Yellow pea prices hover around $14 per bushel at the elevator, so growers want to be confident their drill isn’t damaging valuable seeds.
Charley Sprenger, an engineer at the Prairie Agricultural Machinery Institute, did a study to determine the level of seed damage caused by large air seeders. These require higher air velocity and volume for adequate seed distribution and to prevent plugging.
Her research also investigated the effect of seed moisture content on seed damage. The report was first published in Pulse Beat: the Science Edition, the online magazine of the Manitoba Pulse Growers.
Sprenger found that varying the fan speed did not affect seed germination, vigour or seed coat. Seed moisture was the primary factor determining damage.
“This wasn’t really a surprise. Our conclusions were in line with previous studies on seed damage in air delivery. The drills are getting bigger, so fan speeds are increased to ensure seeds get all the way out to the ends,” Sprenger said in a phone interview.
The stationary study was carried out with a 65-foot 2010 Bourgault Paralink hoe drill 3310 with a 6550 cart. This rig has six secondary manifolds, each with 11 openers, for a total of 66.
The air drill was selected from a list of commonly used seeding implements in Manitoba. This configuration has the potential for increased seed damage.
“We did the testing in the lab,” Sprenger said. “We sent the seed from each setup to the seed lab for tests on germination and vigour.”
Pea seeds were tested at three different moisture contents:
- Dried to 11.4 percent
- As received at 13.6 percent
- Wet at 15.1 percent
The three moisture samples were run through the Bourgault stationary air drill at three different fan speeds. Basic fan speed was set according to the manufacturer-recommended speed, beginning with medium, which was 4,250 rpm.
Researchers then reduced fan speed by eight percent to achieve 3,900 rpm. Finally, they cranked fan speed up by eight percent to hit 4,600 rpm.
AAC Carver yellow pea seed was used. It has an average thousand seed weight of 240 grams, representing an average pea seed size.
Seeding rate was 222.7 lb./acre (3.7 bu./ac), calculated to target approximately 7.4 to 8.4 live plants per square foot.
The fertilizer used was MES15 at a rate of 20 lb. P2O5/ac, resulting in 59.7 lb./ac of product.
Each treatment was run for the equivalent of 0.5 seeded acres with a targeted ground speed of three mph. Germination, vigour and seed coat damage using the soak test were assessed before and after treatments.
Seed moisture content, rather than fan speed, had the most significant impact on germination, vigour and seed coat damage. Damage is defined as percentage of wrinkled and smooth seed coats.
Pea seed dried to moisture content below the recommended level, down to 11.4 percent seed moisture, had significantly lower germination and vigour. These peas had more than a 10 percent reduction.
Results reflect similar findings from previous PAMI research on
air seeder distribution and seed damage to wheat, canola and soybeans. In soybeans, drier seed at eight percent moisture resulted in poorer germination than seed with 13 percent moisture.
The pea research showed that maintaining moisture content at the recommended level is imperative for good seed germination, vigour and seed coat quality.
