Response of Soil, Cane Yield and Cane Quality Parameters to Zinc Fertiliser Under Alfisols Condition in Sri Lanka: A Preliminary Investigation

The low sugar recovery rate is becoming a key issue in the sugar sector in Sri Lanka. In order to improve cane quality and sugar recovery, some countries use zinc sulphate (ZnSO₄) as a soil microelement fertiliser. Therefore, this study was conducted to assess the impact of ZnSO₄ on soil chemical properties, cane yield and cane quality of the sugarcane variety SL 96 128 under Alfisols conditions in Sri Lanka. A field experiment, utilizing RCBD with five replicates under irrigated conditions was carried out at the research farm of the Sugarcane Research Institute, Uda Walawe. At 90 days after planting, 7.5 kg/ha of ZnSO₄ (Zn—22%) was applied to the treated plots (T1) together with the recommended dose of fertilizers (urea—325 kg/ha, triple super phosphate—50 kg/ha, muriate of potash—225 kg/ha), while untreated plots (T2) were kept without ZnSO₄. Basic chemical parameters of the soil, before treatments and after-harvesting were examined. The major cane quality parameters were assessed at 10, 11, and 12 months of crop age. There was no significant effect on main soil properties from applied ZnSO₄. The untreated plots (T2) showed a significant (P < 0.001) declining trend for brix%, Pol%, purity%, and pure obtainable cane sugar (POCS) % during the 10–12 months period. At harvest (12 months), T1 recorded significantly high Pol % (14.73, 13.04), purity % (91.60, 85.97), POCS % (11.35, 9.68) and sugar yields (10.60, 8.73 t/ha) compared to T2. However, the cane yields of T1 (93.67 t/ha) and T2 (90.42 t/ha) were not significantly different. Thus, the positive influence of Zn creates an extra gain for both farmers and millers financially. Therefore, to uplift the current situation, a recommendation on Zn is needed together with additional field and industry-level studies.