The US leaf tobacco sector may be one of the most efficient in the world. We examine some of the latest technologies that have been incorporated into production and assess the benefits.
Less nitrogen
The rising cost of fertilizer has led farmers in the US to reassess the amount of fertilizer they need to produce a crop in the twenty first Century Burley growers in particular had a chance to save some money on sidedressing nitrogen, says Tennessee Extension tobacco agronomist Paul Denton.
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"In most of this state, we didn't have enough rain [in June] to leach a substantial amount of nitrogen," he said. Since the nitrogen was presumably still there, the farmers were often able to cut back a bit on sidedress applications.
A fringe benefit of less nitrogen was in some cases improved maturity and timing.
"A significant portion of Virginia's flue-cured has been overfertilized in recent years, and the season has run longer than necessary as a result," David Reed, Virginia Extension tobacco agronomist says. "If we can change that by keeping nitrogen applications low, we can avoid extending the season and save some on late-season labor."
But you can economize too much on fertilizer, says J. Michael Moore, Georgia Extension tobacco specialist. One shortcut that didn't pay off in Georgia this season was the use of fertilizer materials containing high levels of chlorine. They sell for a lower price, but there are undesirable effects on the leaf.
"These are not good choices for tobacco," said Moore.
Another fertilizer cost-cutting strategy backfired this spring when some Georgia farmers tried to 'mine' the residual potassium they had in the soil.
"On our long-time tobacco soils, we may be able to make use of some residual potassium," said Moore. "But on newly cleared soils where there has not been time for a buildup of P and K, low levels are frequently seen. A soil test will tell. You don't want to treat all your fields the same way."
Finally, on a related note, American growers have learned they can grow tobacco with fewer cultivations than their grandfathers did.
"The tendency now is to cultivate less than in the past," says Moore. "Cultivation is still a good way to manage weeds that are not effectively controlled by herbicides, and it improves aeration and water penetration. But fewer cultivations than in the past are certainly acceptable."
How to cut the high cost of curing
"The single greatest cause of burner inefficiency in a flue-cured barn is too little or too much air," said Grant Ellington, NC Extension associate in engineering.
"The proper air-fuel ratio can best be achieved with a combustion analyzer," he said.
When too little air is present, the burner will produce partially unburned fuel or smoke, he says. Smoke wastes fuel and can deposit soot inside the heat exchanger, reducing efficiency and increasing fuel consumption by as much as 8%.
"When too much air is present, the excess air cools the combustion gases and carries heat out before it can be captured by the heat exchanger," he said. In this situation, find a combustion analyzer to assist with adjusting the heat exchanger burner.
Ellington says there are several steps a farmer should take to increase curing efficiency:
1) Load your racks or boxes uniformly with quality tobacco.
2) Maintain an adequate air flow through the tobacco.
3) Maintain proper control of the curing conditions.
4) Make sure that your equipment and barns are energy efficient and well maintained.
In the states, a farmer is advised to aim for an average curing efficiency of at least 10 pounds of cured leaf per gallon of LP gas, especially if he is using box barns. Curing efficiencies will be less with lowerstalk leaf but will increase in the middle and upper stalk. If you can't achieve this level of efficiency, it is an indication that the heat exchanger, the curing management, the barn or some aspect of the system itself is not operating efficiently. Installation of a gas meter provides accurate fuel consumption and curing efficiency over the entire season.
A big step
There has been a big step in curing technology among US flue-cured growers in recent years. Automated ventilator controls have caught on big time.
"They allow you to set a path from one step of the curing process to the next," says agronomist Moore of Georgia. "Instead of attending to a barn every two to four hours, it allows you to program the next step."
Most growers who install these controls find they can get by with less fresh air than they have been using and save some fuel in the process, he added.
Further advances are much to be hoped for because the cost of fuel for curing just keeps going up.
"We saw LP gas prices [in 2008] at about double what we had last year," says Moore. "If you paid US$1.05 last year, you probably paid about $2.10 this year. That's a tremendous increase, way above what the [state universities] budgeted before the season."
Still, diesel is even higher. "[In fact] if you are using diesel, a conversion to LP gas makes good dollars and sense," Moore said.
Squeezing out a little more lemon
It is quite clear that American flue-cured growers are not producing as much 'lemon' leaf as the People's Republic of China (PRC) would like to buy here. But it appears they are learning how to do it.
The Chinese demand for flue-cured leaf with a lemon color is well established. But until this season, the Americans' success in producing it was mixed.
That's because growing lemon leaf is not exactly a science. Agronomists say nitrogen application must be reduced and harvest dates moved up a bit earlier. Growers get little help from variety choice, since most varieties currently in use in the USA don't easily produce lemon leaf.
In the dry 2007 season, growers learned another lesson: lemon color is very difficult to produce in a dry year. This season was dry too, but there was considerably more rain, and as harvest got going, there appeared to be a chance for more lemon color.
Most Chinese purchases of US flue-cured are from the midstalk positions of lugs and cutters, the grades that tend to cure a lemon color most often. They buy some tips, but usually just the thinner ones.
Another US buyer with considerable experience in the China market pointed out that the Chinese demand for light leaf was based on appearance more than flavor.
It has been suggested that American flue-cured growers might get more lemon leaf if they would separate a cutter grade from their leaf. US cutters have been in very low demand for a long time, and many if not most farmers have gotten into the habit of including their cutter leaves in their leaf grades and not marketing a cutter grade at all.
Perhaps for not quite the same reasons, Chinese purchases of US burley have come from a similar part of the stalk.
"The Chinese tend to buy burley from the middle of the stalk, and they don't care much for the tips or the lower stalk," said Brian Furnish, general manager of the Burley Tobacco Growers Cooperative Association in Lexington KY. "We have had a lot of interest from China, and from the Philippines and Indonesia as well." Enditem
