California, September 22, 2003 (ENS): There
is new reason to reconsider the phrases "common
as dirt," according to researchers from the University
of California at Berkeley (UC Berkeley).
A new paper published in the journal "Ecosystems"
finds that certain soils are becoming increasingly rare,
with some at risk of becoming extinct.
The study details that in some agricultural regions,
such as in the Midwest, up to 80 percent of soils considered
rare have been reduced to less than half of their original
"Over the past two centuries, we have reconfigured
part of a continent to the point where today's landscape
is almost unrecognizable from its natural state,"
said Ronald Amundson, professor of ecosystem sciences
at UC Berkeley's College of Natural Resources and lead
author of the paper. "The Great Plains used to
be characterized by tall grasses and prairies. They
have now been replaced by crops and housing tracts."
Soils, like their plant and animal counterparts, have
their own taxonomy - in the United States, there are
11 soil orders that are ultimately divided into 13,129
Soils that comprise less than 25,000 acres are considered
rare. Soils that are classified as "rare unique"
exist only in one state and make up less than 25,000
The researchers considered a rare or rare-unique soil
endangered if more than half of its area was tilled,
excavated or otherwise disturbed.
Using these definitions, the UC Berkeley researchers
found 508 endangered soil series in the United States.
Six states have more than half of their rare soil series
in an endangered state, with Indiana leading the group
at 82 percent, followed closely by Iowa at 81 percent.
Most of the soil danger hotspots reside in the country's
The researchers also found that 31 soils are effectively
extinct because they have been nearly completely converted
to agricultural or land use.
The cause for concern, Amundson said, is that soil
diversity is in essence tied to biological diversity.
"Soil that has been cultivated is like an animal
that has been domesticated," said Amundson. "It
retains some resemblance to its wild or native ancestor,
but there are enormous and profound changes in its characteristics."
"We certainly need land to farm and develop -
I am not advocating the discontinuation of agricultural
expansion," said Amundson. "But I think it
would be fair to set aside modest areas of these remaining
natural landscapes for study and contemplation."
To conduct this study, Amundson and the other researchers
combined data from digitized maps on soil types compiled
by the U.S. National Resource Conservation Service with
information from maps of agricultural and urban growth
provided by the U.S. Geological Survey and the Environmental
"Never before has soil in the United States been
analyzed in such a way," said Peng Gong, professor
of ecosystem sciences at UC Berkeley's College of Natural
Resources and coauthor of the paper. "Our study
is the country's first quantitative analysis of soil
"Some of these soils developed over thousands
to millions of years," Gong said. "We can
destroy that in a few hours. It is a preservation issue.
We need to save it for future generations."