4.5 Soil Temperature Class

4.5Soil Temperature Class

Soil temperature class, as named and defined here, is used as part of the family name in soil survey of Kuwait. The Celsius (centigrade) scale is the standard. It is assumed that the temperature is that of a soil that is not being irrigated.

4.5.1 Control Section for Soil Temperature

The control section for soil temperature is either at a depth of 50 cm below the soil surface or at the upper boundary of a root-limiting layer, whichever is shallower. The soil temperature class is defined in terms of the mean annual soil temperature and the difference between mean summer and mean winter temperatures.

4.5.2 Key to Soil Temperature Class

Hyperthermic is the only soil temperature class identified in Kuwait. The soils that have a difference in soil temperature of 6 °C or more between mean summer (June, July, and August) and mean winter (December, January, and February) and a mean annual soil temperature of 22 °C (72 °F) or higher.

Hyperthermic

4.6Soil Depth Classes

Soil depth class is used in families of Kuwait mineral soils that have a root-limiting layer at a specified depth from the mineral soil surface. The root-limiting layers included in soil depth classes are petrocalcic and petrogypsic horizons and lithic contact. One soil depth class name, “shallow,” is used to characterize certain soil families that have one of the depths indicated in the following key.

4.6.1 Key to Soil Depth Classes

Mineral soils that are less than 50 cm deep (from the mineral soil surface) to a root-limiting layer (petrocalcic & petrogypsic horizons) and are not in a Lithic subgroup.