Cooperative Extension Service Communications and Technology Department 3354 1000 E. University Ave. Laramie, WY 82071 (307) 766-2540 • fax (307) 766-3998 • www.uwyo.edu

 

For Immediate Release

 

Contact: Robert Waggener, Editor

Phone: (307) 766-3571

E-mail: robertw@uwyo.edu

 

Date: April 12, 2006

UW grad student has good news for regional sugar beet farmers

University of Wyoming graduate student Sara Skalsky has good news for sugar beet farmers in Wyoming and surrounding states unable to obtain dry ammonium nitrate to fertilize their fields.

            Research by Skalsky, who is working toward a master’s degree in the College of Agriculture’s Department of Agricultural and Applied Economics, shows that knife or spoke injections of liquid urea-ammonium nitrate (UAN) are more cost effective than using dry fertilizers.

            Dry ammonium nitrate is in short supply because a significant portion of the domestic industry is no longer producing the product, which has been under increased scrutiny by both state and federal governments since it can be used to make bombs, according to The Fertilizer Institute based in Washington, D.C.

            Skalsky said knife injections of UAN produced an average of 26.8 tons of sugar beets per acre and revenue of $1,199 after mid-season fertilizer costs. Not included are land, equipment, labor, herbicides and pre-plant fertilize costs.           

            “The $1,200 per acre looks like a great return, but in reality the net return is much less,” said Bart Stevens, who assisted Skalsky with her research, conducted in 2004 and 2005 at the Powell Research and Extension Center.

Stevens is a former Powell R&E Center soil specialist now with the U.S. Department of Agriculture’s Agricultural Research Service in Sidney, Mont.

The spoke injections resulted in 26 tons of beets per acre and revenue of $1,184 after mid-season fertilizer costs.

This compares to 25.9 tons and $1,144, respectively, for the same amount of granular ammonium nitrate.

Coulter injection of liquid UAN produced 25.6 tons of beets and $1,141 in per-acre revenue after mid-season fertilizer costs.

 Skalsky’s research focused on mid-season fertilizer treatments.            

“Based on my findings, I would use a knife or spoke injection of liquid UAN depending on the availability of equipment,” said Skalsky, of Powell.

The spoke system is said to cause minimal soil disturbance while placing the fertilizer in a good position for root uptake. The coulter and knife systems put the product in small furrows that are subsequently filled with loose soil above the fertilizer band.

Some sugar beet producers apply all of the nitrogen needed by the crop before planting. Others apply a portion before planting and the remainder to the growing crop in early summer. Because of its favorable chemical properties, dry ammonium nitrate has been a good fit for both pre-plant and mid-season applications. 

The most economical alternative is dry urea, but this fertilizer can injure seedling sugar beets when applied in large amounts prior to planting and can volatilize into the atmosphere when applied mid-season. As dry ammonium nitrate becomes less available in the marketplace, split application may become even more common so that large pre-plant urea applications can be avoided.

Skalsky said it’s important for farmers to conduct soil tests prior to planting and soil or petiole tests before applying fertilizer mid-season.

The petiole is the stalk that attaches a leaf to a stem. It conveys nitrogen from the root, where it is absorbed from the soil, to the leaves, where it promotes photosynthesis and leaf expansion. Too little nitrogen can result in poor leaf canopies, premature yellowing and reduced yields. Too much nitrogen can cause reduced sugar content and increase impurities.

            “Providing the right amount of nitrogen at the right time promotes the rapid establishment of a full leaf canopy, which is critical to maximizing sugar production,” Stevens said. The bigger the leaf is, the greater its capacity to capture sunlight, which can then be converted to sugar. When fully grown, a sugar beet weighs from two to five pounds and produces 10 to 25 tablespoons of sugar.

 “If nitrogen is limited in the soil at the time of mid-season application, nitrogen should be placed near the plant row,” said Skalsky, whose research recommends liquid nitrogen instead of dry because it is absorbed faster by the plant.

Stevens noted, “If nitrogen is not limited at the time of application, the least expensive source and application method would seem to be best, and that is typically broadcasted dry nitrogen. The caveat is that any fertilizer broadcast onto the dry side of the plant row will likely be unavailable to the plant until significant rain falls (at least three-quarters of an inch). This didn’t seem to be a problem in either of the two years of our study.”

If dry nitrogen is to be broadcast prior to planting, sufficient preseason nitrogen (100 to 120 pounds per acre) should be applied. The first irrigation for germination should be as brief as possible to help prevent nitrogen from leaching away, and mid-season nitrogen should be applied as early as possible, according to the researchers, whose mid-season application was in mid-June.

After learning dry ammonium nitrate would be in short supply, Skalsky expanded her project last year to include dry urea, Agrotain-treated urea and dry ammonium sulfate.

Stevens said Agrotain inhibits the activity of the urease enzyme that converts urea to ammonia. Warm, windy conditions can cause this ammonia to be lost to the atmosphere when urea granules are on the soil surface. Slowing the conversion to ammonia may reduce this volatilization loss.

Agrotain produced the highest revenue ($1,229) after mid-season fertilizer costs of all the fertilizers tested last year, but Skalsky cautioned that is only based on one year’s data.

“I believe weather played a big role in that. It rained in April and May before the mid-season application, which meant more pre-plant nitrogen was available to the plants, limiting the need for the plants to absorb the mid-season nitrogen quickly,” Skalsky said.

 Stevens added, “No clear differences were observed among the different dry treatments. We got very little ammonia volatilization from the untreated urea. It appears the nitrogen uptake with ammonium sulfate was delayed somewhat based on a comparison of the petiole nitrate levels on the first sample date, but levels apparently never became deficient.”

Skalsky’s graduate adviser is Jim Jacobs, former director of the Wyoming Agricultural Experiment Station, which oversees the Powell R&E Center and other centers near Sheridan and Lingle. He is now a professor in the Department of Agricultural and Applied Economics.

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