Weak corn emergence

Every spring is unique, but some principles are timeless and should be kept in mind at the start of every season. Below are several to remember as you consider your plan.

Environmental Requirements for Corn Emergence

A uniform corn stand is essential to producing maximum corn yields. Here are the environmental requirements for a seed to develop into a vigorous seedling:

1. Soil temperature: Should be greater than 50° F.
2. Seed-to-soil contact: Contact with moist soil is essential because a seed must absorb water equal to or greater than 50% of its mass in order to germinate. Poor soil contact can cause emergence delays, which lead to inconsistent ear size on the late-emerging plants.
3. A low-salt diet: Excess salt near the seed can cause seedling burn and leads to weakened seedlings that are more susceptible to pathogens. Limit pop-up fertilizer (fertilizer applied directly to the seed in the furrow) to a maximum of 5 gallons per acre. If you need to apply more than 5 gallons per acre of starter fertilizer, place the material at least 2” to the side and 2” below the seed.
4. Well-oxygenated soil: Cell division in a corn seedling is a respiratory process and requires an adequate supply of oxygen for proper development. Field conditions that can limit oxygen to the seedling can include either the physical destruction of pore space by compaction or cold spring rains that saturate and displace oxygen from the soil.

Management Decisions for Uniform Emergence and Early Growth

Knowing the environmental requirements for uniform emergence, let’s look at 4 key management decisions that must be evaluated before planting.

1. Is the soil dry enough? All potential benefits of early planting will be lost if you till wet soil or no-till into wet field conditions. Working wet soil produces “clods” that reduce seed-to-soil contact, thus causing emergence delays. Cloddy seed beds can also cause planter units to bounce and dramatically affect planting depth. Sidewall compaction in wet soil causes emergence problems and hinders future root development. Compacting the soil reduces soil pore space, which limits root access to oxygen, moisture and fertility. Soil compaction also reduces water infiltration rates and increases run-off potential. Because of these factors, corn planted in compacted soil is very susceptible to injury from damping off and other diseases, as well as drought.
2. Is your planter in excellent condition? Worn planter parts can cause problems in achieving uniform corn stands. Worn disk openers are a major cause of poor seed-to-soil contact and can affect the target seeding depth needed to establish a uniform stand. Worn drive chains and seed meters can affect plant spacing and target populations needed to maximize yield potential.
3. Planting depth: Maintain a planting depth of 2”. While shallow-planted corn (planted less than 1.5”) may occasionally emerge faster, the long-term benefits of proper planting depth will outweigh the quick emergence associated with shallow planting. If you plant corn less than 2” deep, you could reduce the space available for proper nodal root development, causing these roots to develop at or near the soil surface. Nodal roots will either not develop or develop slowly when confronted with soil surface conditions. A seed planted at the proper depth in a non-compacted environment will grow a healthy seedling and root system, which will support a uniform stand and maximize the field’s yield potential.
4. Manage residue: Residue from a previous crop is a major cause of poor uniformity. Residue in the seed furrow can drastically reduce seed-to-soil contact and can cause planter units to bounce, dramatically affecting planting depth. Residue will also increase variability in soil moisture and soil temperature, causing variability in plant vigor and uniformity.

Achieving Uniform Corn Stands

Maximizing a field’s potential requires establishing a uniform stand. To do so, it is critical to independently evaluate each field and their unique management practices. Remember to till and/or plant a specific field only when:

1. Soil temperature and moisture conditions are good.
2. Your planter is properly set and maintained.

For questions or more information on corn emergence, contact your NK^® agronomist or NK sales representative.

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