Run Import Planting Schedules from the Other Utilities panel to load default Planting and Seed Mix Schedules.

The Artisan - Seed Mix Schedule is displayed in the Project Browser...

Select Artisan - Seed Mix Schedule to open...

The Artisan - Seed Mix Schedule is filtered to display only Seed Mix records...

The Total column is a calculated value based on the Application (Sow) Rate and the associated area...

Use standard Revit tools to modify schedule as required.