The Shmitta year and the Yovel, Jubilee year - the rest every seven years is supposedly a chok - a mitzvah without rational explanation. The second of the double weekly reading -B'Chukotai - with my "chok"(plural) tells of the blessings and curses which result from following or disregarding these Mitzvot (commandments)
Leviticus 25:10 includes the words on the liberty bell: Keratem dror b'artzechah - Proclaim release/homecoming throughout the land. This is a spiritual homecoming. I disagree that the laws of Shmitta and Yovel are without explanation. They certainly are among the most radical and difficult and laws, particularly for the wealthy and powerful, to observe. It requires them to abandon free their slaves, to open their fields for the poor, and the wild beasts (!) and to become equal in status to other human beings. To give up the idea that they are entitled to what they or their ancestors have wrested from the earth and from others because (variously in the text): "G8d said so", or because it is what the eretz or earth requires, or because it's right. Here is one verse, and the Rashi Text that is interestingly an encapsulation of these laws.

The word "hefker" means owner-less - like a $20 bill you find on the street and nobody claims it. And the word "s'fiyah" means "with a mind of its own" This isn't just about grapes, it's about us, about wildlife. "In wildness is the preservation of the world, said Thoreau, We are meant to belong only to the One who formed us, and to have a mind of our own, at least every seven years, and to sound the shofar of freedom on the 50th year. Otherwise the wealthy and powerful feel they are entitled to own land, to own humans, to despoil the earth. Every 7 and then 50 years sounds about right to me, how about you?