target spraying or fertilizer application to specific locations. These technologies improve on the conventional practice of simply irrigating or spraying pesticides and fertilizers across an entire field without any consideration for site-specific differences in conditions across the farm. The goal of this high-tech, precision agriculture is to increase productivity, decrease the use of inputs like water and agricultural chemicals, and minimize the impact of agriculture on the environment. All of these outcomes have the added benefit of improving a farmer’s profitability.
Farming Without Soil
Hydroponics and aquaponics are ways to grow crops without the use of soil. Hydroponics grows plants by suspending them with their roots placed in a water–mineral nutrient solution. Aquaponics builds on this idea by incorporating aquaculture, or raising aquatic animals like fish, with a hydroponic system (see Figure 4.5). One advantage of aquaponics is that the waste products from the fish portion of the system can be used as fertilizer for the plants, and some of the plant material can be fed to the fish. In this way, aquaponics resembles the kind of closed-loop, cyclical system involving crop–livestock integration common in traditional farming, just with a modern approach.
Figure 4.5: Aquaponics
This aquaponics example is a self-contained, closed-loop system that requires only sunlight and rainwater.
Illustration of vertical system with a tank at the top, which collects rainwater that filters down to a fish tank at the bottom. Between the two tanks are hydroponic crops, which receive nutrients from the water pumped up from the fish tank.
Adapted from normaals/iStock/Getty Images Plus
Hydroponics and especially aquaponics offer a number of benefits over conventional approaches to farming. Because water is recycled through these systems, hydroponics and aquaponics use only about one tenth the amount of water used by conventional farming. Since these are usually indoor systems, they also do not require as much chemical pesticide application. Hydroponic and aquaponic systems can be built at many different scales and can be an important part of urban farming and education programs.
On the other hand, there are a few challenges and limitations to the use of hydroponics and aquaponics. These systems require a fair amount of up-front investment and specific knowledge to build and maintain. Likewise, indoor hydroponic and aquaponic systems require energy and electricity for lighting and climate control.
Case Study: High-Tech Farming in the Netherlands
The small European country of the Netherlands is a pioneer in the use of precision agriculture techniques as well as hydroponics. For almost 2 decades, the Dutch have been focusing government and private resources on sustainable agriculture, with impressive results. Water use for key crops has dropped almost 90%, chemical pesticide use in greenhouses has been almost eliminated, and poultry and livestock producers have reduced the use of antibiotics by 60% (Viviano, 2017). At the same time, crop yields and productivity have risen across the board, and the Netherlands is a world leader and top exporter of potatoes, onions, and a number of other vegetables.
Part of this success comes from the widespread use of climate-controlled greenhouse complexes. The Dutch countryside is dotted with clusters of agricultural greenhouses, in which farmers can carefully control conditions to maximize productivity and minimize inputs. The Dutch have also fully embraced the use of drones, soil and moisture sensors, robots, and GPS in agriculture. In many cases energy to heat the greenhouse complexes comes from ground-source geothermal systems, a sustainable and nonpolluting energy source. Overall, the Dutch are proving that large strides, not just incremental change, can still take place in agriculture.
4.11 Genetic Engineering and Genetically Modified Organisms
For almost as long as humans have been farming, they have been manipulating plant and animal species to favor some traits over others. Crossbreeding and selective breeding have been used by farmers for thousands of years to favor crops that produce more seeds or fruit or to favor animals that produce more wool or milk.
However, all of those efforts involved favoring or breeding for traits that already existed within a species or between closely related species. For example, a rice plant that produced abundant grain but was easily damaged by wind could be crossbred with a different rice plant that produced less grain but had a stronger stem that could withstand wind. The resulting rice plant, after repeated breeding, would feature both desirable traits—high grain production and strong stems—in a single seed.
Genetic engineering, or the genetic modification of crops and animals, represents a fundamentally new approach. Genetic engineering involves the removal of genetic material (genes) from one organism and combining it with the DNA of another. These gene transfers are often described as “novel” because they would never occur on their own in the natural world. For example, genetic material from fish high in omega-3 fatty acids has been inserted into soybean plants to try to produce soybean oil high in the fatty acids believed to be beneficial to heart health. Genetically modified organisms (GMOs) are organisms that have had their genetic material modified in ways that would not have been possible in nature.
Advantages and Opportunities
Proponents point to a number of advantages and opportunities in genetic engineering and GMOs. They argue that genetic engineering opens up new ways to introduce desirable traits into plants and animals. These include both “input” traits—such as developing animals that are resistant to disease or developing crops that are resistant to drought—as well as “output” traits—like breeding crops that have higher nutritional content. A few examples of GMOs that have already been developed help illustrate these arguments.
Almost 20 years ago, crop scientists in Asia engineered a new rice variety that contains beta-carotene (vitamin A) in the grains. Vitamin A deficiency is a serious public health challenge in poorer regions of Asia, where rice is a staple crop. The new rice variety, named “golden rice” because of its yellow color, has not yet been widely adopted by farmers or accepted by consumers in the region.
As another example, genetic material from a bacteria known as Bacillus thuringiensis (Bt) has been successfully inserted into corn and cotton plants to fight insects. Bt produces a toxin that kills insects that eat the plant but is not harmful to people. When insects feed on what is known as Bt corn or Bt cotton, they are poisoned and die, reducing the need for applications of pesticides on these crops. Bt corn and cotton currently account for about 80% of the total production of these crops in the United States each year (USDA, 2018b).
Finally, Canadian scientists have recently taken genetic material from Pacific chinook salmon as well as from another fish known as ocean pout and inserted these into Atlantic salmon to promote faster growth. These “GM salmon” grow twice as fast as and consume less feed than conventional Atlantic salmon, potentially lowering the cost of production of this healthy food option. In 2015 the U.S. Food and Drug Administration approved the sale of GM salmon in this country, although actual marketing of this fish in the United States was not scheduled to happen until 2019.
A Cautionary Word
Butterfly in a cornfield.
Ginton/iStock/Getty Images Plus
It’s not yet clear how genetically modified foods could affect our environment in the long run. These types of crops could be affecting other species, such as the butterflies visiting the fields for pollen.
Despite the apparent advantages of genetic engineering and GMOs, some scientists, public health experts, consumer advocates, and environmental groups have come out strongly against this approach. Most of the arguments against genetic engineering are based on issues of safety and ethics and on whether this technology is resulting in even more market power and control for large corporations.
In terms of safety, concern has been expressed for both human health impacts and unintended environmental consequences of GMOs. Because GMOs involve the creation of “novel” or new organisms, there are concerns that they could result in an increase in allergic reactions in some people, although it’s not clear yet whether this is already happening. Likewise, GMOs might be having unintended environmental consequences. For example, some butterfly species appear to have been negatively impacted by consuming pollen from Bt corn.
At a more basic level, many people argue against genetic engineering and GMOs on ethical or philosophical grounds. They suggest that genetic engineering is “tinkering with nature” and that GM foods are not natural and are instead a type of “Frankenfood.” This contributes to arguments for mandatory labeling of foods that contain GMOs, something that is not required in the United States but is more common in other countries. (See also Apply Your Knowledge: Are GMOs Safe?)
Lastly, because research, development, and marketing of many GMOs are dominated by large multinational corporations, many skeptics of genetic engineering argue that this technology is concentrating more power over our food system in the hands of a small number of companies. These corporations are patenting the new organisms they develop, giving them market control over basic food commodities. Overall, critics and skeptics of genetic engineering argue that perhaps we should adopt more of a “precautionary principle” when it comes to this technology and allow for its development and commercialization after more careful review and testing.
Apply Your Knowledge: Are GMOs Safe?
Scorpion DNA in cabbage? Corn that is immune to herbicides? GMOs are certainly very strange, and some people are worried that they represent a health risk to the humans who consume them. This feature box will analyze some data at the heart of this conversation and explore both sides of the GMO debate.
The data in Figure 4.6 come from a 2003 experiment designed to understand the health risks of consuming genetically modified tomatoes (Chen et al., 2003). In this study researchers began with young rats that were divided into four experimental groups. Three groups were fed diets containing different amounts of disease-resistant tomatoes that were modified with virus DNA. The remaining group of rats was fed a non-GMO diet in order to provide an example of normal rat development. This provided a baseline measurement that the other groups could be compared against, which researchers call an experimental control. Rats were weighed each week of the 4-week study, and their growth trends are shown in Figure 4.6. Based on this data, do you think that genetically modified tomatoes impacted the growth of the rats in this study?
Figure 4.6: Male and female rat growth with GMO diets
Plots showing male (a) and female (b) rat growth over the course of the 4-week study.
Two graphs showing change in rat weight for rats with different diet. There is very little difference between the control, little GMO tomato content, moderate GMO tomato content, and high GMO tomato content diets.
Data from “Safety Assessment for Genetically Modified Sweet Pepper and Tomato,” by Z. Chen, H. Gu, Y. Li, Y. Su, P. Wu, Z. Jiang, . . . L. Qu, 2003, Toxicology, 188.
At first glance, you might notice that the data points fall really close to one another. In fact, it is even hard to tell one point from another because the individual symbols overlap. We can take this analysis a step farther if we notice the error bars that are associated with each data point. Because experiments are never perfect, measurements like these are just our best attempts to approximate the “true” values that describe the system. Therefore, we often calculate error bars to represent the uncertainty of our measurements. In general, the ranges indicated by the error bars are where we are most likely to find the “true” value of our measurement. If we take this into account, we might notice that all of the data points at each time interval have overlapping error bars. This means that all of the data points might share the same “true” value. In this situation, we cannot make an argument that our data points are statistically different from one another. It appears that the rats consuming the genetically modified diets behave like the control rats.
The rats in this experiment were similar in other ways too. In addition to growth, the researchers in this experiment compared the blood, organs, and biological processes of all the rat groups, and none of these measurements showed statistical differences.
Several other studies have reached similar conclusions about other GMO foods. Researchers have found no negative consequences for rats that consumed GMO sweet peppers, rice, potatoes, and corn, among other GMO crop varieties (Chen et al., 2003; Hammond et al., 2006; Schrøder et al., 2007; Seek Rhee et al., 2005). Other studies have explored long-term exposure to GMO foods over several generations of reproducing rats, and once again, GMOs do not seem to pose a significant risk (Seek Rhee et al., 2005; Brake, Thaler, & Evenson, 2004).
Does that mean GMOs are safe? Even though studies like these provide us with important information, it is also important to think critically and recognize the limits of this information. The studies mentioned were carried out on a few types of food with populations of rats for limited amounts of time. Unfortunately, we still do not know for sure how people will react to a variety of genetically modified foods over the course of human lifetimes and generations. Even though much of the science suggests that GMOs are safe to eat, we may not know for sure until people have been eating them consistently for several decades.
GMOs demonstrate that matters of health and the environment often get messy when a lot is at stake. To make the best decisions going forward, we need to make sure that we pay attention to the best information available. This often requires us to seek out and understand the most reliable science behind a particular issue. At the same time, we need to question that information and recognize the gaps in what is known about a particular topic. As is often the case, the loudest voices in the GMO debate are coming from the two extremes, and the best path forward may lie somewhere in the middle.
The Bottom Line
Regardless of what position one takes on genetic engineering, the reality is that GMOs are already in widespread use and are present in many of the processed foods sold in American supermarkets. Though only introduced in roughly the past 20 years, it’s estimated that in the United States today, 94% of all soybeans, 96% of all cotton, and 93% of all corn being grown are in the form of genetically engineered varieties (USDA, 2018b). Likewise, it’s estimated that well over 70% of all processed foods sold in the United States contain at least some GMO ingredients (Center for Food Safety, 2019).
Globally, the land area planted with GM crops has grown from just over 1 million hectares (2.5 million acres) in the late 1990s to almost 200 million hectares (494 million acres) today (Silva, 2017). The United States leads in terms of land area planted with GMOs, followed by Brazil, Argentina, India, and Canada. However, widespread adoption of GM crops is uneven. In Europe some countries have placed outright bans on the cultivation of GM crops, and strong anti-GMO sentiment among consumers keeps the demand for foods made with GMOs well below what it is in the United States.
Ultimately, debates over the advantages, disadvantages, and future of genetic engineering and GMOs boil down to questions of whose opinion counts and how we should approach risk. Like many other public health and environmental controversies, it’s easy to find experts on both sides of the GMO debate. It’s also the case that some of the promises and potential for GMOs have been exaggerated, furthering suspicion that this technology is really designed to enrich powerful corporations. However, given the need for an “all of the above” approach to agriculture in order to feed a growing population without wrecking the environment, it seems shortsighted to completely rule out the use of genetic engineering unless stronger evidence emerges of negative public health or environmental impacts.
Bringing It All Together
Dutch plant scientist Ernst van den Ende summed up the agricultural challenge facing the world today by pointing out that we must produce more food in the next 40 years than all of the food ever produced by all farmers over the past 8,000 years (Viviano, 2017). Given the environmental impacts that agriculture is already imposing on the planet, we need to figure out ways to produce food in a more sustainable fashion. Agricultural activities already push us close to planetary boundaries for water use, biodiversity loss, nitrogen pollution, and global climate change, so doing more of the same is simply not an option.
In short, a new Green Revolution—one that focuses not just on crop productivity but also on environmental considerations, diet choices, food waste, agricultural policy, and new technologies—is in order. Ideas for how to bring about this revolution, both old and new, were also covered in this chapter, and many of these involve the actions and efforts of individual consumers.
The next chapter will take a more in-depth look at one of the most critical resources needed for and impacted by agriculture: water. We’ll see that continued wasteful use of water by agriculture simply cannot continue, given other pressures being placed on world water supplies.
Additional Resources
Food Security and Sustainability
In this TED Talk, Sara Menker describes a rapidly approaching global food crisis and the steps we can take today to avoid it.
https://www.youtube.com/watch?v=OzA6jRYjVQs
The WRI has an excellent collection of reports and data on food, agriculture, and their connection to the environment. In particular, the 2018 WRI report Creating a Sustainable Food Future provides a “menu” of options for how to feed a world of 10 billion people without destroying the environment in the process.
https://www.wri.org/our-work/topics/food
Climate change may threaten the varieties of crops we grow today. In this TED Talk, Cary Fowler describes how a global seed bank is being used to protect our food future.
https://www.youtube.com/watch?v=Uwl012o8P7I
The National Academies of Sciences, Engineering, and Medicine recently published a comprehensive report on how science and technology will change agriculture in the years ahead. Some are calling the report a “road map for a second green revolution.”
https://www.nap.edu/catalog/25059/science-breakthroughs-to-advance-food-and-agricultural-research-by-2030
The Johns Hopkins University Center for a Livable Future has an excellent Food Systems Primer that contains a lot of resources for anyone interested in learning more about our food system and its impact on the environment.
http://www.foodsystemprimer.org
Food Safety
Scientific American published a troubling story on how drug-resistant bacteria get into our food system and threaten our health.
https://www.scientificamerican.com/article/how-drug-resistant-bacteria-travel-from-the-farm-to-your-table
Sustainable Farming
The Yale Environment 360 online newsletter/magazine has an excellent collection of essays and features on issues of food and agriculture.
https://e360.yale.edu/topics/food-agriculture
The Solutions Journal recently published an interesting essay on “Solutions for a Win–Win Partnership Between Agriculture and Biodiversity.”
https://www.thesolutionsjournal.com/article/solutions-win-win-partnership-agriculture-biodiversity
Consumer Choices and Preferences
In addition to the Local Harvest website introduced in the Close to Home: Developing a Local Diet feature box, the USDA Agricultural Marketing Service offers two different databases that can help you connect with local food. The first provides information on local farmers’ markets and the second on community-supported agriculture programs that might exist in your area.
https://www.ams.usda.gov/local-food-directories/farmersmarkets
https://www.ams.usda.gov/local-food-directories/csas
Choosing less meat is one way to shrink your environmental footprint, but it can be a hard change to make. In this TED Talk, food innovator Bruce Friedrich talks about how science is generating appealing alternatives to meat.
https://www.youtube.com/watch?v=vZCGSP3A0Fo
Plant Chicago is an interesting project focused on urban agriculture, energy conservation, and waste minimization.
https://plantchicago.org
Food Loss and Waste
Yale Environment 360 produced a short documentary video on why we throw so much food away.
https://e360.yale.edu/features/the_big_waste_why_do_we_throw_away_so_much_food
Genetically Modified Foods
WHO has an easy-to-follow and reasonably balanced summary of frequently asked questions on genetically modified foods.
https://www.who.int/foodsafety/areas_work/food-technology/faq-genetically-modified-food/en
Key Terms
agriculture
An approach to land management designed to grow domesticated plants and raise domesticated animals for food, fuel, and fiber.
aquaponics
A soil-free method of growing plants that incorporates hydroponics with raising aquatic animals, like fish.
biomagnification
The increasing concentration of a toxin in an organism due to eating other organisms lower on the food chain.
community-supported agriculture (CSA)
A food distribution system in which consumers purchase a “share” in a local farm and receive regular deliveries of farm products in return.
concentrated animal feeding operations (CAFOs)
According to the USDA, an animal feeding operation with at least 1,000 “animal units” (1,000 cattle, 2,500 pigs, 55,000 turkeys, or 125,000 chickens) confined for at least 45 days a year.
contour farming
The practice of plowing sideways across a hillside, following the natural contour of the land.
cover crops
Plants used to hold soil in place and slow erosion.
crop rotation
The practice of planting different crops on the same piece of land every few years.
desertification
A process by which land becomes increasingly arid and unsuitable for farming.
fertilizers
Natural or synthetic substances that add nutrients to the soil, thereby encouraging plant growth.
food security
The situation in which everyone has access to an adequate and reliable food supply.
genetically modified organisms (GMOs)
Organisms that have had their DNA modified in ways that would not have been possible in nature.
genetic engineering
The modification of crops and animals by removing genetic material from one organism and combining it with the DNA of another.
Green Revolution
A dramatic increase in global agricultural production and crop yields in the late 20th century due to the industrialization of agriculture.
groundwater
Water found underground in the spaces in soil and rock.
hydroponics
A soil-free method of growing plants by suspending them with their roots placed in a water–mineral nutrient solution.
industrial agriculture
A form of agriculture that mimics industrial systems and relies heavily on mechanization, fertilizers, pesticides, water, and energy. Also known as industrialized agriculture and factory farming.
integrated crop–livestock systems
An approach to farming in which a variety of crops and animals are raised on the same farm and animal wastes are used as fertilizer. Sometimes referred to as agroecology, permaculture, and low-input farming.
integrated pest management (IPM)
An approach to managing agricultural pests with few or zero chemical pesticides.
intercropping
See strip cropping.
irrigation
The deliberate diversion of water to crops.
low-till farming
A farming technique that uses minimal or shallow tilling to minimize erosion.
monoculture farming
The cultivation of a single crop with the intent of maximizing crop yields.
no-till farming
A farming technique that avoids plowing, or tilling, to minimize erosion.
organic farming
A form of agriculture that complies with governmental standards forbidding the use of synthetic pesticides, fertilizers, hormones, genetic modifications, and so on.
pesticides
Substances intended to kill organisms that are harmful to humans or domesticated plants and animals; includes insecticides, herbicides, fungicides, and rodenticides.
pests
Organisms that damage or consume crops intended for human use.
polyculture farming
The cultivation of more than one (often compatible) plant or animal species simultaneously.
precision agriculture
A form of agriculture that makes use of technology to manage crops better and use resources more efficiently.
soil
The uppermost part of the Earth’s crust that supports plant life; a mixture of sand and gravel, silts and clays, dead organic material, fauna and flora, water, and air.
soil erosion
The displacement of soil, often by water or wind.
soil fertility
The ability of soil to support plant life; influenced by nutrient levels, soil pH, and soil structure.
soil horizon
A horizontal layer of soil with distinct qualities.
soil salinization
The accumulation of salts in soil.
strip cropping
The practice of growing a mix of different crops in the same area.
sustainable agriculture
Farming that meets our needs in ways that do not undermine critical natural capital systems and the ability of future generations to meet their own needs.
terracing
The practice of cutting into steep terrain to create a series of steps or platforms that can hold soil and irrigation water in place to grow crops.
topsoil
The upper portions of the A horizon, where most living soil organisms reside and where most plant roots are established; often the basis for soil health.
traditional agriculture
A form of agriculture that uses primarily natural and cyclical approaches to nutrient management, pest control, animal husbandry, and water management.
weathering
The process of larger rocks being worn away or broken down into smaller particles by physical, chemical, and biological forces.
weeds
Plants that compete with crops.
