By Robert Battel
See how responses to corn seeding rates stacked up over the years.
Michigan State University Extension educators in Michigan’s Thumb area studied corn seeding rates in multiple on-farm studies over an eight-year period, including 2009, 2010, 2013 and 2016. These studies represented a total of 60 site years. Planted populations ranged from 24,000 to 38,000 seeds per acre in 2008 through 2010; 30,000 to 44,000 in 2013; and 28,000 to 40,000 in 2016. Seeding rates increased in increments of 2,000 seeds per acre. Corn was planted in 30-inch rows.
See the table below for results for individual years. In determining per acre seed costs, a per 80,000 seed count bag price of $240 was used. Each 2,000 seed rate increase cost $6 per acre.
| Effect of corn population on yield over multiple years |
|---|
| Per acre seeding rate | 2008 yield (bu/A) | 2009 yield (bu/A) | 2010 yield (bu/A) | 2013 yield (bu/A) | 2016 yield (bu/A) | Average yield (bu/A) | Per acre seed cost |
|---|
| 24,000 | 191 | 179.7 | 157 | No data | No data | 175.9 | $72 |
| 26,000 | 196 | 183.5 | 156.7 | No data | No data | 178.7 | $78 |
| 28,000 | 201 | 196.2 | 158.8 | No data | 199.7 | 188.9 | $84 |
| 30,000 | 207 | 196.1 | 169 | 190.4 | 201.2 | 192.7 | $90 |
| 32,000 | 208 | 201.5 | 173.6 | 196.1 | 201 | 196 | $96 |
| 34,000 | 209 | 200.3 | 171 | 198.2 | 205.3 | 196.8 | $102 |
| 36,000 | 209 | 203.2 | 169.2 | 198.8 | 208 | 197.6 | $108 |
| 38,000 | 210 | 198.8 | 175.3 | 202.7 | 208 | 199 | $114 |
| 40,000 | No data | No data | No data | 204.4 | 209.2 | 206.8 | $120 |
| 42,000 | No data | No data | No data | 200.1 | No data | 200.1 | $126 |
| 44,000 | No data | No data | No data | 205.1 | No data | 205.1 | $132
|
Below is a graphical representation of the data above. As you can see, corn yield plateaus at about 36,000 seeds per acre. At lower seeding levels, incremental yield increases rapidly and levels off at 36,000 seeds per acre.
Corn yield response to seeding rate.
It should be noted that these studies were conducted on high-yielding, well-tiled, finely-textured soils in the Thumb. The Corn Marketing Program of Michigan provided funds that made these studies possible.