Part 1, Section 4: Corn
Corn
ESTABLISHMENT
Seed coverage
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 shallow (1.5 inches) when soil is cold and/or moist; plant deeper when soil is warm and/or dry. Plant shallower in heavy soils or where soil crusting is anticipated. Shallow planting (1.5 inches or less) 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.
Several planter considerations can help improve seed placement and seed-to-soil contact. Adjust the coulter down pressure and depth to slice cleanly through residue in no-till situations. This improves seed-to-soil contact and prevents pinning of the residue in the seed furrow. Worn double disc openers can contribute to a W-shaped seed furrow and poor seed-to-soil contact. Inspect the openers and replace them when they are less than the manufacturer's recommended size. The tension and placement of the closing wheels also should be adjusted to ensure that the furrow is being closed and firmed adequately. Row cleaners can remove residue from the row and reduce the potential of hairpinning residue in the row. Also, seed firmers can help to firm the seed in the furrow and improve seed to soil contact.