Farmers continue to increase corn plant density

As technologies improve over time, management decisions need to be adjusted to keep up with the changing times. Better equipment, improved bio-engineered hybrids, better seed treatments, irrigation technologies, new pesticides, etc. have all contributed to corn grain yield progress. One management decision that continues to evolve is plant population. For some recent articles on this topic click here and here. For the latest USDA-NASS data collected in farmer fields during August, see Figure 1. Field plant populations are increasing at the rate of 270 to 300 plants/A*yr. Usually about 5 to 10% of the seed planted does not emerge, so seeding rates are 31,000 to 35,000 seeds/A.

Figure 1. Corn plant density changes over time for selected U.S. states. The rate of change (slope) in plants/A*yr since 1982 is reported for each state. Data derived from USDA-NASS (1982-2021). Click to enlarge.

It is clear from our research data that maximum yield plant densities (MYPD) and economic optimum plant densities (EOPD) are increasing. Recent research has shown that each hybrid has a MYPD and EOPD. There is gathering evidence that even each field within a farm may have a corn MYPD and EOPD. In many years (not 2022), seed cost can be as big of an input cost as nitrogen cost (Figure 2). Input adjustments can mean significant cost savings when corn grain prices are low (again not 2022).

Figure 2. USDA-ERS cost of production estimates for corn (last updated October 1, 2021). The Northern Crescent includes the northern tier of U.S. states along the Great Lakes. The Heartland includes Midwest Corn Belt states. Click to enlarge.

Adjusting plant density for your fields is one of the key production decisions for producing high yielding corn. Clearly farmers are adjusting plant densities higher. One approach to adjusting this decision is to plant the majority of your field to a target plant density based upon your experience. Then for one round (or pass) in a couple parts of the field, increase plant density 10%. Measure yield at the end of the season and during the season watch for "runt" plants, tillering, prolificacy, ear bareness. big versus small ears, ear tip "nose-back" and plant lodging. Adjust the field accordingly the following year.

Please forward this article to those who may find the information useful.
Click to subscribe or unsubscribe.