Sugarcane cultivation with source potassium low water-soluble

ABSTRACT. Thermopotash is a fertilizer with low solubility but has a release level compatible with plant demands. This study aimed to compare the effect of Thermopotash to that of KCl in sugarcane. Field work was conducted during two crop seasons, in a randomised block design. Treatments were applied to the bases of the furrows before planting the sugarcane, arranged in a 2 x 5 factorial design to evaluate two K sources (TK47 - Thermopotash, KCl - potassium chloride) at five levels of K (0, 50, 100, 150, and 200 kg ha-1 K2O). The variables analysed included leaf and soil K, Ca, Mg and Si, soil pH and productivity. The effects of the TK47 fertilizer on sugarcane stalk production were not initially superior to that of the soluble source, but over time, differences between the soluble and insoluble sources increased. The maximum expected sugarcane productivity for both sources was 133 Mg ha-1, which was achieved at an application level of 121 kg ha-1 K2O. TK47 fertilizer provided K, Si, Ca and Mg to the sugarcane in both the first and second harvests. Thus, TK47 may be a viable source of K for sugarcane.