Navigation

ชมรมดินปุ๋ยบนเว็บ

DEB.Udivitrands

Key to Great Groups 

DEB. Other Vitrands. Udivitrands, p. 320 

DEB. Udivitrands are the more or less well drained Vitrands that have a udic moisture regime. Characteristically, these soils have an ochric epipedon and a cambic horizon. Some have an argillic horizon. Most of the Udivitrands in the United States developed in Holocene deposits under coniferous forest vegetation. 

Definition 

Udivitrands are the Vitrands that have a udic soil moisture regime. 

Key to Subgroups 

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

DEBB. Other Udivitrands 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 Udivitrands 

DEBC. Other Udivitrands that have, at a depth between 25 and 100 cm either 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 Udivitrands 

DEBD. Other Udivitrands that have both:

1. An argillic or kandic horizon that has its upper boundary within 125 cm of the mineral soil surface or of the upper boundary 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 the upper 50 cm of the argillic or kandic horizon. Ultic Udivitrands 

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

DEBF. Other Udivitrands that have a melanic, mollic, or umbric epipedon. Humic Udivitrands 

DEBG. Other Udivitrands. Typic Udivitrands 

Definition of Typic Udivitrands 

Typic Udivitrands are the Udivitrands 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 an argillic or kandic horizon that has its upper boundary within 125 cm of the mineral soil surface or of the upper boundary of an organic layer with andic soil properties, whichever is shallower; and

5. Do not have a melanic, mollic, or umbric epipedon.

pages by <SoClaimon> sootin claimon : sootinc@gmail.com