Effect of Different Levels of Potassium on Soil Potassium Fractions and on Sugarcane Yield and Quality

A Field experiment was conducted on effect of various levels of potassium application on soil potassium fractions and sugarcane yield at Regional Agricultural research station, Anakapalle, Andhra Pradesh. The experiment comprised six treatments and four replications in Randomized Block Design. The treatments comprised of T1:Control (0 K), T2:50% Recommended dose of Potassium (60 kg K/ha),T3:75% Recommended dose of Potassium (90 kg K/ha),T4:100% Recommended dose of Potassium (120 kg K/ha),T5:125% Recommended dose of Potassium (150 kg K/ha) and T6:150% Recommended dose of Potassium (180 kg K/ha). Results revealed that number of milliable cane, cane yield (t/ha) and sugar yield (t/ha) was found to be significantly high with treatment receiving 150% recommended dose of fertilizers (79855, 82.12 t/ha and 12.04 t/ha respectively), however, it was statistically on par with the treatments receiving 125% recommended dose of potassium fertilizers(79855,82.12 t/ha and 12.04 t/ha respectively) and 100% recommended dose of potassium fertilizers application (79315,81.86 t/ha and 11.57 t/ha respectively). Increasing levels of K significantly increased all the K fractions. However, highest value of water soluble K (29.5 mg kg-1 at 0-15 cm depth and 31.6 mg kg-1 at 15-30 cm ) exchangeable K (205 mg kg-1 at 0-15 cm depth and 228 mg kg-1 at 15-30 cm depth) non-exchangeable K (854 mg kg-1 at 0-15 cm depth and 971 mg kg-1 at 15-30 cm depth), lattice K (2110and 2381 mg kg-1 at 0-15 and 15-30 cm ) and total K (3267 and 3718 mg kg-1) were recorded with the application of with the application of 150% recommended dose of potassium application (180 kg ha-1) followed by application of 125% recommended dose of potassium application (150 kg ha-1) . The sequential order of dominance of different fractions of K were lattice K>nonexchangeable K> exchangeable K and water soluble K. The per cent contribution of different fractions of K to total K were followed in the order of lattice K (64.02 to 74.94% at 0-15 and 15-30 cm depth), non-exchangeabl K (15.46 to 17.79% at 0-15 and 26.4 to 27.43 % 15-30 cm depth), exchangeable K (6.32 to 8.39% and 5.60 to 7.69% at 0-15 and 15-30 cm depth), and water soluble K (0.81-0.90% and 0.69 to 0.85% at 0-15 and 15-30 cm depth) There exists positive and significant correlation among various K fractions indicating dynamic equilibrium.