Final Exam Questions

Hi Maja, on the 2004 final, the question 5b wants us to identify the soil order. (b) Ah (0-13 cm), Ae1 (13-25 cm), Ae2 (25-36 cm), Bt (36-66 cm), Btj (66-86 cm), Ck (86+ cm). (deciduous forest under humid to sub-humid climate; good natural drainage) I am hesitating between chernozemic order and luvisolic order. Based on the lab manual, chernozemic order should be identified before luvisolic order. However, the lab also said that the leaching process of luvisol is more intensive that chernozem, and that soil sample has a really huge Ae horizon. Could you please tell me which one is correct? Thank you very much!

That's my last question.

^Hey DepengR8198uan I am almost certain that soil is a luvisol, you wouldn't find a chernozem in the environment that this soil is referenced in. Chernozems are more in continental grassland environments.

Thanks Gwendolyn, I also think luvisol should be the correct one.

I second what Gwen has said. This soil is a Luvisol (diagnostic horizon = Bt, which is 30 cm thick). And as Gwen has said, you cannot have a Chernozem in a non-grassland ecosystem, in a region with a sub-humid climate.

You have to be careful re. making decisions about a soil being a Chernozem, since many soil types will have an Ah horizon. But not every Ah is the Chernozemic Ah (diagnostic horizon. The Chernozemic Ah horizon, need to have several specific properties (e.g., C/<17/1, base satauration >80%, Ca2+ as the dominant ion on the exchange complex)

Based on that, I guess the question will provide more information about Ah horizon for us, so we can identify that soil order. Thank you very much, Maja!

yes, that is correct - if a soil is Chernozem those additional details about the Ah horzion would be provided

Hi Maja,

Will a soil with no B horizon always be classified as Regosol? For example soil with Ap=10cm, Cg1=20cm, Cg2=30cm is not Chernozemic for sure, but could it be Gleyesol?

Thank you

Soil without B horizon is a Regosol

Hi, I am wondering what is the distinction between C factor and P factor for soil erosion? Is it correct to say that C factor only considers the influence of vegetative cover and related management such as tillage on erosion, whereas P factor incorporates various combinations of management practices?

C factor (in the Universal Soil Loss Equation) refers to all management practices (tillage, fertilization, addition of organic amendments, etc) that are needed to grow a particular crop on the site P factor refers to the conservation practices (terraces, contour cropping, etc) that are done to protect the soil from erosion