• Soybean seed size is influenced by both genetics and the environment. Under similar growing conditions, varieties will differ from each other in the seed size they produce – small, medium, or large. Genetic effects on size of seed are largely predictable, but weather conditions and their effects on seed size are not. Consequently, growers are sometimes faced with using seed sizes that are above or below the norm. With appropriate planter adjustments, however, excellent planting accuracy and stands can be achieved, even with large or small seed.
• This article, produced in a collaborative effort between Pioneer and equipment providers, offers management tips to help growers maximize planter performance and ensure the highest possible planting accuracy with larger soybean seed. Refer to your planter manufacturer’s owner’s manual for complete recommendations.

Central Commodity System (CCS™), Bulk Fill, or Air Seed Delivery (ASD) planter systems may be challenged by larger seed as well as treated seed. To help ensure a high level of performance, proper attention must be given to:

• Planter Lubricants: The liberal use of talc, graphite, or a talc/graphite blend, specific by planter type, is critical. Thorough mixing of these lubricants in seed generally produces the best results.
• Seed Treatment: The planter performance of untreated versus treated seed may be different. Generally, larger seed combined with treatment will require a higher level of management. Tank pressure, fan speeds, and other adjustments should be made for the specific seed/ treatment combination that is being planted. Refer to the planter operator’s manual for recommendations.
• Ground Speed: High population settings, especially when combined with high ground speed, may provide challenges. With higher ground speeds, the metering units are operating at faster RPM’s, making it more challenging to keep seed in place as the unit rotates. If meters are “starving” for seed, a reduction in ground speed may provide a solution. Do not exceed the planter manufacturer’s recommendations for ground speed.

Kinze^® Brush Meter: Brush meters have two discs available for soybeans. When the size falls on the split, typically you will need the 48-cell (dark blue) plate.

Table 1. Kinze brush meter plates for soybean.

Kinze EdgeVac^®: Kinze recommends graphite and does not generally support talc/graphite blends except for extremely high-humidity conditions.

Case IH^® Vacuum Planter: The soybean seed disk with 130 holes can create a low vacuum issue when the larger soybeans touch each other. This causes the soybean seeds to sit in the pocket incorrectly. Use the soybean disk with 80 holes. If the maximum planting speed is too slow with the 80-hole soybean disk, use a 100-hole soybean disk.

Table 2. Case IH vacuum planter disks for soybean.

John Deere^® Vacuum: Start with eight inches of vacuum, and adjust to match seed size/treatment. John Deere recommends talc only and does not support the use of graphite or talc/graphite blends.

John Deere Radial Bean Meter: There are three standard soybean seed size settings. Refer to operator’s manual for the correct setting to match the seed that is being planted.

• Pioneer conducted plantability tests of 2016-produced soybean seed using seven different planter metering units.
• Seed tested included 10 sources, ranging in size from 1,985 to 2,726 seeds/lb.
• Planter-stand seed drop of 1,000 seeds would represent perfect plantability.

• Seed size had very little effect on seed drop and singulation for any of the meters tested over the range of 1,985 to 2,726 seeds/lb.
• Results indicate that acceptable plantability could be achieved with seed as large as 1,985 seeds/lb with proper planter settings or plate selection on any of the planters tested.