Introduction to Ecological Risk Assessment - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 614

two there has been a growing awareness of the fact that short-term soil manage-
ment approaches, which focus on short-term profits at the site of application only,
are failing. The side effects of large scale artificial fertilizers, for example, although
effective in the short-term at the sites where these have been applied, have long been
underestimated. With regard to ecological effects in the long-term, accumulation
of contaminants in soils hampers effective ecological functioning and application
of pesticides has adverse effects on disease controlling organisms, for example.
Ecological effects also may reveal themselves at other locations than those where
the contaminants were applied, for example, in surface waters and groundwater due
to intensive manuring.
Although many soil factors can indeed be 'established' through human manipu-
lation, the general feeling is that the negative side effects are too much of a burden
since they have grown significantly. Moreover, it is more and more the belief that
sustainable agriculture, with the application of organic fertilizers, a minimum of
pesticide use and tillage, is a preferable procedure from an economic and social per-
spective as well. Similar examples could be given for contaminated sites in urban
areas where the ecosystems are often challenged beyond their capabilities to recover.
Except for creating good conditions for above-ground vegetation, the 'cleaning'
function of organisms is of major importance at these sites.
An extraordinary situation in which sustainable soil management proves its ben-
efits are land transitions, that is, situations in which the land use changes. Generally,
the frequency in change of land use has intensified over the last few decades in
most developed countries, and probably will continue to grow. Specifically, the
transition from agricultural land to nature reserves and to residential or industrial
areas has often taken place in many developed countries in Europe, for example.
A sound sustainable policy anticipates soil dynamics and increases change possi-
bilities for successful land-use transition in the future. In cases of transition from
agricultural land to a nature reserve, for example, agricultural soil management may
have resulted in nutrient-rich soil layers that block natural developments for periods
varying from decades up to a century.
13.8.3 Agriculture
Descriptions of good soil quality for agricultural purposes include many structural
aspects such as 'crumbles easily', 'drains well', 'warms up quickly', 'does not
crust', 'soaks up heavy rains', 'stores moisture', 'has few clods', 'has no hard-
pan', 'resists erosion', 'allows root penetration' (see Section 13.4.3.2 for more
details). Moreover, a decent humus formation, good nutrient supply and disease
control (see Section 13.4.3.3 , 13.4.3.4 , and 13.4.3.6 , respectively) are indispens-
able for an optimal agricultural production. And all these characteristics may be
seen as the overall result of a healthy soil ecosystem. Of course, humans can stimu-
late good soil structure by ploughing, either by hand or mechanically. And humans
also can improve the chemical quality of the soil, through nutrient supply and
the addition of lime and, indirectly, by stimulating nutrient buffering. But the soil