Geoscience Reference
In-Depth Information
phosphates is a late 19th
early 20th century invention, only possible by means of
-
fossil energy.
Anthrosols, termed so for the reason that they bear more than just the mark of
human intervention, because they are essentially man-made, can be found in gar-
dens (hortisols) and
elds (e.g. plaggen soils). The most astounding example of an
anthrosol is that of the terra preta and terra mulata patches in the Amazon basin.
Aside from fertilizer, available through mining and the Haber-Bosch synthesis,
the invention of potent pesticides marks a decisive event in the environmental
history of soils. Their massive impact on soil biota long went largely unnoticed
because many soil organisms have never been identi
ed, let alone their changes due
to chemical interventions monitored.
The widespread changes of agricultural practice according to the theory of
mineral plant nutrition as elaborated by Liebig in the 19th century are probably the
most important contribution of chemistry to the use of soils. Plants which do not
respond well to the availability of mineral nutrients in large quantities are no longer
used as cultivars and breeding was and is done to enhance nutrient uptake. One can
argue that agricultural practice was changed in order to match the simpli
ed theory
that inorganic nutrients are the single most important factor in soil fertility.
All the described changes correspond with an increase in the intensity of human
impact on soils, fueled by the abundance of fossil energy. Due to the abundance of
energy, humanity can currently afford not to adapt their cultivation to the soil, but
rather adapt soils to their necessities, with consequences such as farm-machinery
induced compaction, pollution and erosion. Hydroponics, the cultivation of plants
in greenhouses with nutrient solutions rather than on soils,
nally detaches plants
from the soil, but at high energy cost. Massive colonizing interventions into plant
life are counterbalanced by a decrease in impact on soils. As so often in environ-
mental history, this is a mixed blessing at best.
3.4 Concluding Remarks
In environmental history and beyond, monocausal explanations are more often
wrong than right. By identifying soil degradation as the culprit for the collapse of
agricultural empires, one tends to oversimplify stories in which sustainable use of
soils plays a very important part. But not all agriculture was sustainable. In par-
ticular colonization of new territories, which brought with it the loss of acquired
knowledge about soils, could bring dramatic consequences. Pioneers were often
harbingers of soil destruction.
The abrupt failure of the control system for the Yellow River in 1855 and
catastrophic displacement of its mouth by 400 km,
75
the Dust Bowl phenomenon of
the U.S. Great Plains during the 1930s, with dust storms blackening the skies and
75
Dodgen (
1991
).
