Response of potato tuber yield and uptake to potassium and nitrogen in sandy soils

Abstract

AbstractPotassium (K) is essential for potato (Solanum tuberosum L.) production, influencing physiological processes, nutrient uptake, and tuber quality. This study evaluated the interactive effects of K and nitrogen (N) on potato yield and quality in Florida's sandy soils to determine optimal K application rates for maximum yield and improved N use efficiency. A 2‐year experiment was conducted in a split‐plot design with three N rates (168, 224, and 280 kg N ha−1) in the main plot and six K rates (0, 112, 224, 336, 448, and 560 kg K2O ha−1) in subplots in four replications in Hastings, FL. Results revealed a significant effect of seasons on the soil K availability, uptake, tuber yield, and nutrient use efficiency. The soil K levels and uptake increased with higher K application rates across all potato growth stages. Regression analysis identified optimum K rate of 425 and 535 kg K₂O ha−1 for total and marketable tuber yield, respectively. In the first season, total tuber yield increased by 33% and 38% at K application rates of 336 and 560 kg K₂O ha−1, respectively, compared to no K application. Tuber specific gravity was not affected by K rates, while the higher K application rates increased the N use efficiency and decreased benefit‐cost ratio. The study concludes that K application rates above 425 kg K₂O ha−1 maximize potato tuber yield and enhance N efficiency, supporting the revision of K recommendations in sandy soils based on low K status.