Polymer Coated Urea for Improving N Uptake in Strip-till Sugarbeet.

Performing strip tillage for sugarbeet (Beta vulgaris L.) in the fall rather than in the spring allows for a wider window of time to perform tillage when soil conditions are favorable and a finer seedbed resulting from soil settling and improved soil structure due to freezing and thawing. A disadvantage is that N fertilizer applied early in the fall, is more susceptible to N movement before planting, especially in sandy-textured soils. Polymer-coated urea (PCU) may offer a solution to this problem by delaying the dissolution and dispersion of urea-N. A field study was conducted from 2008 to 2011 at the NDSU/ARS Mon-Dak Irrigation Research and Development Project in western North Dakota. Irrigation is by a linear-move sprinkler system. Strip tillage, including fertilizer application, was performed in the fall with uncoated urea applied at 210 lbs/acre to 18 rows in each plot and PCU (ESN; Agrium, Inc.) applied at 218 lbs/acre to six rows in each plot. Fertilizer was banded 7.6 cm directly below the seed row. Mid-season plant samples and harvest samples were collected. Soil NO₃-N concentration, petiole NO₃-N concentration and total N concentration were generally higher for PCU than for urea indicating the N availability uptake was improved somewhat with the use of PCU. Mid-season plant dry matter was from 4 to 12% greater with PCU than with urea. Nitrogen uptake was greater with PCU than with urea through early summer. Under the conditions of the study, the yield advantage provided by PCU was varying but consistent. Application of PCU increased root yield by 5 to 10%. Root sucrose concentration 2.6% lower with PUC than with urea in 2008 but differences were not significant in 2009-2011. Results suggest that PCU may provide an advantage over uncoated urea in sugarbeet production where fall strip tillage is practiced.