Response of Soil Chemical Properties, Performance and Quality of Sweet Potato(Ipomoea Batatas L.) to Different Levels of K Fertilizer on a Tropical Alfisol

Background:The optimum rate of nutrient must be defined with reference to soil properties for individual crops and soil.Objective:Field experiments were carried out in 2015 and 2016 cropping seasons to determine the various levels (0, 40, 80, 120 and 160 kg ha-1) of potassiumfertilizer (muriate of potash , KCl), on soil chemical properties, leaf nutrient contents, performance and proximate quality of sweet potatoes(Ipomoea batatas L.).Method:The five treatments were arranged in a randomized complete block design with three replicates.Results:Studies showed that K fertilizer in both the years significantly influenced N, P and K concentrations compared with the control and also increasedthe soil concentrations of these nutrients from 0 - 160 kg ha-1 K fertilizer. However, soil K only increased up to 80 kg ha-1 fertilizer after whichthere was a decrease. There was a reduction in the values of Ca and Mg in the soil as the levels of K increased. Leaf nutrient concentration of thesweet potato was consistent with the values of soil chemical properties recorded. 80 kg ha-1 K fertilizer was observed to be the highest value ofsweet potato growth and tuber yield after which there was a reduction. The yield decrease was adduced to excessive K application leading toimbalanced sweet potato plant nutrition compared with N, P, Ca and Mg. K fertilizer significantly influenced moisture, vitamin C and carbohydratecompared with the control. The highest values of fibre and protein were obtained at 80 and 40 kg ha-1 K fertilizer, respectively. Dry matter and fatcontents of the sweet potato reduced by K application from 0 - 160 kg ha-1 application rate.Conclusion:For best tuber yield, quality and economic response of K fertilizer to the sweet potato in the agro-ecological zone or in other similar soil conditionselsewhere in the tropics could be achieved by applying 80 kg ha-1 K fertilizer.Keywords: Soil, Ipomoea batatas, Muriate of potash, Leaf nutrient concentration, Quality, Vitamin C