Potassium Fertilization for Fresh Market Potato Production in Tropical Soils

Abstract

Potassium (K) is the most taken up and removed nutrient by potato (Solanum tuberosum L.), and has a great influence on tuber yield and quality. This study was performed to evaluate the effects of three rates (100, 200, and 400 kg K2O ha−1) and two timings of application of K (single application at planting furrow and split application of 50% at planting furrow plus 50% at hilling), as potassium chloride, as well as a control (without K application) on the plant nutrition and tuber yield and quality of potato ‘Agata’ grown in tropical clay soils. The split application of K fertilizer had little influence on plant nutrition and tuber yield and quality. The influence of K fertilization on increasing K and reducing Ca and Mg concentrations in the leaf was more significant in soil with low exchangeable K. In this soil, the maximum tuber yield (33.6 Mg ha−1; 107% higher than the control) was obtained with an estimated rate of 325 kg K2O ha−1, while in the soils with medium and high exchangeable K, the tuber yield was increased between 22 and 34% and only up to a rate of 200 kg K2O ha−1. The critical leaf K concentration to reach 95% of the maximum yield was 29.3 g K kg−1, but there was an extreme increase in the tuber yield even with K rates that provided leaf K concentrations above this limit. Potassium fertilization increased the firmness and reduced soluble solids and protein in tubers.Core Ideas K is the nutrient that is most taken up and removed by the potato crop. In clay soils, the splitting of K fertilization has little influence on potato tuber yield and quality. K fertilization increases tuber yield more, and up to higher rates in soil with low K concentration. K fertilization increases the tuber firmness, but reduces the soluble solids and protein concentration.