Soil, is a thin layer
of the earth with unconsolidated materials where Plants and Animals derive
their living. Or Soil, is a layer of organic and weathered in organic material
found in the earth surface which capable sustaining for growth of plants. Soil
is composed by Organic matter; these are formed due to the decomposition of
Plant and Animal remains (humus). Micro organism help in decomposition of dead
Animals and Plants to form Humus. Humus is important to improve soil structure,
supply nutrients, and regulating temperature in the soil and soil pH. And it
composed about 5%. In organic matter; is formed from parents rock through
weathering processes where rock disintegrate into small particles and it
composed about 45%. Soil air; within soil there are pores space, when these
pores space are not filled by water they occupied by air, Air accelerated
oxidation and biological activities, well aerated soil is productive while poor
aerated is unproductive, it composed about 25%. Soil water; water in the soil stored
in the pores space or soil porosity, the main source of water in the soil is
precipitation, irrigation and snow melting, water get into the soil through
various ways like infiltration, permeability and percolation. Soil water is
important in regulating temperature, dissolving and transfer nutrients also
control chemical reaction on the soil, Water composed about 25%.
Soil formation, Soil is formed through physical, chemical
and biological weathering. Also there are some processes involved in soil formation,
these processes are categorized into two processes which are simple processes
includes Weathering, Leaching, Elluviation, Illuviation, Humification, Organic
sorting. And Complex processes include Podzolization, Lateritisation,
Calcification, Salinisation, and Gleisation. The
development of a soil reflects the weathering process associated with the
dynamic environment in which it has formed.
Five soil-forming factors have been identified that influence the development
of a specific soil. Wherever these five factors have been the same on the
landscape, the soil will be the same. However, if one or more of the factors differ,
the soils will be different. The factors as follows:
Parent material, is made of rock and minerals. When the other
four soil-forming factors
act
on parent material, it is weathered into smaller particles forming soil.
There
are many types of parent material with different mineral contents. The Earth is
believed
to be about three billion years old. Mountains have been created and eroded
away
and then created again. Seas have covered the land and receded leaving layers
of
mud, sand and lime carbonate
thousands of feet thick when volcanoes have erupted. Glaciers
have
formed during long periods of cold weather and melted during long periods of
warm
weather.
Parent material can be rock formed in place or the remnants of rock that was
moved by
wind,
water, ice or even gravity. A variety of parent material can be found in
Nebraska
ranging
from sand in the Sand hill Region to clays in the Missouri and other river
bottoms.
In
the Great Plains, especially in the south, parent materials are primarily
associated with
Ancient
seas. These seas came into the region and receded several times, leaving
Sediment
behind, which, over time, became sandstone, limestone and shale bedrock
Formations.
Bedrock soil formations are classified as residuum parent materials and can
be
exposed and broken down to form soil.
Climate, this involves precipitation, temperature, and wind. The
amount of water entering in a soil influences the movement of calcium and other
chemical compounds in the soil. Ultimately, if more chemicals are removed, the
soils will be deeper and more developed. Precipitation influences vegetation
and therefore, greatly determines the organic matter content of soils. Because
of greater precipitation in Eastern Nebraska, native vegetation included
luxuriant growth of the tall grass prairie. In Western Nebraska where
precipitation is about half that in the east, plants of the short grass
prairies grow much less abundantly. Thus, soil organic matter content is greater
in the east than in the west. Higher temperatures can speed the rate of organic
matter decomposition. Temperatures are typically higher in the southern portion
of the state than in the northern portion. Because of this trend, organic
matter content decreases from north to south. However, the change in organic
matter content from north to south due to temperature is minuscule when
compared to the change from east to west due to precipitation.
Soils
in eastern Nebraska commonly contain 3 percent organic matter as compared to
about
1 to 2 percent in the west.
Living organism, it involves flora and fauna. In the soil there
is vegetation, vegetation influences the kind of soil developed because plants
differ in their root systems, size, above ground, vegetative volume, nutrient
content and life cycle. Soils formed under trees are greatly
different
from soils formed under grass even though other soil-forming factors are
similar.
Trees
and grass vary considerably in their search for food and water and in the
amount
of
various chemicals taken up by roots and deposited in or on top of the soil when
tree leaves and grass blades die. Soils formed under grass are much higher in
organic matter than soils formed under forests because of their massive fibrous
root structure and annual senescence of above ground vegetation. Grassland
soils tend to be darker, particularly to greater depths, and
have
a more stable structure than forest soils. Soils developed under grass are
generally
more
fertile and best suited for crop production. The kind of plant growing
influences residue composition. For example, the decay products from conifer
tree needles are different from those of hardwood tree leaves. These decay
products affect soil formation and development differently when water moves
them through the soil. The kind of vegetation and climate also affects the kind
and numbers of other organisms that lives in the soil, such as insects, small
animals, and micro organisms. Organisms chew, tear and digest plant and animal
material, causing it to undergo further biochemical action as it decays. The
activity of soil organisms is strongly influenced by soil temperature, acidity
and soil water. Times the mass of earthworms that can be present because of the
quantity of organisms present in the soil and their ability to accelerate the decay
of organic material, they play a major role in soil formation
Topography, this is the shape of land surface, its slope
and deposition on the land scape, greatly influence the kinds of soil formed.
Topography affects moisture and temperature relations. The slope, the more influence topography has
on soil development on hills and steep
land. Runoff is accelerated on sloping land, so less water
infiltrates the soil. Plants,
therefore, tend to have shallower root systems; and less organic
matter is produced, as
compared to nearly level land. Steep slopes are also subjected
to more erosion which
removes soil as fast, or faster, than it forms. On nearly level
land, water tends to pond on
the soil surface. Here, plant growth may be prolific, resulting
in the production of large
amounts of organic matter. Slopes with a southern exposure are
warmer and drier than slopes with a northern exposure. In fact, topography
affects the micro-environment for soil formation in a manner similar to climate’s affect on macro environment for soil formation.
Time,
soils have been referred to as young, mature, and old, depending on the degree
of
weathering. A mature soil is in equilibrium with its environment
and shows full. Development of layers or horizons in its profile. Soils probably never reach equilibrium, but they do get
older and are weathering all the time.
The rate of weathering however, slows considerably as the soil nears
equilibrium with its environment. The longer a parent material has been
exposed, the greater the degree of weathering and the more developed the soil.
Soils in southeast Kansas, for
example, are highly weathered. Parent materials in southeast
Kansas have been
exposed for about 200 million years. This compares to the loess
soils in Nebraska, which
are only 10 to 50 thousand years old.
In
fact that, soil physical, chemical and biological properties affect many
processes in the soil that make it suitable for agricultural practices and
other purposes. Texture, structure and porosity influence the movement and
retention of water, air and solutes in the soil, which subsequently affect
plant growth and organism activity. Most chemical properties are associated
with the colloid fraction and affect nutrient availability, biota growing
conditions, and in some cases, soil contribute to soil aggregation, structure
and porosity as well as decomposition and mineralization. Organism activity is
controlled by various soil conditions and may be altered by management
practices. Many soil properties are interrelated with one another
C
REFFERENCE
OF BOOKS.
1.
Brady, N. and R. Weil. 2002. The nature and properties of soils, 13th
edition. Prentice Hall. Upper saddle River, New Jersey. 960 p.
2.
Gardiner, D.T. and R.W. Miller.2004. Soil in our environment, 10th
edition. Pearson education, inc. upper saddle River, New Jersey.641 p
3.
Balba, A.M. 1995. Management of problem soil in Arid Ecosystems. CRC press. Boca
Raton, Florida. 250 p
4.
Spellerberg, I.F & Sawyer J.W.D
(1999). An introduction to applied
Biogeography. Cambridge university Press
Raven, P & Berg,
L (2004) Environment. 4
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