Current recommendations are to plant corn seed 1.5 to 2 inches deep, if planting conditions are dry. Planting to moisture is often practiced to help with uniformity of emergence, but this may be affected by soil texture. In heavy soils, corn seed should not be planted deeper than 2.5 inches regardless of the conditions. In lighter sandy soils planting 3.0 inches deep may be necessary. Some states recommend planting shallower in no-till conditions. Planting shallower than 1.5 inches might affect corn growth and development with some herbicides, such as Prowl.
Corn should be planted at 1.75- to 2.0-inch depth because when corn seed are planted too shallow, the "nodal" roots develop above the soil line and fail to aid corn plants in absorption of water and nutrients. Nodal roots that develop above the soil surface also fail to brace the plant to prevent lodging. Planting corn at the right depth can increase yields.
For more information on this and other topics related to corn production, contact your state extension corn specialist or your local extension educator/agent.
Following is the link to the corn extension specialists: state extension corn specialist.