Product cuts nitrogen volatilization, enhancing fertility regimes

02/22/2012 10:59:00 AM
By Jerry Jackson

When crop yield and environmental benefits are enhanced by the same product, it makes for the proverbial win-win situation.

That accounts for some of the marketing success of the nitrogen stabilization product Agrotain.

More farmers have been adding Agrotain to their fertility programs in recent years, particularly in the Midwest and South, as evidence of its benefits spread.

The product has been around for more than a decade, and university research confirms that it can help prevent loss of fertilizer potency to varying degrees, depending on the circumstances.

But now the brand, which was acquired by Koch Industries in 2011, is attempting to make inroads into California, where the wide range of specialty crops and fertilization techniques are significantly different from the typical top-dressed fertilization method used for traditional field crops.

And California has some of the toughest regulatory hurdles for farm chemical use.

Bill Ulrich, regional manager for Koch Agronomic Services in Sacramento, says the market for Agrotain in California has been growing during the past two years.

“We’re still addressing issues and gathering data,” he says. “We have a lot more work ahead.”

Not surprisingly, the product’s best penetration in the state so far has been in wheat, Ulrich says, as California wheat growers follow similar fertilization practices as their counterparts in the Midwest.

Scott Foth, a pest control adviser with Simplot Grower Solutions in Five Points, Calif., says the growers he advises have clearly benefited from using Agrotain along with their urea fertilizer.

“This is the third year, and my growers ask for it now because they’ve seen it work,” Foth says.

The increased yield in wheat, barley, oats and other grains more than offsets the cost of the Agrotain, which averages about $8 per acre, Foth says.

“It’s paying for itself probably 10 times over. You don’t have to time the rains as closely,” he says.

Field trials with some of the state’s specialty crops also prove promising, Ulrich says.

How it works

Fertilizer applied to the surface of fields—traditional top dressing—begins losing potency as nitrogen in the urea essentially floats away as it interacts with air, soil moisture and microbes.

Technically known as volatilization, the process can cause urea-based fertilizer to lose nearly a third of its nitrogen efficiency in less than a week, though more typically the loss is 10 percent to 20 percent.

That loss of potency can be particularly challenging for fields where no-till, or less tillage, is the preferred technique and crop residue is significant, industry specialists say.

But even in clean pastures and forage fields, Agrotain has been shown to slow the loss of nitrogen for weeks.

And recent studies in California and Arizona have documented increased harvests in specialty crops, such as lettuce.

One study at the University of Arizona’s Yuma Field Station showed that lettuce yields rose by about 2.6 tons per acre to 19.5 tons when Agrotain Plus was used in addition to the standard UAN 32, at an application rate of 134 pounds of nitrogen (N) per acre.

The treatment method was sidedressed and shanked in, with a split application—at 30 days after planting and then at 50 days after planting. At a rate of 200 pounds of N per-acre, the increase in yield was slightly less, about 1.5 tons per acre.

Agrotain Ultra is the more recent trade name for the original product called Agrotain, which has a urease inhibitor as the active ingredient.

Another formulation called Agrotain Plus has an additional nitrogen stabilizer, a nitrification inhibitor, which holds ammonia in the soil longer.

Basic Agrotain is a liquid and can be used with dry urea or tankmixed with liquid urea-based fertilizers, such as urea ammonium nitrate or UAN. Agrotain Plus is a dry concentrate.

Charles Sanchez, the director of the Yuma field station who oversaw the iceberg lettuce trials there about three years ago, says Agrotain slows nitrogen loss. The harvest yield increase he saw was not that impressive.

“But I can say for certain the urease inhibitor works.”

Separate studies by University of California Cooperative Extension in Monterey County also showed increases in lettuce yields with Agrotain Plus, for both surface drip irrigation and shallow-buried drip irrigation, though at smaller rates than in the Arizona trials.

Tim Hartz, vegetable Extension specialist with UC Davis, says the crops he works with do not use surface application of fertilizer, so the urease inhibitor part of Agrotain is really not needed.

Urease is an enzyme that promotes volatilization. Once fertilizer is tilled in or absorbed into the soil via irrigation or rainfall, a urease inhibitor has little or no effect. Agrotain Plus contains the urease inhibitor and a nitrification inhibitor, which acts through a separate mechanism to slow nitrogen loss.

Dow Chemical has a stand-alone nitrification inhibitor, but it is not yet registered for use in California, Hartz says. “The only legally approved nitrification inhibitor in California is the one contained in Agrotain Plus. But it’s not sold separately.”

Research at other universities around the country has shown that the combination of using less fertilizer and increased crop yield can more than offset the cost of Agrotain, though weather, soil conditions and other factors can affect the outcome.

As urea fertilizer prices go up, the benefits of using Agrotain also rise, when the spread between costs is maintained, Ulrich says. That has been the case in recent years, accounting for some of Agrotain’s popularity.

Other benefits cited

The benefits also seem to accrue for other crops in California, including almonds and a wide range of vegetables.

A test by Zaccaria Agricultural Consulting in Kern County showed when Agrotain Plus was used, almond production rose to more than 4,000 pounds per acre from about 3,800 pounds in the second year of a three-year study.

The Agrotain Plus cost was $18.25 per acre, and the increase in revenue from the harvest was $429 per acre.

Tree crops pose special challenges for researchers, as the effects from applications do not surface immediately and may be cumulative.

Ulrich says evidence for positive results from Agrotain use is accumulating, and he predicts that more growers will give it a try.

“I’m confident enough now to say that across the board, there is potential benefit for every crop and for every [fertilization] practice,” he says. “It’s not crop specific.”



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