How many fields in northern Virginia are turf field and not grass?
Can't give you a number but the far majority of them are turf.
I believe most in Prince William County are turf except for Gar-Field and Brentsville District. Maybe there's another one with grass. Not sure.
James Monroe is grass.
Everything in Stafford is turf.
Kettle Run and Fauquier have grass while Liberty has turf.
Everything in Loudoun is turf.
As for Fairfax City/County and Arlington, I believe all of them now have turf fields.
I hope this helps! Was there anyone specific you were looking for?