Why were farmers not a good choice for industrial work?

Farmers faced tough times. While most Americans enjoyed relative prosperity for most of the 1920s, the Great Depression for the American farmer really began after World War I. Much of the Roaring '20s was a continual cycle of debt for the American farmer, stemming from falling farm prices and the need to purchase expensive machinery. When the stock market crashed in 1929 sending prices in an even more downward cycle, many American farmers wondered if their hardscrabble lives would ever improve.

What war are you specifically talking about?