Determining Planting Depth for Corn for Different Soil Types

Harvest should now be complete and reflections are being made on what worked and what didn’t for producing the crop. Now is a time to consider what changes can be made to help minimize risk for the next crop. One of the first risks we can help minimize is planting depth as it relates to soil texture (Figure 1). Targeting the proper depth based on the soil texture can help maximize emergence uniformity, root development, and other factors that can affect potential yield. 

Following one metric on planting depth can be detrimental to the end of season results.  Factors to consider include soil texture, moisture, temperature, timing, and the weather forecast. The rule of thumb for seed placement for most of the Corn Belt is 2 inches deep. This rule of thumb is just that, a rule of thumb. You may not see the worst results, but you will also not see the best results.

The first factor to consider when determining seed placement is soil texture. In fine textured soil (clay), seed placement should be on the shallow end of the depth range (1.75 to 2 inches in optimal field conditions). Fine textured soils tend to stay a little wetter, shrink when dry, are more susceptible to compaction, and carry higher risk of crusting. In fine textured soils, it’s imperative to wait until the time is right so we can get the seed placement a little deeper with reduced problems. 

In moderate textured soils (silt to loam), staying 2 to 2.5 inches deep in optimal field conditions should be the goal. These soils are less susceptible to compaction which helps allow for achieving the ideal planting depth.

In course textured soils (sandy), planting a little deeper from 2.5 to 3 inches in optimal field conditions should be the goal. In coarse soils, moisture levels are usually lower in the soil profile and there is not a good soil structure for roots to become established.

Research has shown 2 to-2.5 inches is the ideal planting depth in a perfect year for plant emergence and development throughout the year. Stated above are basic rules for planting depth in ideal field conditions. Depending on field moisture, temperature, and other factors, planting depths may need to be adjusted. Regardless of soil texture and field conditions, seeds should not be placed shallower than 1.5 inches as this can lead to emergence and development issues throughout the year. If conditions are dry, planting a little deeper may be necessary to reach some moisture. There has been more harm in planting too shallow than too deep.

Elmore, R. 2013. Corn planting FAQs. Integrated Crop Management. ICM News. Iowa State University. https://crops.extension.iastate.edu/cropnews/2013/04/corn-planting-faqs

Luce, G.A. 2016. Optimum corn planting depth – “Don’t plant your corn too shallow”.  Integrated Pest Management. University of Missouri. https://ipm.missouri.edu/cropPest/2016/4/Optimum_Corn_Planting_Depth-Dont_Plant_Your_Corn_Too_Shallow/

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