Iowa farmers who farmed round their hills — the contour method — in 1943 got more corn, oats and soybeans to the acre than the farmers who farmed up and down their hills. At least this was the conclusion we reached after comparing yields of these crops grown by the two methods side by side in the same fields. We had results from 61 fields of corn, 38 of soybeans and 18 of oats in different parts of Iowa.
Browning, G. M. and Russell, M. B.
"Contouring Paid in 1943,"
Farm Science Reporter: Vol. 5
, Article 3.
Available at: http://lib.dr.iastate.edu/farmsciencereporter/vol5/iss2/3