Did they test the soil and plant a control crop of corn only in nearby similar conditions?

When it comes to gardening I’ve heard countless stories of people trying some intervention and declaring “it works for me” without ever having tested the conditions or using a control. Those kinds of results can be safely ignored as unscientific.

Heck, one thing I’ve noticed with gardening is that even if you attempt to plant a bunch of crops under identical conditions (as best as you can manage) there’s so much variability that you get widely varying yields from one plant to another for completely unknown reasons.