I would like to substitute farro for barley. What changes would I make?

Hi Nancy! If you still have the package, you can follow its instructions for soaking vs not soaking and cook time. If it's pearled farro, you should be able to skip the soaking step and add it in later (it cooks quicker). Here's a chart from https://www.walderwellness.com/how-to-cook-farro/

Pearled farro: 15-20 minutes
Semi-pearled farro: 25 minutes
Whole farro: 30-40 minutes + overnight soaking