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Six Steps To Perfect Pulse Inoculation

The number of acres of pulse crops planted across the prairies is growing and so is the number of farmers who are becoming adept at cultivating them. Aside from their yields, they’re reaping added benefits, since pulse crops fix their own nitrogen. In order to do that, pulse plants team up with soil bacteria. Here are a few tips from industry leaders on how to best make that match work.


Dale Risula, provincial special crop specialist with Saskatchewan’s Ministry of Agriculture, urges farmers to check pulse crop inoculant product labels carefully because each type of pulse has specific Rhizobium bacteria to match. Each bacteria is identified by its scientific name on the label. If growers are uncertain whether or not the inoculant they’re purchasing is designed for the pulse crop they’re planting, then they should ask the ag-dealer or call their provincial agriculture department’s toll free line. Pulse crop inoculant product information can also be found on the Saskatchewan Agriculture web-site at


Proper application of the inoculant is key. Garry Hnatowich, senior research agronomist with Novozymes, lays out some guidelines. Peat-based inoculants are best applied as a slurry application. If growers are applying it dry, he says, the seed should be dampened slightly to make the peat stick better. When applying liquid inoculants, growers should shake the bag well prior to application.

Application is less tricky with granular inoculants because they’re applied at the time of seeding and go down like a fertilizer. There is, however, a maximum number of bags that can be loaded in the tank at a time. Too many can cause compaction and plugging will occur. Hnatowich also advises farmers to check the amount of seed-placed fertilizer going down with the crop inoculants because inoculants can be “burned” just like seed. Growers should follow manufacturers’ instructions for safe levels of fertilizer placed with inoculated seed.


Inoculants contain living organisms that are subject to drying out and dying. Risula describes heat and sunlight as “enemies of the bacteria” so farmers should store the inoculant in a cool, dry place, out of direct sunlight. Hnatowich concurs, “Regardless of the formulation, inoculants should be kept in as cool a place as possible without freezing.” Hnatowich emphasizes that growers need to keep inoculant out of direct sunlight even out in the field.


Risula recommends preparing seed-based inoculants within half a day of when they’ll be put into the field. Though some companies claim their products can be stored overnight, Risula doesn’t think it’s a good idea. His advice is to prepare the inoculant in two different batches instead.

If growers experience a delay due to inclement weather or to equipment breakdown, Hnatowich encourages them to contact the manufacturer and find out whether re-inoculation is required.

Maurice Berry, former chair of the Saskatchewan Pulse Growers, agrees. He farms 4,900 acres in southeastern Saskatchewan in a pulse, oilseed and cereal rotation. Because the inoculant expires, Berry is very careful to order early and to order exactly the amount he needs. His main challenge with granular inoculants has been caking. Berry says, “We try not to leave it in the tank overnight or if we have to, we rotate it.” Berry finds that if the weather is very dry, caking may not be a problem, but on damp mornings it is.


According to Risula, some research suggests there may be benefits to using granular inoculants. Because they are applied in furrow rather than on the seed, plants obtain a greater degree of inoculation, usually covering the whole root of the plant. In seed-based applications, nodules have been found to congregate close to the seed, limiting their nitrogen-fixing capacity.

Hnatowich’s rule of thumb goes like this: “A granular inoculant will be better than or equal to a peat-based seed-applied inoculant, which will be better than or equal to a liquid seed-applied inoculant.”

Granular inoculants find favour on a couple of fronts. It’s applied in much higher volume, potentially translating to some pretty high numbers of bacteria onto field. Second, Hnatowich says, granular inoculants are more durable in terms of survivability. Peat and liquid inoculants can perform as well as granulars under ideal conditions, but “the further you move from ideal conditions, the greater the difference in the effectiveness between them,” he says.

Third, granular inoculants can be used with conventional seed treatments; many peat or liquid formulations can’t. “The planting window or survivability of an inoculant, whether peat or liquid, will be affected if combined with a seed treatment,” Hnatowich says.

For Berry, granular inoculants are most effective on land where pulses have never been planted before. He finds using them a lot easier, both for calibrating and applying, because of the third tank on the air seeder. Over the years Berry has also applied inoculants with peat, slurries, and liquids; he maintains they’re all effective if they are applied correctly, but the greatest success he’s had is with granular.


Finally, Hnatowich’s biggest piece of advice is not to rush. “Don’t rush your application. Take time to do it right. What you’re doing is equivalent to pounds and pounds of nitrogen fertilizer so it’s worth doing it carefully,” he says.

Patty Milligan is a freelancer writer from Bon Accord, Alta.

About the author


Patty Milligan is a freelance writer based at Bon Accord, Alta.

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