By Robert Battel
A 2016 study of seven corn populations determined which one returned the most for an investment.
Michigan State University Extension educators who work with the Thumb Ag Research and Education project evaluated optimal corn seed populations in 2016. Planted populations ranged from 28,000 seeds per acre to 40,000 seeds per acre with incremental increases of 2,000 seeds. This population study was established at four sites in Michigan: Capac, Kingston, Croswell and Unionville. This study was similar to a series of studies established during 2008-2010, where the 32,000 seeds per acre rate was found to be the most profitable (see “Maximizing returns on seed corn investments”), and in 2013, where a 36,500 seeds per acre rate was found to be the most profitable population (“see “Maximizing returns on seed corn investments – 2013 trial results”).
The corn was established in 90-foot long by 15-foot wide plots on 30-inch spacings. Six rows were established in each plot, and the center four rows were harvested for data. Plots were established in a randomized complete block design with four replications. The hybrid used in this study was Rupp XR D94-26. The price of seed used for the net income calculation was $240 for an 80,000 count bag, therefore every 2,000 seeds per acre increase equaled an increased cost of $6 per acre—roughly 2 bushels per acre.
The table below lists the target population treatments and the corresponding final population. All final populations were within at least 96 percent, and up to 99 percent of the target population. Note that these plots were established on highly productive fields with soils ranging from sandy loams to clay loams.
Target population | Final population |
|---|
28,000 | 27,250 |
30,000 | 29,375 |
32,000 | 31,625 |
34,000 | 33,750 |
36,000 | 35,125 |
38,000 | 37,250 |
40,000 | 38,750 |
Averaged across five sites, yields from all populations were statistically similar. One site, Croswell, had some statistical differences where the populations of 34,000 and more yielded statistically more than the populations of 32,000 seeds per acre and less.
Population | Capac | Kingston | Croswell | Unionville | Average | Seed cost per acre |
|---|
40K | 189.2 | a | 214.9 | a | 219.2 | a | 213.4 | a | 209.2 | a | $120 |
38K | 189.9 | a | 215.0 | a | 215.5 | a | 211.7 | a | 208.0 | a | $114 |
36K | 193.0 | a | 213.8 | a | 216.6 | ab | 208.7 | a | 208.0 | a | $108 |
34K | 188.8 | a | 208.4 | a | 223.1 | a | 200.8 | a | 205.3 | a | $102 |
32K | 190.2 | a | 208.3 | a | 212.0 | b | 193.6 | a | 201.0 | a | $96 |
30K | 186.3 | a | 213.2 | a | 210.0 | b | 195.4 | a | 201.2 | a | $90 |
28K | 185.7 | a | 209.0 | a | 206.9 | b | 197.1 | a | 199.7 | a | $84 |
Average | 189.0 | 211.8 | 214.8 | 202.9 | 204.6 | — |
|---|
High | 193.0 | 215.0 | 223.1 | 213.4 | 209.2 | — |
|---|
Low | 185.7 | 208.3 | 206.9 | 193.6 | 199.7 | — |
|---|
CV (%) | 3.8 | 4.7 | 3.8 | 8.4 | 9.3 | — |
|---|
LSD 0.05 | 8.7 | 12.2 | 9.9 | 20.8 | 12.9 | — |
|---|
Values in the same column followed by the same letters are not significantly different.