Geoscience Reference
In-Depth Information
fi ght to eliminate weeds being one of the main problems of agriculture, various
types of tillage were gradually developed and recommended by Columella. In order
to slow down a decrease of fertility or even to stop it, the liming of soil with ground
marble was mentioned in Columella's
De Re Rustica
. Noticing its simplistic name
in English,
About Agriculture
, we learn that the antique Romans did not get a head-
ache inventing titles of their practically oriented topics. The content was much more
important. Accordingly, we should not be surprised that Columella devoted several
paragraphs to soil erosion and its consequences.
Lasting for centuries after the time of classical Romans, the quality of soils was
guessed just for estimating taxes. In Europe there were instructions for deciding to
which of three bounty classes a soil belonged. By the end of the seventeenth cen-
tury, we fi nd that the system already consisted of eight bounty classes determined
by the size of harvest. In spite of Renaissance love for Greek and Latin writing, it is
apparent that the fi rst observations of soil properties described by Varro and
Columella were forgotten.
Parallel to Europe, there were several other centers of development of agriculture
with their own approach to a simple classifi cation of soils. As for example are the
Aztecs who divided soils according to their utility and who recognized soils with
agricultural potential and those useful for other practical applications such as pot-
tery clay. The Indus Valley Civilization developed on the fertile plains of the river
Indus. Soils were probably classifi ed into three separate types according to their
productivity: those where the fertility was regularly kept at high levels by sequences
of river fl oods, where such renewal of fertility was absent, or where the threat of
salinity existed.
12.4
Pedological Darwin
A completely new approach to observe and subsequently study soil could start only
after a transition from alchemy to chemistry was successfully realized. After that
transition was completed and coupled with the fi rst steps of mathematical descrip-
tions of physical laws, a more comprehensive understanding of soils and nature
began. Up to 80 years of the nineteenth century, the top part of the soil was studied
with research ending at the bottom boundary of the root zone of plants. The research
was mainly focused to determine the amount of plant nutrients in the A horizon. The
most famous was the German chemist Justus Liebig (1803-1873). He was pro-
moted into the rank of noblemen as Justus von Liebig (1845). By this promotion, his
extraordinary merits in development of sciences were publicly appreciated. He pro-
vided a revolutionary concept for studying soil, since he was the fi rst to introduce
newly developing chemistry to soil-plant relations.
Two crucial factors account for Liebig's decision to become a chemist and have
a major interest in agronomy, especially in plants-soil relationships: (1) Liebig,
apprenticed to the pharmacist
practice of his father, performed his fi rst experiments
in his father's pharmacy. (2) At the age of 13, Liebig lived through the year “without
