How deep should baseball infield mix be?

3 to 6 inches is recommended.  Infield mix depth a new field can be easily planned and budgeted.  Adding more dirt to an existing infield may be a little more tedious.  Overall, you do not want the sub-base mixing with the infield mix surface when dragging or playing.  Low spots may need infield mix added more than other areas.  A 3 to 4 inch minimum will help keep the infield dirt surface free of contaminants and unsuitable dirt from below.