To describe the key to soil orders, suborders, great groups and subgroups for the soils of Kuwait, the excerpt from US Keys to Soil Taxonomy (Soil Survey Staff 2014) relevant to the soils of Kuwait is extracted and described below.

5.4Key to Soil Orders

The soils that:

1.Have:

a.An aridic soil moisture regime; and

b.An ochric epipedon; and

c.One or more of the following within 100 cm of the soil surface: a cambic horizon with a lower depth of 25 cm or more; a calcic, gypsic, petrocalcic, petrogypsic, or salic horizon; or

d.An argillic horizon; or

2.Have a salic horizon; and

a.Saturation with water in one or more layers within 100 cm of the soil surface for 1 month or more during a normal year; and

b.A moisture control section that is dry in some or all parts at some time during normal years.

Aridisols, p. 63

or

Other soils that do not classify as Aridisols.

Entisols, p. 75

5.5Key to Suborders of Aridisols

It is to be noted that very few auger holes/profiles were described in the argids and cambids suborders during the soil survey of Kuwait. Therefore, due to their minor extent, they were not identified as separate soil families or series, and thus not included in the map units, however, they are included in Kuwait Soil Taxonomy.

Aridisols that have a salic horizon within 100 cm of the soil surface.

Salids, p. 72

Other Aridisols that have a gypsic or petrogypsic horizon within 100 cm of the soil surface and do not have a petrocalcic horizon overlying these horizons.

Gypsids, p. 67

Other Aridisols that have an argillic horizon within 100 cm of the soil surface.

Argids, p. 64

Other Aridisols that have a calcic or petrocalcic horizon within 100 cm of the soil surface.

Calcids, p. 65

Other Aridisols that have a cambic horizon within 100 cm of the soil surface.

Cambids, p. 67

5.5.1 Argids

Key to Great Groups

Argids that have a gypsic horizon within 150 cm of the soil surface.

Gypsiargids, p. 65

Other Argids that have a calcic horizon within 150 cm of the soil surface.

Calciargids, p. 64

Other Argids that have only argillic horizon within 150 cm of the soil surface and lack properties of other horizons.

Haplargids, p. 65

Calciargids

Key to Subgroups

Calciargids that have a texture class (fine-earth fraction) of coarse sand, sand, fine sand, loamy coarse sand, loamy sand, or loamy fine sand throughout a layer extending from the soil surface to the top of an argillic horizon at a depth of 50 cm or more.

Arenic Calciargids

Other Calciargids that represent the central concept of the great group.

Typic Calciargids

Gypsiargids

Key to Subgroups

The argids that have only a gypsic horizon within 150 cm of the soil surface. These soils represent the central concept of the great group.

Typic Gypsiargids

Haplargids

Key to Subgroups

Argids that have only argillic horizon within 150 cm of the soil surface and lack properties of other horizons. These soils represent central concept of the great group.

Typic Haplargids

5.5.2 Calcids

Key to Great Groups

Calcids that have a petrocalcic horizon within 100 cm of the soil surface.

Petrocalcids, p. 65

Other soils which are most extensive in the Calcids and do not present petrocalcic horizon within the upper 100 cm of the soil surface.

Haplocalcids, p. 65

Haplocalcids

Key to Subgroups

Haplocalcids that have a calcic horizon within 100 cm of the soil surface and lack all other characteristics of any other subsurface diagnostic horizons. These soils represent the central concept of the great group. (Fig. 5.3)

Typic Haplocalcids

Petrocalcids

Key to Subgroups

Petrocalcids that have a calcic horizon overlying the petrocalcic horizon.

Calcic Petrocalcids