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GDC.Argigypsids

Key to Great Groups 

GDC. Other Gypsids that have an argillic horizon that has its upper boundary within 100 cm of the soil surface. Argigypsids, p. 379 

GDC. Argigypsids are the Gypsids that have an argillic horizon. These soils are known to occur in the Four Corners area of the western part of the United States and in Texas. They are used primarily for grazing. 

Definition 

Argigypsids are the Gypsids that:

1. Have an argillic horizon that has its upper boundary within 100 cm of the soil surface;

2. Do not have a natric, petrocalcic, or petrogypsic horizon with an upper boundary within 100 cm of the soil surface. 

Key to Subgroups 

GDCA. Argigypsids that have a lithic contact within 50 cm of the soil surface. Lithic Argigypsids 

GDCB. Other Argigypsids that have:

1. Cracks within 125 cm of the soil surface that are 5 mm or more wide through a thickness of 30 cm or more for some time in normal years, and slickensides or wedge-shaped aggregates in a layer 15 cm or more thick that has its upper boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil surface and either a depth of 100 cm or a densic, lithic, or paralithic contact, whichever is shallower. Vertic Argigypsids 

GDCC. Other Argigypsids that have a calcic horizon overlying the gypsic horizon. Calcic Argigypsids 

GDCD. Other Argigypsids that have one or more horizons, within 100 cm of the soil surface and with a combined thickness of 15 cm or more, that contain 20 percent or more (by volume) durinodes, nodules, or concretions. Petronodic Argigypsids 

GDCE. Other Argigypsids that have both:

1. A moisture control section that is dry in all parts for less than three-fourths of the time (cumulative) when the soil temperature is 5 oC or higher at a depth of 50 cm and a soil moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness of 18 cm or more within 75 cm of the soil surface, one or both of the following:

                a. More than 35 percent (by volume) fragments coarser than 2.0 mm, of which more than 66 percent is cinders, pumice, and pumicelike fragments; or

                b. A fine-earth fraction containing 30 percent or more particles 0.02 to 2.0 mm in diameter, of which 5 percent or more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted by ammonium oxalate) times 60] plus the volcanic glass (percent) is 30 or more.Vitrixerandic Argigypsids 

GDCF. Other Argigypsids that have, throughout one or more horizons with a total thickness of 18 cm or more within 75 cm of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser than 2.0 mm, of which more than 66 percent is cinders, pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more particles 0.02 to 2.0 mm in diameter, of which 5 percent or more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted by ammonium oxalate) times 60] plus the volcanic glass (percent) is 30 percent or more. Vitrandic Argigypsids 

GDCG. Other Argigypsids that have a moisture control section that is dry in all parts for less than three-fourths of the time (cumulative) when the soil temperature at a depth of 50 cm is 5 oC or higher and have a soil moisture regime that borders on xeric. Xeric Argigypsids 

GDCH. Other Argigypsids that have a moisture control section that is dry in all parts for less than three-fourths of the time (cumulative) when the soil temperature at a depth of 50 cm is 5 oC or higher and have a soil moisture regime that borders on ustic. Ustic Argigypsids 

GDCI. Other Argigypsids. Typic Argigypsids 

Definition of Typic Argigypsids 

Typic Argigypsids are the Argigypsids that:

1. Do not have a lithic contact within 50 cm of the soil surface;

2. Have either:

                a. No cracks within 125 cm of the soil surface that are 5 mm or more wide through a thickness of 30 cm or more for some time in normal years, and no slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its upper boundary within 125 cm of the soil surface; or

                b. A linear extensibility of less than 6.0 cm between the soil surface and either a depth of 100 cm or a densic, lithic, or paralithic contact, whichever is shallower;

3. Do not have a calcic horizon overlying the gypsic horizon;

4. Have a moisture control section that is dry in all parts for three-fourths or more of the time (cumulative) when the soil temperature at a depth of 50 cm is 5 oC or higher;

5. Do not have one or more horizons, within 100 cm of the soil surface and with a combined thickness of more than 15 cm, that contain 20 percent or more (by volume) durinodes, nodules, or concretions;

6. Do not have, throughout one or more horizons with a total thickness of 18 cm or more within 75 cm of the soil surface, either of the following:

                a. More than 35 percent (by volume) fragments coarser than 2.0 mm, of which more than 66 percent is cinders, pumice, and pumicelike fragments; or

                b. A fine-earth fraction containing 30 percent or more particles 0.02 to 2.0 mm in diameter, of which 5 percent or more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted by ammonium oxalate) times 60] plus the volcanic glass (percent) is 30 or more.

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