Fall Application of Polymer-Coated Urea in Strip-till Sugarbeet.

Advantages to fall strip tillage for sugarbeet (Beta vulgaris L.) include 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 the freezing and thawing. A disadvantage is that N fertilizer is applied early in the fall, increasing the potential for N movement before planting, especially in sandy-textured soils. Controlled-release urea may offer an economical solution to this problem by delaying the dissolution and dispersion of urea-N. A field study was conducted in 2008 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 polymer-coated urea (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. In 2008, mid-season plant dry matter was 12% greater with ESN than with urea. Nitrogen concentration did not differ significantly, but ESN produced a narrower top C:N ratio (7.14) as compared to urea (7.45). Nitrogen uptake was 15% greater with ESN than with urea through early summer. Root yield was 3.1 tons/acre greater with ESN than with urea, but root sucrose content was 0.46 percentage points lower with ESN. Despite these offsetting effects, ESN still resulted in 723 lb/acre more gross sucrose per acre than urea (P<0.10). In 2009, there were no significant differences observed between the two fertilizer treatments. Results suggest that ESN may provide an advantage over uncoated urea in strip till sugarbeet production where fall strip tillage is practiced.