Derived from decomposition of plant and animal residues
Range in thickness from absent to meters thick.
The A MASTER HORIZON - Topmost MINERAL horizon (topsoil)
Subject to significant weathering
Zone of gas and water exchange
High in plant roots, biotic activity
Cycling of carbon and nutrients
Accumulates OM
,Typically darker than soil below
The E MASTER HORIZON - Zone of ELUVIATION
E = eluviation = exit
Maximum losses by translocation
1. OM
2. Clays
3. Carbonates
4. Fe/Al oxides
5. Light-colored
6. Contains quartz (resistant primary minerals)
The B MASTER HORIZON - Accumulates material lost from above, or forms in place. (translocation,
transformation)
Zone of ILLIVIATION = additions
The subordinate horizon indicates WHAT is accumulating
1. OM
2. Clays
3. Salts
4. Fe/Al oxides
5. high reactivity
6. color
7. concentration of secondary minerals/OM
, B Master Horizon SUBORDINATE DISTINCTIONS - Bt = accumulation of silicate clays
Bh = accumulation of OM (spodic horizons)
Bw = early stages of soil development; weakly developed
Btg = gleying (wet/low oxygen)
Iron Oxides - Fe3+ = aerobic; forms solid, immobile oxides (rust)
Fe2+ = anaerobic; forms soluble, mobile compounds in soil
The C MASTER HORIZON - Closely resembles parent material
Unconsolidated
Little to no evidence of alteration or development
The R MASTER HORIZON - Bedrock
Unweathered Parent Material
g SUBHORIZON - gleying
anaerobic (reduced) conditions, color, Fe depletions
h SUBHORIZON - illuvial organic matter
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller oneclass. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $13.48. You're not tied to anything after your purchase.