INFLUENCE OF POTASSIUM FERTILIZER ON POTATO TUBER YIELD AND QUALITY

Irish potato is the second most important food crop after maize in Kenya. However, the national average tuber yield is 9.8 tonnes/ha compared to optimum production of 41 tonnes/ha. There is also unmet production demand for potato tubers with high processing quality. Potassium (K) being one of the macronutrients taken up in larger amounts by potato is known to enhance both its yield and quality traits. Field experiments were conducted at University of Eldoret farm in Uasin Gishu County in Kenya to determine the effectiveness of potassium fertilizer on tuber yield and quality enhancement as well as profitability due to the fertilizer application. Two K sources; MOP and SOP were used. Destiny potato variety was planted. In the long rains, MOP at 30kg K/ha gave tuber yield of 40.54 tonnes/ha and profit of 111.86%. SOP significantly enhanced tuber dry matter compared to MOP by 5.6% in both seasons while SOP at 180kg K/ha gave the highest tuber vitamin C concentration (19.56 mg g-1). In the short rains, 120kg K/ha yielded highest tuber starch content. For in depth understanding of K influence, similar study to be done with different varieties in different soils in potato growing areas.