Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

Figure 18. Breaking new land with disk plows, Greely County, Kansas, 1925 (courtesy
of Kansas State Historical Society).
peasants, the spread of tractors displaced those lacking the capital to join
the party.
By 1928, when Hugh Bennett and W. R. Chapline published the first
national soil erosion assessment, topsoil loss amounted to five billion tons
a year—several times faster than soil loss in the nineteenth century and ten
times faster than soil formed. Nationwide, virtually all the topsoil had
already eroded from enough farmland to cover South Carolina. Six years
later Bennett and Chapline’s report seemed understated. Even in drought
and Depression, the number of tractors working Oklahoma farms increased
from 1929 to 1936. New disk plows, with rows of concave plates set out along
a beam, thoroughly diced the upper layers of soil, leaving a pulverized layer
that could easily blow away in dry conditions.
The first major windstorm of 1933 swept through South Dakota on
November 11. Some farms lost all their topsoil in a single day. The next
morning the sky remained dark until noon—one part air to three parts
dust. No one knew this was just a preview.
On May 9, 1934, fields from Montana and Wyoming were ripped up by
high winds. Blowing across the Dakotas, the wind kept picking up dirt
until a third of a billion tons of topsoil was heading east at up to a hundred
miles an hour. In Chicago four pounds of dust dropped out of the sky for
dust blow 151