Results of a study on nitrogen (N) sources showed that ammonium nitrate produced higher yields than either urea or UAN solutions on winter wheat. The study, which began in 1997, was conducted by Dr. Donald H. Howard at the University of Tennessee and is sponsored by Mississippi Chemical Corporation. The Potash and Phosphate Institute recently published the study results.
  The two-year study compared ammonium nitrate, urea and UAN solutions as N sources for top dressing wheat. Two-year data shows winter wheat yields were consistently higher where ammonium nitrate was used. In the study, yield averages across the three N sources increased incrementally, with N rates up to a maximum of 77 bu/A with 120 lb/A of spring-applied N. However, when ammonium nitrate was applied, yields were increased up to 90 lb/A indicating a greater efficiency of this N source. Across N rates, yield averages showed ammonium nitrate yielded the most - 76 bu/A - while the other N sources, urea and UAN solutions, yielded 74 and 70 bu/A respectively.
  The nitrogen research project was designed to determine yield differences of N sources in west Tennessee during the spring top dressing season. Yield, disease severity, flag leaf N concentration, N uptake, grain moisture and test weight were measured in the study.
  "This test site was selected because of the climate," Howard said. "Tennessee is a pivotal state for temperatures and moisture conditions for urea volatilization. These are two important factors in volatilization losses from urea-containing fertilizers. Since volatilization of urea begins as temperatures rise above 60 to 70 degrees, we knew that if ammonium nitrate was a superior N source in Tennessee, the results should apply to the entire mid-south region."
  "We can make several recommendations to growers based on the N source study results," Howard said. "The average yields of the study showed ammonium nitrate produced higher yields at a much lower N rate than the other sources. This saves the producer money and protects the environment."
  Working with growers in western Tennessee, Mississippi Chemical field sales representative Jim Harrelson has experienced similar results in testing of N sources on wheat since 1995.
  "We have found that ammonium nitrate is a more effective source of N for wheat growers in this part of the country," Harrelson said. "Even though UAN solutions are less expensive, the yield increases with ammonium nitrate have proved worth the extra cost and extra application." Plots fertilized with ammonium nitrate yielded 73 bu/A and those fertilized with UAN solution yielded from 64 to 70 bu/A.
  Bob Thompson, manager of agronomic services for Mississippi Chemical, plans to use the study results in educational programs for fertilizer dealers, agricultural consultants and field salesmen.
 "When useful information comes from a credible, thorough study such as this, we want to educate growers in the latest scientific findings and effective growing methods," Thompson said. "This study on nitrogen sources could mean the difference between profit and loss for some growers."

One on one with Joe Ewing
  In August 1999, Joe Ewing was named Mississippi Chemical Corporation's Vice President; Marketing and Distribution. A graduate of Mississippi State University, Ewing has served the company in various positions since 1981.
Following is a discussion with Ewing regarding the company's relationship with its customers in Mississippi and other areas of the country.
DBJ: How has Mississippi Chemical changed to meet the needs of farmers today?
Ewing: In the fall of 1999, we reorganized our sales, marketing and distribution division to better respond to the needs of our customers and to provide more individual attention to each customer. In recent years, Mississippi Chemical has faced a consolidation of its customer base, resulting in fewer, but larger, customers. We believe we should always anticipate the needs of our customers. The dynamics of our customer base have changed over the years, and our reorganization was a response to the needs of our customers.
DBJ: How, specifically, has service from Mississippi Chemical to its customers improved?
Ewing: We now have one point of contact for all the products we sell providing more attention to specific needs of individual customers. In the past, two different sales representatives may call on one customer - one to sell potash and another to sell nitrogen. Now, one sales representative can sell a customer any product needed.
  We have also divided our sales territories into two main geographical regions to give our sales staff better access to customers.