The silver-white, soft light metal (Ca = calcium) is the third most common metal after iron and aluminium and the fifth most common element in the earth's crust. Due to its reactivity, it is only found chemically bound in over 700 minerals, mostly as carbonate, fluorite or sulphate. Minerals containing calcium such as basalt, dionite, calcite, chalk, gypsum, granite, marble and marl are present in large quantities. The Alps consist mainly of limestone. As an essential component of living matter, it plays a major role in the structure of leaves, shells, bones and teeth. Due to its frequency, deficiency symptoms occur rather rarely. Carbonates are mainly the remains of marine life (corals, shells, snails), which have accumulated over millions of years.
Calcium is very important as one of the most important nutrients for the growth of the vine. It strengthens the cell wall structure, activates numerous enzymes and prevents the penetration of harmful micro-organisms in the berry skins. In the vineyard, calcium positively ensures optimal water drainage or the removal of excess water. It also improves the availability of other nutrients for the vine. An excess of calcium favours the occurrence of chlorosis, and to an extreme degree it is negative for viticulture. Too little calcium causes acidic soils with a low pH value. This occurs mainly in areas with high rainfall and impairs root growth. At pH values below 5.9, fertilisation (limescale) is recommended. Calcium and magnesium have partly the same functions in the nutrient supply of plants and can replace each other to a certain extent. In wine, the formation of tartar can cause calcium cloudiness. See also soil type for lime and limestone.