Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

without the least reference to the interests of future generations.” 2 Shaler
considered those who abused land to be among the lowest of criminals.
Shaler understood how plowing altered the balance between soil production
and erosion. “In its primitive state the soil is each year losing a portion
of its nutrient material, but the rate at which the substances go away
is generally not more rapid than the downward movement of the layer into
the bed rock. ...But when tillage is introduced, the inevitable tendency
of the process is to increase the rate at which the soil is removed.” 3 Disturbance
of such a balance led to predictable consequences.
Satisfied that modern evidence supported his ideas, Shaler concluded
that soil erosion shaped ancient history throughout the Old World. Once
the soil was lost, recovery lay beyond history’s horizon. “Where subsoil as
well as the truly fertile layer has been swept away the field may be regarded
as lost to the uses of man, as much so, indeed, as if it had been sunk beneath
the sea, for it will in most instances require thousands of years before the
surface can be restored to its original estate.” 4 The six thousand square miles
of fields by then abandoned to erosion in Virginia, Tennessee, and Kentucky
testified to the American tendency to repeat Old World mistakes.
Although Shaler advised tilling down through the subsoil to break up
decaying bedrock and speed soil creation, he argued that land sloping
more than five degrees should be spared the plow. He predicted that fertilizers
could replace rock weathering, but did not foresee how mechanized
agriculture would further increase erosion rates on America’s farmlands.
Nonetheless, soil erosion was becoming a national problem. In 1909 the
National Conservation Congress reported that almost eleven million acres
of American farmland had been abandoned because of erosion damage.
Four years later, the U.S. Department of Agriculture (USDA) estimated
that annual topsoil loss from U.S. fields amounted to more than twice the
quantity of earth moved to dig the Panama Canal. Three years after that,
Agricultural Experiment Station researchers estimated that half the tillable
land in Wisconsin suffered from soil erosion that adversely affected economic
activity.
At the start of the First World War, the USDA’s annual yearbook
lamented the economic waste from soil erosion. Rain fell like “thousands
of little hammers beating upon the soil” and ran off bare ground in rivulets
that were slowly stealing the nation’s future. “Under the original process of
nature the soil was continually wearing away on the top, but more was
forming, and the formation was somewhat more rapid than the removal.
The layer of soil on hillsides represented the difference between the
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