Evaluation of Co-Granulated Potassium and Boron on Potato Yield and Quality.

Applying boron (B) evenly is both challenging and important because B is required in small amounts and the window between deficiency and toxicity is narrow. A new fertilizer formulation has been developed to facilitate even B application by granulating it with potassium (K) (Aspire; Mosaic; 0-0-48(K)-0.5B). In a three-year field study on a Hubbard loamy sand soil, we evaluated the effectiveness of Aspire as a K and B source for Russet Burbank potatoes. Six treatments were applied in which potato plants received either: (1) no K or B, (2) 279 kg·ha-1 K as muriate of potash (MOP) at planting, (3) 279 kg·ha-1 K and 2.8 kg·ha-1 B as Aspire at planting, (4) the same rates of K and B as MOP with granulated 14.3% B at planting, (5) 279 kg·ha-1 K as MOP split between planting and hilling, and (6) 279 kg·ha-1 K and 2.8 kg·ha-1 B as Aspire split between planting and hilling. Based on petiole and tuber K and B concentrations, MOP and Aspire were similarly effective as K sources, and Aspire and granular B were similarly effective as B sources. Potassium fertilization increased tuber yield and size in both years. Aspire produced similar yields but larger tubers than MOP in 2015 and 2016 when applied at planting alone. However, differences in size distribution were not apparent when applications were split between planting and emergence. Granular B with MOP resulted in a tuber size distribution intermediate between single applications of MOP alone and Aspire. Tuber quality was not affected by treatment, except that tuber specific gravity in 2015 was higher for the check treatment and those receiving a single application of MOP than for the other treatments. Our results indicate that granulating K and B can be an effective method of producing even and adequate applications of B.