Optimizing fertilizer nitrogen use efficiency by intensively managed spring wheat in humid regions: Effect of split application

Abstract

Efficient N fertilizer management is critical for the economical production of wheat and the long-term protection of the environment. Six experiments were conducted at three locations in the south-east of the province of Buenos Aires (SE), Argentina, during a 4-yr period, on Typic Argiudoll and Petrocalcic Paleudoll. The study was designed to evaluate the effects of splitting nitrogen (N) fertilizer on N use efficiency (NUE) in wheat (Triticum aestivum L.). Rates of 0 to 150 kg N ha1 were used, applied at tillering (Z24) or split between Z24 and flag leaf (Z39). The experimental design was a randomized complete block with three replications. Grain yield ranged from 3522 to 8185 kg ha1, according to N availability and application time. In the experiments without water stress (three out of six), average grain yield (across experiments) was 6669 and 6989 kg ha1 for full and split fertilization, respectively. In four out of six experiments, average N in aboveground biomass (NAB), N recovery fraction (NRF), and grain protein content (GPC) for split N application were greater than for full N at Z24 (NAB, 176 and 157 kg N ha1; NRF, 66 and 51%; GPC, 100 and 92 g kg1, for split and full N application, respectively). In years without water stress, splitting N between Z24 and Z39 is an appropriate strategy to improve NRF, reducing N losses, and minimizing the environmental impact of fertilization.