Geoscience Reference
In-Depth Information
Long-lasting interventions by humans change a soil profoundly, so that the
resulting fertility of the cultivated soil can be much greater than the natural one (e.g.
in the case of plaggen soils). While this cultivated fertility can be considered an
acquired long- or at least mid-term characteristic of soils, the yearly yield will
depend on short term in
uences of both natural and anthropogenic origin. If human
interventions lower fertility, one speaks of anthropogenic soil degradation.
Soil ecosystems are complex in many ways this primer cannot adequately
address. As but one example, Fig. 3.2 shows factors in
uencing the availability of
nutrients. Not all nutrient pools in the soil, are available to plants, and the soluble
fraction can be quite small, but on the other hand fully mobile ions run the highest
risk of being leached, nutrient management thus tries to create large amounts of
easily exchangeable nutrients which are bound to surfaces.
Minerals and
Morphology
Climate
Organisms
Natural Soil Fertility
Long-Term Cultivation
(fertilizing, tillage, crop rotation)
Fertility of Cultivated Soil
Natural Influences
(weather, pathogens, pests,
air quality)
Short-Term Cultivation
(tillage, plant protection,
fertilizer, crop)
YIELD (Production)
Fig. 3.1 Factors inuencing yield in an agrosystem (After Gisi et al. 1997 )
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