Basic Soil
1
Soil Profile
2
Soil Horizons
3
Soil Series
4
Texture
5
Soil Color
6
Soil morphology
7
Soil moisture
8 Soil PH
9
Soil pore Space
10
Soil drainage
11
Soil Consistence
12
Soil Structure
13
Bulk Density
14
Eluvium
15
Alluvium
1.Soil Profile
Soil
Profile refers to the layers of soil; horizon A, B, and C. If you're wondering
what horizon A is, here's your answer: horizon A refers to the upper layer of
soil, nearest the surface. It is commonly known as topsoil. In the woods or
other areas that have not been plowed or tilled, this layer would probably
include organic litter, such as fallen leaves and twigs . The litter helps
prevent erosion, holds moisture, and decays to form a very rich soil known as
humus. Horizon A provides plants with nutrients they need for a great life.The
layer below horizon A, of course, has to be horizon B. Litter is not present in
horizon B and therefore there is much less humus. Horizon B does contain some
elements from horizon A because of the process of leaching. Leaching resembles
what happens in a coffee pot as the water drips through the coffee grounds.
Leaching may also bring some minerals from horizon B down to horizon C.
2.Soil
Horizon
A
soil horizon is a layer parallel to the soil surface, whose physical characteristics
differ from the layers above and beneath. Each soil type has at least one,
usually three or four are horizons. Horizons defined in most cases by obvious
physical features, chiefly color and texture. These may be described both in
absolute terms (particle size distribution for texture, for instance) and in
terms relative to the surrounding material, i.e. ‘Coarser’ or ‘sandier’ than
the horizons above and below. Horizon formation (horizonation) is a function of
a range of geological, chemical, and biological processes and occurs over long
time periods. Soils vary in the degree to which horizons
are expressed.
Relatively new deposits of soil parent material, such as alluvium, sand dunes,
or volcanic ash, may have no horizon formation, or only the distinct layers of
deposition. The following horizons are listed with their position from top to
bottom within the soil profile. The horizon not listed is the O horizon which
is grass and animal/plant life. Soil has three main horizons (A, B, and C),
which will be explained below along with other layers.
A
horizon
The
A horizon is the top layer of the soil horizons or 'topsoil'. This layer has a
layer of dark decomposed organic materials, which is called "humus".
The technical definition of an A horizon may vary, but it is most commonly
described in terms relative to deeper layers. "A" Horizons may be
darker in color than deeper layers and contain more organic material, or they
may be lighter but contain less clay or obsequiousness. The A horizon is a
surface horizon, and as such is also known as the zone in which most biological
activity occurs. Soil organisms such as earthworms, pot worms (enchytraeids),
arthropods, nematodes, fungi, and many species of bacteria and Achaea are
concentrated here, often in close association with plant roots.
E
horizon
“E”,
being short for eluviated, is most commonly used to label a horizon that has
been significantly leached of its mineral and/or organic content, leaving a
pale layer largely composed of silicates. These are present only in older,
well-developed soils, and generally occur between the A and B horizons. In
regions where this designation is not employed, leached layers are classified
firstly as an A or B according to other characteristics, and then appended with
the designation “e” (see the section below on horizon suffixes). In soils that
contain gravels, due to animal bioturbation, a stonelayer commonly forms near
or at the base of the E horizon. The above layers may be referred to
collectively as the "solum". The layers below have no collective name
but are distinct in that they are noticeably less affected by surface
soil-forming processes.
B
horizon
The
B horizon is commonly referred to as "subsoil", and consists of
mineral layers which may contain concentrations of clay or minerals such as
iron or aluminum oxides or organic material moved there by leaching.
Accordingly, this layer is also known as the "illuviated" horizon or
the "zone of accumulation". In addition it is defined by having a distinctly
different structure or consistency to the A horizon above and the horizons
below. They may also have stronger colors (is higher Chroma) than the A
horizon.
C
horizon
The
C horizon is simply named so because it comes after A and B within the soil
profile. This layer is little affected by soil forming processes (weathering),
and the lack of pedological development is one of the defining attributes. The
C Horizon may contain lumps or more likely large shelves of unweathered rock,
rather than being made up solely of small fragments as in the solum.
"Ghost" rock structure may be present within these horizons. The C
horizon also contains parent material.
3 .Soil Series
Soil
series is a category in the system of soil taxonomy in the same way that order,
great group, subgroup, and family are categories. A soil series is a conceptual
class that has, or should have, defined limits in the same way as a great
group. The link between the conceptual entity, soil series, and real bodies of
soil is the pedon. Any pedon may be classified as a unique soil series, but
series have been named for only a very small proportion of the kinds of pedons
that occur.
4.
Soil Texture
Soil
texture is a qualitative classification tool used in both the field and
laboratory to determine the classes for agricultural soils based on their
physical texture. The classes are distinguished in the field by the 'textural
feel' which can be further clarified by separating the relative proportions of
sand, silt and clay using grading sieves.
5. Soil Color
Soil
color does not affect the behavior and
use of soil, however it can indicate the
composition of the soil and give clues to the conditions that the soil is subjected
to. Soil can exhibit a wide range of color; gray, black, white, reds, browns,
yellows and under the right conditions green. Varying horizontal bands of color
in the soil often identify a specific soil horizon. The development and
distribution of color in soil results from chemical and biological weathering,
especially redox reactions. Soil color is influenced by the content of organic
matter and water as well as the presence and oxidation state of iron and magnesium. Yellow or red soil indicates the presence of iron oxides). Dark
brown or black color in soil indicates that the soil has a high organic matter
content. Wet soil will appear darker than dry soil. However the presence of
water also affects soil color by affecting the oxidation rate. Soil that has a
high water content will have less air in the soil, specifically less oxygen. In
well drained (and therefore oxygen rich soils) red and brown colors caused by
oxidation are more common, as opposed to in wet (low oxygen) soils where the
soil usually appears gray.
6. Soil morphology
Soil
morphology deals with the form and arrangement of soil features.
Micromorphology is using micromorphological techniques (e.g. Thin sections) and
measurements in the laboratory. Field morphology is the study of soil
morphological features in the field by thorough observation, description and
interpretation. Observations may be refined with the aid of a hand lens. Simple
tests are also used in the field to record salient chemical properties (e.g.,
pH, presence of carbonates). In addition, field observations and measurements
may be refined through a range of laboratory analytical procedures that include
more sophisticated evaluation of chemical, biological and physical attributes.
7.Soil moisture
Soil
moisture deals with the percentage of water in soil. It is important for plant
and animal living. The soil moisture shows the condition of the place of the
soil. The water supply,climate, soil age or soil behavior on agriculture
Soil Consistency Detection
To
measure the consistency of the soil we had to measure the water content in the
soil. First, determine stickiness, that is, the ability of soil materials to
adhere to other objects. Then, determine plasticity, that is, the ability of
soil
materials to change shape, but not the volume,continuously under the
influence of a constant pressure and to retain the impressed shape when the
pressure is removed.
A ) Soil Stickiness
Soil
from Eluvial horizon was taken to measure soil consistency. Then we test the
Soil in free hand that it it had moisture or not. We found the soil had a low
percentage of water. This means our soil
had a great parentage of clay partials which is around 60%
B
) Soil moisture detection
TO
measure the moisture in the soil we took another sample of soil and tried to
crush it with a free hand. We found our soil is easily breakable which means
the soil is very friable.
8
Soil PH
The
soil pH is a measure of the acidity or basically in soils. PH is defined as the
negative logarithm (base 10) of the activity of hydrogen ions (H+) in solution.
It ranges from 0 to 14, with 7 being neutral. A pH below 7 is acidic and above
7 is basic. Soil pH is considered a master variable in soils as it controls
many chemical processes that take place. It specifically affects plant nutrient
availability by controlling the chemical forms of the nutrient. The optimum pH
range for most plants is between 6 and 7.5, however many plants have adapted to
thrive at pH values outside this range.
9.Soil
pore Space
A
pore is not simply a void in the solid structure of soil. There are three main
categories for pore sizes that all have different characteristics and
contribute different attributes to soils depending on the number and frequency
of each type.
Macropore:
The
pores that are too large to have any significant capillary force. These pores
are full of air at field capacity. Macropores can be caused by cracking,
division of peds and aggregates, as well as plant roots, and zoological
exploration. Size >75 μm.
Mesopore:
The
pores filled with water at field capacity. Also known as storage pores because
of the ability to store water useful to plants. They do not have capillary
forces too great so that the water does not become limiting to the plants.
These mesopores are ideally always full or contain liquid to have successful
plant growth. The properties of mesopores are highly studied by soil scientists
to help with agriculture and irrigation. Size 75 μm–30 μm.
Micropore:
The
pores that are filled with water at permanent wilting point. These pores are
too small for a plant to use without great difficulty. The water associated is
usually adsorbed onto the surfaces of clay molecules. The water held in
micropores is important to the activity of microbes creating moist anaerobic
conditions. The water can also cause either the oxidation or reduction of
molecules in the crystalline structure of the soil minerals. Size <30 μm.
10 . Soil drainage
Pore
space controls soil drainage characteristics.
In other words, drainage problems often arise from lack of large-sized
pores.In soils dominated by large pores (i.e., sandy soils), water moves
rapidly. Soils that allow rapid leaching
(water movement down through the soil profile) also pose environmental hazards
because rain or irrigation water moving through the soil profile takes
water-soluble pollutants with it. Ground
water pollution is a sensitive issue on coarse-textured sandy soils.In
comparison, in soils dominated by small-sized pores (i.e., compacted soils and
soils with greater than 20% clay content), water is slow to move or may not
move at all. Soils easily waterlog.
11.Soil
Consistence
Soil
consistency is the strength with which soil materials are held together or the
resistance of soils to deformation and rupture. Soil consistency is measured
for wet, moist and dry soil samples. For wet soils, it is expressed as both
stickiness and plasticity, as defined below. Soil consistency may be estimated
in the field using simple tests or may be measured more accurately in the
laboratory.
12 Soil Structure
Structure
refers to the arrangement of soil particles. Soil structure is the product of
processes that aggregate, cement, compact or unconsolidate soil material. In
essence, soil structure is a physical condition that is distinct from that of
the initial material from which it formed, and can be related to processes of
soil formation. The peds are separated from the adjoining peds by surfaces of
weakness. To describe structure in a soil profile it is best to examine the
profile standing some meters apart to recognize larger structural units (e.g.
Prisms). The next step is to study the structure by removing soil material for
more detailed inspection. It should be stressed that soil moisture affects the
expression of soil structure. The classification of soil structure considers
the grade, form, and size of particles.
13
Bulk density
The
bulk density of soil depends greatly on the mineral make up of soil and the
degree of compaction. The density of quartz is around 2.65 g/cm3 but the bulk
density of a soil may be less than half that density.Most soils have a bulk
density between 1.0 and 1.6 g/cm3 but organic soil and some friable clay may
have a bulk density well below 1 g/cm3Core samples are taken by driving a metal
core into the earth at the desired depth and soil horizon. The samples are then
oven dried and weighed.
Bulk
density = (mass of oven dry soil) /volume
The
bulk density of soil is inversely related to the porosity of the same soil. The
more pore space in a soil the lower the value for bulk density.
14
Eluvium
Eluvium
is material displaced across a soil profile, from one layer to another one, by
the action of rainwater. The removal of material from a soil layer is called
eluviation. The transport of the material may be either mechanical or chemical.
The process of deposition of eluvium is termed illuviation.
15 Alluvium
Alluvium
is loose, unconsolidated (not cemented together into a solid rock) soil or
sediments, which has been eroded, reshaped by water in some form, and red
posited in a non-marine setting. Alluvium is typically made up of a variety of
materials, including fine particles of silt and clay and larger particles of
sand and gravel. When this loose alluvial material is deposited or cemented
into a lithological unit, or lithified, it would be called an alluvial deposit.
