9 Flashcards
describe the soil composition
Minerals
OM
Micro orgs
Gas
Liquid
how mater phases are in soil
all 3 phases: solid, liquid and gas
recognize kaolinite
layering of clay
K= silica sheets and aliumia are together, but each sheet is held via string HB
what are the physical properties of soil
particle size
texture
permeability and permebility
general pathways by which rocks get transformed into the soil (3)
physical
chemical
biological
what are the components of soil organic matter
4 main components are
finely divided material
various lvl of OG matter
water
air
what are the chemical properties of soil
OM
pH
available elements
cation exchange capacity
what are 2 characteristics of colloids
large SA and high cation exchange capacity
what are colloids
molecule that are larger than atoms but small enough to be undetected by the unaided eye. (1 nano-1 micro)
they do not settle in solution
they still have a lrg SA and are neg charged (clays and humic mat)
base saturation
The # of occupied sites by Ca Na K or Mg/ total sites. Looks to show how saturated the surface of a soil particle is by cations
what is the land composed of
rock and soil
what is soil
the producut of the weathering of rocks which is able to support plant growth
what are the soil horizons
O- humus
A- top soil (minerals and OM)
B- sub soil (minerals but low OM)
C- parent mat
D- bed rock
which minerals are most abundant in the soil
oxygen and silicon
what are the subcategories of finely divided mineral matter
primary
- minerals from their source (quartz)
secondary
-post weathering processes (silicate clays)
what is the size of clay
anything less than 2 micro meters
montmorillonite
M= aluminum layers sandwiched between silica layers. each group is held together via a mix of Ca, Mg and K iconic bonds (via neg clay surface).
this loose bonding allows for the penetration of water easily. this clay will swell and shrink with ease.
illite (differences)
aluminum layers sandwhiched between silica. Each group is healed together bia ioninc bonds by K only (and the neg clay surface). this is tight, and not water is able to pass
what type of “hedron” do silicas form?
tetrahedron
what type of “hedron” do aluminum form
octahedrons
physical weathering
by temp
erosion via water or wind
plant or animals contribute too
chemical weathering
hydration
A and B rxn- via CO2 dissolving in H2o
hydrolysis
complexation rxn
redox
hydration
a chemical weathering porecess where water moles are incorporated into minerals. common is secondary min.
minerals will swell and become deforemd
hydrolysis
water reactswith a mineral in the presence of an acid, realising ions assaioated ith OG mineral identiy
complexation
removal of Fe3+ and Al3+ via the formation of soluble complexed while in soil. water will carry away.
complexation
removal of Fe3+ and Al3+ via the formation of soluble complexes while in soil. water will carry away.
biological weathering
the weakening od disintegration of rocks by plants, animals, and microbes
-burrowing animals
-root growth
-a symbiotic relationship that microbes have with rocks, promoting the breakdown
how can particle size impact soil
those that have alot of sand are well drained but have a poor source of nutrients
though those with lots of clay are very dense and don’t drain well. but they have goof nutrient retention
best soilds are a combo
soil texture
a physical property
the defintion of the type of soil by the proportion of different sized particles
permeability
a physical property that decrsibes the interconnectedness of the pore of a soil. how well water is male to drain through the soil
total elements
chemical property
just a list of all elements found in sample
OM
a chemical property
also described as humus and is composed of three layers
Humin(black)
Humic acids (grey/brown)
Fulvic acids (yellow)
available elements
those that can be absorbed to taken up by a plant.
determined by mixing soil with an aq solution containing chemicals to displace certain target elements that are supposed to be ready for plants
cation exchange capacity
most messured property
how well is soil able to hold positively charged nutrients
the absorption of cations to the surface of the soil via electrostatic interactions
soil pH
basic of they are rich in dolomite (8.7)
acidic if they are rich in humic materials (4.6)
problems with soil erosion
loss of nut and arable land.
diff to reverse
water imbalance problems
difficult to sustain productivity
-ehter too dry or water clogging
nutrient leaching problems
via fluxes of water, soil texture and overall plant cover
can be avoided by plant uptake, high CEC, and soils containing clay
acidification problems
source from excess Al3+ and Fe2+, microorgs (via resp CO2) and anthropogenic (acid rain)
can be avoided with carbonate buffering
salinity issues
salts can accumulate near the surface when in regions with low precip and high evap
metal contamination issues
not Ca, Mg, K or Na
sourced from ore or mining deposited
note that the retention of the pos metals will be determined by the CEC of the soil (common that pH7-8 will retain metals the most, but is the pH drops to 7-4 then the metals can be leached into water systems)
this can contribute to acid mine drainage as a positive feed back loop is often formed via the release of Fe (OH)3 and H2SO4
