Geoscience Reference
In-Depth Information
that we start to see a transition in the nature of
human society. During the so-called agricultural
(or Neolithic) revolution that occurred at this
time, humans gradually moved away from a
society that was based upon hunting and gather-
ing the food and resources that they needed, to
an agricultural type of society. There are many
different theories as to why this great change in
human society occurred. Some claim that the
transition may have been a fortunate accident, as
early hunter-gatherers noticed that the seeds they
dropped in the soils around their camps produced
the very foodstuffs they had travel so far to procure.
However it occurred, what is clear is that the
adoption of agricultural techniques had signifi-
cant advantages for early human communities.
By growing the crops that they required in close
proximity to their places of dwelling, human
communities no longer had to expend energy
searching for naturally occurring foodstuffs. The
domestication of plants (namely bringing plant
growing under human control) was followed by
the domestication of animals, whereby animals
were reared for milk or food production close to
human settlements. In addition to making human
life far less energy intensive, the agricultural
revolution also made life far more secure. This
security can be observed at two levels. First, the
deliberate cultivation of crops and animals enabled
humans to develop a more reliable source of
food: with the vagaries of finding and successfully
hunting food over long distances replaced by more
reliable harvests. Second, agricultural techniques
enabled human communities to become geo-
graphically settled. Migrating communities of
hunter gathers were thus gradually replaced by
sedentary communities that could offer collective
protection and support for their residents (in
Chapter 6
we explore how the new securities
that agriculture offered human society enabled
the formation of the first large-scale urban
settlements).
The new found securities associated with
agricultural society enabled human communities
to flourish and resulted in significant increases
in human population. As human populations ex-
panded, however, it became necessary to cultivate
expanded tracts of soil. Some 6000 years ago (4000
BCE
), the increasing demand for soil led to the
first large-scale forest clearances in Europe (see
Chapter 5).
Inevitably, however, there are limits
to the amount of new agricultural lands that can
be created by forest clearances. It is in this context
that modern forms of agriculture have sought to
develop ways of increasing the productivity of
soils. During the industrial revolution that started
in Britain during the eighteenth and nineteenth
centuries, agriculturalists became increasingly
aware of the benefits of adding inorganic and
artificial fertilizers to soils. Farmers have been
adding fertilizers to soils for many centuries.
These so-called organic fertilizers include animal
manure, compost and seaweed, among other
things, and essentially result in the natural cyc-
ling of nutrients that are already present in
the biosphere. During the industrial revolution,
however, new opportunities emerged for the
application of inorganic fertilizers.
Inorganic fertilizers are minerals that are
comprised of nitrogen, potassium or phospho-
rous compounds,
inter alia
. Inorganic fertilizers
come in two basic forms. First, are 'mined'
minerals, which are extracted directly from the
earth, before being processed and applied to the
soil. Second, are chemically synthesized inorganic
fertilizers that are produced following specific
chemical procedures, such as the Haber-Bosch
Process. What unites both of these forms of
artificial fertilizer is that unlike organic sources,
they introduce nutrients to soils that would not
have been in the ecosystem if they had not been
introduced by human beings. During the industrial
revolution in Europe, significant advances were
made in both mining techniques and chemical
sciences. These processes combined to ensure that
there were more readily available supplies of
inorganic fertilizers that could be added to soils.
Recent estimates claim that the last 50 years have
seen an unprecedented rise in the application of
inorganic fertilizers to global soils (Glass, 2003).
