Farmers turn to engineered corn to adapt to drought. But will it be enough?

August 15, 2012

Out in western Kansas, the corn looks unsalvageable. The landscape is rife with curled brown leaves, an unmistakable sign of severe drought.


Not a pretty sight. (AFP)

Yet beneath those wilted leaves, some of the corn shows promise. The kernels have held up surprisingly well in a few places given this summer’s swelter. At hundreds of sites across the Great Plains, seed companies like Monsanto and Pioneer have been testing a slew of new corn varieties engineered to withstand drought. Now, as the harvest approaches, they’re anxious to see the results.

This year, the worst U.S. drought in half a century could cause an estimated $18 billion in damage to corn, soybeans and other key crops. On the heels of a severe Texas drought last year that cost nearly $8 billion, farmers are more interested than ever in innovations that can make their crops more resilient. That includes improved farming practices, better plant-breeding techniques or even — most controversially — genetic engineering.

Given the severity of this year’s drought, many crops will wither no matter what. Still, some farmers remain cautiously optimistic.

“I’ve been surprised so far, the plants are responding well,” says Clay Scott, a grower in Kansas who volunteered to plant two plots of Monsanto’s genetically-engineered DroughtGard corn among his 3,000 acres of regular corn. The experimental strain, which carries a gene that helps it draw water more gradually from the soil, is slated for wider release in 2013. “The ear size, kernel counts, the ear weights look good,” Scott said. But, he cautions, “pretty corn doesn’t always result in yield.”

For Scott, who lives in a region prone to dry spells, where irrigation water from the nearby Ogallala Aquifer needs to be conserved, new drought-tolerant crops could prove indispensable — if they work.

It’s a pitched battle between nature and human ingenuity. And the current drought offers a reminder that the battle will only grow more difficult. The world’s population is soaring past 7 billion. Climate models suggest that drought will become more frequent in North America if the planet keeps heating up. Water will become increasingly precious. Feeding the world, then, will require wringing as much food as possible from every last drop of water.

And it’s far from assured that human ingenuity will win out.

“This is perhaps the biggest challenge that we face,” says Mark Edge, who’s in charge of marketing DroughtGard for Monsanto, the world’s largest seed company. “And there’s so much complexity to it, that it’s one of those things you dive into with humility and trepidation over what you’re actually going to be able to accomplish.”

Adapting to drought

Since the 1920s, crop scientists have focused on breeding improved strains of corn and wheat in order to provide ever bigger yields. In the past decade, however, researchers at private companies and land-grant colleges have put a renewed emphasis on developing crops that can also withstand extreme weather events. Like drought.

“Ultimately, plants need water,” says Thomas Sinclair, a crop scientist at North Carolina State University. “If they don’t have the water, then farmers are going to take a yield loss. But our work is to minimize that yield loss as best we can.”

Traditionally, this has been accomplished by breeding hardier crops. Scientists might look for genetic traits that allow certain corns to adapt to drier areas. These traits could include roots that burrow deeper in the soil, or stomata that close earlier in the growing cycle to retain moisture. By interbreeding these varieties with high-yield corn, scientists can create crops that use water more efficiently or withstand dry spells.

The process involves plenty of trial and error. Yet recent genomic techniques have enabled breeders to track traits more accurately and efficiently.

A slew of drought-tolerant hybrids are now appearing on the market. In 2011, Dupont Pioneer released eight versions of its conventionally bred AquaMax corn, which was found to boost yields by up to 7 percent in certain drought conditions compared with regular corn. The company is introducing 17 varieties this year.

Then there’s genetic engineering. In recent years, seed companies like Monsanto have taken crop science to a new level by either manipulating a plant’s genes directly or transplanting genes from unrelated organisms. Monsanto’s DroughtGard, for instance, contains a bacterial gene that enables it to retain water. The corn is targeted at farmers in the drier Great Plains and is the only genetically engineered crop bred for drought tolerance that’s so far been approved by the Department of Agriculture.

Yet scientists caution that while both techniques are promising, there are huge challenges in breeding — or engineering — drought-tolerant crops.

For one, there’s no such thing as a single drought. Some dry seasons are driven by a lack of rain early on, others suffer from a lack of rain late. Some droughts occur because of a lack of precipitation, others are driven by extreme heat.

“A genetic trait that expresses itself well for early drought tolerance may not be a solution for a drought later on in the season,” says Tony Vym, an agronomist at Purdue University. “And something that expresses itself well as being drought tolerant under normal temperatures may not help when temperatures are extremely high.”

Climate change could make these problems far more complicated if it leads to more extreme variation in weather — say, a drought one year and a flood the next. That means crop scientists need to breed plants to withstand a variety of conditions.

“The big challenge with climate change is that I can’t just work on drought,” says Mitch Tuinstra, a corn breeder at Purdue. “It’s the variability of all these different stresses that makes this so difficult.”

Genetically engineering a plant to withstand drought, meanwhile, poses its own set of challenges. In the past, companies like Monsanto have focused on genetically modifying crops that are resistant to pesticides or pests, such as Bt corn. But that often involves manipulating a few genes. Drought can prove more complicated.

“The reality is that drought impacts every process in the plant,” Sinclair says. “There’s not one magic gene out there that’s going to make the plant perform better under drier conditions.”

In June, a report by the Union of Concerned Scientists questioned whether genetically engineered crops would play a central role in tackling drought and water stress anytime soon. Developing and testing such crops can take 10 to 15 years. The seeds are often more expensive. And the benefits appear modest so far — the report estimated that Monsanto’s DroughtGard would boost U.S. corn productivity by just 1 percent. (That's assuming that the corn performs 6 percent better than conventional varieties under moderate drought and gets planted on a certain fraction of corn fields.)

“There’s little to suggest that genetic engineering will make a major contribution to drought tolerance and water-efficiency use in the next five to 10 years,” report author Doug Gurian-Sherman said. “But 20 years down the line? I don’t know.”

Other options

The slow pace of biotechnology is one reason why experts say it’s crucial not to overlook less-flashy improvements in agricultural practices that can help farmers conserve water and minimize losses during dry years.

“I sometimes worry we put too much emphasis on the genetics,” says Larry Wagner, an agronomist at South Dakota State University. “Certainly the genetics are getting better. But farming practices are getting better every year, as well.”

The practice of no-till farming — in which seeds are planted without churning up the soil — has become more widespread in recent decades, Wagner says. Modern equipment allows farmers to plant seeds through old crop residue, enabling the soil to hold more moisture. Computer technology can allow planters to analyze their soil and calculate exactly how much fertilizer to use in each area.

These techniques add up. One 2009 study estimated that a combination of improved practices and conventional breeding had boosted the drought tolerance of U.S. corn by 1 percent a year in the past few decades.

Drought anxiety has also revived interest in organic farming practices, such as covering the soil with compost or cover crops to hold more moisture. A recent Nature paper found that soils managed with organic techniques tend to hold more water and perform better in dry conditions than conventional farming. Amid the current drought, Iowa State’s Kathleen Delate has been studying these farms to see how they fare. “Overall, the organic plots seem to be faring better,” she noted, “but we need to quantify this.”

Other experts, such as William Moseley of Macalester College, argue that the U.S. may need to rethink its dependence on corn, a lucrative, much-subsidized crop that is especially susceptible to drought. Planting a wider variety of crops, such as alfalfa or sorghum, could prove wiser in areas like the central plains.

“All of these agro-ecosystem approaches that build soil fertility are extremely valuable,” Gurian-Sherman says. “But they don’t get nearly as much money or attention from the big companies.” He noted that the U.S. government spends just 2 percent of its agricultural research budget on sustainable farming.

Climate change has given the task a renewed urgency. Recent modeling work by Aiguo Dai of the National Center for Atmospheric Research suggests that droughts in the United States could become far more frequent and persistent in the next 20 to 50 years, thanks to rising temperatures and natural variations in ocean cycles. “These two factors lead to very dire outlook for the U.S., especially the West, in the coming decades,” Dai said.

It’s still an open question how far new technology will enable farmers to adapt to that hotter, drier world. “There’s more investment now [in drought-tolerance] than there was 20 years ago,” Vyn says. “But is that enough? I’m hopeful that the science will continue to improve. But I’m also mindful of the ticking clock.”

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Ezra Klein | August 15, 2012