EDMONTON – Getting inoculant rates right might require exceeding recommended rates on the label.
Research at the Saskatoon branch of European agricultural giant Novozymes Biologicals, formerly known as Philom Bios, has shown that increasing the number of rhizobium in the field may be necessary for producers targeting high pulse crop yields.
Research agronomist Garry Hnatowich has 14 site years of data on pea yields with varied rates of nitrogen-fixing rhizobium inoculant.
“If you have the (plant) genetics, if you have the water, if you have the other nutrients and you get some sunshine and you want to set a very high target for your yields, then you need to increase your inoculant,” he said.
Read Also
VIDEO: Green Lightning and Nytro Ag win sustainability innovation award
Nytro Ag Corp and Green Lightning recieved an innovation award at Ag in Motion 2025 for the Green Lightning Nitrogen Machine, which converts atmospheric nitrogen into a plant-usable form.
Hnatowich developed a production model that was based on pea prices of $5 per bushel.
“My model appears to have very rapidly gone out of date. Peas are bringing a lot more than that so my estimates will be very conservative about the (financial) benefits of additional inoculant,” he said.
Hnatowich told producers attending the Farm Tech 2008 conference in Edmonton that the recommended rate of slightly more than four pounds of granular inoculant is sufficient if they target pea yields of about 30 bushels per acre.
“If you plan on 40 bu. you might want to lean towards five lb. If you think 50 bu. is in reach, then maybe 5.5 lb. If 60 bu. is your goal, you will likely need more bugs and that will require six lb.” he said.
Westco Fertilizer researcher Rigas Karamanos said an average pea crop of 30 bu. per acre requires about 150 lb. of nitrogen to reach that yield. The plants are capable of fixing far more nitrogen than that from the air, provided rhizobium are able to form nitrogen fixing nodules and have enough phosphate to power them.
Phosphate levels in the field should be established through a soil test, and producers targeting high yields need to ensure enough is available to the plants.
Hnatowich’s estimated net return to producers, based on $5 peas and $3.50 per lb. granular inoculant, range from $20 per acre for 40 bu. peas to more than $40 per acre for a 55 to 60 bu. crop.
“With two additional pounds of granular inoculant costing $7, the returns are significant.”
Hnatowich said other formulations of inoculant delivery, such as liquids and peat, will also deliver similar results but require greater attention to application detail to ensure that enough bacteria are in the seed row and available to the growing root structure.
“We prefer the seed row placed granular (inoculant) because it isn’t prone to desiccation the way liquids and peat are … and it gets the bugs into seed row better.”
Hnatowich said granular inoculant tends to create nitrogen-fixing nodules on lateral roots as well as the crown region of the root structure, creating greater nitrogen-fixing capability.
Granular delivery requires a seed tank and meter.
Otherwise, producers may be limited to using peat or liquid based inoculants.
