Field Evaluation of Urea Fertilizers Enhanced by Biological Inhibitors or Dual Coating

Abstract

Relative to soluble N sources, enhanced-efficiency fertilizers (EEFs) support steady turfgrass growth and dense canopy quality while abating N loss as nitrate, ammonia, and/or N2O from turfgrass systems. Modern EEFs provide turfgrass managers greater operational effect and versatility in their nutrient management efforts and compel field characterization of their temporal response. Likewise, field confirmation of commercial EEF nutrient recovery helps stakeholders select the appropriate EEF for their specific application. Our research objective was to quantify the temporal response of Kentucky bluegrass growth/yield, canopy density and color, and fertilizer N recovery to a practical application of conventional urea or an enhanced-efficiency granular fertilizer. In May 2014 and June 2018, Kentucky bluegrass plots were fertilized by granules of conventional urea, N-(n-butyl) thiophosphoric triamide (NBPT)-, and dicyandiamide (DCD)-stabilized urea, or polymer-/sulfur-coated urea (PSCU) at a N rate of 43.9 kg ha−1 (0.9 lbs/1000 sq. ft.). The dependent variable response over the two growing seasons was highly affected by efficiency enhancement. Following the repeated 16.5-week evaluations, the mean percent of fertilizer N recovered from conventional urea, stabilized urea, and PSCU totaled 57.5, 68.4, and 89.1%, respectively. In the 23 to 51 days from treatment (DFT), recovery of PSCU-N significantly exceeded that from conventional or stabilized urea.

Keywords

• dicyandiamide (DCD)
• multispectral radiometry
• N-butyl-thiophosphoric triamide (NBPT)
• nitrogen
• nutrient fate
• nutrient management