JCD.Kandiustalfs

Key to Great Groups 

JCD. Other Ustalfs that:

1. Have a kandic horizon; and

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

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

                a. Do not have a clay decrease with increasing depth of 20 percent or more (relative) from the maximum clay content [Clay is measured noncarbonate clay or based on the following formula: Clay % = 2.5(% water retained at 1500 kPa tension - % organic carbon), whichever value is greater, but no more than 100]; or

                b. Have 5 percent or more (by volume) skeletans 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. Kandiustalfs, p. 237 

JCD. Kandiustalfs are the Ustalfs with thick argillic horizons that have relatively high base saturation but a low cation-exchange capacity. Many of these soils occur on the older surfaces in warm, humid or semihumid areas. Kandiustalfs occur in Africa and South America. They are commonly used as rangeland or cropland. 

Definition 

Kandiustalfs are the Ustalfs 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 and do not have a duripan within 100 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 150 cm of the 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 skeletans on faces of peds and there is at least a 3 percent (absolute) increase in content of clay below this layer;

4. Do not have plinthite that forms a continuous phase or constitutes more than half the volume of some subhorizon within 150 cm of the mineral soil surface; and

5. Do not have a natric horizon. 

Key to Subgroups 

JCDA. Kandiustalfs that have a sandy or sandy-skeletal particle-size class throughout a layer extending from the mineral soil surface to the top of a kandic horizon at a depth of 100 cm or more. Grossarenic Kandiustalfs 

JCDB. Other Kandiustalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil surface, redox depletions with chroma of 2 or less and also aquic conditions for some time in normal years (or artificial drainage); and

2. A sandy or sandy-skeletal particle-size class throughout a layer extending from the mineral soil surface to the top of a kandic horizon at a depth of 50 to 100 cm. Aquic Arenic Kandiustalfs 

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

JCDD. Other Kandiustalfs that have, in one or more horizons within 75 cm of the mineral soil surface, redox depletions with chroma of 2 or less and also aquic conditions for some time in normal years (or artificial drainage). Aquic Kandiustalfs 

JCDE. Other Kandiustalfs that have both:

1. A sandy or sandy-skeletal particle-size class throughout a layer extending from the mineral soil surface to the top of a kandic horizon at a depth of 50 to 100 cm; and

2. When neither irrigated nor fallowed to store moisture, either:

                a. A mesic or thermic soil temperature regime and a moisture control section that in normal years is dry in some part for six-tenths or more of the cumulative days per year when the soil temperature at a depth of 50 cm below the soil surface is higher than 5 oC; or

                b. A hyperthermic, isomesic, or warmer iso soil temperature regime and a moisture control section that in normal years:

                                (1) Is moist in some or all parts for less than 90 consecutive days per year when the temperature at a depth of 50 cm below the soil surface is higher than 8 oC; and

                                (2) Is dry in some part for six-tenths or more of the cumulative days per year when the soil temperature at a depth of 50 cm below the soil surface is higher than 5 oC. Arenic Aridic Kandiustalfs 

JCDF. Other Kandiustalfs that have a sandy or sandy-skeletal particle-size class throughout a layer extending from the mineral soil surface to the top of a kandic horizon at a depth of 50 to 100 cm. Arenic Kandiustalfs 

JCDG. Other Kandiustalfs that, when neither irrigated nor fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a moisture control section that in normal years is dry in some part for six-tenths or more of the cumulative days per year when the soil temperature at a depth of 50 cm below the soil surface is higher than 5 oC; or

2. A hyperthermic, isomesic, or warmer iso soil temperature regime and a moisture control section that in normal years:

                a. Is moist in some or all parts for less than 90 consecutive days per year when the temperature at a depth of 50 cm below the soil surface is higher than 8 oC; and

                b. Is dry in some part for six-tenths or more of the cumulative days per year when the soil temperature at a depth of 50 cm below the soil surface is higher than 5 oC. Aridic Kandiustalfs 

JCDH. Other Kandiustalfs that, when neither irrigated nor fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a moisture control section that in normal years is dry in some part for 135 cumulative days or less per year when the temperature at a depth of 50 cm below the soil surface is higher than 5 oC; or

2. A hyperthermic, isomesic, or warmer iso soil temperature regime and a moisture control section that in normal years is dry in some or all parts for less than 120 cumulative days per year when the temperature at a depth of 50 cm below the soil surface is higher than 8 oC. Udic Kandiustalfs 

JCDI. Other Kandiustalfs that have, in all subhorizons in the upper 100 cm of the kandic horizon or throughout the entire kandic horizon if less than 100 cm thick, more than 50 percent colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. Value, moist, of 3 or less; and

3. Dry value no more than 1 unit higher than the moist value. Rhodic Kandiustalfs 

JCDJ. Other Kandiustalfs. Typic Kandiustalfs 

Definition of Typic Kandiustalfs 

Typic Kandiustalfs are the Kandiustalfs that:

1. Do not have, in any horizon within 75 cm of the mineral soil surface, redox depletions with chroma of 2 or less and also aquic conditions;

2. Have a texture finer than loamy fine sand in one or more subhorizons within 50 cm of the mineral soil surface;

3. Have, in all horizons within 150 cm of the mineral soil surface, less than 5 percent plinthite, by volume;

4. When neither irrigated nor fallowed to store moisture:

                a. Have a mesic or thermic soil temperature regime and both are dry in some part less than six-tenths of the time and are dry for more than 135 cumulative days per year in some part of the moisture control section (not necessarily the same part) in normal years and during a period when the soil temperature at a depth of 50 cm exceeds 5 oC; or

                b. Have a hyperthermic, isomesic, or warmer soil temperature regime and:

                                (1) Are dry in some or all parts of the moisture control section for 120 or more cumulative days per year; and

                                (2) Are moist in some or all parts of the moisture control section for 90 or more consecutive days per year both in normal years and during a period when the soil temperature at a depth of 50 cm exceeds 8 oC; and

                                (3) Are moist in some or all parts for six-tenths or more of the cumulative days per year when the soil temperature at a depth of 50 cm below the soil surface is higher than 5 oC;

5. Do not have, in all subhorizons in the upper 100 cm of the kandic horizon or throughout the entire kandic horizon if less than 100 cm thick, more than 50 percent colors that have all of the following:

                a. Hue of 2.5YR or redder; and

                b. Value, moist, of 3 or less; and

                c. Dry value no more than 1 unit higher than the moist value.

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