Summary + Lectures second part - Natural Processes
37 views 10 purchases
Course
GEO1-2412 - Natural Processes
Institution
Universiteit Utrecht (UU)
Book
Fundamentals of the Physical Environment
A summary of chapter 18 to 22 of the book 'Fundamentals of the Physical Environment (4ed)' of the course Natural Processes and the lectures that corresponded to it (integrated). Written down pointwise, the main concepts are explained.
College notes GEO1-2412 - Natural Processes (GEO1-2412) Fundamentals of the Physical Environment, ISBN: 9780415232944
All for this textbook (2)
Written for
Universiteit Utrecht (UU)
Global Sustainability Science
GEO1-2412 - Natural Processes
All documents for this subject (5)
Seller
Follow
floor-vc
Content preview
Summary Natural Processes PT2 Book & Lectures
Chapter 18: Soils in their environment
Lecture 1: Soil Science
Residual soils: soil which is still at the place of the original parent material.
Transported soils: transported from original parent materials (by water,
glaciers, wind, etc.)
18.1 Soil formation
Two soil formation processes
1. formation of soil parent materials through weathering. This is the C
horizon material.
2. formation of the soil profile. This is when the C horizon material is
changed into A, E, and B horizons. This happens near the surface.
Vertical organisation: sequence of soil layers (horizons) with different
characteristics. Downwards:
- O: organic matter
- A: topsoil
- E: eluviated topsoil (bleached)
- B: subsoil
- C: parent material
- R: bedrock
How to determine the composition of soils
Antropogenic controls: fertilizers, heavy metals, etc.
Geogenic controls: parent soil material, climate, etc.
Q1: Which type of control dominantly determines the composition of
agricultural soils?
A1: parent soil materials so, geogenic
Controlling factors in soil formation (PClORT):
Parent material (e.g. limestone)
- Weathered bedrock
- Freshly deposited sediments
- C horizon
- Large variety of chemical deposition (this composition determines
the speed of the weathering)
Q2: Why is parent material important in soil formation?
A2: The parent material has a vertical influence on the topsoil.
,Summary Natural Processes PT2 Book & Lectures
Climate
- Temperature is very important (high temp, high activity /
weathering / amount of water)
- Precipitation
o Precipitation > evaporation: leaching, peat formation
o Precipitation < evaporation: e.g salt accumulation
- Soil water balance (precipitation)
o tropical soils: intense weathering, low organic matter
(because it decomposes really quickly)
o desert: little leaching, low organic matter
o steppe: high organic matter, high leaching
o taiga (naaldwouden/boreal forest): slow decomposition, high
organic matter, high leaching
- climate determines growth rates and decomposition
Q3: Why is climate an important factor in soil formation?
A3: Climate governs the amount of CO2, the amount of
precipitation and temperature (determining weathering). Climate is
the most important factor in soil formation.
Biota (organisms)
- Flora
o The main source of organic material
o Plants enhance consolidation, the compaction of clay, which
influences the hydrology
- Fauna
o Organisms and plants can move/transfer soils etc and
determine structure. Moles, worms, roots, etc.
o Humans also influence soil with agriculture
Q4: why are the biota important in soil formation?
A4: Important for the mixing of the soils, getting minerals
everywhere, mixing, etc. (?)
Topography (relief)
- Slopes influence the water content of the soil
- Influences erosion and transport of materials
Q5: Why is topography important for soil formation?
A5: Transfer of materials and water distribution which also
influences the decomposition etc.
Time
- Whether or not the soil is disturbed
- Soil processes take time – ‘new’ soils (azonal) have yet to develop,
while older soils have clear horizons
Zonality:
Zonal soils: typical for certain climate
Azonal soil: younger, not yet in balance
Intrazonal soils: climate is not the determining factor (e.g. parent material, salt
etc)
Important groups for soil formation processes:
- Additions (inputs)
o Weathering of parent material
Unloading (remove pressure from top layer, stone expands
and breaks)
Thermoclasty (expanding and shrinking of rocks bc of
temperature changes)
Gelicfraction (by ice)
Halofraction (volume changes bc of salt)
o Sedimentation
o Atmospheric depositions (wind etc)
o Anthropogenic influences
o Litterfall
- Losses (outputs)
o Erosion
o Leaching
Leaching: continuously washing the soil with rain water.
Well leached soils have a lower pH.
In solution (nitrate)
In suspension (clay)
Decalcification: removal of free calcium carbonate by
leaching. Leads to lower pH.
Calcifiation: In arid regions, bases will be washed
downwards during rainfall but moved up by capillary
movement in dry periods. Causes the accumulation of
calcium and other bases.
Podzolisation: pale (bleached) horizon between eluviated
(washed out) and illuviated (washed in) soil. Due to extreme
leaching of fulvic acids (litter). Temperate climates.
- Transformations (internal change)
o Chemical weathering
Acid dissolution, chalk dissolution, etc.
o Organic material (decomposition, mineralisation)
o Redox processes (high ground water levels)
Redox is the exchange of electrons.;
+ is oxidation
- is reduction
Aerobic, is O2 the e- acceptor
Anaerobic is e.g. NO3- e- acceptor
Gleying: when a soil is filled with water. Driven by seasonal
soil water differences. Colour changes: reddish/iron,
grey/manganese etc.
o Soil maturation (change of fresh soil to older soils)
Physical (soil dries out, etc)
Chemical (oxidation>reduction, dehydration, etc)
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 floor-vc. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $4.89. You're not tied to anything after your purchase.
