Effect of potassium fertilization on sweet potato cultivation

Abstract

The sweet potato yield in Brazil remains significantly below the crop potential, primarily due to either the absence or inadequate application of fertilizers. This study aimed to assess the sweet potato yield, soil potassium availability, nutrient uptake in shoots, storage roots and whole plant, as well as the correlation between nutrients, with increasing rates (0, 50, 100, 200 and 350 kg ha−1) of K2O, in Humic Cambisol. After harvesting, the total and marketable yield of storage roots, soil available K levels, and nutrient contents in shoots, storage roots and whole plant were assessed. The maximum efficiency was achieved at 229 kg ha−1 of K2O, while the economically optimum rate was observed at 171 kg ha−1 of K2O. The sweet potato’s response to the potassium fertilizer application in Humic Cambisol tends to diminish if the available K content exceeds 146 mg dm−13. The use of KCl as a K source may induce a reduced sulfur absorption, probably due to the antagonistic effect between Cl−1 and SO42−.