Chapter 20. Chapter 20: Feeding the World - A Gene Revolution

What are the trade-offs of using genetically modified organisms...?

Why You Should Care

One of the two most commonly grown GMOs are modified to be resistant to herbicides, which allows growers to spray entire fields with the herbicide as the crop is growing. With non-GM crops, a grower would only be able to spray before sowing the crop or apply herbicide just to weeds, which is very labor intensive and therefore costly. The other common type of GMO crop are Bt crops, which have been modified to produce the Bacillus thuringensis protein, a substance approved for spraying on organic crops to prevent insect pests. Rather than needing to be sprayed with Bt, the modified crops produce it at levels sufficient to kill most pests.

Genetically engineering crops was initially seen as an ideal way to make modern agriculture more environmentally sustainable. It should have greatly reduced the amount of chemicals needed to raise crops—chemicals that killed non-target organisms when they were over-sprayed or ran-off in rainwater and that required non-renewable resources for their production. Now that GMO crops have been grown for over a decade we know that the environmental benefits were short-lived if not nonexistent. Weed species eventually became resistant to the herbicides used on GMO crops, both through natural selection and through transfer of the engineered genes. Just as alarming, some insect pests have begun to develop resistance to Bt, meaning that more hazardous pesticides may need to be used in the future to achieve the same effect. What's more, Bt is one of the only pesticides approved for use by certified organic growers; if insect pests become Bt-resistant, those growers will have one less option for protecting their crops.

All of the GM crops grown in the U.S. have been approved by government agencies as safe to eat, but some researchers claim to have found evidence to the contrary. Even if they are completely safe, most consumers do not like the thought of eating them and probably would not eat them knowingly. Efforts to pass laws requiring manufacturers to label foods that contain GMOs have met overwhelming opposition, so most people do not realize that nearly all processed foods now contain GMOs. Like or loathe them GMOs seem to be a fact of life for the near future.

Although some GMO seeds are being distributed in developing countries, it is still prohibitively expensive for most people to buy them without external aid. So to maintain productivity, farmers in developing countries have examined both current and past agricultural practices to determine what 'low-tech' strategies seem to work best: many times, it's a return to traditional methods. One example is polyculture—the growing of more than one crop in the same place or even the raising of crops and food animals together. You will see in Chapter 22 that, if the right combinations of organisms are grown together, polycultures mimic the interactions of natural ecosystems and improve yields without expensive equipment or chemicals. Another example is crop rotation—alternating the crops grown from year to year, which is a well-established method to prevent excessive loss of soil nutrients and build up of soil pathogens and predators. In Burkina Faso, farmers use traditional Zai pits, which conserve water and help provide nutrition for their crops, but they also use modern methods like micro-fertilization to improve yields. For countries with compromised food security like Burkina Faso, providing adequate food for all will likely require a scientific approach to determine which combination of modern and traditional farming methods will be both financially feasible and maximally productive.