Water storage capacity is one aspect of the complex process of plant water balance. Other components are water extraction and water stress (see there in detail).

Water supply

For optimal growth, vines require soils with good water storage capacity and a constant, but not excessive, water supply. A soil with this characteristic can store water efficiently and release it slowly, which enables even irrigation and reduces the risk of drought stress. The essential water seeps into the soil after precipitation (rain, hail, sleet, snow).

Surface precipitation

A small proportion also comes from surface precipitation formed by condensation (dew, frost), which is absorbed directly by the dew roots located just below the surface. The non-solid soil substance consists of pores of different sizes that are filled with air and/or water. The pores can make up around one third to two thirds (30-60%) of the total volume. The porosity - the ratio of the void volume to the total volume - depends on the pore volume. In dry soil, all pores are filled with air.

Soil water: Figure 1 = load-bearing meniscus, Figure 2 = soil article, Figure 3 = air-bearing soil pore, Figure 4 = adhesive water/capillary water, Figure 5 = adsorption water= dead water, Figure 6 = groundwater or stagnant water

Adhesive water

The infiltrating water displaces the air first in the fine pores until finally, when the soil is moist, air remains only in the coarse pores....