Rough seed handling influences germination, emergence and even harvest
Multiple studies show rough handling of seed prior to planting can damage seed coats and bruise seed embryos. This damage is enough to degrade germination and emergence by as much as 20%.
Aside from money wasted on soybeans that don’t germinate or emerge, the biggest cost of seed damage comes at harvest. Soybeans in fields with reduced final populations take advantage of the extra room between individual plants, which can create challenges at harvest.
“There are two issues with soybeans growing at lower populations,” says Mike Staton, Michigan State University Extension. “One is that soybean plants at lower populations tend to have stems like tree trunks. That can make them harder to cut if you have 1½" sickle sections rather than 3" sections on your soybean harvesting header.”
The second issue is due to increased penetration of sunlight to the base of plants, which encourages low branching and podding. Soybean branches and pods that develop less than 2" above the ground are difficult for platforms to cut and collect, leaving “stringers” waving behind combines and unthreshed pods in the field.
The advent of bulk seed and seed tenders has escalated the need for gentle seed handling.
According to a study at Ohio State University by Ben Rethmel, steel augers produced the most seed damage, followed by brush-flighted augers and belt conveyors. Plastic-cupped augers caused the least damage.
The speed and incline of seed transfer equipment play a role in minimizing seed damage, notes Mark Hanna, Extension agricultural engineer, Iowa State University.
Minimize the distance soybeans have to fall when filling the planter to avoid seed damage.
“The steeper the auger, the more potential for seeds to slide back between the housing and the auger flighting, which increases the potential for damage,” he says. “Speed is also a factor. The faster you run an auger or conveyor, the more potential for seed damage. Speed also creates the potential for impact damage.”
Impact damage can be caused by how the seeds strike deflectors and ends of augers and conveyors, says Kenneth Hellevang, Extension agricultural engineer, North Dakota State University.
“The way seeds exit an auger or conveyor is a critical part of seed handling,” Hellevang says. “Seeds striking a hard metal surface at a right angle have more damage than seeds striking an angled or padded surface.”
To minimize seed damage, experts recommend the following:
- Operate augers or conveyors on seed tenders and other transfer equipment at the flattest angle possible, at the slowest speed possible and as full as possible.
- Seeds should strike impact plates or deflectors at an angle.
- Use padded strike plates with rubber from inner tubes to reduce impact damage.
- Minimize the distance soybeans “free fall,” especially when striking a metal or hard plastic surface.
“In work we did with pinto beans, which are somewhat more delicate than soybeans, any time we had more than 6' of free fall, we could measure increased damage,” Hellevang says.
A final tip to minimize seed damage: Transfer seed to planters and seed tenders as the last job for the evening rather than first thing in the morning.
“Damage to seeds during transfer can vary with temperature,” Hellevang says. “There is a slight potential for more damage to seed that’s transferred in the morning at 40°F than in the afternoon at 75°F.”