The bluish-silky, soft alkali metal is the seventh most abundant element (K) in the crust with a share of around 2.5%. The name derives from the Arabic "al kalja" for "potash" (Pottassium), an old name for derived from wood ash potassium carbonate. The reactive element occurs in nature only in bound form. It is found in many minerals such as mica, feldspar, kainite, potash, polyhalite and clay. Experiments with increased potassium fertilizers have shown that vines respond to this with increased production malic acid react. Potassium, together with other factors, has an effect on the acid in the wine. Potassium-rich wines have a "buffered or integrated acidity", which as balanced is felt. In comparison to other minerals, potassium is contained in a high amount in must (up to 1.5 g / l) or wine.
Potassium is one of the most important nutrient for the growth and metabolism of the vine by activating many enzymes, Simplified, it can be said that potassium strengthens wood formation and plant static. In detail, the soil permeability is increased, the photosynthesis, Flower and fruit formation, wood maturity and saccharification promoted, as well as the Protein metabolism and over the stomata of the leaves the water balance is regulated. A high content of potassium gives the soil a permeable crumb with good water discharge,
In heavy soils, potassium can be bound to clay minerals and is thus no longer available to plants. Too low a potassium content leads to water loss due to evaporation. It manifests itself by dark purple, dark brown or blackish discoloration, wavy distortions and oily glossy leaves, as well as remarkably small grapes. A fertilization takes place in the form of potassium salts (potassium chloride) and potassium sulphates. A balance with calcium and magnesium has great importance and must therefore be taken into account. The potassium compound pyrosulphite is used in viticulture as an antioxidant.