Most soil sulfur comes from the weathering of sulfur containing minerals. Some of it comes from industrial pollution as sulfur dioxide in acid rain.Sulfur is changed by microorganisms in the soil to sulfate ions.Plants absorb sulfate to make protein and other compounds,thus immobilizing the sulfur.When leaves fall, they decay and soil flora mineralize the sulfur in the leaves to sulfate ions.Some sulfate is taken up again by plants,some is again immobilized in the bodies of microorganisms,and some leaches away