There are as great differences in the yields secured from different strains of the same variety of corn as between distinctly different varieties adapted to the same locality. A difference of 13 bushels per acre was found between two different strains of Reid's Yellow Dent in the 1923 test. Recognizing these facts the Iowa Corn Yield Test was inaugurated in 1920 by the Iowa Corn and Small Grain Growers' Association and has been continued during the past four years. This test differs materially from the acre yield test of previous years, in that the relative ability to yield is very carefully and accurately determined for each lot of corn entered, by growing the different kinds under exactly the same conditions, side by side on the same soil. Each corn entered is grown on three testing fields in the section of the state for which it is adapted or is entered.
Iowa Corn and Small Grain Growers' Association; Farm Crops Section, Iowa Agricultural Experiment Station; and Office of Cereal Investigations, Bureau of Plant Industry, United States Department of Agriculture, "Iowa Corn Yield Test, Results of 1923 Tests, Plans for 1924 Tests" (1923). Iowa Corn Yield Tests. 7.