Calibrating Your Grain Drill

In last week’s post, I mentioned that small grain seeding rates should be increased once we are past the optimum time to offset the loss of tillers and ultimately reduced yield potential caused by the delayed planting date.  Consequently, you need to recalibrate your drill. Recalibrating your drill every spring is a good practice anyway as seed size and weight of different seed lots vary year-over-year and among varieties.

Modern air seeders and drills with central seed metering are relatively easy to calibrate and your user manuals have detailed instructions on how to calibrate them.  Older double disk drills are a little different story and the seeding rate tables seeding rate tables found in your operator's manual or on the inside of the seed hopper lid are a guideline at best.

Calibrating your drill in the yard is an easy way to take the guesswork and some of the stress out of it prior to getting in the field.  By measuring the circumference of the press wheel or drive wheel and then turning the wheel a certain number of times we can calculate the distance traveled.  This number multiplied by the row spacing gives the area seeded.  Catching and weighing the seed dropped by a few of the metering wheels will then allow you to calculate the seeding rate in lbs. per acre for each lot. 

The Samuel Roberts Noble Foundation from Oklahoma created a useful YouTube video that explains the steps described above very well. A cover story in Prairie Grains issue 7 describes how the Ramstad brother from Ada built a device that hooks an electrical motor on the drill frame to drive the press wheel the correct number of revolutions.