120
4.2
Changes in the Pedosphere
Soil is the uppermost, typically 1–2 m thick fertile layer of the Earth’s crust formed by life via
altering natural rocks. It is different from rocks in
several characteristics, one of the most important
of which is the fact that it contains specific
organic matter, humus compounds (together:
humus) that are the most important factors of fertility: they are capable of adsorbing nutrients in
large quantity and supplying them for plants. The
solid material of soils is composed of minerals
from the crust and humus in a loose structure
enabling water and air to fill the space in the
pores providing in this way ideal conditions for
plant roots to take nutrients. Soils are generally
very rich in microorganisms and higher order living beings also live in them (e.g. worms and other
soil dwelling animals). Life in soils has special
roles in certain processes and thus in maintaining
fertility. As a result of the above soils are regarded
to form a separate sphere on Earth called pedosphere even though it cannot be separated completely from biosphere: it feeds life while it is
produced by life, humus is formed repeatedly
from the remnants of the bodies of dead living
beings and the fallen leaves of trees.
Natural fertility of soils is variable depending
on geographical conditions but natural vegetation
settling at a given locality accommodates well to
this variable fertility. Humanity interfered with
natural processes in soils first by growing plants
in cultivation and this changed many properties
of soils.
4.2.1 Major Processes Contributing
to Soil Degradation
Crop cultivation and related stock breeding are
the most important sources of food for humanity.
Agriculture also supplies food for fresh water fish
breeding as well either directly or indirectly. As a
result, soils have a decisive role in feeding
humans by supplying nutrients for plants.
Good conditions, appropriate nutrient and
water budget of the soils are fundamental conditions to the healthy growth of plants at both natural and agricultural areas. In natural conditions a
self-sustaining relationship develops between
soil and plant as they form a joint system. Soil
provides nutrients and water while the plant protects the soil with its foliage, leaf-litter and roots
against the deterioration effects of water and
wind while contributing to humus formation and
thus to the continuous renewal of the soil with its
dead remnants (leaves, stem and root).
Humanity disturbs this fine system when original vegetation is cleared and soil is frequently
destroyed physically. The aim of such activity
can be variable, the most important ones include:
1. providing areas for the extension of
settlements,
2. using soil for agricultural purposes,
3. mining at a given site,
4. using the area for infrastructure (road, railway, etc.).
Extending settlements result in the complete
destruction of soils in the given areas, as it has
been mentioned in Sect. 4.1.2.3. This also applies
for roads, railway lines and other linear constructions. Soil properties also change in areas not
covered by building material since soils are frequently placed to their final position following
several reworking. Their composition may
become increasingly disturbed as they are frequently referred to as urban soil. Urban soils are
generally not counted when food production is
analysed. Only orchards in suburbs may contribute to supplying the inhabitants. Soil contamination is significant in major cities and in their
immediate surroundings; therefore, their
application is limited. Gardeners responsible for
town green areas are often concerned about the
plants to survive at all on the contaminated soils.
Some of the plants with high tolerance could be
used for detoxicating soils in a way that they take
toxic material via their roots and then the plant
full of toxic material is removed from the area.
This process is called phytoremediation. Mostly
cruciferae, euphorbia and robinia species could
be applied for removing heavy metals. Trees tolerating contaminated urban environment include
celtis, fraxinus and ailanthus.
4 Changes on Earth as a Result of Interaction Between the Society and Nature
4.2
Changes in the Pedosphere
Soil is the uppermost, typically 1–2 m thick fertile layer of the Earth’s crust formed by life via
altering natural rocks. It is different from rocks in
several characteristics, one of the most important
of which is the fact that it contains specific
organic matter, humus compounds (together:
humus) that are the most important factors of fertility: they are capable of adsorbing nutrients in
large quantity and supplying them for plants. The
solid material of soils is composed of minerals
from the crust and humus in a loose structure
enabling water and air to fill the space in the
pores providing in this way ideal conditions for
plant roots to take nutrients. Soils are generally
very rich in microorganisms and higher order living beings also live in them (e.g. worms and other
soil dwelling animals). Life in soils has special
roles in certain processes and thus in maintaining
fertility. As a result of the above soils are regarded
to form a separate sphere on Earth called pedosphere even though it cannot be separated completely from biosphere: it feeds life while it is
produced by life, humus is formed repeatedly
from the remnants of the bodies of dead living
beings and the fallen leaves of trees.
Natural fertility of soils is variable depending
on geographical conditions but natural vegetation
settling at a given locality accommodates well to
this variable fertility. Humanity interfered with
natural processes in soils first by growing plants
in cultivation and this changed many properties
of soils.
4.2.1 Major Processes Contributing
to Soil Degradation
Crop cultivation and related stock breeding are
the most important sources of food for humanity.
Agriculture also supplies food for fresh water fish
breeding as well either directly or indirectly. As a
result, soils have a decisive role in feeding
humans by supplying nutrients for plants.
Good conditions, appropriate nutrient and
water budget of the soils are fundamental conditions to the healthy growth of plants at both natural and agricultural areas. In natural conditions a
self-sustaining relationship develops between
soil and plant as they form a joint system. Soil
provides nutrients and water while the plant protects the soil with its foliage, leaf-litter and roots
against the deterioration effects of water and
wind while contributing to humus formation and
thus to the continuous renewal of the soil with its
dead remnants (leaves, stem and root).
Humanity disturbs this fine system when original vegetation is cleared and soil is frequently
destroyed physically. The aim of such activity
can be variable, the most important ones include:
1. providing areas for the extension of
settlements,
2. using soil for agricultural purposes,
3. mining at a given site,
4. using the area for infrastructure (road, railway, etc.).
Extending settlements result in the complete
destruction of soils in the given areas, as it has
been mentioned in Sect. 4.1.2.3. This also applies
for roads, railway lines and other linear constructions. Soil properties also change in areas not
covered by building material since soils are frequently placed to their final position following
several reworking. Their composition may
become increasingly disturbed as they are frequently referred to as urban soil. Urban soils are
generally not counted when food production is
analysed. Only orchards in suburbs may contribute to supplying the inhabitants. Soil contamination is significant in major cities and in their
immediate surroundings; therefore, their
application is limited. Gardeners responsible for
town green areas are often concerned about the
plants to survive at all on the contaminated soils.
Some of the plants with high tolerance could be
used for detoxicating soils in a way that they take
toxic material via their roots and then the plant
full of toxic material is removed from the area.
This process is called phytoremediation. Mostly
cruciferae, euphorbia and robinia species could
be applied for removing heavy metals. Trees tolerating contaminated urban environment include
celtis, fraxinus and ailanthus.
4 Changes on Earth as a Result of Interaction Between the Society and Nature