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USDA Experiments Aim to Help Farmers Cope with Warming Climate

Scientists are hanging heaters over crop fields to simulate temperatures in 2050. Their goal: to understand climate impacts on food and help farmers adapt

Mar 9, 2011

Farmers fed up with climate change-induced heat waves, droughts and flooding may one day get to reap rewards of a unique U.S. government experiment that aims to understand how crops will adapt to even harsher conditions.

In a field in Maricopa, Arizona, about 35 miles south of Phoenix, a group of researchers at the U.S. Department of Agriculture (USDA) are simulating high temperatures anticipated to occur in 2050, using infrared heaters suspended above wheat plants.

The results of these experiments, they say, might tamp down future food crises by helping growers and ranchers manage their crops and livestock as temperatures change.

For many, relief can't come too soon, as climate-related impacts are already affecting food supplies. The spring wheat crop in North Dakota, for instance, is being threatened by potential heavy rain and flooding, and last summer's drought and heat wave in Russia damaged crops that contributed to higher global wheat prices.

"No one knows how changing conditions will affect yields in the decades ahead, and we're trying to give growers an idea about what they might expect," said Bruce Kimball, a retired soil scientist with the Ari-Land Agriculture Research Center in Maricopa, a project of the USDA's Agriculture Research Service (ARS).

Kimball developed the T-FACE, or temperature free-air controlled enhancement, apparatus that raises the temperature of experiment crops in open fields.

The device is being shared with scientists working on cropland in Australia, China and Mexico and on native range lands in Colorado.

The first results of the ARS field experiment were published on February 24 in the journal Global Change Biology. Kimball and the other ARS scientists say their preliminary results closely resemble what they had expected after examining the computer model predictions of global warming effects on food crops.

'A Little Global Warming' Has 'Dramatic Effect'

Kimball, together with ARS plant physiologists Gerald Wall and Jeffrey Whit, and Michael Ottman, an agronomist from the University of Arizona, used six 1,000-watt infrared heaters suspended above the plants in a hexagonal pattern, which allowed them to boost the temperature of crops in open fields.

Typically, Arizona wheat is planted in mid-winter and harvested in late May. Temperatures can range from below freezing in winter to above 100 degrees Fahrenheit in May, Kimball told SolveClimate News.

As part of the experiment, the team planted wheat every six weeks in separate plots between March 2007 and May 2009.  The researchers applied heat to six of the 15 plantings so that the temperatures rose by 2.7 degrees Fahrenheit in the daytime and five to six degrees Fahrenheit at night.

Not surprisingly, the warmer temperatures helped the wheat grow faster, allowing the crop to be harvested one week earlier than normal, Kimball said. Also expected was that wheat planted six months earlier, in spring rather than mid-winter, suffered.

There was at least one surprise, however, the scientists noted.

Wheat planted three months earlier in September grew for a longer period of time — enough to allow the crop to remain undamaged when frost began to dust the fields around the last week of December.

"The heaters actually saved the wheat that was planted early," Kimball said. "So you can say a little bit of global warming can really have a dramatic effect on wheat yields," Kimball said.

The findings imply that wheat grown in warm-weather climates resembling the Maricopa region might be able to survive a seven-month growing season, instead of the typical five-month season, Kimball said.

T-FACE Experiments Pricey but 'Must Be Done'

David Lobell, an assistant professor of environmental earth system science at Stanford University, said that employing T-FACE in the field is unique and very expensive, "but it must be done if you are going to find out how to adapt."

That's mainly because it provides information on plant biochemical processes that can't be modeled, Lobell said. Most research on plant tolerance, ecosystem change and global warming has been done using computer models rather than in the field.

Today, more scientists are screening plant varieties for drought tolerance than for other impacts of climate change, Lobell explained, and the reason is simple.

Scientists measured a dangerous 30 percent to 40 percent drop in major crop production caused by Russia's heat wave last summer and the European heat wave in 2003, which compares with the estimates developed by models, he said.

Experiments on Grasses, Maize and Soybeans

Meanwhile, two other ARS groups are using T-FACE to raise temperatures and then adding carbon dioxide to their field experiments to examine how the plants photosynthesize the gas.

Jack Morgan, plant physiologist with the ARS Rangeland Resources Research Unit at Fort Collins, Colorado, is experimenting on native grasses in semi-arid grassland in Wyoming, though results have yet to be collected.

The research has a practical value in a warming world, Morgan said.

"We know that ecosystems system will change a little bit in terms the plants they support, which means that the livestock they support and the people that depend on the livestock will be affected."

Another group is experimenting on maize and soybean in Urbana, Ill., said Carl Bernacchi, a plant physiologist with the ARS Global Change and Photosynthesis Research Unit in Urbana.

"The ultimate goal of this research is to understand the underlying changes in photosynthesis that occur when plants are grown under what is predicted to be future atmospheric and climate conditions," Bernacchi said.

He continued: "No results have passed the review process, but to some extent, I can say that the picture that is unfolding is a lot more complex than previous experiments that have been done just dealing with heat," adding that this is the first time that heat and CO2 have been applied to crops in the field.

ARS scientists also developing a model for farmers that incorporate data from these field experiments plus results on how various wheat varieties withstand various climate conditions.

"These data will help farmers somewhat indirectly, as it trickles down and is incorporated into the plant growth models growers can refer to today," Kimball said. "In the case of a heat wave, for example, we can say, 'Okay, this is the best time to plant.'"

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