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Corn Seed Size and Planting

Categories: PLANTING, CORN
Planter accuracy is dependent on many factors and is commonly associated with seed size. Seed can range in shape and size, influencing seed drop if not managed properly. Standardizing seed size would be highly inefficient, as growing conditions of seed production areas and genetic tendencies of hybrids both impact the variation. The evolution of planting technology has done an incredible job of overcoming seed size differences, but the right combination of plate sizes and air pressure is required to achieve good accuracy. With the proper combination, nearly any seed size can be planted accurately. Seed Size Information To maintain uniformity for planters, seed is sized and separated by shape and size fraction. Golden Harvest corn seed is divided into categories of flat or round, then divided into four seed size categories, 1, 2, 3, or 4, based on seeds per pound (table). The following tips can help maximize seed drop accuracy with your specific type of seed meter.

Finger Meters
  • Properly maintained finger pickup meters can plant wide ranges of seed sizes and weights.
  • Finger meters work particularly well with larger seed sizes (such as R3 and F3), which minimize space between seed and fingers to help reduce doubles and triples.
  • Smaller seed sizes (R1 and F1) can be successfully planted with proper adjustment.
    • Finger tension is critical to minimize slop in fingers that allows multiple seeds to be captured or large rounds from escaping.
    • Adjust the brushes to the proper seed size.
  • Finger meters are more sensitive to excessive planter speeds, requiring very specific speeds to minimize skips.
    • Planting speeds of 4.5 to 5 miles per hour (mph) maximizes most finger meters.
  • Always use appropriate amounts of graphite seed lubricant to ensure spacing.
Vacuum Meters
  • Vacuum seed meters can operate at faster planting speeds (up to 8 mph), but planter unit bounce at higher speeds (5.5 mph or greater) can impact seed placement.
  • Properly adjusted down pressure can mediate planter bounce, but excessive pressure can cause sidewall compaction.
  • Changes in seed size do require adjustment when using vacuum meters:
    • Larger seed will tend to require additional vacuum pressure (see below reference chart).
    • Depending on planter type, seed discs may need to be swapped if changing to different seed sizes (see reference chart). Proper seed disk size can minimize vacuum pressure needs, lessening hydraulic demand on tractors.
    • Flat disks provide singulation with varying seed size/shapes, but do not have a cell to help carry the seed and often require higher levels of vacuum.
  • Always utilize proper amounts of talc or seed lubricant based on manufacturer recommendations.
It is important to consult the operating manual of planters to become familiar with the necessary adjustments for each seed size and to ensure the best stands possible

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