Last month the British Royal Society's flagship scientific journal, The Philosophical Transactions of the Royal Society, reported the results of a three-year Farm Scale Evaluation (FSE) study that compared conventional crops with genetically enhanced herbicide-resistant crops. Anti-biotech activists immediately claimed that the FSE results supported their demands for a total ban on genetically modified agriculture.
"For years the GM corporations have been claiming that their crop would reduce weed killer use and benefit wildlife," Greenpeace responded in a statement. "Now we know how wrong they were." Tony Juniper, director of Friends of the Earth, argued, "These trials have shown that GM oilseed rape and beet cause more damage to the environment than even conventional crops. The maize results are at best inconclusive. Going ahead with the commercialization of any of these GM crops would be totally unacceptable."
But do crops that are genetically enhanced to tolerate herbicides hurt the environment? Looking at the details of the FSE study reveals the evidence of harm to be less than compelling. The very limited question that FSE researchers were asked to investigate was whether or not there was any "difference between the management of GMHT [genetically modified herbicide tolerant] varieties and that of comparable conventional varieties in their effects on wildlife abundance and diversity." To find out, farmers planted several score fields half with conventional varieties, and half with GMHT varieties. The researchers then looked at the abundance of weeds, invertebrates (insects, spiders, snails, etc.) and vertebrates (chiefly birds) living in the farm fields and along the uncultivated margins of the fields.
What did they find? They found that fields growing herbicide-tolerant beets and canola had fewer bees and butterflies. Why? Because bees and butterflies consume nectar, and the GMHT fields had fewer flowering weeds for them to feed on. The researchers noted that "the results for bees and butterflies relate to foraging preferences and might or might not translate into effects on population densities." In other words, bees and butterflies prefer to flit off to areas where flowers bloom and stay away from relatively weed-free fields. Meanwhile, another group of insects—springtails—increased in GMHT fields because they feed on dead plant matter, e.g., the weeds killed by herbicides. Except for those groups, the researchers concluded, "The FSEs have shown that GMHT management has no strong effect on the majority of the higher taxa of aerial and epigeal arthropods…" Translation: Surface dwelling and flying invertebrates were largely unaffected by GM crops.
What about weeds? By engineering in herbicide tolerance, farmers can use safer, less toxic herbicides to control weeds throughout a crop's growing period. For conventional crops, farmers typically pre-treat a field with herbicide to kill off weeds before or shortly after they plant. Since their crops are generally susceptible to herbicides, farmers are limited in the herbicides they can use once their conventional crop begins growing. So weeds that escaped the pre-treatment continue to grow and compete with crop plants for nutrients and sunlight. Since herbicide-tolerant crops can be treated at any time, this means that farmers can more easily control weed infestations.
So it is not surprising that the FSEs found that there were fewer weeds in beet and canola fields, and therefore there were fewer weed seeds available to feed wildlife such as birds. On the other hand, weed densities were greater for GMHT maize, most likely because the conventional herbicide (atrazine) has such a long-lasting effect that it kills far more weeds during and after treatment. Maize fields, both conventional and GMHT, had far fewer weeds per square meter than either beets or canola. In fact, choosing to grow maize rather than beets or canola has a far greater effect on wildlife than growing genetically enhanced crops.
The Greenpeace claim that GM growing does not reduce the amount of weed killer used by farmers was shown by the FSE study to be dramatically false. Farmers used 48 percent less herbicide for GM beets, 43 percent less for maize, and herbicide applications were not significantly different for canola, although in the U.S., canola farmers typically use 60 percent less herbicide than do conventional growers.
The FSEs clearly provided some fascinating new information about the differences in the conventional and genetically enhanced crops. The investigators should be applauded for rigorously and fairly answering the questions given to them. However, their findings do not ineluctably tell policymakers or the public what to do about genetically modified agriculture, no matter what the anti-biotech activists may claim. The future direction of farming depends far more on value judgments and aesthetic concerns than it does on scientific studies like the FSE. The central question probably is: What kind of landscape do people prefer?
Consider that no matter what effects either conventional or GM crops have on wildlife, they pale in comparison to the impact that the introduction of modern herbicides and pesticides 50 years ago had on farmland biology. Farmers' fields became dramatically more productive, and comparatively weed- and pest-free.
Of course, this modern revolution in farming has boosted food production many fold, and makes food cheaper and more abundant than it has ever been in history. Few people would advocate doing away with conventional farming in order to boost wildlife populations, if by doing so we increased the risk of starvation. Farming, it's worth remembering, is the opposite of letting nature run wild—that's why agriculture is so much more productive than hunting and gathering.
Besides, the FSE researchers themselves point out that an alternative to banning GM crops would be to manage the landscape to produce the sort of plants that would support the preferred collection of insects, spiders, birds, mammals, and so forth. In fact, if protecting wildlife is the right goal, the higher productivity of genetically enhanced crops means that less land has to be planted to grow food for people, thus leaving more land for nature. So there may be less wildlife in the fields, but more across the whole landscape, after it has been allowed to revert to nature.
But why not ask a deeper question? Why favor the sorts of wildlife that thrive in relatively open areas like farms in the first place? Chopping down essentially all of Britain's forests to create farms had a far greater effect on wildlife than herbicides or genetically enhanced crops do. In the United Kingdom today, 85 percent of the total arable land surface is sown in crops. Why not get rid of farms entirely and restore Britain's once dominant woodland species? After all, farmers in the European Union have no business at all growing highly subsidized sugar beets, since the sugar they produce costs several times the world market price for that commodity. It's the same with maize-—farmers in Ohio can grow corn much more cheaply than the British.
The FSE program offers some fascinating scientific insights, but it cannot tell us how farmland should be managed. If anti-biotech activists want to favor certain wildlife and not others, that is their choice. But they cannot make the case for their preferences by arguing that "science" has somehow proved their point.