Biological Systems Engineering, Department of



Stephen D. Kachman

Document Type


Date of this Version



Published in Applied Engineering in Agriculture Vol. 27(2): 177‐183. Copyright 2011 American Society of Agricultural and Biological Engineers. Used by permission.


Variation in corn seed spacing from a John Deere MaxEmergeTM Plus Vacumeter planter was evaluated on the University of Nebraska Planter Test Stand in a laboratory setting for two seed tube conditions (new or worn) with two examples of corn seed shape (round or flat). Seed spacing uniformity was measured using three seed spacing uniformity parameters: Coefficient of Precision (CP3), ISO Multiples index, and ISO Miss index.

Differences were detected in all three seed spacing uniformity parameters due to the seed tube condition. The new seed tubes had better seed spacing uniformity than the worn seed tubes, within each example of the seed shapes (round or flat) used in this experiment. For the seed used in this experiment, the round corn seed had better seed spacing uniformity than the flat corn seed, within each of the seed tube conditions (new or worn).

A recommended schedule for seed tube replacement to maintain seed spacing uniformity has not been developed, and more research in this area is needed. Currently, sugarbeet growers in western Nebraska use one of three options: a) test one of their seed tubes on a good planter test stand every year before sugarbeet planting season and replace all tubes when results indicate it will improve seed spacing uniformity to the desired level; b) feel the inside front surface of the seed tube every year before sugarbeet planting season and change seed tubes when the feel of the surface changes from a slick plastic to a very fine sandpaper; or c) replace seed tubes before sugarbeet planting season when they have planted over approximately 150 acres of corn per planter row with their current seed tubes.