The roots of the vine can - depending on the soil conditions, of course - bore to a depth of 15 to, in extreme cases, 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 that can only then be absorbed by the roots in a watery solution. The soil water with its constituents 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, the water supply is left to nature, as artificial irrigation for quality wines is generally prohibited and, in exceptional cases, subject to approval.