Causes
During early European and American exploration of the Great Plains, the region in which the Dust Bowl occurred was thought unsuitable for European-style agriculture; the region was known as the Great American Desert. The lack of surface water and timber made the region less attractive than other areas for pioneer settlement and agriculture. Following the Civil War, settlement was encouraged by the Homestead Act, the transcontinental railroad, and waves of new immigrants, and cultivation increased. An unusually wet period in the Great Plains mistakenly led settlers and the federal government to believe that "rain follows the plow" (a popular phrase among real estate promoters) and that the climate of the region had changed permanently. The initial agricultural endeavors were primarily cattle ranching, with some cultivation; however, a series of harsh winters beginning in 1886, coupled with overgrazing followed by a short drought in 1890, led to an expansion of land under cultivation.
Continued waves of immigration from Europe brought settlers to the plains at the beginning of the 20th century. A return of unusually wet weather seemingly confirmed a previously held opinion that the "formerly" semiarid area could support large-scale agriculture. Technological improvements led to increase of mechanized plowing, which allowed for cultivation on a greater scale. World War I increased agricultural prices, which also encouraged farmers to dramatically increase cultivation. In the Llano Estacado, the area of farmland doubled between 1900 and 1920, and land under cultivation more than tripled between 1925 and 1930.
The favored agricultural methods of farmers during this period created the conditions for large scale erosion under certain environmental conditions. The widespread conversion of the land by deep plowing and other soil preparation methods to enable agriculture virtually eliminated the native grasses which held the soil in place and helped retain moisture, even during dry periods. Furthermore, cotton farmers left fields bare over winter months, when winds in the High Plains are highest, and burned the stubble as a means to control weeds prior to planting, thus depriving the soil of organic nutrients and surface vegetation.
The environmental conditions created when severe drought struck the Great Plains region in the 1930s exposed the increased risk for erosion that was created by the farming practices in use at the time. The drought dried the topsoil and over time it became friable, reduced to a powdery consistency in some places. Then, without the indigenous grasses in place, during the drought, the high winds that commonly occur on the plains created the massive duststorms that marked the Dust Bowl period.
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