Nitrogen fixing bacteria need to be added to every pulse crop.
Fran Walley of the University of Saskatchewan told producers attending the Pulse Days seminars at Saskatoon’s Crop Production Week that recent research supports the idea of adding more rhizobia to the mix each time pulses are planted.
Rhizobia that infect pulse crops’ roots help the plants to better remove nitrogen from the air and sequester it in the ground. But rhizobia are not that tough and in harsh conditions, their population and abilities to trigger nitrogen sequestration can falter.
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In testing 28 prairie soils that have had long-term inoculated pulse crops under ideal laboratory conditions, 24 of those delivered a benefit from a fresh inoculation when producing a pulse crop.
Benefits varied. In most cases yield was higher due to inoculation. In many cases, both yield and the amount of nitrogen fixed in the soil were increased through inoculation.
In a few cases, the response was not significant, but researchers say other factors in the soil may have also been at work.
In four field scale studies of long-term inoculated fields, three showed significant yield improvements and enhanced nitrogen fixation due to inoculation.
Lentil yields rose by up to eight bushels per acre due to inoculation, with a low of a two bu. per acre increase being seen in another field.
At 25 cents per pound, eight bu. of lentils is worth $120. A two bu. increase at the same price would have a value of $30.
“We can be sure that inoculation pays off at harvest time,” said Walley.
Not tested in the lab or the field were resistance to disease or physical stressors such as hail or extremes of weather that are known to be enhanced by inoculation.
