Wednesday, November 7, 2007
299-2
Evaluation of a Polymer-Coated Urea during Crop Production.
Shawn Tingle, Gregory Binford, and David Hansen. University of Delaware, 16483 County Seat Hwy, Georgetown, DE 19947
Improving N management during crop production is a goal that producers constantly strive to achieve. In recent years, polymer-coated fertilizers have been developed that could potentially be a cost effective method of improving N efficiency during winter wheat production. Our goal with this work was to evaluate the use of a polymer-coated urea fertilizer during winter wheat production in Delaware. Studies were conducted at numerous locations over the last few years. Our findings indicate that this polymer-coated urea should not be used by applying 100% of the N in a fall application because significant amounts of N will be lost during the winter and early spring because the winter months in Delaware are warm enough to allow N release from the polymer and subsequent loss of this N to the environment. These studies have also shown that a spring top-dressing of 100% polymer-coated urea at green-up in the spring will often result in significant N deficiency due to delayed release of N from the polymer relative to winter wheat demand for N. Our studies have shown that if this polymer-coated urea is mixed with a soluble source of N (e.g., ammonium nitrate) that N efficiency can be improved relative to applying UAN solutions, which is the most common N source used on winter wheat in Delaware. For spring top-dressings at spring green-up, our work suggests that a fertilizer containing between 30 to 50% polymer-coated urea and 70 to 50% soluble N works well and often results in greater winter wheat grain yields than UAN fertilizer.