Abstract
Nitrogen (N) fertilization is a key factor in determining potato (Solanum tuberosum L.) yield, especially on sandy soils. A two-year field study was conducted in the Columbia Basin region of Oregon to determine the effect of N fertilizer rates (0, 157, 280, 404, and 527 kg ha(- 1)) on tuber yield and quality. Elevated tuber yield and high tuber quality were associated with Castle Russet and Echo Russet, suggesting that the newly released cultivars suit the Columbia Basin region. Regardless of cultivars and years, the total and US No. 1 tuber yields increased when the N rate was 280 kg N ha(- 1). Increasing N supply further did not affect or even tended to decrease potato yield especially when N was at 527 kg N ha(- 1). The yield of tubers > 283 g and culls increased with increasing N rates up to 280 kg ha(- 1) but then decreased at 404 kg N ha(- 1) and at 527 kg N ha(- 1). Moreover, the specific gravity and the fry color of potatoes were not affected by the N rate. As the petiole nutrient concentrations were associated with tuber yields, their values at the N levels of 280 to 404 kg ha(- 1) might be used by producers in deciding fertilization, especially N. More data should be collected to create the critical petiole nutrient concentrations for developing management practices for these new cultivars.