Is it permissible for a father to acquire agricultural land with his son's money and then dispose of it by selling or bequeathing it without his son's permission?

The money you sent to your father, if it was a gift, then it belongs to him. However, if it was for assistance with expenses and the remainder belongs to you. It is the right of parents that their children show them piety and help them, especially in building his new family, while noting that describing the Sharia as "bitter" is not befitting a Muslim. Resolve the disagreement with your father respectfully, and remember the words of Allah Almighty: "And do not forget the favor between you. Indeed, Allah is Seeing of what you do" (Quran 2:237). You can seek the help of some influential individuals to resolve the issue amicably.