Effects of Genetically Modified Crops on the Environment

Rosemary Huggins – Animal Science

Jennifer Schaler – Plant Biotechnology

Vincent Scifo – Turf Management

Our global population is currently greater than 7 billion people, and it is estimated that it will reach 9.6 billion by 2050 (United Nations, 2015, p. 2).  This translates to an additional 80 million mouths to feed each year, but we only have 1.5 billion hectares of land available for farming (United Nations, 2015, p. 2; James, 2014).  It is estimated that there are currently 795 million people who are habitually undernourished, claiming the lives of 3.1 million children every year (von Grebmer et al., 2015; Black et al., 2013).  In order to eliminate world hunger and sustain our growing population without depleting all our available land, we need high yielding crops so we can utilize the land to its fullest potential. Low yielding crops, such as organically grown conventional crops, are not nearly efficient enough to maximize the land available. However, growing conventional crops on a large scale requires the use of chemicals, such as pesticides, that harm the environment.

Mass-produced conventional crops require large quantities of pesticides and can have many environmentally harmful consequences.  The term pesticide is a general term that encompasses insecticides, herbicides and fungicides, which are used to control insect, weed, and fungal populations respectively (Environmental Protection Agency [EPA], 2013).  In 2008, pesticide use on corn crops in Germany had unprecedented effects on bee populations.  The president of the German Professional Beekeepers’ Association, Manfred Hederer stated, “50-60% of the bees have died on average and some beekeepers have lost all their hives” (Benjamin, 2008, para. 3).  We rely on bees for pollination of important plant species, so the declining bee populations diminishes plant diversity and growth.  Pesticides often harm non-target organisms, or organisms other than the one the pesticide is meant to protect a crop against.  Insecticides often harm important pollinators, such as bees, while herbicides frequently contaminate water sources and affect aquatic plant species (Benjamin, 2008; Davies et al., 2003).  By negatively impacting non-target organisms on land, in the soil, and in the water, pesticides have huge deleterious effects on the environment (Aktar, Sengupta & Chowdhury, 2009).  A somewhat controversial solution that would provide enough food for the world without inducing significant harm on the environment is genetically modified (GM) crops.

In reality, we have genetically modified crops and animals for centuries just through breeding in favor of specific traits. This process, known as selective breeding, has the same functional outcome as genetic modification: to produce better or more efficient organisms.  Unlike selective breeding, genetically modified organisms (GMOs) are produced by introducing a beneficial target gene into an organism (World Health Organization [WHO], 2015).  This process is more time-efficient and precise than selective breeding, but it is controversial in the public eye (EPA, 2013).  However, the scientific community advocates that GM crops are either neutral or beneficial to the environment.  Continuing to use conventional crops on the scale necessary to feed the growing population would significantly harm the environment through the use of pesticides, an increase in tilled land, and disruption of soil microfauna (Areal & Riesgo, 2015; Valboa et al., 2015; Duc, Nentwig & Lindfield, 2012).  Switching to GM crops would meet the needs of the world while also taking into account the delicate balance of the environment.  GM crops reduce the use of pesticides and decrease the carbon footprint of farming without affecting critical soil diversity.

GM crops reduce the need for insecticides that are often used with conventional crops. When comparing the number of insecticide sprays and the amount of active ingredient used on both GM crops and conventional crops, GM crops require less insecticide usage overall (Areal & Riesgo, 2015).  This decrease is due primarily to the fact that GM crops can be modified to carry genes that make them resistant to pests that would harm conventional crops.  Because this defense mechanism is internal, unlike the less controllable, external use of insecticides, there tend to be less widespread harmful effects on non-target organisms and the environment when using GM crops (Areal & Riesgo, 2015).

Conventional farming lends itself to insecticide spraying to keep yields at an appreciable amount, but with GM crops modified with Bacillus thuringiensis (Bt), the need for insecticide decreases by a reported 2.5 million lbs/year in the United States (United States Department of Agriculture [USDA], 2010). Bt engineered crops are made to produce a crystal protein naturally produced by Bt bacteria that is toxic to insects that eat the crops.  These proteins are specific to certain receptors in an insect’s gut.  Not all insects have the same receptors, making Bt highly specific to the target insect. Humans and other vertebrates are not affected by Bt crystal proteins because these receptors are not present in our systems (University of California San Diego [UCSD], 2003).  In a comparison between Bt maize, conventional maize and conventional maize treated with a common insecticide called Baythroid, only spider communities that were exposed to Baythroid insecticide had “a reduced weight increase, a lower survival, and a longer reaction time” (Ludy & Lang, 2006, p. 151).  There was not a dramatic difference between spiders exposed to conventional maize (without Baythroid) and those exposed to GM Bt maize, but  Baythroid caused significant harm to this beneficial spider species.  In addition to neutrality towards non-target organisms, GM crops have also “reduced chemical pesticide use by 37%, increased crop yields by 22%, and increased farmer profits by 68%” (Kluemper & Qaim, 2014, p. 1).

With the high level of success of GM crops, we can assure high yield production and reduce the amount of insecticide that is sprayed, leading to a reduction of carbon dioxide created by insecticide use.  Phipps and Park (2002) state that:

If 50% of maize, oilseed rape, sugar beet, and cotton grown in the EU were GM varieties, pesticide used in the EU/year would decrease by 14.5 million kg of formulated product [and] there would be a reduction of 7.5 million hectares sprayed, which would save 20.5 million liters of diesel and result in a reduction of approximately 73,000 tons of carbon dioxide being released into the atmosphere. (p. 1)

The reduction of diesel fuel is a result of reduced field operations that are necessary to carry out application of pesticides, whether it was insecticide or herbicide (Phipps & Park, 2002). This is a massive amount of non-renewable resources saved from use and a great direction of where GM crops can take our economy and help in conserving our environment.

Pesticides are a significant concern to the environment, but using conventional crops without pesticides is extremely impractical. In order to grow crops at the scale necessary for our growing population, some method other than simple conventional crops must be used. Organic crops grown without pesticides produce 25% lower yields than conventional crops grown with pesticides (Seufert, Ramankutty & Foley, 2012).  The few methods available to organic agriculture for limiting crop loss to pests are not sufficient.  Bt protein spray, which is a crop protection method that uses the Bt protein described earlier, is allowed in organic farming because it originates from a naturally occurring bacterium.  However, Bt protein spray is not efficient because it washes away quickly (UCSD, 2003).  Increased crop loss translates to a need for even more land to grow the same amount of crops, which increases deforestation and biodiversity losses.  While this lower yield is due to many contributing factors, the inability to guard against pests using insecticides and herbicides when growing organic crops is a significant factor.  This leaves two alternatives – either grow crops using pesticides which are known to harm the environment, or grow GM crops that innately ward off pests.

In addition to limiting pesticide usage, GM crops reduce global warming by reducing tillage practices and farm land expansion. Between 1996 and 2013, the world produced 441.4 million tons of GM food, feed and fiber. If these were not produced by GM crops, you would need an additional 132 million hectares of conventional crops in order to reach the same outcome due to the inefficiency of conventional crops (Barfoot & Brookes, 2014).  To put this in perspective, the 132 million hectares that would have to be cleared for the use of conventional crops is equal to 273.6 million football fields, or slightly larger than the country of Peru.

Farmers using conventional crops resort to tilling their land to get rid of weeds before their crops come up. The process of tillage breaks up the topsoil structure, which can lead to a decrease in soil integrity that takes years to come back from with continued use. Tillage degrades soil quality and releases carbon dioxide stored in the soil into the atmosphere (Helsel, Grisso & Grubinger, 2012).  “Up until the late 1950s, tillage (plowing) released more carbon dioxide into the atmosphere than all the burning of oil and coal in history” (Hofstrand, 2007, p. 2). A conventional tillage process requires around five gallons of diesel per acre (Helsel et al., 2012, p. 1). In 2012, the average U.S. farm size was 434 acres, requiring 2,170 gallons of diesel (USDA, 2014, p. 1). About 22.38 pounds of carbon dioxide are produced from a gallon of diesel fuel (U.S. Energy Information Administration, 2015, p. 1). That is equal to producing nearly 49,000 pounds of carbon dioxide for the average farm in conventional tilling. Tillage also causes surface water runoff because the soil integrity is lost, leading to water erosion and erosion of the loose topsoil by wind. Tillage reduces the population density of soil microorganisms that are responsible for the vast majority of decomposition. As those populations decrease, the organisms are not there to bind soil particles. Soil integrity is lost and organic matter can very easily be lost to erosion and runoff, leaving the farmland non-arable (not suitable for growing crops).

The need for tillage can be reduced by using herbicide-tolerant (HT) GM crops (Valboa et al., 2015).  HT crops often require zero tilling, reducing the need for herbicides by leaving the plant material from the previous season on the soil.  This residual plant material inhibits light from hitting the seeds of weed species, which prevents germination and the movement of weed seeds by equipment (Bot & Benites, 2005).  A decrease in herbicide use would reduce environmental harm by eliminating the accidental contamination of nearby land and water supplies, leading to a decrease in negative effects on non-target plants (Buckelew, Pedigo, Mero, Owen & Tylka, 2000).  Farmers that reduce tillage can also take advantage of carbon credit programs in which they get paid for keeping the carbon in the soil.  The credits they receive are sold to companies that want to reduce their emissions (Hofstrand, 2007). Thus, with HT crops, the reduction of tillage sustains soil health and overall integrity for continued use while also providing economic benefits to the farmers who grow them.

Despite the benefits of herbicide tolerant GM crops in reducing tillage and overall herbicide use, many are concerned that the transgenes of GM crops that give them herbicide resistance will transfer to weeds and produce “superweeds” that are also resistant to herbicides (Gilbert, 2013, p. 24). However, the National Research Council reported in 2010 that “resistance has evolved in only three pest species in the last 14 years” due to transfer of resistance genes from GM crops (p.96). On the other hand, at least 8 weed species have developed herbicide resistance due to herbicide use on crops (Duke & Powles, 2009). Based on research, there is a greater risk of resistance development when using herbicides directly than when crops are genetically modified to resist pests.

In addition to reduced tillage and decreased carbon emissions, GM crops also have a neutral effect on soil organism diversity.  Many people are concerned that GM crops would decrease soil quality by affecting microfauna, including decomposer species. Decomposers break down soil organic matter to produce nutrients available to crops (Duc et al., 2012). These non-target organisms must be evaluated because they are constantly exposed to crop residues that may have the potential to negatively impact soil organisms.  In a study observing 43 species of decomposers and other soil microfauna, there was no difference in organism diversity between GM and conventional wheat crops (Duc et al., 2012).  Another concern about GM crops is that they may alter soil functioning by negatively impacting soil fungi. Arbuscular mycorrhizal (AM) fungi provide mineral nutrients through the soil to maize crops (Verbruggen et al., 2012).  There was no significant difference in “AM fungal richness” (Verbruggen et al., 2012, p. 7389) between GM and conventional maize, indicating that the fungal diversity was not impacted by using GM crops instead of conventional.  GM crops did not affect the soil fauna or AM fungi present either in their population density or their ability to decompose plant material, indicating that the use of GM crops does not negatively impact soil function or diversity.

Using GM crops in the place of conventional crops will allow us to grow a sufficient amount of food without harming the environment.  In order to accomplish this, farmers must be encouraged to use GM crops — through the carbon credit program for reducing tillage, for example.  Although growing GM crops can be more expensive than conventional seeds by about $81 per acre, they are a better investment in the long run both environmentally and economically (Royte, 2013).  The USDA reported that growing GM crops results in “higher crop yields, and/or lower pesticide costs, and management time savings” (Fernandez-Cornejo, Wechsler, Livingston & Mitchell, 2014, p. 41).  There must also be an acceptance of GM crops by the general public through increased exposure to research information.  The Assistant to the President for Science and Technology, Dr. John Holdren (2013), has made efforts to increase access to research results by directing federal agencies with more than $100 million in research spending to make published research results available for free to the public after a year.  The significant portion of federally funded research would increase public awareness of research, providing data-driven information for people to base their views of GM crops on instead of the often uninformed, opinion-based media outlets.

Our population is growing at an unimaginable rate, which begs the question: where are we going to find/get the food to keep up with this growth? In order to address our current shortage of food and to provide sufficient food for our ever-increasing numbers, we need more efficient ways of growing crops. Genetically modified crops are the answer to this food struggle.  GM crops have no known impact on soil microfauna (Duc et al., 2011; Verbruggen et al., 2012), and the reduction of pesticides makes them environmentally superior to traditional crops (Areal & Riesgo, 2015; Ludy & Lang 2006).  Using herbicide-tolerant GM crops also reduces the need for farmers to till their land, which decreases the amount of carbon dioxide released into the atmosphere (Areal & Riesgo, 2015).  Our current pattern of climate change predicts an increase in frequency and intensity of heatwaves and droughts that would lead to even lower crop yields and less arable land (National Climate Assessment, 2014).  The land and trees that would be cleared to grow enough conventional crops to alleviate world hunger would release an unimaginable amount of carbon dioxide into the atmosphere.  The carbon stored in the Amazon rainforest has already dropped by one third in the last 20 years (Welch, 2015).  If we begin using more GM crops across the globe in the place of conventional crops, we may be able to halt this destructive pattern.




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