Abstract

This study investigates the effects of N, Pand K on cane yield and quality of the plant crop of two new sugarcane varieties, SL 96 128 and SL 96 328 and determines the optimum level of N. A field trial was carried out in a confounded-factorial design with 18 treatment combinations with 5 levels of N and 4 levels of each Pand K, with 3 replicates at the research farm of the Sugarcane Research Institute, Uda Walawe, Sri Lanka from September 2010 to November 2011. Cane yield and quality parameters such as brix, pol, and fibre percent of cane were measured and pure obtainable cane sugar (POCS) was calculated at harvest of 12-month old crop. Sugar yields were estimated using cane yield and POCS. The analysis of variance was performed on cane yield, POCS and sugar yield to examine the effects of N, Pand K on these three variables. The optimum level of nutrients was determined by estimating the income and value:cost ratios for each fertiliser level. The results showed that both varieties were responsive to N, and not so to Pand K. The optimum level of N for the variety SL 96 128 was between 150 and 200 and that for the variety SL 96 328 was between 100 and 150. Analyses of soil and leaf in ratoon crops are required for devising a comprehensive recommendation.