[RetroTechie]

Article doesn't state yield w/ respect to best-yielding fields. But up to 40% higher yields on fields that had a good deal of pathogen fungi in the soil ("unhealthy" soils, if you will).

So this is not upping yields 40% across the board. More about bringing poorer-performing fields up to the level of better-performing ones.

Personally I think a well-managed field wouldn't need this type of inoculation, as it would have the beneficial fungi in its soil already (and these research findings seem to indicate this). The #1 thing there would be to disturb that soil as little as possible (like, no-till farming).

For less-well managed fields, this might be a quick 'n dirty fix to undo some of the shortcomings in a field's condition.