Perspectives On Line

NC State University

Winter 2001 Contents Page Features Partners for Preservation Back to the Future Keen ObservationStream of ConscienceNatural Remedies Reaching Consensus
Noteworthy News Giving Alumni Items of Interest From the Dean College of Agriculture and Life Sciences  



































































"Essentially what
we're doing is going
back to curing to-
bacco the way we
did before World
War II."

— Mike Boyette

  Photo by Communication Services

emember tobacco? Big leaves? Foundation of North Carolina agriculture? Cultural icon for generations of North Carolinians?

It has been perhaps a little too easy to forget tobacco lately. Tobacco growers seem to have absorbed one body blow after another.

Domestic demand for tobacco declined, tobacco exports decreased and the amount of surplus tobacco from previous years held in storage increased. As a result, the quota, or amount of tobacco farmers may produce each year, dropped precipitously. Quota has been cut roughly in half since 1997. At the same time, lawsuits have cost the big tobacco companies, the buyers, tens of millions of dollars.

It has seemed at times that tobacco, the crop that for generations defined North Carolina agriculture, was destined to dwindle away in a state that appears increasingly to be turning to high-tech enterprises, where forests and fields are being replaced by houses and highways at a sometimes alarming rate.

But don’t write tobacco’s obituary just yet.

While tobacco is no longer the billion dollar crop it once was — it was worth close to $800 million to North Carolina growers in 1999 — it is still among the state’s major agricultural money makers. This year’s crop is said to be particularly high quality, the best in 10 to 15 years. And tobacco growers have reason to be pleased with the way their industry has responded to one of its most recent challenges.

Late in 1999, growers got what appeared to be the latest bad news. The big tobacco companies began to signal their concern that tobacco produced in the United States contains unacceptably high levels of substances called tobacco-specific nitrosamines, carcinogens that can be formed during the curing process. The tobacco companies announced that beginning in July 2001, they would no longer buy high-nitrosamine tobacco, and several companies began contracting with growers to produce tobacco containing lower amounts of nitrosamines. It became clear that if growers were to continue to produce tobacco, they would have to change the way they did business, and they would have to do so quickly.

That’s when Dr. Mike Boyette, Philip Morris Associate Professor of Biological and Agricultural Engineering, became involved. Boyette is an expert on postharvest handling of crops. For tobacco, that means the curing process.

Boyette worked with the Tobacco Industry Leadership Group, which is made up of representatives from farm organizations, cigarette manufacturers, leaf dealers, tobacco equipment manufacturers and others, to develop guidelines for the equipment needed to retrofit tobacco curing barns with the heat exchangers needed to produce low-nitros-amine tobacco, to establish a time line for barn conversion and to develop a program to help farmers pay for the retrofits.

Photo by Herman Lankford

In some ways, that was the easy part. Boyette then began meeting with tobacco growers to explain to them why retrofitting their barns was necessary.

“We went to meetings where we expected 30 growers, and we got 600,” Boyette recalls. And the growers were not necessarily in the best of moods, which was understandable. They were being told they would have to make a significant change in their operations. Yet no one knew exactly how to make that change. The equipment necessary to retrofit barns wasn’t readily available. And while financial assistance was being promised, it wasn’t clear early in the year when Boyette was meeting with growers when that assistance would be available.

“Some of the meetings were rowdy,” Boyette recalled.

But faced with the knowledge that tobacco contains nitrosamines and knowing how to remove nitrosamines, tobacco companies felt they had no choice but to demand low-nitrosamine tobacco from growers, Boyette added.

Nitrosamines are formed in flue-cured tobacco when the tobacco is exposed to combustion gases produced during the curing process. Before this year, virtually all the flue-cured tobacco produced in North Carolina was cured in direct-fired curing barns. A burner that burns natural or propane gas is attached to each barn. This burner heats the air in the barn, curing the tobacco.

Tobacco was not always cured this way in North Carolina. Boyette said that before World War II wood was the preferred fuel for curing barns. A wood fire burned just outside the barn. The heat and combustion gases flowed through a flue, usually made of brick, that snaked across the floor of the barn, then rose up through the barn. Because the gases moved through the flue, the tobacco was never exposed to them. The barns were heated, and the tobacco cured, but the heat was indirect. Presumably, the tobacco from those barns contained low levels of nitrosamines.

Ironically, this is generally the way tobacco is cured today in other parts of the world, particularly in areas like Brazil and Zimbabwe, whose farmers are major competitors of American tobacco growers. As a result, this foreign tobacco is low-nitrosamine. In other words, low-nitrosamine tobacco is available, so if American growers wish to remain competitive in global markets, they have no choice but to reduce nitrosamine levels.

After World War II, Boyette added, tobacco growers began to switch from wood to fuel oil as a heating source, but they still used flues that carried the combustion gases through the barn. Then, with the energy crisis of the early 1970s, growers began to switch to natural or propane gas, which was more readily available than fuel oil. Because gas burns so cleanly, growers were able to get rid of flues, and began using direct-fired barns.

Now, growers are being told they must retrofit their barns with heat exchangers in order to remove the tobacco from contact with combustion gases. It is a back to the future movement, for the heat exchangers growers are using are little more than updated versions of the flues growers once used. Boyette explained that most heat exchangers consist of lengths of pipe that connect to a burner and stretch across the floor of curing barns. Like the flues of years ago, heat exchangers carry combustion gases through and out of the barn.

To retrofit a tobacco barn with a heat exchanger is not a terribly challenging technological feat. “Essentially, what we’re doing is going back to curing tobacco the way we did before World War II,” Boyette said. But retrofitting an estimated 30,000 to 35,000 curing barns over a two-year period without a standard design for a heat exchanger and without heat exchanger manufacturers in place, that’s a feat.

Yet it’s a feat tobacco growers appear to be tackling successfully.

“Although we’ve only retrofitted 15 to 20 percent of the barns, we’re past the point where there was a real steep learning curve,” Boyette said. “We now know what to do and how to do it.” He added that it appears most growers have retrofitted a few of their barns and have experimented with these barns. Based on what they’ve learned from these first retrofits, growers plan to retrofit their remaining barns in time for next year’s crop.

Boyette pointed out there were no tobacco barn heat exchanger manufacturers early this year. Now there are now roughly 20 such firms.

Boyette and North Carolina Cooperative Extension tobacco agents have been busy, in the meantime, testing heat exchangers.

They’ve found that all the heat exchangers that have been installed in barns do what they’re supposed to do. Nitrosamine levels in tobacco from barns equipped with heat exchangers are down 92 to 95 percent from comparable barns that have not been retrofitted.

Since all the heat exchanger designs seem to work, Boyette and tobacco agents have gone a step further. They’ve been testing the efficiency of various heat exchangers so they can tell growers where they’re likely to get the biggest bang for their buck, which systems will cure the most tobacco with the lowest fuel usage. That will be particularly valuable information as farmers continue to retrofit their barns.

Boyette credited Extension tobacco agents across the state with being particularly diligent in working with growers to retrofit barns. “This has really been Cooperative Extension at its best,” Boyette said.

Boyette is confident the barns that have not been retrofitted will be by next year’s deadline. And he’s not surprised growers have reacted as they have.

“This industry can turn on a dime,” he said. “We have educated farmers.”

He added that growers are willing to make whatever changes are necessary to produce a product buyers want.

And Boyette thinks reducing nitrosamines in tobacco may ultimately help preserve the industry, since nitrosamines are thought to be a primary carcinogen in tobacco.

“Nitrosamines may not be the last thing we have to deal with,” Boyette said. “But I’m convinced there will be a time when there’s a safer cigarette.” The production of such a product would help ensure the future of North Carolina tobacco growers.


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