The Victory Corps was a voluntary program open to American high school and college students during the Second World War. It was established in September of 1942 with an eye toward preparing teenagers for military service. Although its primary concern involved weapons training, physical fitness and mathematics, it also had a "farm volunteer" arm, as this article about one branch of the Sacramento Victory Corps makes clear (the volunteers pictured above seem to be collecting scrap metal).
More about youth and the war effort can be read here...