Application Placement and Timing of Nitrogen Solution for No‐Till Corn

Abstract

AbstractFertilizing no‐till corn (Zea mays L.) with urea‐based N sources requires managing for N losses such as immobilization and NH3 volatilization. In this study the interactive effects of fertilizer N application time and placement method were evaluated by applying urea ammonium nitrate (UAN) solution to no‐till corn. Eight site‐years of data were collected from sites in central, northeast, and northwest Missouri on Ochraqualf, Albaqualf, and Udifluvent soils, respectively. Experimental design was a complete factorial of N application time (preplant and sidedress), placement method (knife, dribble and broadcast) and rate (67, 135, and 202 kg N ha−1). Knife injected N increased yields relative to broadcast and dribbled N in five of eight site‐years. Yields from knife injected N ranged from 4 to 20% more than dribble and 5 to 40% more than broadcast. Ear‐leaf N concentration and grain N uptake were increased from knife injected N in six of the eight site‐years. Dribbled and broadcast UAN performed similarly in most site‐years for grain yield, ear‐leaf N and grain N uptake. Except for two site‐years in which sidedress resulted in lower grain yields, application time had no effect on grain yield. No interaction of application time and placement method was apparent, as knife injection was superior to broadcast and dribble at both application times. This suggests that N losses associated with surface application of urea‐based N sources were similar for preplant and sidedress application times.