Humic substances

-Yes, lab assignments #8 are due next week even though classes will be over. Drop in boxes will be waiting for you.......

-Lecture slides for soil classification are presented in a somewhat random order. We did start with 2 least developed orders (Regosol and Brunisol) but all other orders are comprised of well developed soils. Both Regosol and Brunisol could develop into a soil that belongs to another order, given enough time and assuming that one (or several) of soil formation factors change.

-Decomposition of organic matter (carried out by a group of heterotrophic organisms) releases simpler organic compounds and also mineral forms of nutrients that are then taken up by another group of soil organisms that will synthesize new organic compounds (e.g. humic substances).

-So during the decomposition of organic matter by a group of soil microbes, some of the new simpler organic compounds may get polymerized by soil microbes to become more complex (i.e. humic substances) but they can also just remain simple compounds to be further broken down into even more simpler compounds right? And these would just be non-humic substances. Yes, this is correct [Maja]

-For soil classification, can the prefix b, indicating a buried horizon, be used on any horizon? Including the organic horizons and mineral A,B, and C? Yes, it can in buried soils or so-called paleosols (this was not mentioned in our course). However, "b" is most commonly used with the A horizons in Regosols. [Maja]

-Is the distinction between the 5 soil forming factors (t, r, p, cl, and b) and the soil forming processes (additions, translocations, losses, and transformations) that the 5 factors affect the development of a soil whereas the soil forming processes influence the type of horizons in/of the soil? Yes, this is correct [Maja]