Corn Population Trials Propel Allee On-Farm Trial Project

Mark Licht, Field Specialist-Crops, Northwest Area

Problem Statement:

Trends show that corn seeding rates are increasing on average of 400 seeds per acre per year. Research and trial data indicates that higher corn seeding rates are resulting in mixed returns. Iowa State University now recommends a corn seeding rate in the range of 30,000 to 35,000 seeds per acre to result in economically optimal yields. Corn growers across west-central Iowa are asking how far they can push corn planting populations without hurting return on investment.

Programmatic Response:

To get a better handle on optimum seeding rates with improved hybrid genetics a series of corn plant population trials was proposed in conjunction with the Allee On-Farm Trial project. A group of six famers where approached with this trial idea and four of those setup a trial looking at corn planting populations. Targeted corn plant populations were based on the farmer’s normal practices with two additional rates being used in the trials. The additional rates were plus and minus one planter gear setting which resulted in approximately plus/minus 2,000 seeds per acre.


The results of the on-farm trials reinforced Iowa State University Extension’s recommendations for optimal planting populations. These trials also, support continued on-farm efforts due to the variability both within and across field locations. Having on-farm trials was important in helping cooperating farmers make planting decisions as confirmed by a farmer near Sac City who said; “I plan to use the results of this trial as the population I plant with next year.”

All cooperating farmers that conducted an on-farm plant population trial have indicated a desire to conduct a similar trial in 2009. Each participating farmer estimated that their individual involvement with the on-farm trials helps them make better management decisions. A cooperating farmer near Nemaha said that involvement in the Allee On-Farm Trial project provided “invaluable, site specific data and only required an additional hour during planting and harvest.”

February 20, 2009

100 – Corn and Soybean Production and Protection

Page last updated: February 20, 2009
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