Nitrogen Response Patterns of Three Potato Varieties as Affected by Rate, Source, and Timing of Application.

Newer potato varieties have been released by potato breeding programs over the past ten years in an effort to replace Russet Burbank, the traditional variety used for both processing and fresh market. Specific advantages of the new varieties include better tuber uniformity and less susceptibility to tuber defects. Potatoes in the upper Midwest are often grown on irrigated, coarse textured soils and therefore how these varieties respond to nitrogen (N) is important from both a production and environmental standpoint. A field experiment was conducted at the Sand Plain Research Farm in Becker, Minn. to evaluate the effects of nitrogen rate, source and timing on yield, quality, and N recovery of three processing potato varieties: Russet Burbank, Umatilla, and Premier in 2008 and these same three varieties plus Bannock in 2009. Ten N treatments were evaluated. Six of the ten treatments were conventional N sources with the following N rates (kg ha-1): 34, 136, 204, 272 (early), 272 (late) and 340. Four of the ten treatments were Environmentally Smart Nitrogen (ESN) manufactured by, Agrium, Inc. The four ESN treatments were: ESN preplant at 204 and 272 kg N/ha or ESN emergence at 204 and 272 kg N/ha. Optimum yields of Russet Burbank and Premier were between 204 and 272 kg/ha N depending on timing and source. For Umatilla, yield increased with increasing N rate over the range of N rates tested. At the 270 kg/ha rate, early conventional N and ESN applied preplant were optimum for Russet Burbank and Premier, while late season conventional N and emergence applied ESN were optimum for Umatilla. Overall yields were higher for Russet Burbank and Premier compared with Umatilla.