Does the 18 cm mixing rule apply to all epipedons, or just to mollic and umbric? I cannot see it applying to yermic, or even ochric. How about none, the provision for fine strata near the soil surface?by ttcf - Soil Taxonomy Forum
Measure soil temperature at 50 cm depth in a region, and determine the average number of days that it is higher than 5C. Then multiply that number by 0.6 to get the number of days that it must be dry.in the soil moisture control section.by ttcf - Soil Taxonomy Forum
If there is more than one subgroup, I believe they are listed in alphabetical order.by ttcf - Soil Taxonomy Forum
If there is more than one subgroup, I believe they are listed in alphabetical order.by ttcf - Soil Taxonomy Forum
Has anyone seen relict or current mollic epipedons in areas thought to have aridic soil moisture regimes, or azonal mollic epipedons? 1. Aridic moisture regimes have desert vegetation or sparse vegetation and do not appear to have site conditions (favorable aspect, high water table, or concave landform that collects extra runoff) that would give it more favorable local moisture conditions. A relby ttcf - Soil Taxonomy Forum
The Xerertic subgroup name is an intergrade to Xererts, a Suborder of Vertisols. This means it is a Calciargid that has many of the properties of Xererts but not enough to have identified as one (Vertisols key out before Aridisols). For example, maybe it has less than 30% clay in the upper part, and thus failed to be a Vertisol. Thus "Xerter" + "ic" to indicate the intergrade.by ttcf - Soil Taxonomy Forum
A histic epipedon is almost always composed of fibric, hemic, or sapric organic soil materials, or any combination of these. However, in plowed fields, a histic epipedon may be composed of minral material very high in OC. A histic epeidon:... Is an Ap horizon that, when mixed to a depth of 25 cm, has an organic-carbon content (by weight) of: a. 16 percent or more if the mineral fraction contby ttcf - Soil Taxonomy Forum
Dear Neal: Yes, we are proposing a soil order similar to "Technosols" and "Anthrosols" in WRB. The new soil order will recognize hazardous (hazic) material that is radioactive. We will make our propoisal beginning at the NCSS meeting in Rhode Island.by ttcf - Soil Taxonomy Forum
I believe there are some fragipans that have a significant amount of albic materials, such as a Btx/E horizon. However I think the albic horizon must be at least 85% albic materials while the fragipan must be 60% or more by volume brittle, so it seems very unlikely a single horizon would qualify for both an albic and a fragipan.by ttcf - Soil Taxonomy Forum
Is the material underneath pavement considered soil if it has horizons different than the original material? At some point do extensive runways and huge parking lots become miscellaneous land types?by ttcf - Soil Taxonomy Forum
Christian, what do you mean by "management to crop production"? In the 2nd Edition of Soil Taxonomy, found at https://tinyurl.com/y9ydtqa3 there are sections that describe the use and management of the different soils. Use the search feature and look up the words such as "crop" or "wheat" or "cotton" etc.by ttcf - Soil Taxonomy Forum
Since there is enrichment of carbon in the surface horizon, I would name it an A horizon despite absence of soil structure. There is little chance for moderate structure to form in the absence of clay, but the carbon may allow some very weak structural units to form. I would not consider the absence of soil structure to be the same as the structure of the rock or sediment. I would only consider thby ttcf - Soil Taxonomy Forum
Yes, that means the argillic must extend to that depth unless a paralithic or lithic contact occurs shallower.by ttcf - Soil Taxonomy Forum
If a subsoil horizon is part of a fragipan, can it also be part of a glossic? of an argillic?by ttcf - Soil Taxonomy Forum
When measuring rock fragments for size class, do you measure across the narrowest axis, the intermediate axis, or the longest/widest axis? This question especially applies to channers and flags that are very thin but also very wide and very long. For example, 1/2 inch (1.25 cm) thick; 16.5 inches (42 cm) long, and 4 inches (10 cm) wide. Is this a channer or a flag?by ttcf - Soil Taxonomy Forum
Excellent. Thank you for the reference.by ttcf - Soil Taxonomy Forum
Very interesting. Thank you for these suggested categories.by ttcf - Soil Taxonomy Forum
Thank you for the slideshow file and the explanation. I had overlooked the definitions in NSSH and the Glossary. To summarize, would it be correct to say that saprolite fragments resemble bedrock fragments but are no longer cemented due to isovolumteric chemical weathering, while pararock fragments are still at least very weakly up to moderately cemented? In otherwords, can rupture resistance be uby ttcf - Soil Taxonomy Forum
This is a very useful description of saprolite. However, in Soil Taxonomy we use the term paralithic materials (made of pararock fragments) for material that can be be dug with hand tools but is still at least very slightly cemented. The material should not slake in water. The concept of slaking in water is valuable and is a test we have used for other materials such as fragipans. Discussioby ttcf - Soil Taxonomy Forum
I am in agreement about the notation of saprolite or saprolitic material being non-cemented, since we allow paralithic material to be as little as very slightly cemented. This definition keeps the two separate. The concept of slaking in water is valuable and is a test we have used for other materials such as fragipans. Discussion of the volume occupied is also valuable. We consider saprolite toby ttcf - Soil Taxonomy Forum
The t designation is used whenever you can detect the presence of illuviated or authigenic clay films, coatings, or bridging of sand grains. I believe it is used primarily for layered clays such as phyllosilicates rather than for oxides. My best advice would be to add a t to horizons where you see the clay accumulation evidence, and a w for those where you do not. The papules might also be calledby ttcf - Soil Taxonomy Forum
The Soil Survey Manual lists saprolite in Ch. 3 but I see no definition in the SSM, NSSH, or in the Keys to Soil Taxonomy or in the big book of Soil Taxonomy. Yet the term is used in many places in several of those standards. I feel it should be defined. Did I overlook the definition? Saprolite is listed in Ch. 3 as one of the materials for a C horizon, with reference to Table 3-7. I think that saby ttcf - Soil Taxonomy Forum
Is there a requirement that the organic carbon in a mollic epipedon be of Holocene age? Is older carbon such as might come from applications of coal or bedrock products excluded from the minimum amount required?by ttcf - Soil Taxonomy Forum
In the following description, is the E/B horizon part of the albic horizon? Do you read the color mixed in such a horizon? E--8 to 14 inches; dark gray (10YR 4/1) silt loam, gray (10YR 5/1 & 6/1) dry; E/B--14 to 16 inches; dark gray (10YR 4/1) silty clay loam (E), gray (10YR 5/1 & 6/1) dry, very dark gray (10YR 3/1) clay (B), dark gray (10YR 4/1) dryby ttcf - Soil Taxonomy Forum
Andrew, my understanding is that the top of the argillic is where you see evidence of translocation of clay, as long as the clay increase requirements are met. The clay increase must be met within 30 cm of that depth. However, if a lithologic discontinuity or the bottom of a plow layer where the translocated clay is observed, the clay increase requirements are waived.by ttcf - Soil Taxonomy Forum
Yes, that is confusing to contain the word in it's own definition. I looked it up in standard online dictionaries and it seems to mean either "inside something" or up the limit of a range. In that second case, the "less than or equal to" seems to fit well.by ttcf - Soil Taxonomy Forum
You have raised some valid questions. I did my dissertation on creating an expert system program for Soil Taxonomy way back in 1997. I called the people in charge of the Keys at that time, and their response was the same as I stated earlier. I suspect that when you find inconsistencies as you pointed out with paralthic and lithic depth criteria that it is an oversight left from some of the older vby ttcf - Soil Taxonomy Forum
I have always interpreted "within" to mean "less than or equal to" because when the rule is meant to be "less than" certain value it is specifically stated that way.by ttcf - Soil Taxonomy Forum
Can anyone tell me why there is a dry color rule for mollic epipedon? I understand the genetic bias towards grassland soils versus forested soils. But how much difference does it make from an interpretive standpoint, or a use and management and functionality perspective does it make? How many soils would qualify for mollic if the dry color requirement were waived?by ttcf - Soil Taxonomy Forum
Can anyone tell me if they have any soils that use these exceptions to the standard color rule for mollic epipedon? If so, how do you determine the calcium carbonate equivalent in the field? b. A fine-earth fraction that has a calcium carbonate equivalent of 15 to 40 percent and colors with a value and chroma of 3 or less, moist; or c. A fine-earth fraction that has a calcium carbonate eqby ttcf - Soil Taxonomy Forum