Optimum potassium fertilization level for growth, yield and nutrient uptake of wheat (Triticum aestivum) in Vertisols of Northern Ethiopia

Potassium fertilization was started in 2014 using K containing blended fertilizers in Ethiopia. However, there was no evidence whether the recommended rates of K in the blended formula (which is between 7 and 12 kg/ha in the form of K2O) meets the crop demand on different soil reference groups or not. So, a field experiments were conducted to determine the optimum rate of potassium for yield and nutrient uptake of wheat in Vertisols of northern Ethiopia. The experiments were laid out in Randomized Complete Block Design with 4 levels of potassium (0, 30, 60, 90, of kg/ha K2O) in three replications. Results depicted that the highest biological yield (straw + grain) and grain yields of wheat were increased with K rates. But, the partial budget analysis revealed that 60 K2O kg/ha is economically feasible rate for wheat in Vertisols of the area. On the other hand, the highest apparent K recovery and agronomic use efficiencies were found at 30 kg/ha K2O. Then it is concluded that the level of K in the blended formula was not enough to meet the yield requirement of wheat. Therefore, K should be applied independently rather than in blended for Vertisols of the area studied