Just for reference ... here's some volumes of tree "boxes".
24" (inner base 18"x18", inner top 24"x24", inner vertical height 24") : 45.8 gallons
28" : 75.6 gallons
32" : 108.6 gallons
Shown in the foreground of the photo from left to right: a 24" tree box, some black 15 gallon nursery pots, and a black 25 gallon nursery pot.
