Red ink will be hard to avoid this spring when pencilling out seeding choices, but some production investments could help make the best of it.
Fran Walley, a professor and head of soil
science at the University of Saskatchewan, said when it comes to pulse crops, inoculating them with Rhizobium bacteria “is the best bargain out there.”
“You get more bang from your buck than just about anything you can give a plant to improve production,” she said on Jan. 10 at Saskatchewan Pulse Growers’ Pulse Days held during Crop Production Week in Saskatoon.
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Although air contains 78 percent nitrogen, the gas is unavailable to plants.
Pulse crops have the ability to take the nitrogen they find in the air and, with the help of a symbiotic relationship with Rhizobia bacteria, break its atomic bonds so that plants can convert the nitrogen into plant proteins.
Walley said that while Rhizobium do continue to live and often thrive in soil long after their host legume crops have been replaced by cereals and oilseeds in a rotation, farmers shouldn’t consider cutting costs by failing to reinoculate their seed during planting.
Recent work by Kevin Vessey of the plant science department at the University of Manitoba has shown that even if producers have been growing and inoculating their pulse crops with commercial inoculants, they should still apply fresh Rhizobium each year.
“Inoculation of grain legumes in soils already containing the appropriate Rhizobia to infect the seeded legume crop will result in a significant yield response commonly one-third to one-half of the time, but sometimes much higher in some species such as chickpea,” he reported.
Calvin Sonntag, president of the inoculant producer Philom Bios, said inoculants cost about $4 per acre.
“Relative to buying nitrogen it’s a bargain,” he said.
Walley agreed.
“If you were to buy the nitrogen, even if the pulse crop could take advantage of it, which research has shown in most cases it can’t, it would cost far more than the N the plant can fix from the air.”
Liquid inoculants cost about $1.30 per bushel treated while self-stick peats cost $1.50 and granular runs $4 per acre.
If a pulse crop fixes 58 pounds of nitrogen from the air in a season, Walley said, the cost of the nitrogen is 15 cents per lb.
“Fertilizer use efficiency of N is about 50 percent for most systems. Some is lost to the air in gaseous forms, some remains in the soil. Therefore to supply that 58 lb. of N from fertilizer it would take an application of 116 lb. of N to the soil. That’s worth about $56,” she said.
“Given the cost of inoculation it is easy to see the kind of bargain nitrogen fixation is.”
