Potassium and sulfur are among the most important nutrients limiting sesame production. EthioSIS soil testing map indicate that nutrients such as K and S are deficient in the study site. Study was carried out to investigate response of sesame to K and S application at Humera Agricultural Research Center, Kafta Humera district, Tigray, Ethiopia in 2016 main cropping season. Treatments consisted four levels of potassium (0, 20, 40 and 60 kg K2O ha-1 as KCl) and four levels of sulfur (0, 20, 40 and 60 kg ha-1 as CaSO4.2H2O). The experiment was laid out as Randomized Complete Block Design (RCBD) in factorial arrangement with three replications using Setit-1 sesame variety. Soil sample was taken, result of soil analysis revealed that the soil was clayey textural class, neutral in soil reaction (pH = 7.35), low organic matter content (0.73 %), very low total N (0.03 %) and very low available P (0.74 mg kg-1), high soil cation exchange capacity (CEC) (40 cmol(+) kg-1), medium exchangeable K (0.26 cmol(+) kg-1) and low extractable sulfur (4.78mg kg-1). Maximum sesame grain yields (1371.67kg ha-1) was obtained from plot treated with 20 kg K2O ha-1 + 40 kg S ha-1 which resulted 145.3% increase over the control plot`s yield. From plots fertilized with K and S levels at a rate of 20 kg K ha-1 and 40 kg S ha-1 was obtained higher yield of sesame. It is recommended, therefore, further studies to be done on Application of K and S at the study site.

Keywords: Potassium, Sulfur, grain yield