Effect of Counterions on the Foliar Absorption and Transport of Potassium in Soybeans [Glycine max (L.) Merrill]

Foliar spraying of chemical fertilizers is a strategy that complements soil fertilization. This study aimed to investigate the leaf absorption and translocation of potassium from potassium sulfate, potassium nitrate, potassium formate, potassium acetate, and potassium carbonate in soybean leaves. Potassium was applied on soybean leaf surfaces at a concentration of 3 g of K L –1 and subsequently monitored over 144 h using X-ray fluorescence microanalysis. The results showed that the highest absorption rates were for potassium carbonate, potassium acetate, and potassium formate. Potassium after absorption was translocated to other tissues, and the sources that were well absorbed also allowed better translocation. This study reinforces that the counterion not only influences the uptake but also plays a role in phloem loading.