Effects of different source sulfur applications on soil quality

This research was conducted to determine the effects of different sulfur sources (elemental sulfur - EK, ammonium sulfate - AS, sulfuric acid - SA) on the physical, chemical, and biological properties of 5-year-old apricot (Prunus armeniaca L.) saplings showing growth retardation in calcareous soils (CaCO₃ 24%, pH 8.3, EC 0.42 dS m⁻¹, OM 1.25%) in the Yukarı Girmana Neighborhood of the Hekimhan district of Malatya province. The experiment was set up in 2 m × 2 m plots, each supplemented with 4 different doses (0, 250, 500, 1000 g/plant) and farm manure (20 kg/plant), using a randomized block design with 3 replications. After application, soil pH decreased by 10.1% (from 8.3 to 7.46) with SA and 7.4% (from 8.3 to 7.68) with EK; however, the pH change was limited in AS application (from 8.3 to 8.05). EC values increased from 0.42 to 0.63 dS m⁻¹ in SA and from 0.42 to 0.58 dS m⁻¹ in AS (p<0.05). OM content increased from 1.25% to 1.88% in the EK+farmyard manure combination and to 1.74% in AS+farmyard manure. CaCO₃ content decreased from 24.0% to 19.8% in SA+farmyard manure. In terms of nutrient levels, EK and AS treatments increased total N by 18% and 14%, respectively, while SA treatment showed a 12% decrease in Mg content. Among the micronutrients, Fe content increased by 22% with SA, while Zn and Mn values increased significantly in all treatments (p<0.05). Microbial biomass carbon (Cmic) increased by 26% with EK treatment, and microbial biomass nitrogen (Nmic) increased by 21% with SA. The results revealed that SA and EK treatments were effective in lowering pH, increasing CaCO₃ solubility, and improving micronutrient availability in calcareous and high-pH soils. The combination with farmyard manure played a significant role in increasing organic matter and microbial activity. The study suggests that the combination of SA (500 g/plant) and farmyard manure may be the optimal solution for soil amendment in Malatya apricot cultivation.