SOILS Flashcards
a hexagonal column of soil measuring from 1 to 10
m2 in top surface area
Pedon
an essential soil individual, comprising an
identifiable series of soils in an area
an essential soil individual, comprising an
identifiable series of soils in an area
the study of soils
with principal interest on characterization and
differentiation of their properties and with only
minor emphasis on their practical use
Pedological approach
the study of soils
with emphasis on their practical use, particularly
the relationship of soil properties to plant growth
Edaphological approach
characteristics, processes, or reactions of
a soil caused by physical forces
Soil Physics.
interactions of solid, liquid, and gaseous…,·
phases or components of soil
Soil Chemistry
protection of
soil against physical loss by erosion or cher:n1ca
deterioration
Soil Conservation and Management.
deals witfi tche
structural characteristics, mode of origin, and systematic
arrangement of soils
Soil Survey and Classification
structural chemistry of the solid
components of soil
Soil mineralogy
deals with the allocation of lands for general
or broad purposes such as agriculture, forestry,
settlement and military reservations
Land use:
Mineral matter, 45%
Organic matter, 5%
most soils contain less than 20%
organic matter, thus classified as mineral soils
Soil pores N O2 and C02
78, 20 , 0.5
a solvent that can release
nutrients from minerals.
carbonic acid
aggregates of minerals
Rocks
study of rocks
Petrology
The most common soil-forming igneous rocks are
granite, diorite, gabbro, ryolite, andesite, basalt,
and obsidian
Granite and diorite are lighter in color due to the
high proportion of light-colored minerals such as
feldspar and muscovite.
Gabbro is dark in color due to the predominance of
dark-colored minerals such as
biotite, hornblende,
and augite.
Granite is acidic while basalt is basic.
are among the dominant soilforming
rocks in the Philippines
Basalt and andesite
The most important soil-forming sedimentary
rocks are
limestone, dolomite, sandstone, and
shale.
process of sedimentation
fragmentation, transport, and recementation
Limestone is made up chiefly of the
mineral, calcite or CaC03.
also a carbonated material composed
of calcium magnesium carbonate CaMg(C03h.
Dolomite
is made up of fine particles of clay which
become consolidated after deposi’t’on · bedie of
water.
Shale
Soils derived from limestone are soil series-.,, of
Faraon, Bolinao, Binangonan, and Alimodian which
are the soils in Cebu and Bohol
Soils derived from shale/ sandston are soil series
of
Alaminos, Bantay, Bauang, Lugo and Ubay.
The most typical soil-forming metamorphic rocks
are
gneiss, schist, quartzite, slate, and marble
metamorphic form of limestone.
marble
happens when the magma is ejected out of the
earth’s crust through volcanic eruption and
solidifies on the surface
There is abrupt cooling
Extrosive {volcanic} formation
happens when magma solidifies within the earth’s
crust
Introsive {plutonic} formation
Oxygen
46.6
Silicon
27.7
Aluminum
8.13
Iron
5
magnesium
2.09
calcium
3.63
sodium
2.83
potassium
8.13
a naturally occurring inorganic substance with
more or less definite chemical composition and
specific physical properties
Mineral
study of minerals and their properties
Mineraloqv
persist in the soil in their original state due to high
resistance to decomposition
Primary minerals
contributes K
upon weathering
Orthoclase, (anorthite)
contributes Na upon weathering
Sodium-plagioclase, (albite)
cotributes calcium upon weathering
calcium palgioclase
white mica
muscovite
black mica
biotite
quartz
microline
most important primary minerals
Quartz
Orthoclase
Sodium-plagioclase
Calcium-plagioclase
Muscovite
Biotite
Hornblende
Augite
Apatite
arise from the chemical breakdown of the least
resistant primary minerals
Secondary minerals
The more commonly occurring secondary minerals
are:
Calcite
dolomite
gypsum
limonite
hematite
gibbsite
kaolinite
montmorillonite
illite
refers to the
imperceptible movement of rock formation
towards the earth’s surface resulting in cracking or
rocks.
unloading
the reaction of water with the
mineral resulting in the destruction of the
original chemical structure and the formation
of an acid and base
hydrolysis
nvolves the reaction of water
with the mineral but not leading to the
destruction of the chemical structure; The
result is a rigid attachment or association with
a water molecule.
hydration
reaction of carbonic acid with a mineral to produce a
soluble product
carbonation
the dissolution of minals thrgh
the solvent action of H2C03 o H ions which
results into the separation or dissociation of
component cations
solution
affects the amount of leaching that takes
place in the soil and the speed with which soil horizons
develop
Climate
factors of soil fomation
climate
living organism
relief or topography
parent material
time
For every 10 °C rise in temperature, the rate of
biochemical reactions doubles.
the mixing of the soil by o ganisms
bioturbation
Soils of forested areas
dipterocarps
the partly weathered mineral or organic debris
from which true soil (solum) is formed
Parent material
those that develop in
place and formed from the rock below where it
is found
sedentary or residual.
those which are transported by
various agents and deposited in other sites
where they form the soil. The different types
based on the agent and manner of transport
are the following:
transported.
accumulated from running
water
Alluvium
materials that are
accumulated in former lakewaters
Lacustrine
materials that are
accumulated in former oceans
Marine
those that are
carried and deposited by moving
glaciers
galcial till or moraine
those that are carried and
deposited by the wind
aeolian
a stratified rock
hardened (lithified) from deposited
fine dust or ash emitted on a volcanic
eruption
volcanic tuff
transported and deposited by gravity
collovium
is generally a young soil because ot
the constant deposition which re\ev s the parent
material.
Alluvial soil
Old soils have thick solum but are generally acidic
and low in fertility
a vertical cross section of the soil exposing
all of its horizons
Soil profile
a layer of soil or soil material
approximately parallel to the land surface and differing
from adjacent horizons in physical, chemical and biological
properties
Soil horizon
process wherein each horizon
acquires distinctly different properties from the others due
to various mechanisms of addition, losses, translocation
and transformation
Horizon differentiation
mechanism of addition and transformation
enrichment
melanization
comulization
mechanism of translocation
illuviation
calcification
decalcification
salinization
akalinization
podzolization
laterization
leucinization
lessivage
general term for the addition of any
material to the soil body
Enrichment
admixing of organic matter to the
mineral matter which darkens the soil
Melanization
addition of mineral matter trough wind
and water to the soil body
€umulization:
general term for the movement of soil
material from one part of the soil to another resulting in
the formation of argillic (clayey) layers
illuviation
the transfer and accumulation of calcium
carbonate in particular soil horizon
Calcification
removal of calcium carbonate from the
soil horizon
decalcification
accumulation of soluble salts of sulfates
and chlorides of calcium, magnesium, sodium and
potassium in certain horizons
salinization
accumulation of sodium
ions
Alkalinization (solonization)
the translocation of
aluminium and iron and/or organic matter thus,
concentrating the silica in the leached layer
Podzolization (Silication)
the transfer of silica from
the solum, thus concentrating the aluminium and iron
oxides and sesquioxides in the leached layer
Laterization (Desilication
paling or loss of dark colorof the soil
due to the removal of organic matter from the solum
Leucinization
movement fo the fine mineral particles from the top soil resulting in the enrichment of clay of lower horizons
lessivage
A and B, zone of pedogenic activity; considered
as the true soil because these are the layers reacheqand
used by the roots as source of water and nutrient
Solum
all loose materials above the bedrock (A,B,
and C horizons)
Regolith
Horizon dominated by organic matter
o
Organic-rich, mineral horizon at or adjacent to the
surface
A
Mineral horizon of maximum eluviation
E
Mineral horizon of maximum illuviation and formed
beneath an O,A, or E
B
Weathered parent material
C
underlying consolidated bedrock
R
Mainly influenced by the addition of
organic matter
Surface Horizons:
developed due to the translocation,
transformation and losses
Subsurface horizons
the relative proportion of the various size
fractions: sand, silt and clay in the soil
Soil Texture
No amount of organic matter added can alter soil
texture
provide for the
framework for the soil
sand and silt fractions
usda
United States Department of Agriculture
issa
International Soil Science Society
Sand
2 - .05 (USDA)
2 -.02
silt
.05 - .002
.02 - .002
clay
<.002
shows the percentage of sand, silt
and clay at various textural classes.
Textural Triangle:
The moist sample is kneaded into a od an
texture is approximated by the abilit to form
or of the rods to remain intact bent i
loop
Roll method
states that the settling
velocity of soil particles in an aqueous medium is
directly proportional to the square of their
diameter multiplied by a constant
Stoke’s Law of
sedimentation
-Destroying the organic matter to remove the
cementing material of the soil separates
-Dispersing the soil vigorously with sodium
hexametaphosphate
Hydrometer method
refers to the clustering of the soil particles into
characteristic aggregates of various sizes, shapes
and stability
Soil structure
The major cementing agents in soil structure
formation are
colloidal clay, oxides of iron and
aluminium (sesquioxides) and organic matt r
Calcium-rich ( calcareous) soils are generally
well granulated while sodium -rich (sodic) soils
are highly dispersed
The best soil structure for good plant growth is the
granular specifically, crumb structure because it
has good distribution of large and small pores.
The best soil structure for good plant growth is the
Granular / crumb structure
pillar-like with level tops
Prismatic structure
pillar-like with rounded tops; like
prismatic structure, commonly occur in subsoils and in
soils of arid and semi-arid regions
Columnar structure
cube-like and has more or less sharp
edges and the rectangular faces are distinct
Blocky structure
has edges which are
more or less rounded; like the blocky structure, typical in
clayey subsoils particularly in humid regions
Sub-angular blocky structure
has disc-like aggregates; commonly
found in virgin soils and subsoils
Platy structure
rounded aggregates which are
more porous; characteristic of surface soils especially
those high in organic matter content
Spheroidal structure
fraction of the soil volume occupied by air and
water
Soil pore spaces
are formed in
between aggregates; they drain excess water
macropores
are formed
within the aggregate; they store water.
micropores
-the mass (dry weight) per unit volume of soil
-a measure of degree of compaction of the soil
and an indicator of porosity
Bulk density
The range of bulk density values for sand and
sandy loam soils is
1.2 - 1.8
The range of bulk density values for clay, clay
loam and silt loam is
1 - 1.6
normal bulk density
1 - 1.3
- mass (dry weight) per unit volume of soil
excluding the pore spaces within that soil volume - may indicate the mineral ancestry of the soil
Particle density
may indicate soils have
high organic matter
PD of < 2.5
P. D. of organic matter is
1.2 - 1.5
As the bulk density approaches the value of the
particle density, the percentage porosity
approaches zero.
the volume of soil pore spaces left occupied by air after the other pore spaces are filled with moisture
aeration porosity
the force by which water is held in the soil
Soil moisture tension {SMT)
1 atm
1.01325 bar
1 bar
0.9869 atm
A graph showing the relationship between
moisture content and moisture tension of the soil,
and the characteristic of the soil itself
Soil moisture -release curve
MC by weight (MCw)
- the weight ( or mass) of water per unit weight of
soil in which it is contained
Gravimetric.
MC by volume (MCv)
- the volume of water per unit of bulk volume
including soil solids plus pore spaces of the soil
Volumetric.
All pore spaces are completely filled with water
(maximum water holding capacity)
Water at saturation; SMT = 0
An estimate of the upper limit of the available
moisture range
Field Capacity {FC}; SMT = 1/3 bar;
an estimate of the lower limit of the available
moisture range
Permanent Wilting Point {PWP}; SMT = 15
the water film at the immediate surface of the soil
particle
Hygroscopic {water} coefficient; SMT 31
Computed by getting the difference between FC
and PWP
Available Water{AW}
- also called drainage water; the water which soon
drains out of the macropores - the difference between the water at saturation and
the water at field capacity
Gravitational water
small cubes of gypsum connected to wires and
buried at specified depths of the soil where water
status is to be monitored
Gypsum blocks
consists of a long tube filled with water and with a
porous cup buried in the soil and a mercury gauge
above the ground
Tensiometer
Upward movement of water
capillary movement
Downward movement of water
Infiltration and percolation
the downward entry of water via the
soil surface
Infiltration
the downward movement of water
through the soil; the water moves at a greater
depth in the soil profile
Percolation
the physical condition of the soil manifesting
cohesion and adhesion forces acting within the soil
at various moisture contents
Soil Consistency
soil is easily puddled
which is attained at paddy rice culture.
Liquid consistency
the soil is plastic and
sticky
Plastic consistency
Soil best for cultivation
since it is soft, friable, mellow and soil
structure is rejuvenated.
Friable consistency.
the soil is hard and
requires high energy to pull the plow, resulting
to cloddy seed bed.
Harsh/ hard consistency
are very old soils which
are acidic and low in basic cations.
reddish soils
in subsoils indicates good
drainage.
Red yellowish color
indicates poor drainage.
Dark bluish or grayish color
are generally more fertile
dark colored soils
the standard color comparison chart
munsell color chart
the dominant spectral color
hue
darkness or lightness of color
value
gradation of purity of color
intensity or brightness of a color
chroma
very small particles of matter (0.2 micron to 1
micron)
Soil colloids
-constituted by organic complexes occurring in
colloidal form
- represented by humus
constituted by organic complexes occurring in
colloidal form
The main source of negative charges in humus
dissociation of H+ from carboxylic and phenolic
functional groups at high pH.
types of inorganic colloids
Crystalline Silicate clays
Amorphous {non-crystalline} silicate clays
Amorphous Non-silicate clays
composed of sheet-structured alluminosilicates of
various types
Crystalline Silicate clays
types of crystallines sylicate clays
1: 1 non expanding type
2: 1 expanding type
2: 1 limited expansion type
2:1 non expanding type
2:2 type
1: 1 non expanding type
kaolinite and
halloysite
2: 1 expanding type
smectites
(montmorillonite)
2: 1 limited expansion type
(vermiculite)
2:1 non expanding type
(Illite)
2:2 type
( chlorite)
most chemically reactive type of crystalline sylicate clays
montmorillonite
represented by allophone and imogolite
Amorphous {non-crystalline} silicate clays
occur as amorphous hydrous oxides of Iron and
Aluminum
Amorphous Non-silicate clays
examples of amorphous non silicate clays
hematite
geothite
limonite
boehmite
gibbsite
arise mainly from exposed hydroxyl groups at the broke nedges of crystals
negative charges
Agriculture important soils are net-negatively
charged.
arise from the protonation or addition of H+ to OHgroups
on the edge of minerals such as
sesquioxides, allophone and kaolinite
positive charges
does not lsoe its color when it reacts to positve ly charged soil
eosin red
loses its color when it reacts to negatively charged soil
gentian violet
a reversible process by which ions are exchanged
between solid and liquid phases and between solid
phases if in close contact with each other
ion exchange
list of important cations
(NH4+, Ca2+,Mg2+, Na+, H+, K+)
list of important anions
(NO3-, PO4-, SO4- )
the ability of the soil to adsorb and exchange
cations with those in the surrounding
soil solution
as well as with the plant roots
Cation Exchange Capacity (CEC}
adsorption stregth order of cations
(Al3+ , H+)> Ca2+ > Mg2+ > K+ > Na+
the degree by which the exchange sites in the
colloids are occupied by basic cations
Percent Base Saturation (0/o BS}
list of basic cations
Ca2+, Mg2+, K+, Na+, NH4+,
the degree by which the exchange sites of colloids
are occupied by sodium ions
Exchangeable Sodium Percentage (ESP}
also referred to as soil reaction
soil pH
The lower the pH value, the higher is the W
concentration and the lower is the OHconcentration.
The most favourable pH for growing most
agricultural plants is between
6-7
The range of pH in the Philippines is
5.5 -6.5
