Made from finely ground mollusk shells, Aragonite is high in calcium and low in magnesium. Calcium is a critical nutrient for plant growth and for keeping a soil loose or "friable". Over use of limestone with a high magnesium level can bind up soils if the magnesium levels are to high. Aragonite will help correct this with its low magnesium content. Use at a rate of 10 lbs per 1000 sq ft. Typical analysis 0-0-0-39% calcium.