Sulfate Status and Wheat Yield Response to Sulfur Fertilizer in Acidic Soils of Tsegede Highlands, Northern Ethiopia

A soil survey and two greenhouse experiments were conducted in acidic soils of the Tsegede District, Tigray Region, Ethiopia to determine available sulfur (SO4-S) status in three land use types across three sites and wheat yield response to different sulfur (S) fertilizer levels applied in the form of gypsum (CaSO4.2H2O) and potassium sulfate (K2SO4) along with and without lime. Composite soil samples were collected and analyzed following the standard procedures. Two experiments were conducted following the randomized complete block design with ten treatment combinations: two levels of lime (with and without lime) and five levels of S (0, 25, 50, 75, and 100 kg ha-1 S), one using CaSO4.2H2O and the other using K2SO4 as increasing of SO4 replicated three times. The results revealed significant (P
0.01) changes in soil SO4-S status with the change in site and land use type. Its content in the forest land soils was significantly higher by about 162 and 160% over the cultivated and grazing land soils, respectively; the results showed a positive correlation (r = 0.773**) with soil pH and a negative correlation with exchangeable acidity (r = -0.786**) and Al (r = -0.806**). Grain yield and S use efficiency of wheat crop was significantly (P
0.05) affected by the application of S in the form of K2SO4 than gypsum. Successive increasing of S fertilizers in the form of K2SO4 up to the level of 50 kg ha-1 S has been observed to increase biomass and grain yield of wheat considerably. Furthermore, soils treated with S fertilizer along with lime achieved significantly higher yields than those without lime. The findings indicate that due consideration of the impact of land use transformation on soil sulfate status and application of S fertilizers in the form of K2SO4 along with lime could improve wheat crop production in the S-deficient acidic soils of the Tsegede highlands.