Genetic Engineering Benefits: Promise vs. Performance

Genetic engineering (GE) has often been touted as a crucial part of the solution to the agricultural challenges of the 21st century. Are these claims borne out by evidence?

Palmer's amaranth (pigweed), one of several weeds that have become resistant to glyphosate herbicide due to overuse of GE herbicide-tolerant crops.

Benefits with tradeoffs 

Genetically engineered crops have provided benefits in some areas, though these benefits tend to come with problematic tradeoffs.

For example, the use of herbicide-resistant GE crops haves saved farmers time formerly devoted to mechanical cultivation and spot spraying, but has also driven the consolidation of monoculture farming at larger scale. Monoculture by definition reduces biodiversity, making farmers dependent on chemical inputs rather than natural processes to manage pests and the soil nutrient cycle.

GE technologies have made it easier to use "conservation tillage", or reduced plowing, a practice that significantly decreases soil erosion. Heavy tillage was previously used largely to control weeds. However, conservation tillage in the context of industrial agriculture is turning out to be a mixed blessing—and overuse of engineered herbicide-resistant crops has driven a destructive epidemic of herbicide-resistant "superweeds," which is reviving tillage.

And while conservation tillage has some important benefits, it needs to be incorporated into broader agroecological farming practices to address most of the challenges of industrial agriculture. Genetic engineering so far is not leading to the adoption of agroecological farming.

Similarly, Bt corn has reduced the use of sprayed insecticides, but its adoption has coincided with sharp increases in the use of neonicotinoid seed treatments, which have been tied to declining populations of birds and beneficial insects such as honeybees. And as with herbicide-tolerant crops, the benefits of Bt corn are being eroded as pest insects develop Bt resistance, forcing farmers to look for other, potentially more toxic options.

In both of these cases, the use of agroecological practices combined with crop breeding can deliver greater benefits without many of the undesired side effects of the GE alternative.

Falling short on three major fronts

Furthermore, several important hoped-for benefits of GE—yield increases, reduced fertilizer use, and drought tolerance—have yet to materialize, or have been of relatively small magnitude, as UCS analysis has shown in the trilogy of reports below. And while some scientists and others point to a brighter future in which GE will make unique and major contributions to agriculture, the reports do not find that current science supports such claims.

The bottom line? It's true that GE has provided some real benefits to farmers—but those benefits have fallen far short of making a convincing case that GE will be a key component of a sustainable long-term approach to agriculture in the United States. And when it comes to public investment in GE, the costs of foregoing other, better options due to limited public funds should be considered. There may be some instances where GE is the best and cheapest approach, but to date no such cases have actually been developed.


Failure to Yield

This 2008 study reviewed two dozen studies of genetically engineered crop varieties, concluding that herbicide-tolerant GE corn and soybeans had produced no yield gains over the preceding 13 years, while insecticide-tolerant GE corn had produced only marginal gains. Most of the yield gains for these crops had resulted from modern crop breeding methods or improvements in agricultural practice. In light of these results, the report recommended that the U.S. Department of Agriculture, state agricultural agencies, and universities increase their research on crop breeding and sustainable farming, and that international food aid groups make these more promising and affordable options available to farmers in developing countries.


No Sure Fix

Released in 2009, this study turned to the question of nitrogen pollution. Crops engineered to use nitrogen fertilizer more efficiently would provide significant reductions in nitrogen pollution from fertilizer runoff, a leading cause of "dead zones" at the mouths of major waterways. However, No Sure Fix showed that a decade's worth of research had failed to produce any commercial GE crop varieties with this useful trait—while again, modern crop breeding methods, in combination with improved practices such as cover crops and precision farming, were shown to be a viable and affordable solution to the problem.


High and Dry

This 2012 conclusion to the trilogy analyzed performance of corn varieties engineered for drought tolerance, finding that the one commercial variety of drought-tolerant GE corn provided only modest benefit in moderate drought conditions, and little or no benefit in severe drought conditions. Furthermore, the GE variety did nothing to improve water use efficiency—meaning that it would provide no help in conserving fresh water resources. Once again, modern crop breeding methods and agroecological practices promised to provide similar or superior benefits to farmers at a much lower cost.

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