Ideal plant populations for corn

This is my last post from the CCA convention last week.  Dr. R. L. Nielsen spoke to the group about ideal corn populations.  Nielsen pointed out that plant population is only one factor in the biological factory in a corn field.  Climate and weather, soils, pests and genetics are also factors.

He pointed out that some of the top contest yields that he has seen are not necessarily those with the highest population, although some high population fields do produce top yields.  He also stressed the importance of looking at populations at the V6 stage and at harvest because they are more important numbers than seeds planted.

Nielsen said that his numbers show the ideal final plant population to be around 31,000 plants per acre.  That would require a seeding rate of about 33,000 plants per acre if mortality rate is average.  He found no difference in row spacing.  Nielsen also said that using higher nitrogen rates with higher population does not pay off in high enough yields to justify the extra N.

Another finding was that in fields with fairly uniform soils, variable rate seeding does not seem to give any advantage.  In fields with highly contrasting soils, they may be merit in cutting back seeding rates to around 25,000 on soils that have lower water holding capacities.

Nielsen had lots of data to back up what he told us. Here is a 2011 presentation on the subject. 

On the other hand, I would not dismiss people like Marion Calmer and Greg Sauder who continue to push the envelop on yields with higher plant populations.  Maybe we are not there yet, but these guys are convinced it is the way to go.  My advice would be to plant what the seed company says or if you think they are just wanting to sell extra seed then cut back conservatively.  If you want to have variable rate seeding pay off do it where soils are very contrasting.  In addition, make sure your planter is planting stands as evenly as possible.  I have done yield checks  in Sauder's fields and it would be hard to say that uniform planting does not pay.