Nitrogen Use Efficiency and Yield Effects of Urea Formaldehyde Polymer (UFP) Fertilizer in Winter Wheat and Maize

Abstract

The potential for improved fertilizer nitrogen (N) use efficiency (NUE) and yield in winter wheat (Triticum aestivum L.) and maize (Zea mays L.) was tested using a new, controlled release urea formaldehyde polymer (UFP). This polymer was compared with conventional aqueous urea-ammonium nitrate (UAN) [(NH2)2CO—NH4NO3] fertilizer during a two-year field experiment in North Carolina from 2004 to 2006. The crops were grown on three soils: Candor (sandy, siliceous, thermic Grossarenic Kandiudult), Portsmouth (fine-loamy over sandy or sandy-skeletal, mixed, semiactive, thermic Typic Umbraquult) and Cape Fear (fine, mixed, semiactive, thermic Typic Umbraquult). The sandy soil was irrigated as needed to avoid drought stress. Treatments were N source (UAN and UFP) and N rate (0, 50, 78, 106, 134, 162, and 190 kg N ha-1 or 0, 45, 70, 95, 120, 145, and 170 lb ac-1 for wheat and 0, 39, 78, 118, 157, 196, and 235 kg N ha-1 or 0, 35, 70, 105, 140, 175, and 210 lb ac-1 for maize) arranged as randomized complete blocks with four replications. The UAN and UFP were applied as a split application for wheat, while maize received UFP at planting and split UAN. Timing of the materials was determined either by label (UFP) or prior experimental experience (UAN). Harvest biomass, grain, and mid-season soil sampling were performed to assess N availability. For both crops, UAN performed statistically similar to or better than UFP at both sites with regards to yields and NUE. Also, soil sampling and incubation results showed no consistent difference between N sources, implying the slow release properties of the UFP were not seen under the site and laboratory conditions. The release time for both sources at both sites was approximately 14 days (2 weeks). Since the cost of UFP is substantially greater than UAN and form did not significantly affect yield, UFP may not be as economical as UAN, depending on pricing of the different fertilizers.