EDMONTON – Using too much fan speed on the drill can bash big seeds like peas and reduce germination levels.
To see how much, the Alberta Pulse Growers and the Alberta Reduced Tillage Linkages teamed up and carried out tests in 2005 and 2006 to determine how to establish a better pulse stand.
At the recent Agronomy Update in Lethbridge, Roger Andreiuk said the work dealt with seeding rate calculations, the impact of air seeders on seed quality and inoculant, nodulation assessment, stand establishment and seeding rates.
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“I always like to ask this question, ‘how do you set your fan speed on the air drill?’ “
He said the farmers usually answer “so it won’t plug.”
But fan speed has implications for plant stand, said Andreiuk, an agronomist with RT Linkages.
To understand what happens to the seed during seeding operations, samples were collected from the truck or the bin and at various points along the path through the drill until the seed got into the soil.
“Seed was sent to 20/20 Seed Labs in Nisku. Germination was done, percent seed moisture, percent splits and inoculant counts using standard plating techniques. Over the two years, there were 96 samples taken from 21 farms that went through this process.”
As a typical sample from the results, farmer 1 used pea seed at 13 percent moisture and maintained germination from the tank to the opener, with only a one percent drop to 93 percent from 94.
Farmer 2 compared germination rates using a low fan speed before the boot and high fan speed before and after the boot.
“He had 10 percent moisture, so right away a flag should be going up. At the truck the germination was 95 percent, but with the low speed it dropped 10 percent and at high speed after the boot, it was down to 74 percent germination,” said Andreiuk.
“Imagine if you lost 20 percent of your germination. You’d done your 1,000 kernel weight calculations and figured out how many pounds per acre of seed you were going to put into the ground, and 20 percent of it is toast. When we’re talking seed bashing, we’re talking stand establishment, too.”
One sample taken in 2005, with peas at 12 percent moisture, didn’t lose much germination comparing the truck results and running through the drill with normal wind speed.
“But when he cranked it up, he lost almost 10 percent germination by going to a high fan speed. Splits went from 0.3 percent in the truck, to 3.3 percent splits after the boot, at high speed,” said Andreiuk.
“Same guy in 2006, at 15 percent moisture, he maintained his germination throughout both wind speeds. So moisture is a big factor to play with in terms of seed bashing with pulse crops.
“A different farm in 2006, one farmer had 10 percent splits coming out of his hose. With that damage on his splits, imagine what his germination was like.”
Seed coat cracking is one concern, but the study also looked at what happens with rhizobium inoculant when it gets bashed through the system.
The Canadian Food Inspection Agency uses 100,000 colony-forming units per seed as its guideline for peas. Andreiuk said the firstfarmer’s sample one had over a million in his tank and was still over 100,000 at the boot.
The second farmer maintained his inoculant numbers in the tens of thousands.
“The third farmer, at his truck, had 73,000, which is close to recommended. As soon as it went in the drill though, the numbers went way down. We were only at 7,000 colony-forming units per seed. What that effect in the field is, we’re not 100 percent sure, but the theory is the more inoculant you put close to the seed, the better nodulation you should get and the better plant you should get.”
Andreiuk said pea plants need good nodulation to take full advantage of nitrogen fixation. A nodulation guide, along with colour pictures, is available as a download from the 20/20 Seed Lab website. At the Alberta Pulse Growers website, there’s a video showing nodulation assessment.
“Basically, with a nodulation assessment, you assess the crop first. Is it yellow, green, tall, short, healthy, etc., and assign a number to that. Then you dig up the plant. Let it soak in a pail of water for a few minutes to separate the soil from the roots. Assess nodule colour and number, position relative to the crown and score that out of 13.”
Andreiuk said there are things a farmer can do to reduce the effect of air seeders on pea seed.
“Check the moisture content of your seed. If it’s on the dry side, you might want to increase your seeding rate to compensate for some bash.”
The Prairie Agriculture Machinery Institute has a research bulletin on its website that explains how to moisturize seed, he said.
“Adjust your fan speed to just enough. That farm 3, who was getting good results with his normal fan speed, after we had taken samples he cranked it down another 100 rpm and plugged it. So he was right on the verge of just having enough fan speed.
“If you’ve got some new openers, seed something else first, or band some fertilizer through them just to wear any sharp edges off before getting into peas. Consider air brakes. There’s one from Australia, the D cup diffuser system, that will help reduce damage at the boot.”
