Seed must contact moist soil; 1.5 to 2.5 inches of soil coverage is desirable, depending on conditions. Remember that corn seeds respond to warm temperatures and moist soil. For optimum stands, planting depth should take this factor into account. For example, plant 1.5 inches when soil is cold and/or moist; plant deeper when soil is warm and/or dry. Plant 1.5 inches in heavy soils or where soil crusting is anticipated. Shallow planting (less than 1.5 inches) increases the risk of poor seed coverage and uneven emergence in dry springs.
Inadequate seed coverage can result in variable plant emergence and variable plant stands. It is important to check the actual seed depth you are achieving in the field at least at the beginning of each day and preferably in each field.