Dolomite is an economical way to increase the soil pH in acidic soils (sweetens the soil) and to raise magnesium levels in deficient soils. Dolomite also adds calcium and helps to improve soil structure and increases the availability of some trace elements.
Applying calcium in isolation can induce a magnesium deficiency (Ca:Mg ratio). Even though calcium is a very important nutrient in the soil, in isolation it can also reduce the availability of potash and phosphate, as well as manganese, molybdenum, boron, zinc and iron. The balance between calcium and magnesium is important, from a pH and a nutritional perspective, but also because they influence the soil structure.
