In my personal experience, organic farming causes much more soil loss than conventional farming.

Organic dryland cereal farming depends on tillage for weed & pest control. Not only is the land plowed during planting and after harvest, every third year the land is left fallow. While left fallow it is plowed monthly.

Conventional farmers have substantially reduced their usage of tillage increasing their chemical usage instead. Those chemicals may be not be good for the ecosystem, but they result in orders of magnitude less soil loss.