Regosolic soil order questions
Hello, according to the lab manual the Regosolic soil order is the only order w/o a B horizon (I could've had misinterpret their meaning though), while on the Canadian system of soil classification stated that Regosolic occurs when all requirements of other soil order has not been met.
So, on the final exam, there are soil order identification questions (given a list of soil horizon, their depths and some extra info, determine soil order and diagnostic horizon). On those questions, is it safe to say that a soil is Regosolic if there are no B horizon present, or should we consider other options if a requirement not involving B horizon is present. (example being that a soil have no B horizon, but has over 10cm of Ah/Ap horizon, so is the soil Chernozemic, or is it Regosolic). (another example being that a soil again has no B horizon, but has a Cz (permafrost layer) within 1m or the soil surface, so is the soil Cryosolic, or Regosolic)
Furthermore, what diagnostic horizon can we identify for Regosolic order? (should we just say that it lacks a B horizon / that it failed to meet any requirement of other soil order. or there is a specific diagnostic horizon even for Regosolic?)
Angelo Be clear on the diagnostic horizons. e.g. Chernozemic Ah > 10 cm BUT also has between 1-17% organic C, C:N ratio < 17:1, base saturation > 80% and Ca2+ is the dominant cation. Be careful not to jump to conclusion that a soil is Chernozem just because the Ah is > 10 cm. Use the other clues given in the question re. the site description.
In this class we focus on soil order. We did give you one example in the lecture notes (lecture #31) of Great Group for Chernozems (Brown Chernozem, Dark Brown Chernozem, Black Chernozem). Thus, combinations such as a Regosolic Cryosol exist (e.g. your example of a soil lacking a B horizon but with permafrost within 1 m of the soil surface). Note Organic soils also do not have a B horizon. However, you are correct that the diagnostic feature of a Regosol is the lack of B horizon. Again, use the information provided in the description portion of the exam (e.g. located on a floodplain such as the example question 7a) on the sample final exam posted in the wiki).
Page 84 of the Lab Manual is really helpful for this. Basically you go through the steps in order, so this tells you which diagnostic horizons override the others. If it has a chernozemic Ah horizon but also has no B horizon, it's a chernozem rather than a regosol. A regosol can't have any of the other diagnostic horizons.