You’ve been growing pulse crops for many years. Each spring you add rhizobium to the seed cocktail that you put in the ground. Do you really need to be adding all those new bugs? Shouldn’t there be enough of the right bacteria in those fields already?
Yes and no, answers a senior soil scientist.
Fran Walley of the University of Saskatchewan told producers attending the Pulse Days seminars at Saskatoon’s Crop Production Week Jan. 13 that recent research is clearly on the side of adding more bugs to the mix.
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Rhizobia that infect pulse crops’ roots are strong when it comes to causing plants to take advantage of their ability to take nitrogen from the air and sequester it in the ground.
However, they are not that tough in the harsh conditions of the soil. In time, their population and special abilities to trigger nitrogen sequestration will falter.
In a study under ideal laboratory conditions that tested 28 samples of prairie soil in which inoculated pulse crops had been grown, 24 delivered a benefit from new inoculation when producing a pulse crop.
Benefits varied, but in most cases yield was higher due to inoculation. In many cases, yield and the amount of nitrogen fixed in the soil increased. In a few cases the response was not significant, but researchers say other factors in the soil may have also been at work to hold back the plants.
In four field scale studies, three found that inoculation resulted in significant yield improvements and enhanced nitrogen fixation. Lentil yields rose by up to eight bushels per acre due to inoculation, with a low of a two bu. increase in another field.
Neither the lab or field studies tested disease resistance or physical stressors such as hail or weather extremes that inoculation is known to enhance.
