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DDC.Haploxerands

Key to Great Groups 

DDC. Other Xerands. Haploxerands, p. 323 

DDC. Haploxerands are the more or less well drained Xerands that do not have a melanic epipedon. These soils have a 1500 kPa water retention of 15 percent or more on air-dried samples and 30 percent or more on undried samples throughout more than 30 percent of the upper part. Characteristically, Haploxerands have a thin O horizon, an ochric or mollic epipedon, and a cambic horizon. The Haploxerands in the United States generally developed in late-Pleistocene or Holocene deposits. Most formed under coniferous forest vegetation, but some formed under grass or shrub vegetation. 

Definition 

Haploxerands are the Xerands that:

1. Do not have a 1500 kPa water retention of less than 15 percent on air-dried samples and less than 30 percent on undried samples throughout 60 percent or more of the thickness either:

                a. Within 60 cm either of the mineral soil surface or of the top of an organic layer with andic soil properties, whichever is shallower, if there is no densic, lithic, or paralithic contact, duripan, or petrocalcic horizon within that depth; or

                b. Between either the mineral soil surface or the top of an organic layer with andic soil properties, whichever is shallower, and a densic, lithic, or paralithic contact, a duripan, or a petrocalcic horizon; and

2. Do not have a melanic epipedon. 

Key to Subgroups 

DDCA. Haploxerands that have a lithic contact within 50 cm of the mineral soil surface or of the top of an organic layer with andic soil properties, whichever is shallower. Lithic Haploxerands 

DDCB. Other Haploxerands that have, in one or more horizons at a depth between 50 and 100 cm either from the mineral soil surface or from the top of an organic layer with andic soil properties, whichever is shallower, aquic conditions for some time in normal years (or artificial drainage) and one or more of the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or more chroma of 2 or less either in redox depletions on faces of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to alpha,alpha-dipyridyl at a time when the soil is not being irrigated. Aquic Haploxerands 

DDCC. Other Haploxerands that have, at a depth between 25 and 100 cm from the mineral soil surface or from the top of an organic layer with andic soil properties, whichever is shallower, a layer 10 cm or more thick with more than 3.0 percent organic carbon and the colors of a mollic epipedon throughout, underlying one or more horizons with a total thickness of 10 cm or more that have a color value, moist, 1 unit or more higher and an organic-carbon content 1 percent or more (absolute) lower. Thaptic Haploxerands 

DDCD. Other Haploxerands that have a calcic horizon that has its upper boundary within 125 cm of the mineral soil surface. Calcic Haploxerands 

DDCE. Other Haploxerands that have an argillic or kandic horizon that has both:

1. An upper boundary within 125 cm of the mineral soil surface or of the top of an organic layer with andic soil properties, whichever is shallower; and

2. A base saturation (by sum of cations) of less than 35 percent throughout its upper 50 cm. Ultic Haploxerands 

DDCF. Other Haploxerands that have both:

1. A mollic or umbric epipedon; and

2. An argillic or kandic horizon that has its upper boundary within 125 cm of the mineral soil surface or of the top of an organic layer with andic soil properties, whichever is shallower. Alfic Humic Haploxerands 

DDCG. Other Haploxerands that have an argillic or kandic horizon that has its upper boundary within 125 cm of the mineral soil surface or of the top of an organic layer with andic soil properties, whichever is shallower. Alfic Haploxerands 

DDCH. Other Haploxerands that have a mollic or umbric epipedon. Humic Haploxerands 

DDCI. Other Haploxerands. Typic Haploxerands 

Definition of Typic Haploxerands 

Typic Haploxerands are the Haploxerands that:

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

2. Do not have, in any horizon at a depth between 50 and 100 cm either from the mineral soil surface or from the top of an organic layer with andic soil properties, whichever is shallower, both aquic conditions and any of the following:

                a. 2 percent or more redox concentrations; or

                b. A color value, moist, of 4 or more and 50 percent or more chroma of 2 or less either in redox depletions on faces of peds or in the matrix if peds are absent; or

                c. Enough active ferrous iron to give a positive reaction to alpha,alpha-dipyridyl at a time when the soil is not being irrigated;

3. Do not have, between depths of 25 and 100 cm, a layer 10 cm or more thick with more than 3.0 percent organic carbon and the colors of a mollic epipedon throughout, occurring below a horizon or horizons 10 cm or more thick with a color value, moist, 1 unit or more higher and an organic-carbon content 1 percent or more lower;

4. Do not have a calcic horizon with its upper boundary within 125 cm of the mineral soil surface;

5. Do not have an argillic or kandic horizon with its upper boundary within 125 cm of the mineral soil surface or of the upper boundary of an organic layer that has andic soil properties, whichever is shallower; and

6. Do not have either a mollic or umbric epipedon.

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