FERTILIZATION OF RUSSET BURBANK IN SHORT-SEASON ENVIRONMENT

A three-year investigation determined effects of N, P, K, and S rates on tuber yield and quality, economic return, and plant nutrient status of Russet Burbank grown on mineral soils in the Klamath Basin of Oreg on. Yield responses were consistent over years. The highest yields and economic returns were achieved with the combination of 202 kg N, 29 k g P, 56 kg K, and 22 kg S ha-1. Petiole NO3-N concentrations were belo w published critical levels at the optimal N fertilizer rate of 202 kg N ha-1. Yield and economic return responses to increasing N rates wer e positive but small. The highest yield occurred at the lowest P rate (29 kg ha-1). Tuber yield, grade, or quality did not respond to K fert ilization. Findings suggest that nitrogen fertilizer management based on petiole analysis may require modifications for short growing-season environments.