Industrial farmers generally use crop varieties that are likely different from those grown in smaller scale organic farms.

I suspect that a valid scientific study to answer this question would have to compare similar soils, growing conditions and crop varieties under controlled organic and non organic growing practices. I doubt that many of the research projects included in this study did this?

It is likely that many who choose "organic" products are more concerned with pesticide use, than marginal differences in nutrient values. I am not sure of the purpose of the study, or who funded it? But, it is likely being broadly "marketed" in the maedia to benefit large agricultural practices, rather than to provide useful information to the consumer.

I found this interesting:
organic and conventional farming practices impacts on nutrients