COMPARATIVE EFFICACY OF UREA FERTILIZATION VIA SUPERGRANULES VERSUS PRILLS ON NITROGEN DISTRIBUTION, YIELD RESPONSE AND NITROGEN USE EFFICIENCY OF SPRING WHEAT

The impact of urea prills (1–2 mm) versus urea supergranules (USGs, ∼10 mm), placed at different depths, on the growth and nitrogen (N) use efficiency of spring wheat was investigated under greenhouse conditions. The amount of fertilizer 15N derived from either form was 50% greater in the top soil than at lower depths. The comparatively slower release and distribution of USG-N resulted in enhanced dry matter production and fertilizer-N uptake during the later growth stages that were also associated with a higher translocation of fertilizer-15N into the grain (34.9% versus 28.7% for the prills). Deeper placements of USGs (5.0–7.5 cm) resulted in greater fertilizer-N recovery in the crop (70.5–78.0%) compared to the use of prills (56.6%). Our results strongly suggest that the proper application of USGs can increase yields and fertilizer-N utilization of wheat and simultaneously decrease N losses compared to equivalent use of prills, and therefore presents important agronomic advantages.