Earlier quoted context omitted.
What do you mean “my” money? When you spend it, it’s no longer yours. You have land now in this line of reasoning.
Can I sell this land to someone else if I need money? Is the use of that land for the new owner restricted or can it be repurposed for agriculture or other uses?
Most of these situations the land is placed in a thing called a 'land trust', at least that is the structure I see most often. These are generally then set out with an elected governing board, and a set of bylaws and rules about the lands. Often these rules can require a voting majority of everyone who placed in money on the land to make decisions about the land. Usually there is a minimum amount of land you personally must purchase in the larger purchase to constitutes a "share" like 1 acre.
If someone has a change of heart later down the line the trust actually is a very hard entity to get around even if you are on the board of a small 5-10 person land trust. There have been examples of such boards being flipped and sold, but more often than not what you encounter is: one of the board members is interested in selling off the land and is utterly unable to because of how the trust is structured. They can be pretty robust.
The only difference between buying land and creating your own trust and foundations like this is, the foundation ultimately controls all the board seats of land trust generally.