WWII - Food was rationed; the gov't asked food producers not to enlist. Need info on this program. Anyone ?

In 1941, my dad was in the Civilian Pilot Training Program at Dodge City, KS, training to be a ferry command pilot. However, his business was a chicken hatchery, and, before he could finish his training, the government asked all food producers to return home and help out the war effort by continuing to produce food. My father was very disappointed he was unable to continue his training and serve his country in the Air Corps Ferrying Command. I am trying to find out more details on the federal program that sent food producers home.