1. Eight hundred seventy-nine entries were made in the 10 harvested districts of the 1936 Iowa Corn Yield Test. The yield test fields in districts 4 and 7 were abandoned because of crop failure. The entries were divided into four groups; regular open-pollinated, experimental open-pollinated, regular hybrids and experimental hybrids.
2. Data were obtained for each entry on acre yield, percentage stand, moisture content at time of harvest, lodging resistance, ear height, percentage of dropped ears and percentage of damaged kernels.
3. The outstanding feature of the 1936 Iowa Corn Yield Test was the superior performance of the hybrid combinations as compared with the open-pollinated varieties. The average yield of all hybrid entries in the 10 fields was 30.8 percent greater than for the open-pollinated strains. In District 11 the hybrids averaged 53.9 percent greater yield than the open-pollinated varieties. The hybrids in District 1, however, had an advantage of only 6.6 percent. This is attributed to the damage wrought by a severe hail storm the latter part of August which brought the effective growing season to a premature end. In addition to producing a greater yield the two classes of hybrid entries had much more lodging resistance.