7tillage methods advocated by Campbell, resulted in the infamous Dust Bowl consid-
ered by many as the worst ecological manmade disaster in U.S. history. Surveys
made during and shortly after the drought years of the 1930s in the southern Great
Plains suggested that 43 percent of the area had serious wind-erosion damage. It
was estimated that 2.6 million ha in the Southern Plains were removed from cultiva-
tion because of erosion but that about 10.3 million ha of less erodible soils made it
through the drought cycle in sufficient condition to return to cultivation in the 1940s.
With increased rainfall and higher crop prices in the early 1940s, the tendency to
convert more grassland to cropland returned (Burnett et al. 1985 ).
3 The Dust Bowl Mandated a Change in Tillage
Extensive wind erosion during the Dust Bowl of the 1930s made it clear that changes
had to be made. The intensive tillage that had worked so well in the beginning had
greatly diminished the soil organic matter content leading to poor soil structure,
lower infiltration, reduced water-holding capacity and uncontrollable wind erosion.
Charles Noble of Alberta, Canada was one of the first to search for a cure. Noble
Fig. 1 Locations where
dryland cropping
experiments were
conducted from 1903 to
1938 by USDA and State
Agricultural Experiment
Stations (Adapted from
Cole and Mathews 1940 )
Dryland Farming: Concept, Origin and Brief History