Gaia's Greensand is mined from ancient, nutrient-rich deposits of oceanic sediment. Over time, this sediment developed into glauconite, which is highly effective as a slow-release fertilizer used to improve the mineral content of soil and other growing media. Greensand is gentle on plants and won’t cause root burn. Greensand is recommended for use on lawns, household plants, golf courses, greenhouses, nurseries, and urban gardens, and is suitable for all plants. Gaia's Greensand contains a natural source of potassium, iron, magnesium, and manganese. It improves friability of hard soils, as well as moisture and nutrient retention. No synthetic additives or chemicals. Guaranteed Minimum Analysis : 23.0% Calcium (Ca), and 18% Sulphur (S).