Grain drill calibration is a critical yet often ignored part of successful forage establishment and pasture renovation. Planting lower seed rates than recommended can result in thin stands susceptible to weed encroachment.

Buckman jm
Extension Agent, Agriculture and Natural Resources / University of Kentucky Cooperative Extension Service
Undergraduate Student / Agricultural Systems Technology / Murray State University

Planting more than the recommended seeding rate is undesirable due to the high seed cost of improved forage varieties. Most farmers just use the seeding chart already on their grain drill. As drills wear, and tires and cogs get replaced, actual seeding rates can vary significantly from seeding charts found on drills.

Grain drill calibration

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We have designed a simple and straightforward calibration method that can be applied across a wide range of grain drill types and manufacturers. This method is centered on a pre-made chart that allows producers to determine the quantity of seed to catch for each disk opener for a desired seeding rate. This minimizes the need for producers to carry out detailed mathematical calculations.

In order to calibrate the drill using this method, you will need the following items: a container to catch the seed, tape measure to determine the circumference of the drive wheel and the disk opener spacing, flags to mark stopping and starting points for in-field calibration, a floor or bottle jack for stationary calibration and a gram scale with 0.1-gram accuracy.


Don't make a mistake - calibrate!

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This procedure and chart were made into a decal that can be affixed to grain drills. This decal has been distributed to counties and soil and water conservation districts in Kentucky that have drills that are loaned or rented. A copy of the procedure/chart and an informational video can be found on the UK Master Grazer web page (University of Kentucky - Master Grazer).  

C.D. Teutsch is an associate extension professor, University of Kentucky – Lexington Department of Plant and Soil Sciences.

Items needed to calibrate drill: