Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

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Figure 22. Bare, rilled field in the Palouse region of eastern Washington in the
1970s (USDA 1979, 6).
In 1979 the Soil Conservation Service reported that three decades of
plowing had lowered fields as much as three feet below unplowed grassland.
Berms of soil four to ten feet high stood at the downhill end of
plowed fields. Experiments conducted with a typical sixteen-inch moldboard
plow pulled along contours showed that plowing typically pushed
soil more than a foot downhill. The process that stripped Greek hillsides
in the Bronze Age was being repeated in the Palouse.
Simply plowing the land pushed soil downhill far faster than natural
processes ever managed. Even so, this process is almost as hard to notice,
occurring imperceptibly with each pass of a plow. Continued for generations,
till-based agriculture will strip soil right off the land as it did in
ancient Europe and the Middle East. With current agricultural technology,
though, we can do it a lot faster.
Wind erosion contributes to the problem. A core from the bed of eastern
Washington’s Fourth of July Lake records that dust fall into the lake
increased fourfold with the introduction of modern agriculture to the
dust blow