This symposium will provide a "state-of-the-art" look at the current basic and applied research associated with gypsum use as a soil amendment. Gypsum use has increased due to reduced sulfur fertilizer inputs from other sources, the ready availability of high quality gypsum from both mined and synthetic sources, and research that has demonstrated benefits of using gypsum as a soil amendment. However, the benefits of gypsum use are often soil and crop specific, excessive application rates can cause nutrient imbalances in soil, and some synthetic sources may contain higher than desired levels of heavy metals.