Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

eplacing water-holding capacity lost to soil erosion and for using fertilizers
to replace lost soil nutrients. They also estimated off-site costs for
increased flood damage, lost reservoir capacity, and dredging of silt-choked
rivers to maintain navigation. They estimated that undoing damage caused
by soil erosion would cost the United States $44 billion a year, and about
$400 billion a year worldwide, more than $70 per person on the planet—
higher than the annual income for most people.
Pimentel’s group estimated that it would take an annual investment of
about $6 billion to bring erosion rates on U.S. cropland into line with soil
production. An additional $2 billion a year would do so on U.S. pasturelands.
Each dollar invested in soil conservation would save society more
than five dollars.
In the short term, though, it can be cheaper for farmers to disregard soil
conservation; the cost of reducing soil erosion can be several times the
immediate economic benefit of doing so. Farmers with high debt and/or a
narrow profit margin can be forced to choose between conserving soil and
going bankrupt or working the land until it becomes economically futile.
Economic and political incentives encourage practices that destroy soil
productivity over the long run, yet preserving the agricultural foundation
of civilization requires protecting land from accelerated soil erosion and
conversion to other uses.
Many soil conservation measures are proven technologies. Measures
adopted to curb soil erosion after the Dust Bowl were not new ideas—
contour plowing and cover cropping were known more than a century
before. Crop rotations, mulching, and the use of cover crops are ancient
ideas. So is terracing, which can reduce erosion by 90 percent, enough to
offset the typical increase in erosion rates from cultivation.
Soil conservation trials in Texas, Missouri, and Illinois slowed erosion by
a factor of two to a thousand and increased crop yields by up to a quarter
for crops like cotton, corn, soybeans, and wheat. Soil conservation is not
radical new territory. Many of the most effective methods have been recognized
for centuries.
Despite compelling evidence that soil erosion destroyed ancient societies,
and can seriously undermine modern societies, some warnings of an
impending global soil crisis and food shortages have been overblown. In
the early 1980s agricultural economist Lester Brown warned that modern
civilization could run out of dirt before oil. Failure of such alarming predictions
to play out over the past several decades helped conventional
dust blow 175