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Wet vs. Dry

In the face of rising nitrogen costs, some tobacco growers are switching from dry nitrogen to liquid nitrogen.

Brandy Brinson

Rising fuel prices are driving up costs of all kinds of farm inputs, including fertilizer. Nitrogen, which is derived from petroleum, is especially expensive this year thanks to the high fuel costs. Since nitrogen is essential for achieving optimal tobacco yield and quality, it can’t be skimped on. However, there is a way for growers to save money on nitrogen—by switching to a liquid form.

Tobacco growers have historically used dry nitrogen to fertilize their crops. However, many are switching to liquid nitrogen, as some of these products are cheaper. Liquid nitrogen products also have the added bonus of having more efficient application techniques.

Loren Fisher, assistant professor and tobacco Extension specialist in the Department of Crop Science at North Carolina State University (NCSU), says, “Fertilization prices will be up this year. We’ve looked at alternative sources of nitrogen, and liquid nitrogen is the cheapest alternative.”

Corn explosion

Fuel is not the only factor affecting nitrogen; another issue affecting supply and demand is the explosion in corn acreage this year.

“Corn is using up a lot more nitrogen, as cotton fields are being converted to corn fields,” says Robbie Parker, an Extension associate in the crop science department at NCSU. Corn requires more than double the nitrogen that cotton does.

In the Southeast, a lot more acreage of corn is being planted because the price of corn has doubled since last year. The increase in demand for corn is attributed to the rising demand for ethanol for use in gasoline. This is driving up the price of corn. Parker says corn is being bought at $4 per bushel this year, versus $2.50 per bushel last year. The increased corn production has created a run on nitrogen fertilizer.

Rising costs

The price of all nitrogen sources is increasing across the board. “The cost of fertilizer has gone up because the price of oil has gone up. To make nitrogen fertilizer, we start with methane. So oil is one of the raw materials—one of the base manufacturing materials,” explains Bill Easterwood, director of technical support and regulatory compliance for Yara North America, which manufactures both dry and liquid nitrogen.

While the price of liquid nitrogen has also increased, there are liquid sources of nitrogen that are much cheaper than dry. Tobacco farmers have traditionally used dry nitrogen and until now have had no reason to switch.

“Historically liquid nitrogen hasn’t been used in tobacco production—it’s easier to buy dry blended nitrogen products,” says Parker. “Cost hasn’t been an issue because tobacco was more profitable.”

He says that up until 2006, the price of nitrogen had not increased much. This has not been a gradual increase—it’s been a sudden and very significant one.

“From 2006 to 2007, I’ve heard from some growers that the cost has doubled,” says Parker. While that’s on the high end, he says that for the most part, nitrogen prices have increased 30 to 40 percent.

Today, prices of 30 percent urea ammonium nitrate (UAN) liquid nitrogen are averaging 40 to 45 cents per pound, while last year they averaged 32 cents per pound, says Parker. “That’s an increase of 25 percent, and that’s the trend we’re seeing across the board.”

He cautions that not all liquid nitrogen is cheaper—“It depends on which liquid nitrogen you’re looking at. Some liquids are just as expensive as dry nitrogen.”

Parker’s research focuses on UAN, which is a specific type of liquid nitrogen. “UAN is used in most of the Southeast for corn and cotton because it’s very available and probably the cheapest.”

The most common fertilizers for tobacco are calcium nitrate, sodium nitrate, 30 percent UAN liquid and 24S liquid. The NCSU flue-cured production guide points out that in the Southeast, the rate and time of application are more important than which type is used.

“Calcium nitrate is a great product; it’s just expensive,” says Parker. “There are starting to be some different blends, and growers need to shop around.”

Paul Denton, professor and burley tobacco Extension specialist at the University of Tennessee, adds that another alternative to dry nitrogen is ammonia gas (anhydrous ammonia), which is used for corn production. Although it’s an inexpensive source, he cautions that it requires more management and is hazardous to handle.

Cost comparison

By his estimates, Parker says 30 percent UAN liquid will result in about a 66 percent reduction in cost over calcium nitrate. In 2006, calcium nitrate cost $1.03 per pound, while UAN liquid nitrogen cost 32 cents per pound.

In order to convert, growers will have to make an up-front investment in equipment for the application of liquid nitrogen. “Traditionally, growers are set up to use dry nitrogen. However, it is not that expensive to retrofit your equipment for liquid,” says Parker. For example, he says it averages $75 per row unit, so a four-row cultivator would cost $300 to retrofit.

“For a grower with 250 acres (which is the average today), I’d say you could easily convert over for $1,500,” says Parker.

The average grower might use about 75 pounds of nitrogen per acre if he is using calcium nitrate. If he spent $19,300 on fertilizer last year and he only had to spend $6,000 this year, that’s a savings of $13,300.

“I talked to an 800-acre grower last week who purchased a machine to apply liquid fertilizer. The machine cost $8,000. He figures he saved $80,000 last year. That’s a savings of $100 per acre over traditional fertilization practices,” says Parker.

Added benefits

Cost is not the only reason to convert. Liquid nitrogen products can also increase efficiency, especially on large farms. “Growers can become more efficient with a liquid product because they can go over more acreage in a shorter period of time with liquid,” says Parker. Plus, it takes less time to fill up the tanks, and they fill them less often.

Easterwood says it makes sense that larger farms are converting to liquid nitrogen, from a labor perspective.

“Filling the hopper [with dry nitrogen] is quite laborious, whereas pumping liquid is much easier from a labor point of view,” he says. “As farms have gotten bigger, it seems more judicious and makes sense that tobacco growers convert to liquid. It’s not surprising that liquids are increasing.”

He adds, “For years tobacco growers have been applying dry nitrogen, and it does a good job. As farms get bigger, the number of growers fewer and time constraints stricter, fluid fertilizer is a viable option.”

Concerns

While most researchers believe liquid nitrogen is as safe and effective as dry nitrogen, there are some concerns about the way it breaks down.

Parker says he has seen no drawbacks to using UAN. “Three years of research shows no differences in yield and quality statistically between the two.” However, he adds, “The only thing that worries me is that urea has to be converted to nitrate or ammonium for plant uptake. If it’s a wet year or a cold spring, it could be a problem.”

He says urea is generally converted to nitrate within 10 to 14 days, and if the timing of the application is done properly, it should not be a problem.

Denton adds, “The concern is that half the nitrogen comes from each. The urea has to be converted to nitrate in soil. For a delayed post-plant application, this could result in too much nitrate, resulting in barn rot.”

However, he says, this is possible to prevent if the side dressing (post-transplant fertilization) is applied early enough. “I think you could use liquid nitrogen pre-plant—no problem—and post-plant and keep the total nitrogen fertilization rate within reasonable bounds,” says Denton.

The trouble is that some farmers go out later in the season and apply because they decide they don’t have enough fertilizer. “If a farmer has not done a good job with soil testing, there could be concerns with urea—that it could acidify the soil.”

He says it shouldn’t be a huge problem, because many growers don’t use fertilizer after transplanting. Denton says the issue of the urea conversion is a greater concern in flue-cured than burley.

Proceed with caution

Extension specialists warn growers to be careful if they decide to convert. “There’s pressure to go that direction as the price of fertilizer increases, and there’s pressure to look at alternatives. There are very few options for fertilizer,” says J. Michael Moore, professor and Extension agronomist in tobacco at the University of Georgia. “I see our farmers decreasing costs by going to blends.”

But he cautions that they need to work with county Extension agents and fertilizer dealers to make sure they are conducting soil tests and following the guidelines.

Moore says there is a tendency for growers to go with fertilizers produced by major manufacturers that include several micronutrients. “This is more of a shotgun approach—using a product with small amounts of less required nutrients. Our approach is to conduct soil tests to determine what is the limiting nutrient and addressing that particular nutrient problem.”

He says there are lots of opportunities to look at cheaper blends and for growers to develop a “prescription” for their fields resulting from soil tests.

Who’s converting

Growers in North Carolina are switching at high rates, while those in Georgia are not moving so quickly.

Moore says, “There has not been a lot of experience with liquid nitrogen in Georgia because not a lot of farmers have been interested in it. We’re still sticking with the dry materials.”

However, he says it’s vital that growers find ways to reduce costs. “It’s probably more important for our farmers than those in other states because of the added pressure of disease and the resulting crop size. They have less money to spend on fertilizer costs, so we need to be looking at all sources and nitrogen specifically.”

One of the reasons it hasn’t taken off is simply lack of availability of the equipment for applying liquid nitrogen. Moore says he spoke with one farmer who planned to convert to liquid nitrogen for 360 acres but couldn’t acquire the proper equipment. “The corn production has gone wild this year. There has been a shortage in the supply of liquid applicators, so that has been a limitation.”

He says that less than six of the 400 growers in Georgia are using liquid fertilizer solutions this year for tobacco.

Meanwhile, Parker sees a significant increase in growers switching to liquid nitrogen in North Carolina. “We’ve been talking about this issue at our grower meetings for the last two years. Most growers are aware of it.” He says interest recently spiked due to the high nitrogen costs. “I’m getting a whole lot more questions about it now.” He estimates that three years ago, probably less than 1 percent of growers were using liquid nitrogen. “Today, 25 to 30 percent have converted, and there will probably be even more convert this year.”

As for burley growers, Denton says a few in Tennessee have converted to liquid nitrogen, but it is more common in Kentucky. Bottom line, says Denton, “There’s an education job to be done here.”