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Desertification as Physical and Biological degradation of the
soil
It has taken millions of years
to produce the agricultural land we have today. We see it and we
know it. Yet we are able to put this soil in crisis and to
degrade it, in only a few decades, through an improper use of
cultivation and farming techniques. All this has made us see how
necessary it has become to invest more in the research sector
aimed above all at conservational farming. Conservational
agriculture and the maximisation of business profits have
followed, up until today, conflicting and hardly compatible
paths. The desertification of vast areas in both developing
countries and industrialized nations, even if with different
problems,
is born, however, from a divergence between the short term
economic needs of businesses and the long term needs of the
ecosystem of the soil. These two needs must be made compatible
if we want to find a policy that satisfies the concept of
Sustainable Development in this sector. According to the OCSE
the principal processes of environmental degradation are
generally traceable to the erosion of the soil, to its
submersion, to the acidification, salinization, sodification,
compactation, formation of superficial crusts and compact layers
along the profile, loss of organic substance, deterioration of
the structure, desertification, accumulation of toxic
substances, loss of nourishing elements, etc. Also in Italy two
thirds of the soil show worrying problems of degradation in
virtue of a territorial management which has not always been
correct. Such phenomena of environmental degradation are more
pronounced where anthropic activity has been strongest. This has
not always occurred in a way which is compatible with the
fundamental criterions of the conservation of the soil. What is
evident is that the modernization of the agriculture over the
last 30 years, even if bringing an increase in production in the
short term, has produced in the long term
in some cases worrying phenomena of degradation of the soil
and therefore of the environment. On the other hand, urban
planning in the territory (industrial and urban areas with
relative infrastructures) has rarely, especially in the past,
taken into account the resulting environmental impact, in
particular with regards to soil, with the subsequent
consequences of phenomena of degradation, which in many cases
are quite severe. It is therefore necessary, first of all, to
quantify these aspects of degradation of the soil and, above
all, it is fundamental to define the threshold over which a
process of degradation becomes irreversible, accelerating in
this way the processes of upheaval and desertification. A
typical example of this is represented by the erosion of the
soil: it is not thinkable to practise an agriculture, even if
sustainable, which is able to ruin it completely; it is
important though to know the limit for every determined
pedologic environment within which the erosion has to be
contained. At the moment, the risk of erosion throughout Italy
can be demonstrated, even though not on an optimal scale. The
quantification of other phenomena of degradation proves to be
harder. Among these are the loss of structure, the formation of
compact layers along the profile, the splitting into crevices,
the formation of superficial crusts, the variations of porosity
and saturated hydraulic conductibility, the release of sediments
from agricultural areas. Data for these indicators are not at
the moment available for all the national territory, even if
various techniques of evaluation are being defined that use, for
instance, aerial photos or satellite reliefs that try to
estimate the phenomena indirectly. An example of an application
of indicator "proxy” is the estimation of the risk of soil
compactation in relationship to the number and the power of the
tractors. Another indicator which can be demonstrated nationwide
is represented by the surfaces occupied by urbanization and road
and railway infrastructures. The ability of a soil to maintain
its many functions is, however, not only connected to the
physical properties previously mentioned, but also to chemical
and biological ones. A lot of these properties are a function of
the content of organic substance, that in turn is the principal
terrestrial reserve of essential elements such as Carbon,
Nitrogen, Phosphorus and Sulphur. The importance of the
biological component of the soil is frequently underestimated,
even if the microbiological processes of mineralization and
conservation of the organic substance of the soil regulate the
cycles and the availability of the elements C, N, P and S and
those of water. The micro-organisms participate in a series of
processes that influence the physical structure of the soil and
its chemical properties, making it favourable to the growth of
vegetables. The consequence of the increase of fertility
mediated by the micro-organisms are the chemical-physical
changes in the soil, such as the stabilization of the organic
substance, the fixation of nitrogen, the movement of the
nutrients, all the biological balances of the soil among which
are the decomposition of numerous contaminating substances and
other alterations in the properties of the soil necessary for
the growth of the plants. Unfortunately there is a great lack of
data on biological indicators and, accordingly, a scarce use of
this type of indicators with regards to soil, as opposed to
other environmental matrixes such as those for water and air. At
present, none of the biological indicators individuated by the
CTN SSC can be represented nationwide, even if some studies are
available at a local level.
An Example of indicators
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Name of the indicator
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Aim
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DPSIR
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Normative
Ref.
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Desertification
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Estimate the risk of the desertification of Italian soil
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P
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Convenzione UN CCD 1994
L 170/97
D. lgs. 152/1999
CE-COM (2002)179
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Risk of the soil becoming compact in relationship to the
number and power of the tractors
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Estimate the risk of the soil becoming compact due to
the passage of heavy vehicles on agricultural soil
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P
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5EAP: cap. 5
(natural resources Agenda 21: chap. 7)
(demand for the use of the territory)
6EAP
CE-COM (2002)179
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Water erosion
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Estimate the risk of erosion of the soil due to the
action of water on the surface in complex agricultural
systems (basins)
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I
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5EAP: cap 5
(natural resources Agenda 21: chap. 7)
(demand for the use of the territory)
6EAP
CE-COM (2002)179
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Guido Bissanti
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Degradation of the Soil
LANGUAGE 
