Evaluation of Environmentally Smart Nitrogen in Winter Wheat in North Carolina

Abstract

Core Ideas Environmentally Smart Nitrogen (ESN) and ESN mixtures with ammonium sulfate did not increase grain yield over urea–ammonium nitrate. Effects of ESN timing varied due to year and physiographic region. Environmentally Smart Nitrogen does not appear to provide agronomic benefit to wheat in North Carolina. Winter wheat (Triticum aestivum L.) field trials were conducted from 2013 to 2015 to evaluate effectiveness of Environmentally Smart Nitrogen (ESN) in two different physiographic regions in North Carolina: Coastal Plain and Piedmont. Trials were designed to (i) determine the effectiveness of ESN alone or in blend with ammonium sulfate compared with standard fertilizer applications; and (ii) identify optimum timing of application. At plant, all plots received starter fertilizer as urea–ammonium nitrate (UAN) at the rate of 30 lb N acre−1. An additional 105 lb N acre−1 was applied as one of six treatments in the winter (late January through early February) and/or spring (early March). Winter treatments consisted of 100% ESN, or blends with ESN providing either 75 or 50% of total N (ammonium sulfate provided the remainder). A fourth treatment consisted of spring ESN application providing 50% of the total N (the remainder from ammonium sulfate). Two final treatments provided N from UAN and ammonium sulfate, either as split application (late winter and early spring) or spring application. Compared with fertilizer applications without ESN, ESN treatments did not differ for grain or straw yield, or grain, straw, or crop N uptake in the Piedmont. In the Coastal Plain, 2013–2014 ESN treatments returned higher yields when applied in spring than in winter applications; spring‐applied treatment without ESN had higher yields than ESN treatments. In 2014 to 2015, there were no yield differences between the ESN treatments and the non‐ESN treatments. Environmentally Smart Nitrogen does not appear to provide an agronomic benefit to wheat production in North Carolina.