Among the nutrients required by the banana tree, the potassium (K) is what most influences the production of the crop. This study aimed to compare the effects of two K sources, potassium chloride (KCl) and potassium sulfate (K2SO4) on production, and estimate the dose of K for maximum physical efficiency (MPE) and maximum economic efficiency (MEE), besides determine the critical levels of leaf K for the banana tree, cultivar Prata anã (AAB) irrigated, cultivated in the semi-arid region of northern Minas Gerais State, Brazil. The experiment was conducted in an oxisol, medium texture. The treatments were derived from the factorial (4 x 2), being four rates of K (0, 400, 800 and 1200 kg ha-1 yr-1 of K2O) and two K sources (KCl and K2SO4), resulting in eight treatments. These were distributed in randomized blocks with four replications. There were no differences among the effects of KCl and K2SO4 on the production of banana. The KCl showed greater economic viability to be used as a source of K. The estimated doses for MPE of banana in the 2nd and 3rd production cycles using the KCl were 827 and 835 kg ha-1 yr-1 of K2O, respectively, while for MEE, doses were 157 and 670 kg ha-1 yr-1 of K2O, respectively. The critical levels of leaf K obtained in the 2nd and 3rd production cycles were 2.85 dag kg-1 for the MPE and for MEE, the values were 2.41 and 2.80 dag kg-1, respectively.
Critical level; economic rate; fertilization