Definition - What does Available Water mean?
Available water, sometimes called Available Water Capacity (AWC) is the range of water in which the soil is able to store and be readily available for growing crops.
The concept of available water involves two factors:
- The plant's ability to readily absorb the water it is in contact with
- The readiness of the soil's water and how it replaces itself once used by the plant
WineFrog explains Available Water
In the field of viticulture, many geographical regions are selected to grow grape vines according to the composition of the soils. In order to produce quality fruit for quality wine, there are specific soil conditions which must be in place. The best soils for the best wines are those that are low in organic matter and high in mineral content. Rich soils do not make for good wine.
Another factor considered when planting a vineyard is its "available water." Some soils are better at holding water than others. For instance, a lower-lying clay layer can be advantageous to those who dry-farm wine grapes. This soil has the ability to hold water, even during dry periods, and make itself available for the vines.
There is less available water in soils consisting of gravel, rocks and sand. These are well-draining soils, which can make vines stronger and thus make for better wine. However, the lack of available water without irrigation could be detrimental to the grapevine.