I used to work for Tennessee Corp., which was a major supplier of micronutrients (they called them trace elements). The major ones were copper, zinc, manganese and iron. Other micronutrients usually accompanied the major ones.
Major quantities of fertilzer were applied as bulk blends of small pellets. Based on soil analysis, the farmer asked for a quantity of fertilizer of a specific N-P-K analysis, with specific micrnutient addition.
An the N-P-K pellets were blended in a mixer, micronutrient powders were added to coat the pellets.
The TVA (Tennessee Valley Authority) at their Fertilizer Research Facility in Alabama once researched adding Sulfur powder to fertilizer pellets. This was to replace sulfur usually washed from the air by rain, since acid rain concerns were causing chemical and power plants to reduce sulfur emmissions.
So, replacement of minerals has been a big business for a long time.