Five-Year Planting Depth Study in Corn

The objective of this study was to determine the optimum planting depth for corn across multiple locations and growing environments.

The study was conducted from 2016 to 2020 on 22* different fields, mostly throughout the U.S. Midwest. Six planting depth plots were established at each location, beginning at 1 inch and increasing to 3.5 inches in half-inch increments.

Results:

When averaged across all locations, planting at 2 inches resulted in the highest overall yield (Figure 1). However, optimum planting depths per location often ranged between 1.5 and 3 inches, depending on field conditions. Planting just a half-inch shallower than 1.5 inches resulted in an average 13 bushel per acre yield loss. On the other end, planting just a half-inch deeper than 3 inches resulted in an average 8 bushel per acre yield loss.

Figure 1. Average grain yield across 22 locations from 2016 to 2020.

Additional Observations:

Stand reductions were often noted when planting at 1-inch deep (Picture 1).
Planting shallower than 1.5 inches can cause non-uniform emergence due to moisture variability and does not allow proper nodal root development.
Planting depths from 1.5 to 3.5 inches deep allow for adequate root development. However, planting deeper than 3 inches sometimes can delay emergence or reduce stands.
Planting depth is extremely important for uniform emergence, growth and development. Consistently achieving the proper depth is challenging, especially in fields with varying soil textures, depending on the time of day, tillage system, and how far ahead of the planter tillage operations occur.

Picture 1: Stand reductions due to shallow planting depth.

Recommendations and Equipment Solutions:

To determine the optimum planting depth, it is important to check for moisture and observe the extended weather forecast. Seeds should be planted into moisture and deeper if extended heat and dry conditions are expected.

Massey Ferguson VE Series Planters and Fendt Momentum Planters come standard with the most accurate depth control systems in the industry.

On every row-unit, seeding depth can be increased/decreased by .25-inch increments
DeltaForce ensures seeds are placed exactly where they are intended by maintaining the correct amount of weight on the gauge wheels of every row, regardless of field variation
Vertical contouring toolbar (Picture 2) on Fendt Momentum planters offers each row-unit up to 65.9 inches of vertical travel to ensure each seed is placed at the correct depth regardless of terrain
Precision Planting’s SmartFirmer® provides seed level temperature and moisture information on the monitor in the tractor cab providing confidence in seed depth settings

Picture 2: Precise seeding depth control with Fendt Momentum vertical contouring toolbar.

Payback:

The cost of planting too shallow (1 versus 1.5 inches) was $58.50** per acre in this study, whereas the cost of planting too deep (3 versus 3.5 inches) was $36 per acre.

*22 U.S. sites: 2016 – Galva, Illinois; Edgewood, Iowa; Amboy, Indiana; New Ulm, Minnesota; Jackson, Minnesota; 2017 – Ionia, Iowa; Morning Sun, Iowa; Judson, Minnesota; Winthrop, Minnesota; 2018 – Bement, Illinois; Union City, Ohio; Falls City, Nebraska; Irwin, Iowa; Fremont, Nebraska; Madison, Wisconsin; Mosinee, Wisconsin; 2019 – Mt Hope, Kansas; Emmetsburg, Iowa; Owensboro, Kentucky; 2020 – Baltic, South Dakota; Chillicothe, Ohio; Stewartville, Minnesota.

**Assumes 13 bushels per acre yield decrease at $4.50/bushel, or 8 bushels/acre at $4.50