This chapter lists the most important processes responsible for soil formation in an alphabetical order.
Adsorption: It occurs when the attractive forces
between the solid soil surface (adsorbent) and the solution component
(adsorbate) overcomes both the attractive forces between the solution
component and the soil solution (solvent), as well as any repulsive
forces between the soil surface and the adsorbing species.
Aggregation: Particles held
together in units of varying size and shape by physical, chemical,
and biological sub-processes. Aggregates are separated from adjoining
aggregates by surfaces of weakness.
Alkalization: Accumulation
of Na ions
Formation of a natric horizon
Audification: Accumulation
of H+ ions
Carbonation (calcification):
Accumulation of calcium carbonate
Chelation: Forming complexes
with metals by organic agents. The metals are trapped in a ring
structure, which is very stable.
Compaction: The physical
reduction of the air content resulting in an increased bulk density
Dealkalization
(solodization): Movement of Na ions out of a section of the
profile
Decarbonation
(decalcification): Movement of calcium carbonate out of a section
of the profile
Decomposition: The
biochemical breakdown of mineral and organic material
Dehydration: Loss of water
reverting the compound to the original state
Deposition is the
sedimentation of transported material.
Accumulation of soil particles /
colluvium
Accumulation of nutrients /
increase of CEC
Relative enrichment of medium-sized
particles
Impeaded ???????? drainage
Desalinization: Movement of
soluble salts out of a section of the profile
Desilication: Movement of
silica out of a section of the profile
Diffusion (into and out of
the soil): Air exchanges between the atmosphere and the soil under
the effects of partial pressures of mass movement.
Disaggregation: Breaking
down of aggregates
Dispersion: The process
where soil structural elements break down in water and sparate into
their constituents
Eluviation: Movement of
material out of a section of the soil profile (literally washing away
of material)
Depletion of the material washed
away (e.g. sequioxides, clay minerals, organic material)
Energy influx / outflux:
Radiation absorption / reflection
Soil temperature
Microbiological activity ->
humification ,decomposition, mineralization
Evaporation
Soil moisture
Erosion is the transport of
soil particles (and organic matter) by water or wind.
Raindrop impact causes breakdown of
soil aggregates
Soil movement / removal of the A
horizon
Smoothing or levelling of the soil
surface
Loss of nutrients / decrease of CEC
Selective particle transport
results in the relative enrichment of coarse and fine particles and
depletion of medium-sized particles
Reduced infiltration / increase in
surface runoff / reduced soil moisture
Sealing of the soil surface
Flocculation: It is a
process where the individual particles of clay are coagulated to form
floccular aggregates
Humification: Formation of
humus from raw organic materials
Hydration: Absorption of
water to form a new compound which differs only slightly from the
original state
Hydrolysis: The replacement
of cations in a mineral structure by hydrogen ions from the soil
solution
Illuviation: Movement of material into a section
of the soil profile (literally washing into or towards)
Accumulation of material washed
into (e.g. sequioxides, clay minerals, organic material)
Induration: Hardening of a
section of the profile produced in association with iron pans and
plinthite, and with other cementing agents (Si or Ca)
Infiltration: The entry of
water into the soil surface
Rainwater infiltrates in the soil
with soluble and suspended matter.
Soil moisture
Interflow (Subsurface flow,
through flow, seepage): Lateral subsurface flow
Lessivage: Physical downward
movement of clay minerals
Leucinization
(decoloration): Lightening the color in a section of the profile
Formation of an albic horizon
Melanization: Darkening the
color of a section of the soil profile
Formation of a mollic horizon due
to incorporation of organic matter
Mineralization: Release of
minerals in various forms during the decomposition of organic matter
Neutralization:
Counteraction of the H+ ions
Outflow: Loss of water from
the pedosphere to the groundwater
Loss of water and soluble and
suspended matter from the system, i.e. loss from the soil zone
(unsaturated and saturated zone) into the groundwater.
Oxidation: Formation of an
oxide or the release of electrons
Pedoturbation: The churning
and disruption of horizon formation by biological, physical and to
some extent chemical activity, such as wetting and drying, swelling
and contraction, freezing and thawing, root pressures, animal
burrowing, acitivty of man
Podzolization:
Precipitation: Separation
and deposition of a substance in a solid form from a solution
Reduction: Loss of oxygen
ions or acceptance of electrons
Salinization: Accumulation
of soluble salts such as chlorides and sulphates of Ca, Mg, Na, or K
Silication: Accumulation of
silica
Solution: Dissolving of
minerals into solution (e.g. calcium carbonate into bicarbonate)
Surface crusting (soil
sealing): A process which results in the formation of soil crusts
on the soil surface, ranging in thickness from a few mm to perhaps as
much as 3 cm, that is much mor compact, hard and brittle, when dry,
than the material immediately beneath.
Surface runoff (overland
flow): Discharge of rainwater over the surface of the land.
Surface runoff is composed of unconcentrated and concentrated flow
Suspension: The floating of
dispersed particles in a medium like water
It is one of the states of particle
transport of eroded sediments, especially for the smaller and lighter
particles such as clay
Synthesis: The biochemical
formation of a new compound by combination of elements or
constituents
Upward
movement: Movement of dissolved or suspended matter by
capillarity
Weathering:
Soil is a three-dimensional body that is variable in time and space. The change of soil morphological features or soil attributes is due to processes acting continuously on soils. This complex network of processes
They do interact with each other, resulting in feedback reactions. For example, process x results in a soil environment that influences process y which results in a soil environment that influences process x. Soils are considered as a system or network in which interconnected processes form soil features. Because of the complexity of the soil system it is not possible to examine and descibe each process and their cause effect relationships. But it is possible to filter dominant processes in a landscape and observe their soil morphological outcome. In this chapter the processes resulting in the addition or loss of some material are described and the impact to other processes and / or soil morphological features.