The lower the corn seed population, the higher the yield? New study says yes
More is better, right?
Wrong. When it comes to corn seeding rates, new research shows a lower rate, with all other inputs equal, actually ends up yielding more grain at the season's end.
"A few seed companies have been discussing with farmers the idea of increasing their corn seeding rates in 2009 from 30,000-32,000 seeds/acre to nearly 40,000 seeds/acre with the idea that this increase in seeding rates will maximize potential corn yield," says Ohio State University (OSU) Extension educator and assistant professor Andy Kleinschmidt.
In a recent study, Kleinschmidt and OSU Extension researcher Gary Prill found that less is actually better; a "head-to-head comparison" between 30,000-seed and 40,000-seed-per-acre field trials showed the former consistently outyielded the latter. WIth 30,000 seeds-per-acre, yields ended up 12 and 17 bushels per acre higher than 40,000-seed plantings with equal amounts of foliar fungicide applied and 180 and 240 pounds of nitrogen added, respectively.
"The results from this one year study did show statistically significant differences in harvest population and yield for the treatments. Significant differences in harvest populations were expected as a result of setting the planter for two different seeding rates. The addition of 60 pounds/acre nitrogen caused a significant yield advantage when comparing the treatment consisting of 30,000 seeds/acre plus 180 pounds/acre nitrogen and the treatment consisting of 30,000 seeds/acre plus 240 pounds/acre, with neither treatment receiving fungicide," according to Kleinschmidt and Prill's study. "Also, the addition of Headline foliar fungicide caused a significant yield advantage when comparing the treatment consisting of 30,000 seeds/acre plus 180 pounds/acre plus Headline and the treatment consisting of the same seeding rate and nitrogen rate without the addition of Headline fungicide. There is no clear reason why the additional nitrogen or fungicide applications did not cause a significant yield response at the higher seeding rates."
This translates to a big swing in per-acre income, Kleinschmidt says. When taking only seed, nitrogen and fungicide costs into account, the net revenue for the 30,000-seed rate is consistently higher than that with 40,000 seeds per acre. The former nets $460 per acre when combined with a 180-pound-per-acre nitrogen application versus $392 for the higher seed count. The difference is magnified when 240 pounds of N are applied: With 30,000 seeds per acre, net revenue is $464 per acre versus $359 for the 40,000-seed rate.
"Using a current corn market price of $3.50/bushel, this would require an additional 5.7 bushels yield increase in corn yield to break even. The addition of 60 pounds/acre nitrogen would require a corn yield increase of 12.3 bushel/acre to break even," Kleinschmidt says. "Likewise, the use of a 40,000 seeds/acre seeding rate compared to a 30,000 seeds/acre seeding rate would require a 7.1 bushel/acre yield increase in corn to break even."