What was the change in mass of the tree?

The original mass was after 5 years weighed 169 pounds however after drying the earth in the vessel. It weighed  164 pounds of wood, bark and roots.

What was the change in mass of the soil?

200 pounds is what the soil mass was originally. After 5 years it was 200 pounds and less about 2 ounces.

What did Van Helmont conclude from this experiment?

He concluded that soil adds to the mass of a tree and that the tree weighed 164 pounds after 5 years.