URBANA, Ill. — While genetic engineering has a role in agriculture, it does not, on balance, improve sustainability, according to a senior scientist at the Union of Concerned Scientists.

Doug Gurian-Sherman of the Food and Environment Program at UCS gave his perspective to lead off the “Understanding and Addressing the Anti-Genetic Engineering Critique” special symposium recently at the University of Illinois.

The challenge that lies ahead for agriculture is meeting the food needs of a growing world population without expanding agriculture’s footprint.

“Agriculture is also the biggest user of water. The figures vary, but typically about 70 percent of the freshwater that we use is used for agriculture,” Gurian-Sherman said.

He said the level of the Ogallala Aquifer in the western states is “going down faster than it can be recharged by rain.”

“So, at some point in the future, we’re either going to have to find a way to cut way back on the water used for crops or we’re going to have to stop farming there or find some other solution that we’re not aware of,” he said.

“This is also happening in many places around the world. We’re going to have to deal with this. In addition, we have potential sources of freshwater being reduced by climate change.”

Gurian-Sherman issued a UCS report in 2009 that disputes the claims from the biotechnology industry that it will feed the growing population through advancements in genetically engineered crops that will produce higher yields.

The report, “Failure to Yield,” claims that despite 20 years of research and 13 years of commercialization, genetic engineering has failed to significantly increase U.S. crop yields.

The report evaluated the overall effect that genetic engineering has had on crop yields in relation to other agricultural technologies and reviewed two dozen academic studies of corn and soybeans, the two primary genetically engineered food and feed crops grown in the U.S.

Based on those studies, the UCS report concludes that genetically engineering herbicide-tolerant soybeans and herbicide-tolerant corn has not increased yields. Insect-resistant corn, meanwhile, has improved yields only marginally.

The increase in yields for both crops over the last 13 years leading up to the report was largely due to traditional breeding or improvements in agricultural practices, according to Gurian-Sherman.

“By our calculations, about 15 percent of the yield increase was contributed by genetic engineering and the rest by breeding and improved agronomy,” he said at the event, hosted by U of I’s Agroecology and Sustainable Agriculture Program.

“More recently, more robust datasets came up with an aggregate of 10-percent yield increase over a similar period of time contributed by genetically engineered traits. But they also see a yield bias.

“One troubling trend is the companies that own much of the seed supply now are focusing most of their best germplasm on the seed that they’re putting the engineered traits into, and that’s what this 5- to 10-percent yield bias represents.

“There have been surveys done that confirm that if you do want to buy conventional varieties, the germplasm is not usually as good overall for yield and so on, and this is potentially a problem for a lot of farmers.”

The UCS also has compared sustainable ag systems with other systems that may work.

“We do know there are some options for controlling some of these pests,” Gurian-Sherman said. “There is some conventional resistance to rootworm over the last years in conventional breeding. We don’t know quite how good it is. It’s sometimes very hard for these public breeders to get these traits into the seed supply now because of the concentration in the seed industry.

“There are some studies that have shown some impact in organic farming of controlling some of the pests that are targets for the Bt traits. Certainly, we know that for rootworm, except where there is rotation-resistant rootworm, historically rotations have worked quite well in controlling them and very little insecticide is needed.

“I would argue that if we had been doing longer crop rotations all along, although speculation on my part, I’m doubtful that we even have the rotation resistance. I would attribute that, although it’s speculation, that rotation resistance more likely to the fact that we’re always doing these short corn-soybean rotations.”

One the benefits that’s been touted for herbicide-tolerant crops is the increase in conservation tillage, particularly no-till.

“It probably does. It certainly makes it easier, but the reality is there hasn’t really been a big increase in no-till acres since Roundup Ready crops were developed, according to a National Academy of Science report,” Gurian-Sherman said.

Regarding an increase in yield since the development of herbicide-tolerant crops, he said, “we don’t really know how much of this can be attributed to Roundup.”

“Most folks are using Roundup for their herbicide treatments now, but no economists have done an analysis to try to estimate what the trend would have been if we didn’t get Roundup,” he said.

“So, it’s probably contributing, but you often hear this touted as having a huge benefit from Roundup Ready crops. Yes, they’re helping, but it’s important to try to keep it in perspective as to how much they may be helping.”

Nitrogen usage also has a major impact on agriculture.

“Synthetic nitrogen fertilizer increases crop productivity a lot, but it also contributes to about 400 dead zones in coastal waters throughout the world,” Gurian-Sherman said. “There’s the famous one in the coastal waters off the Gulf of Mexico, most of which is attributed to the upper Mississippi River Basin, that is impacting fisheries. So we need to get a handle on nitrogen.

“One approach is to use genetic engineering to improve nitrogen use efficiency — can you use less nitrogen to produce a bushel of corn, for example? Breeding has historically been improving nitrogen use efficiency when it’s been tested, even though it has not historically been a target for breeders.

“There has been significant increase through breeding and other methods (to improve nitrogen efficiency), but at the same time, so far, despite a lot of effort, there are no commercially available nitrogen use efficient crops made through genetic engineering.”

He also noted drought-tolerant corn products currently in the marketplace.

“If you look at the data they supplied to USDA, which is somewhat limited, we need more — it provides about a 6-percent yield benefit in moderate drought,” he said. “You may get some benefit in severe drought. It’s not clear that the economics would add up because you’re still going to get big yield losses, not maybe as big.

“If you do the math and you look at where this is probably going to be most useful, it’s probably about 15 or 20 percent of corn acreage under moderate drought. That’s about an average yield benefit of about 1 percent.

“By contrast, Bruce Babcock, a respected ag economist at Iowa State University, published an insurance actuarial study, but the data actually shows historically that drought tolerance has been increasing in maize for the last 30 years at about 1 percent a year.

“It’s important to understand, as well, that conventional breeding is making a lot of strides in improving drought tolerance. There are a lot of crops that are important both in the U.S. and developing countries where there’s been significant improvement in drought tolerance with conventional breeding.”

Conventional breeding often has been referred to as “ancient history — that was great in the 20th century, but it doesn’t have much to offer anymore,” Gurian-Sherman said.

“In fact, maybe ironically, molecular studies have showed there is a huge amount of untapped genetic diversity in virtually all of our major crops. It’s been estimated that we have only tapped about 5 percent of the genetic diversity of wheat, and the same can generally be said for most of our crops. Overall, this all adds up to genetic breeding still drastically outpaces genetic engineering.

“A couple big problems with genetic engineering from our prospective is it’s being used in the same monoculture system that has the benefit of being highly productive, but is contributing to a lot of these problems, so we have to make it more sustainable. Monocultures tend to exacerbate pest problems, and now we’re seeing a huge resistant weed problem and emerging insect resistance problem.”

He sees agroecology offering a positive alternative to the more widely used crop production system, as it “reduces groundwater pollution by 40 percent to 70 percent, reduces erosion, puts sustainable nitrogen in the soil, provides carbon sequestration and so forth.”

“We have good alternatives on a field-scale level in the Corn Belt,” he said. “The four-year rotations have a higher productivity than the short two-year corn-soybean rotation, whether there is genetic engineering or not, and the net profit for those farms is higher.

“The labor efficiency is somewhat lower, but the net profit is higher because the farmers are spending less on expensive inputs and more of that profit is staying with the farmer, staying in local communities, which has an economic multiplier effect, rather than going to a corporate headquarters. There are also great reductions in fertilizer use.

“Genetic engineering so far has not been as successful in addressing these challenges. It’s had some successes around the edges. It faces huge challenges with complex traits. The first traits were very simple genetically — Bt and herbicide tolerance. The next generation usually has multiple genes controlling them.

“It’s much more expensive. It’s not faster — that’s a complete myth. And even where it’s successful, it’s not a systematic approach to improving our farming systems.

“We try to encourage better policies, and part of we do is to suggest the government and the public side should put more of its effort into improving agroecology, making it more farmer-friendly, and more money into public breeding.

“Genetic engineering can and will have a role, but we should keep that in perspective, not sell it as a silver bullet, and really understand that there are other methods and other approaches that, from our perspective, are both cheaper and better.”