Effect of long-term potassium fertilization on the chemical composition of Oriental tobacco

The effects of the different potassium rates (0, 75 and 450 kg K2O ha-1) on nutrient concentrations in the above-ground biomass and chemical characteristics of sun-cured tobacco have been studied in a stationary field trial. Annual fertilization with 75 kg K2O ha-1 was adequate to maintain soil K concentration near the initial value. It was found that yield of cured leaves was not significantly affected by rate of K application when oriental tobacco was grown on soils with high available soil K. With the increase of K fertilization rate the content of the potassium in leaves increased from 0.65 to 4.49%. The concentration of Ca and Mg in the leaves ranged from 2.03 to 5.23% and from 0.52 to 0.71%, respectively and decreased with increases in added potassium. No effect of K rates on nicotine and protein content was noted. Only the reducing sugars’ content tended to increase to 11.42% at the highest K rate. Fertilization with moderate potassium rates (75 kg K2O ha-1) on soils high in available K is necessary to maintain the good potassium reserves. When oriental tobacco was grown on alkaline soils with high available K and Ca, potassium fertilization improves K nutrition and therefore may favorably affect burning properties of tobacco.