2019 ASHS Annual Conference

Potato production requires large quantities of potassium (K) especially in the Columbia Basin where the potato-growing season lasts 5-month long. However, the information related to K fertilization for potato production is relatively limited, especially for new potato varieties. Therefore, there is an urgent need to evaluate the nutrient requirements and develop nutrient guidelines for each specific variety, which would help growers achieve optimal potato production with tailored fertilizer rates. From April 25 to October 3, 2018, a field experiment was conducted on Quincy loamy fine sand soil in Boardman, Oregon followed a randomized complete block design with three replicates. The treatments consisted of the combination of six potato varieties (Clearwater Russet, Castle Russet, Umatilla Russet, Alturas Russet, Echo Russet, and Russet Burbank) and five K rates ranging from 0 to 897 kg ha^-1. Field observation showed that different potato varieties had a different growth pattern; Alturas Russet had the longest vine followed by Clearwater Russet, while the Echo Russet had the shortest vine followed by Castle Russet. The potato vine was longer in fertilized plots than in the non-fertilized plots. The highest yield occurred at a K rate of 448 kg ha^-1 for Alturas Russet, Clearwater Russet, and Umatilla Russet, at a K rate of 224 kg ha^-1 for Russet Burbank, and at a K rate of 672 kg ha^-1 for Castle Russet and Echo Russet. In general, the tested potatoes had good fry quality meeting to USDA standard No.1. The highest K rate tends to have a better fry quality for Alturas Russet, Castle Russet, and Clearwater Russet, while the fry quality for Echo Russet was consistent regardless of K fertilizer rate. A moderate level of K rates had lower fry quality for Russet Burbank and Umatilla Russet. More data are needed in order to develop variety-specific K recommendations for the main potato varieties in the region.