Field experiments were conducted for two consecutive seasons at NARC potato research area
Islamabad, Pakistan, to study comparative effect of source, levels and methods of K fertilization on
yield and quality of potato produce. Nitrogen and phosphorus were applied at 250 and 125 kg ha -1,
respectively whereas three K2O levels, 0, 150 and 225 kg ha-1 from two sources of potash (SOP and
MOP) were tested. Potassium was also applied as foliar spray at 1% K2O solution at 30, 45 and 60
days after germination (DAG) and soil was also amended by 150 kg K2O ha-1. A significant
increase in tuber yield with K application at 150 kg ha-1 as K2O from both the K sources over NP
treatment was recorded. Increase in tuber yield with K2O @ 225 kg ha-1 was statistically nonsignificant
compared to 150 kg K2O ha-1. A positive interaction between soil applied P and K with
N in plant system was observed. Potassium treatments not only increased K concentration but also
affected N and P contents in potato tubers. The quality parameters like dry matter, specific gravity,
starch contents, vitamin-C and ash contents were also affected with P and K fertilization.