2017 NACTA Contest FAQs for 4-Year Universities

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1 2017 NACTA Contest FAQs for 4-Year Universities Do you recognize Cd horizons in the contest area? a. We have Permian mudstones and shales in the contest area that have traditionally been described with a Cr designation, sometimes with the addition of suffix k and/or t (Yes, we can have Crkt). Some people have suggested that our Cr horizons should be designated Cd horizons because material from the material will mostly slake in water, although it could take several days of soaking. Our experience is that these mudstones and shales are at least partly cemented with carbonates. When you see these materials in the field, we are curious about your opinion and whether you would designate them as Cr or Cd. It is not a big deal anyway because paralithic and densic contacts are both root limiting layers. For this contest, we decided to make this an easy decision. We will not use the suffix d on the contest, and densic contact is not on the scorecard. 2. For hydraulic conductivity (Table 10), I see that you have combined the six hydraulic conductivity classes into three: High, Moderate, and Low. This is great, as it is how the NACTA rules have always been. But for the surface runoff classes (Table 18), the six hydraulic classes have not been combined into three, making it hard to choose an answer. Could you look at Table 19 and let me know what answer a student should choose for a slope of 9% and moderate surface hydraulic conductivity? a. Sometimes trying to simplify actually makes things harder. Our intent was to recognize six hydraulic conductivity classes as indicated in the Soil Survey Manual but to lump them into three as has been done in the past to make it easier for the judgers. However, for runoff classes, the judgers need to use the six hydraulic conductivity classes to get the correct runoff classes. Using only the three hydraulic conductivity classes can result in an illogical runoff class for some soils in the contest region. Hence, all six are needed for runoff. Please remember that the contest is open book, so the judgers can use both the hydraulic conductivity and the runoff tables. 3. In the hydraulic conductivity section, it is stated that the presence of a natric horizon at or above the specified judging depth will move the hydraulic conductivity class to the next lower class." Does this apply to the six hydraulic conductivity classes or to the three grouped classes? a. It applies to the six classes. 4. Regarding Table 10, it is specified in several places that hydraulic conductivity class is influenced by the organic matter content of the soil, referencing "high" or "moderate" or "low" organic matter content. However, the thresholds for these three classes are not specified. Similarly, the Moderately Low HC class refers to "high clay content" but

2 does not specify how much clay is considered "high". Would it be more appropriate to use specific class limits based on organic carbon and clay contents? a. These descriptions are meant to be general enough to be used for a wide range of soil properties. We think it is a better learning experience for students if they see how the official judges handle these situations. Then, they can use their best judgement and make their own interpretations about organic matter and clay contents. We do not want to define arbitrary class limits based on organic carbon and clay contents. However, we will add site notes for the practice sites explaining the reasons when the official judges make adjustments in the hydraulic conductivity class because of clay or organic matter contents or shrinkswell potential. 5. Regarding the description of Table 11, it is stated that "If the profile is not visible to a depth of 150 cm, or if you are requested to describe a soil only to a shallower depth, then you may assume that the conditions present in the last horizon described extend to 150 cm." While it would be highly unlikely, what if the pit is 160 cm deep, the depth of description is 110 cm, and there is observable bedrock at 130 cm? Would the visible root restrictive layer be ignored because it is below the depth of description? a. For the scenario mentioned above, we would have made sure that the depth of description included the observable bedrock. For example, we would have given the profile depth as 135 cm (not 110 cm), and we would instruct the pit monitor to make sure that all judgers could see that bedrock was exposed within the profile depth. We should also mention that the depth to bedrock can be quite variable within the pit. In addition, there can be much variation between depth to bedrock from one control section to the other. We will make sure that each profile has the same number of horizons to describe so that each profile has the same number of points possible. Judgers should take the depth measurements from the tape measure anchored to the pit face within the control area. 6. If redox concentrations are present, would they be identified as such and also recognized as Fe-Mn matrix concentrations? a. Redox concentrations would be recognized with a Y in the RMF Conc. column and with an FE-MN in the Matrix Conc. column. 7. I am assuming that marking a Y for RMF Concentrations does not automatically require listing FE-MN under Matrix Concentrations? a. No, this is not our intent. If a Y is marked for RMF, the type of Matrix Concentration must also be given. Soils occur in the contest area that have multiple Matrix Concentrations in the same horizon. For example, we have soil horizons where Fe-Mn matrix accumulations occur with calcium carbonate accumulations. In this case, Y should be marked for RMF, and FE-MN and K should be marked under Matrix Concentration. 1 point would be awarded for the FE-MN and 1 point for the K.

3 8. Is there ever a time when you would put a k, y, or z on the horizon name but not list them under Matrix Concentrations? a. We intend for the students to make two separate decisions in regard to the horizon suffix symbol k, y, or z and the type of Matrix Concentration. In our professional work, those two decisions are not linked. For example, it is possible to have a horizon with disseminated pedogenic carbonate in which the Bk designation should be used. However, the disseminated carbonate would not be considered as a concentration of pedogenic carbonate that occurs in the matrix. Also, coatings of pedogenic carbonate can occur along peds. These features are ped coatings and not concentrations occurring in the matrix. It is up to the coaches to decide how they want to teach this to students. If coaches teach their students to link them, this would be correct most of the time for the soils in the contest area. However, these two decisions will be made separately and not linked by the official judges. 9. Is there ever a time when you would mark Y for redox concentrations but not put FE- MN under Matrix Concentrations? a. We also intend for the students to make two separate decisions in regard to marking a Y (yes) for RMF concentrations and for marking FE-MN as a Matrix Concentration. Please note that RMF concentrations can include pore linings or ped coatings of Fe and/or Mn. These features are coatings (cutans) and not concentrations that occur in the matrix. In this case, if no other forms of RMF concentrations were present, we would mark Y for RMF concentrations and mark a "-" for matrix concentrations. Again, coaches can decide how to teach this to their students. If coaches teach their students to link these two decisions, this would give the correct answer most of the time for the soils in the contest area. However, the official judges will make two separate decisions. 10. What is your interpretation on carbonate 'masses', do you consider them significant for pedogenesis (B vs C horizon nomenclature)? a. We generally do not have carbonate masses in the contest area. The carbonate forms in the contest area typically include nodules, ped coatings, and/or filaments (which are probably ped coatings). We believe these forms are pedogenic. The soils exhibiting these features in the contest area usually have soil structure. We generally would describe these horizons as some type of a Bk such as a Btk, Bkss, Bk, etc. Also, we do have Cr horizons with pedogenic carbonate forms. These will be described as Crk or Crtk. 11. How common is gypsum accumulation in this area? Are there series that have "y" suffixes mapped in the area? (I didn t find any in the OSD's). a. We didn t recognize gypsum accumulation in the contest area until we started soil micromorphology for research projects. Gypsum tends to occur in association with pedogenic carbonate in soils in the contest area that also have elevated Na contents. It is difficult to recognize the gypsum in field examination,

4 except it occurs as white accumulations that do not react with 10% HCl. Gypsum commonly occurs in soils with a parent material sequence of loess over colluvium over residuum. Dwight and Konza often contain gypsum accumulations. We have posted a guidebook for a field trip to the Rannells Prairie on the website. The Konza pedon in the guidebook contains gypsum, and the horizon nomenclature includes a y suffix. We will post % gypsum for any soil horizon where gypsum occurs and if the gypsum content is needed for classification purposes. 12. "k" horizons seem pretty common, but according to the NRCS OSD site, there are no Calciustolls or Calciudolls mapped in the contest area. What part of the "calcic" definition in the Taxonomy is usually NOT met in these Bk's (>15% CCE or one of the following: >5% more CaCO3 compared to C horizon, OR >5% pedogenic carbonates)? (for example: Benefield). a. We will post CCE for soils where the data are needed for classification. In most cases, the soils in the contest area, which have a k designation, will not have the 15% CCE required for a calcic horizon. Many of the soils in the contest area will have >5% pedogenic carbonate accumulations. Hence, we use a k designation, but the classification for a calcic is not met. We could find inclusions in a mapping unit of a soil like Clime that could make the criteria to classify with a calcic horizon. 13. There are a few redundancies on the scorecard. For example, marking a k under horizon subscript and then marking K under Matrix Concentrations while using the same criteria. What is the meaning for this? a. We do not view this as a redundancy because these are separate determinations. The horizon subscript k should be used when appropriate according to the definition found in Chapter 18 of the 2014 Keys to Soil Taxonomy. K should be marked as a Matrix Concentration whenever matrix accumulations of calcium carbonate occurs. Please note to follow this same procedure for a y horizon subscript and a Y matrix accumulation of gypsum. We have soil horizons in the contest area that may have matrix accumulations of both calcium carbonate and gypsum. 14. Many BC horizons underneath argillics would qualify as cambics, but there is no point in recognizing them. Also, we may find a Bw horizon that qualifies for cambic above a Bk horizon that qualifies for calcic. Should we mark cambic if it is not the diagnostic horizon that determines class placement? a. Although it is open to interpretation, the intent of Keys to Soil Taxonomy is probably to not recognize a cambic if it occurs above or below another diagnostic horizon. For this contest, we will not mark cambic if a horizon with cambic properties occurs above or below an argillic or calcic horizon. 15. Are the disseminated carbonates in the contest area visible with a hand lens? a. Yes, disseminated carbonates in the contest area are visible with a hand lens.

5 16. If a Cr horizon is cemented by finely disseminated carbonates, with no visible coatings or masses in the horizon, are those carbonates considered pedogenic? a. In the contest area, the Cr (or Crk) horizons that contain carbonates will exhibit carbonate nodules, masses, and threads (films) of carbonate between mudstone layers that are clearly visible. At least one practice pit will provide an excellent example of pedogenic carbonate forms that occur in Crk horizons in the contest area. Most of the Cr horizons in the contest area have clearly visible pedogenic carbonate forms such as nodules, masses, and threads. Such horizons will be designated Crk. Although rare, Cr horizons can occur in the contest area that lack visible forms of pedogenic carbonate. We will designate such horizons as Cr. 17. The handbook says that if a soil has measureable gypsum content, that data will be given. But for carbonates, it will be given only if needed for classification. Could there be a soil where there are detectible or visible carbonates but where no lab data will be given? a. If a soil horizon has measureable gypsum content, we will provide % gyspum because of the difficulty in identifying the gypsum and distinguishing it from pedogenic carbonate. Some soil horizons in the contest area will have pedogenic carbonates, but the soil matrix is non-calcareous, and the quantity of pedogenic carbonate is low enough so that it is obvious that the CCE is less than 15%. CCE data will be given only if the official judges believe that the data are needed for classification. 18. If lab data reveals any measureable content of gypsum or carbonates or sodium in an A or B horizon, is that enough to warrant use of the lowercase letters for naming the horizon? a. Since gypsum will be difficult for the judgers to identify and separate from pedogenic carbonate accumulations, we will designate any horizon in which the gypsum content is reported with the suffix y. We tend to put a k on any horizon with visible pedogenic carbonate. Many soils in the contest area will have measureable amounts of Na. We will provide SAR data only if needed for soil classification. We tend not to use the n suffix unless the SAR is approaching 13, and the soil morphology is typical for a natric horizon.