Comparison of Fusn and Urea Fertilizers on Russet Potato Yeild and Tuber Quality in Southeast Idaho.

Efficient N management is an essential part of any potato (Solanum tuberosum L.) fertilization program. Nitrogen management can affect potato yield and tuber size and shape, as well as many other tuber quality factors. Fūsn is a relatively new, dry granular ammonium sulfate nitrate fertilizer (26-0-0 14S). The objective of this study was to determine the relative effectiveness of Fūsn compared to urea with respect to yield response and tuber quality in Russet type potato. Three rates (70, 140, and 210 lb-N/ac.) as either urea or Fūsn were compared to a control (0 lb-N/ac.) in Russet Burbank and Russet Norkotah field plots. Five replicates of each treatment were applied in a Randomized Complete Block Design (RCBD). Nitrogen treatments were applied in three splits. NDVI measurements composite petiole samples were taken about biweekly. Tubers were weighed and then graded for quality, size, specific gravity, and defects. An analysis of in-season response to N fertilization using Urea and Fūsn showed that as fertilizer rates increased composite petiole nitrate levels increased at all four measurement dates. In-season NDVI measurements showed no difference among the treatments for the Russet Burbank and Norkotah varieties. Orthogonal comparisons of the control and individual Fūsn and Urea treatments showed that fertilizer treatment yields did increase over the control treatment. For the Russet Burbank variety, the Fūsn 210 lbs/ac rate treatment resulted in increased US No. 1, marketable, and total yield Additionally, the 140 lbs/ac Fūsn treatment showed a higher yield than the control for marketable tubers. Whereas, Urea treatments for the Russet Burbank variety was not different than the control for US No. 1, marketable, and total yield across all urea rate treatments. For the Russet Norkotah variety, all urea and Fūsn treatments had higher US No. 1 and marketable yields than the control. These data suggest that FUSN may improve overall yield and quality over Urea. In conclusion, the data did not show the FUSN had any negative impacts when used in place of urea and may possible result in higher tuber yields and quality.