Effects of Foliar Potassium Supplementation on Yield and Nutrient Uptake of Plant Sugarcane

Sugarcane, a globally significant economic crop, depends on potassium (K) for critical processes such as photosynthesis and sugar translocation. This study explored the impacts of various foliar K supplements, including 2.5% w/v KCl, KNO₃, K₂SO₄, and K₂SiO₃, alongside diluted molasses and vinasse (5 × dilution). The field experiment was conducted on sugarcane grown in soil with sufficient soil K levels, applying foliar solutions at 120 days at 2667 L/ha. The results indicated that combining soil chemical fertilizers with foliar K₂SiO₃ and KNO₃ resulted in the highest yields of 155.19 and 154.81 tons/ha, respectively, significantly outperforming the foliar water combined with soil chemical fertilizers (132.81 tons/ha) and the control (no basal fertilizer with foliar water, at 130.67 tons/ha, P ≤ 0.05). This enhancement is expected to result from the improvement in chlorophyll content and photosynthesis, enabled by timely K and nutrient acquisition, bypassing root transport. However, no significant differences were noted among the foliar K forms. Foliar K application also affected nutrient concentrations and uptake, with molasses showing the highest nutrient absorption in stalks: N (322 kg/ha), K (215 kg/ha), S (80.9 kg/ha), and Si (23.2 kg/ha) (P ≤ 0.05). These findings provide valuable insights and recommendations for utilizing foliar application of K₂SiO₃ and KNO₃ to improve plant sugarcane yield, as well as employing molasses foliar application to enhance nutrient uptake in sugarcane cultivated in soils with adequate K.