EFFECT OF LEVELS OF NITROGEN AND POTASSIUM ON SOIL AVAILABLE NUTRIENT STATUS AND YIELD OF POTATO (SOLANUM TUBEROSUM L.)

A field experiment was conducted on a sandy loam soil during rabi season of 2009-10 with a view to study the effect of levels of nitrogen (0, 60, 120 and 180 kg N ha-1) and potassium (0, 60, 120 and 180 kg K2O ha-1) on potato tuber yield and soil available nutrient status. The tuber yield of potato was significantly increased with nitrogen, potassium and their interactions. The highest tuber yield (223.9 q ha-1) was recorded by combined application of nitrogen @ 180 kg ha-1 + potassium @ 180 kg ha-1 (N3K3) which was on par with nitrogen @ 180 kg ha-1 + potassium @ 120 kg ha-1 (N3K2). The total uptake of N and K by potato at harvest was highest with N3K3 combination and the per cent increase being 139.4 and 142.8, respectively over N0K0. With regard to soil available nutrient status, N3K3 recorded highest available N and K2O contents in soil at all the stages of crop growth, the per cent increase being 72.2 (30 DAS), 114.6 (60 DAS) and 122.3 (at harvest) compared to that of at control (N0K0). Similarly the available potassium increased by 40.3 (30 DAS), 31.5 (60 DAS) and 41.4 (at harvest) per cent when compared against control (N0K0). From the results it was evident that higher levels of N and K had met the requirement of potato crop at different growth stages, which was reflected in terms of yield.