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Corn Planting Depth and Managing Variability

Categories: PLANTING, CORN
Planting depth is one of the most important things to prioritize on the road to maximizing yields. Variability in planting depth can even happen in the same field or change over time with the same planter. Variability in planting depth can lead to uneven emergence and poor root growth. Though this may not be as noticeable early in the season, stress will carry through the entire growing season and ultimately impact yields in the fall. 
Above is an example of how even a slight difference in planting depth can impact emergence.

Variable Seed Depth: Common Causes and Potential Solutions

Cause: Root balls from last year’s crop can cause the planter to bounce, especially at higher speeds. If a row unit bounces for even 0.5 seconds it will have traveled far enough to drop 5 corn kernels. These dropped kernels may all be planted at different depths. At 6 mph that same planter may drop over 8 seeds in 0.5 seconds, causing even greater variability. 
Solution: Slow the planter down in cloddy ground or where large root balls are found.

Cause: Compaction will vary across a field with soil type and traffic patterns. A planter with perfect placement in loose soil may drop seed much shallower in compacted ground. 
Solution: Watch down pressure to make sure it can deal with tighter soils.

Cause: A healthy soil will have 25% or more of air space. Some of this air space may settle and can bring seed closer to the surface, reducing seed depth. 
Solution: Check press wheels to be sure they’re firming loose soil.

Cause: Heavy rain can wash soil over the furrow and bury the seed deeper. This is sometimes seen in combination with aggressive row cleaner settings that have moved too much soil and formed a valley that the seed furrow is in. 
Solution: Set row cleaners to remove only the residue, not move soil.

Cause: Modern planters carry a lot of weight. A large central seed tank or full fertilizer tanks can add significant weight and help to settle the planter deeper than intended. 
Solution: Check the planting depth as the planter empties.

Why 2” is the Optimal Planting Depth?​​​​​​​

Soil stability: Moisture and temperature are more stable at 2”, especially in the spring when temperatures can vary widely. Stability gives corn seedlings the best opportunity to absorb water and nutrients.

Root development: Underground nodal roots have optimal space for growth. This creates a better anchoring system and leads to stronger stands. Shallow planting depths don’t allow for proper nodal root development, causing floppy corn seedlings or rootless corn syndrome.

Chemical layer: Herbicides, fertilizers and other inputs are adequately diluted by rainwater before reaching the seed. If planted too shallow, seeds can absorb very thinly-diluted chemicals, which can cause seeds to become injured and possibly die.

It sounds simple, but one of the best management practices that can be done during planting is to stop and dig up seed behind the planter to check on the planting depth. Always check more than one row unit across the planter as each row unit may vary in performance. 

Prioritizing proper seed depth will show benefits through the entire season. Contact your Golden Harvest Seed Advisor with questions or for additional agronomic insights.

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Syngenta hereby disclaims liability for third-party websites.

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