Evaluating the Performance of Controlled-Release Fertilizers for Potato Production in the Columbia Basin

Controlled-release fertilizers (CRFs) have shown the advantage in reducing nitrogen (N) losses and enhancing N use efficiency (NUE) in many regions. However, little information is available for the Columbia Basin, where N management is critical for potato production. To fill the knowledge gap, two-year field trials were conducted to evaluate the agronomic performance of three CRFs (ESN, SuperU, and Multi-cote) in comparison with the conventional fertilizer, urea, at the Hermiston Agricultural Research and Extension Center during two growing seasons (2023 and 2024), evaluating two application methods (surface vs. deep placement) and three N rates (150, 250, and 350 lbs N/acre). Our results showed that surface-applied ESN and Multi-cote generally outperformed SuperU and urea in both seasons. However, the optimal N rates of ESN and Multi-cote were not being able to be identified in the trials. Yields from SuperU and urea declined at the highest N rate (350 lbs N/acre), suggesting potential over-application or reduced nitrogen use efficiency. Across both years, surface-applied urea consistently outperformed deep placement, likely due to reduced seed germination, especially at higher N rates. All of the fertilizers tended to reduce the specific gravity when compared to the control. The soil and petiole data showed that CRFs did not exhibit consistent improvements in nitrogen contents, particularly SuperU. Overall, these research findings will help growers better understand the performance of the CRFs and make good decisions on fertilization plans.