Since the 1930s, the farm labor force has declined by about three-fourths, and cropland in use has decreased by 10 percent. In contrast, labor productivity in the nonfarm business sector during the same time period has increased only 2.6 fold. Farmers are far more educated. Average schooling increased from about eight years of schooling just after WW II to more than 13 years in the '90s. In addition, the private and public sectors have provided ongoing educational programs for farmers, such as those provided by the Cooperative Extension Service.
Some specific data show the increases in selected areas of farming.
That's about two bushels per year. In fact, U.S. corn yields have doubled about every 30 years in this century, according to Ralph Gann, USDA's Agricultural Statistics Service state statistician for Indiana. Howard Doster, a Purdue Extension farm management specialist, notes that it once took about one hour of farm labor to produce a bushel of corn. That's based on 40 bushels per acre in the late 1930s and an estimate of about 40 hours of labor to produce one acre of corn compared to 120 bushels per acre today with about two hours of labor. U.S. wheat yields also doubled in the last 30 years from about 19 bushels to 38 bushels per acre.