The roots of the vine can - depending on the soil conditions, of course - drill themselves to a depth of 15 to 20 metres and extract a variety of substances from the soil. However, they cannot absorb them in solid form. Weathering converts the substances into tiny particles, which can only then be absorbed by the roots in an aqueous solution. The soil water with its ingredients is called soil solution. A good vineyard soil is characterised by a good water storage capacity and optimal water drainage (without waterlogging). In most European wine-growing regions, water supply is left to nature, as artificial irrigation is generally prohibited for quality wines and in exceptional cases requires a permit.