Here's a little design I came up with after having hundreds of turf and not wanting to store it all in 50+ chests.
A moleworm burrow can hold 50 stacks of items, so each moleworm burrow can be used to store 500 tiles of turf. A lot of people consider turf precious since it's non-renewable without world hopping - so moleworm burrows are a little bit safer than chests because they can't burn.
Each pen has a burrow holding the turf that's underneath the pen. My forest turf pen needs three moleworms to hold all the turf while my grass turf pen needs two. Everything else has a single moleworm. The pens are organized by least dominate to most dominate as one turf will always cover another one when placed next to each other.
Whenever I need turf for a project, I dig it a burrow up and let the moleworms store it again.
www.twitch.tv/moonrockz