Down to Earth's Garden Gypsum loosens clay soil. It is prilled, fast-acting, and easy to apply. Down to Earth Garden Gypsum is a five-pound box of all-natural mineral fertilizer and is listed by the Organic Materials Review Institute (OMRI) for use in organic production. It is commonly used to reduce soil compaction and increase drainage in heavy clay soils. Gypsum is also used to help remediate and revitalize alkaline, sodic, or saline soils. It improves the physical condition of landscape, lawn, and garden soils while adding calcium and sulfur. It is prilled, fast-acting, and easy to apply. It is a registered Organic Input Material (CDFA). Down To Earth's Garden Gypsum improves the physical condition of landscape, lawn, and garden soils while adding calcium and sulfur. It is commonly used to reduce soil compaction and increase drainage in heavy clay soils. Gypsum is also used to help remediate and revitalize alkaline, sodic, or saline soils.