Effect of Seed-Row Placement of Conventional and Polymer-Coated Urea on Winter Wheat Emergence

Polymer-coated urea (PCU) may facilitate nitrogen (N) placement with the seed. Laboratory experiments evaluated the effect of (i) variety and N treatment and (ii) urea contact with the seed on winter wheat (Triticum aestivum L.) emergence. Four varieties were grown in a silt loam soil (–200 kPa Ψ_m, where Ψ_m is matric potential) with control (0 kg N ha^?1), PCU treatment (44% N) at 56, 112, and 168 kg N ha^?1, or urea treatment (56 kg N ha^?1) placed with the seed. One variety had less emergence than the control with PCU at N rates ≥112 kg ha^?1. Urea delayed and decreased emergence of all varieties. In another experiment, urea (56 kg N ha^?1) was placed in contact with or between seeds. The contact treatment exhibited delayed and lower emergence. The no-contact treatment behaved similar to controls. Large amounts of 44% N PCU can be placed with the seed without reducing wheat emergence when soil Ψ_m is at least –200 kPa.