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HBC.Kandihumults

Key to Great Groups 

HBC. Other Humults that:

1. Do not have a densic, lithic, paralithic, or petroferric contact within 150 cm of the mineral soil surface; and

2. Have a kandic horizon; and

3. Within 150 cm of the mineral soil surface, either:

                a. With increasing depth, do not have a clay decrease of 20 percent or more (relative) from the maximum clay content; or

                b. Have 5 percent or more (by volume) clay depletions on faces of peds in the layer that has a 20 percent lower clay content and, below that layer, a clay increase of 3 percent or more (absolute) in the fine-earth fraction. Kandihumults, p. 741 

HBC. Kandihumults are the Humults that have a kandic horizon and a clay distribution in which the percentage of clay does not decrease from its maximum amount by as much as 20 percent within a depth of 150 cm from the mineral soil surface, or the layer in which the clay percentage decreases has at least 5 percent of the volume consisting of skeletans on faces of peds and there is at least a 3 percent (absolute) increase in clay content below this layer. These soils do not have a sombric horizon. They have no horizon in which plinthite either forms a continuous phase or constitutes one-half or more of the volume within 150 cm of the mineral soil surface. Kandihumults are of small extent in California and Hawaii

Definition 

Kandihumults are the Humults that:

1. Have a kandic horizon;

2. Do not have a densic, lithic, paralithic, or petroferric contact within 150 cm of the mineral soil surface;

3. Have a clay distribution in which the percentage of clay does not decrease from its maximum amount by as much as 20 percent within a depth of 150 cm from the mineral soil surface, or the layer in which the clay percentage decreases by more than 20 percent has at least 5 percent of the volume consisting of clay depletions on faces of peds and there is at least a 3 percent (absolute) increase in clay content below this layer;

4. Do not have a sombric horizon within 150 cm of the mineral soil surface; and

5. Do not have plinthite that forms a continuous phase or that constitutes more than 50 percent of the volume of some subhorizon within 150 cm of the mineral soil surface. 

Key to Subgroups 

HBCA. Kandihumults that meet all of the following:

1. Throughout one or more horizons with a total thickness of 18 cm or more within 75 cm of the mineral soil surface, have a fine-earth fraction with both a bulk density of 1.0 g/cm3 or less, measured at 33 kPa water retention, and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling more than 1.0; and

2. In one or more horizons within 75 cm of the mineral soil surface, have redox concentrations, a color value, moist, of 4 or more, and hue that is 10YR or yellower and becomes redder with increasing depth within 100 cm of the mineral soil surface; and

3. In normal years are saturated with water in one or more layers within 100 cm of the mineral soil surface for either or both:

                a. 20 or more consecutive days; or

                b. 30 or more cumulative days. Andic Ombroaquic Kandihumults 

HBCB. Other Kandihumults that have both:

1. Throughout one or more horizons with a total thickness of 18 cm or more within 75 cm of the mineral soil surface, a fine-earth fraction with both a bulk density of 1.0 g/cm3 or less, measured at 33 kPa water retention, and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling more than 1.0; and

2. An ustic moisture regime. Ustandic Kandihumults 

HBCC. Other Kandihumults that have, throughout one or more horizons with a total thickness of 18 cm or more within 75 cm of the mineral soil surface, a fine-earth fraction with both a bulk density of 1.0 g/cm3 or less, measured at 33 kPa water retention, and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling more than 1.0. Andic Kandihumults 

HBCD. Other Kandihumults that have, in one or more subhorizons within the upper 25 cm of the kandic horizon, redox depletions with a color value, moist, of 4 or more and chroma of 2 or less, accompanied by redox concentrations and by aquic conditions for some time in normal years (or artificial drainage). Aquic Kandihumults 

HBCE. Other Kandihumults that:

1. Have, in one or more horizons within 75 cm of the mineral soil surface, redox concentrations, a color value, moist, of 4 or more, and hue that is 10YR or yellower and becomes redder with increasing depth within 100 cm of the mineral soil surface; and

2. In normal years are saturated with water in one or more layers within 100 cm of the mineral soil surface for either or both:

                a. 20 or more consecutive days; or

                b. 30 or more cumulative days. Ombroaquic Kandihumults 

HBCF. Other Kandihumults that have 5 percent or more (by volume) plinthite in one or more horizons within 150 cm of the mineral soil surface. Plinthic Kandihumults 

HBCG. Other Kandihumults that have an ustic moisture regime. Ustic Kandihumults 

HBCH. Other Kandihumults that have a xeric moisture regime. Xeric Kandihumults 

HBCI. Other Kandihumults that have an anthropic epipedon. Anthropic Kandihumults 

HBCJ. Other Kandihumults. Typic Kandihumults 

Definition of Typic Kandihumults 

Typic Kandihumults are the Kandihumults that:

1. Do not have, in any subhorizon within the upper 25 cm of the kandic horizon, redox depletions with a color value, moist, of 4 or more and chroma of 2 or less, accompanied by redox concentrations and by aquic conditions;

2. Have a udic moisture regime;

3. Do not have, throughout a cumulative thickness of 18 cm or more and within a depth of 75 cm, a bulk density, in the fraction less than 2.0 mm in size, of 1.0 g/cm3 or less, measured at 33 kPa water retention, and acid-oxalate-extractable aluminum plus 1/2 acid-oxalate-extractable iron of more than 1.0 percent;

4. Have less than 5 percent (by volume) plinthite in all subhorizons within 150 cm of the mineral soil surface;

5. Do not have, in one or more horizons within 75 cm of the mineral soil surface, redox concentrations, a color value, moist, of 4 or more, and hue that is 10YR or yellower and becomes redder with increasing depth within 100 cm of the mineral soil surface; and

6. Do not have an anthropic epipedon.

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