The Dust Bowl was a period in the thirties when severe dust storms devastated all crops and other ecological components in several American and Canadian soils. This was partly caused by drought as well as the farmers' improper practices.
Because at least a year's worth of crops were gone, the bank cannot buy them and there would be no way for the value of their crops to increase either. Also, they would not be aiming to covet each other's land since most of the land eroded that period, too.
As a consequence for farmers, the government took their land. This was also done by the government in an effort to mitigate the damages done to the areas.
