Database Research Summaries
2018 Soybean planting date and tillage interactions for variable rate seeding across management zones

calendar_today Year of Research: 2018
update Posted On: 12/04/2019
group Missy Bauer (Principal Investigator, B&M Crop Consulting)
bookmark Michigan Soybean Promotion Committee

Research Focus

The focus of this project is to determine if a planting date and tillage environment should be taken into consideration when determining planting populations in variable rate planting.


  • Determine if the yields and economics of variable rate soybean planting can be improved by writing prescriptions based on planting date and tillage.
  • Evaluate the effect of the planting date, tillage, and population on the time to canopy closure.
  • Determine whether yield components are affected differently based on planting date and tillage as populations change.


  1. The early planting date increased yields on average 3.1 to 4.8 Bu/ac. The earlier planting dates resulted in reaching 75% emergence 10 to 19 days sooner than the late planting date. The V1 growth stage was reached 7 to 16 days sooner than the late planting. The sooner V1 is reached the more opportunity for a higher total number of nodes on a plant. The early planting dates increased canopy closure 4.6 to 15 days sooner than the late planting dates.
  2. Vertical tillage increased yields in both the early and late planting date averaging 2.0 Bu/ac across the site year locations. The early planting date averaged 4.1 Bu/ac increase across the locations in 2017 and 2018.
  3. The best economical treatment across the site year locations was early planting with vertical tillage and the lower average population (VRA B). In comparing early planting vertical tillage with VRA B to planting late in no-till with VRA B, yields increased an average of 6.7 Bu/ac across the site year locations. If planting late; vertical tillage and higher populations were important and increased yields an average of 3.2 Bu/ac compared to no-till with lower populations.
  4. Population did not consistently influence tillage. However, in the late planting dates, the no-till treatments did have higher yields with VRA A prescription but it was not always economical.


  • This study may help soybean farmers to improve profitability by fine tuning their seeding rates by planting date and tillage system across management zones.
  • This could also help farmers without variable rate determine if planting date and tillage should be taken into consideration when determining the average planting population on a field-by-field base.

For more information about this research project, please visit the National Soybean Checkoff Research Database.

Funded in part by the soybean checkoff.