Corn Population Trials
In 1994, corn population trials came from both cooperators Ron and Maria Rosmann, Harlan, and the Riceville, Iowa Future Farmers of America, which participated through a Sustainable Projects grant. In all three trials there was a consistent yield response to increasing populations (Table 3 and Fig. 3). The Rosmanns are adjusting their cropping system as they make the transition to organic certification. Not only did they see a yield response to population, they found through stand counts that rotary hoeing and cultivation had thinned the planted population by around 4,700 plants per acre. The finding may refocus their attention on these operations.
The Riceville FFA compared three planting populations, the highest being 32 thousand seeds per acre. That population was the yield winner in both of the corn hybrids evaluated, although crop stands were up to four thousand plants less than seeding rates. Of course, 1994 was a good year for corn. In a more stressful growing season, the yield response could be different. These trials probably should be repeated for a number of years, and results should be considered along with information provided by the seed companies and by third parties like ISU Extension.