An incubation experiment was performed to study the effects of vegetation water on S transformation in a calcareous soil. In addition to raw vegetation water, other preparations were tested including vegetation water devoid of organic matter and deionized vegetation water. The addition of olive wastewater to soil inhibits the formation of S‐SO4=when vegetation water plus elemental S is compared to a treatment consisting of elemental S applied alone. No such effect, however, was seen when the treatment with vegetation water only is compared with control sails. Of the three types of vegetation water tested, the least effective inhibitor of S‐SO4=formation was the wastewater in which all organic matter has been eliminated, while the deionized effluent yielded lowest levels of S‐SO4=. The exclusive application of vegetation water on calcareous soils may raise S‐SO4=levels in the middle run; however when an S deficient soil is fertilized with elemental S, concurrent application of vegetation water is unadvisable, given that it may interfere with soil. S‐SO4=formation.