If dry conditions persist at planting in your part of Iowa, stick with adapted, high-yielding hybrids that show some yield stability over locations and years. Planting much earlier hybrids will likely result in reduced yields.
Row spacing: Yield responses to corn row width are related to sunlight reception
Responses to corn row spacing are related to light interception. What I understand about this is that yield is optimized if corn canopies intercept 95% of sunlight at silking. Interestingly, modern Iowa corn hybrids in 30-inch rows at normal plant populations intercept 95% of the light at silking. That explains why we rarely see row spacings narrower than 30 inches improving corn yields over those of 30 inches.
That means row spacings of 20 inches, 15 inches, 12 inches and/or twin rows rarely improve Iowa corn yields. On the other hand, yields are rarely reduced with row spacings narrower than 30 inches. Remember though, yields are likely reduced in rows wider than 30 inches. However, if early-season stress of some kind reduces canopy closure of corn in 30-inch rows, narrow rows may out-yield those of 30-inch rows. Dry conditions during vegetative development could do this.
Planting date: Optimum planting date depends on soil moisture and temperature
Optimum corn planting dates vary across Iowa, depending on soil moisture and temperature, from April 11 to May 13 in southern Iowa; April 15 to May 2 in central and northwest Iowa; and April 12 to May 2 in northeast Iowa. Although corn kernels absorb soil moisture when soil temperatures are less than 50 degrees F, they will not begin germination until soil temperatures reach almost 50 degrees or higher.
Every decision that you make influences the size and scope for corn yields. From the corn hybrid you select to the seeding rate and row width you choose. Download our FREE report over Maximizing Your Corn Yield.