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Agronomic Crops Network

Ohio State University Extension


Seeding Depth

The appropriate planting depth varies with soil and weather conditions. For normal conditions, plant corn 1.5- to 2-inches deep to ensure adequate moisture uptake and seed-soil contact, provide frost protection and allow for adequate root development. Shallower planting often results in poor root development and should be avoided in all tillage systems. In April, when the soil is usually moist and evaporation rate is low, seed should be planted shallower―no deeper than 1.5 inches. As the season progresses and evaporation rates increase, deeper planting may be advisable. When soils are warm and dry, corn may be seeded more deeply―up to 2 inches on non-crusting soils. 

When corn is planted 1.5- to 2-inches deep, the nodal roots develop about 1/2 to 3/4 inches below the soil surface. However at planting depths less than 1 inch, the nodal roots develop at or just below the soil surface. Excessively shallow planting can cause slow, uneven emergence due to soil moisture variation, and rootless corn (“floppy corn syndrome”) when hot, dry weather inhibits nodal root development. Shallow plantings can increase stress and result in less developed roots, smaller stalk diameters, smaller ears and reduced yields. 

Some corn growers plant at depths less than 1.5 inches. The rationale for this shallow planting is that seed will emerge more rapidly due to warmer soil temperatures closer to the surface. This is an important consideration as corn growers across the Corn Belt are planting earlier so they can complete planting before yield potential begins to decrease after the first week of May. Particularly in soils that crust, speed of emergence is critical in order to establish plant stands before heavy rainfalls “seal” the soil surface. In recent OSU research evaluating varying planting depth, grain yields were about 14 percent greater for the 1.5-inch and 3-inch planting depths than the one-half-inch planting depth in 2011, and 40 percent greater in 2012. The lower yield of the shallow half-inch planting was associated with final stands that were 7,000 to 12,000 plants per acre less than those of the other two planting depths in 2011 and 2012.