Granular inoculants outperformed peat-based systems in pulse crop trials in southwestern Saskatchewan.
Yanti Gan, a plant scientist at the Agriculture Canada research centre in Swift Current, Sask., said the study also showed it matters little where granular inoculants are placed.
Whether they are side-banded or laid with the seed in the row, the effect on the plant is the same.
Gan and his colleagues found that the granular inoculant method outperformed its peat-based counterpart on desi and kabuli chickpeas.
In a series of tests in 1999, 2000 and 2001 that were equivalent to six years of trials, he said results were “very convincing.”
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Granular application of rhizobia inoculant is on average seven percent more effective than peat carriers.
“Lentils had similar results to those of chickpeas. Granular has the edge … it keeps more of the bacteria alive longer and that is key.”
The study also showed that in a test comparing inoculated seed to seed without inoculant, in some soil types kabuli chickpeas showed less response to inoculants than desi varieties.
“It was seven percent in kabulis. In desi, it was 23 percent, similar to lentils.”
Gan believes the deeper, more densely rooted kabuli has a better ability to seek nutrients and water from the soil than its cousin, the desi.
“The ability to fix nitrogen (using rhizobia bacteria) also takes a great deal of energy and I suspect that the kabuli avoids this process because of the energy loss it requires. As a result, it isn’t as dependent on being inoculated.
“It is likely enough of yield increase, the seven percent, to make inoculating pay, but not a lot,” he said.
Some of the tests were done in heavier textured clay soils near Stewart Valley, Sask.
At that site, researchers found more pronounced responses to inoculation. Kabuli chickpeas showed as much as a 20 percent response to rhizobia inoculation compared to seven percent in lighter land near Swift Current.
“In the clay soil it would pay to inoculate the kabuli,” he said.
“We know it is more work for some producers if they have to have a third tank for the granular system. But if they can do it, it is the most effective way we have seen so far.”
All of the trials took place within the brown soil zone of southwestern Saskatchewan.
