If soils at 1.5 to 2 inches are drier than field capacity, you could plant deeper, adjust planter down pressure differently, or plant at 1.5- to 2-inch depths and hope for rain. The first two options are most reasonable unless you are certain of timely rain, then the third option may be best.
Corn can emerge from fairly deep planting depths depending on soil texture. For example, if necessary to reach adequate moisture, plant corn as deep as 3 to 3.5 inches on clay soils, 4 to 4.5 inches on loam soils, and 5 to 6 inches on sandy soils. Remember though, if soil moisture is adequate at shallower planting depths, there is no reason to plant that deep. An array of problems accompanies unnecessarily deep planting: slower and more variable emergence, increased vulnerability to soil crusting and seedling diseases and insects. All of these reduce yield potential…and the crop is hardly out of the starting blocks.
Take time to carefully adjust your planter and speed for conditions in each field
Allow me to add one more thing on seeding depth. Seeding depth that varies among plants, especially in the same row, reduces yield through uneven emergence and thus uneven competition. This sets up a pecking order that chips away at yields all season long. In my experience, planting too fast is a major contributor to this. Time spent carefully adjusting your planter and speed for conditions specific to each of your fields will pay!
Summary: Spring soil and environmental conditions in mid- to late-April and early May usually get corn off to a great start toward maximum yield potential. Full-capacity soil profiles are like a savings account that pays high interest and provides through tough economic times. That is a 'textbook' Iowa spring: our full soil profiles at planting carry us through the vegetative period even during a drought. However, if soil profiles are short of moisture at planting, and it still looks like that is the case in some parts of Iowa as of mid-April 2013, be prepared for conditions we don't normally experience…and thus for situations for which we can only guess at recommendations.
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.