Effect of varying phosphorus and potash levels on agronomic traits and productivity of sugarcane (Saccharum officinarum L.)

An experiment was conducted to study the effect of varying P&K levels on agronomic traits and productivity of sugarcane at the National Agricultural Research Centre Islamabad during 1996-97. Application of either phosphorus or phosphorus and potash, along with nitrogen, significantly improved the tillering of sugarcane at early stages of growth. Millable canes per hectare were the maximum (130.7 thousands) with the application of 200 kg N, 150 kg P2O5 and 150 kg K2O ha-1 and were similar to those treatments where lower doses of P2O5 and K2O ha-1 were applied. Stalk height (290 cm) and girth (31.2 mm) were observed the maximum with the application of 200 kg N, 150 kg P2O5 and 150 kg K2O ha-1 but statistically similar to those produced with lower levels of P2O5 and/or K2O. Total soluble solids were similar at early stages of cane maturity at various levels of P2O5 and K2O and were maximum (20.8%) at harvest with 200 kg N, 150 kg P2O5 and 150 kg K2O ha-1. Sugar recovery was also improved with the application of P & K. Maximum cane yield (138 t ha-1) and sugar yield (16 t ha-1) was produced with the application of 200 kg N, 150 kg P2O5 and 150 kg K2O ha-1.