Shemita, the year of release, is the seventh year of a recurring cycle in which, by biblical command, agricultural land in the Land of Israel lies fallow and debts are released. Exodus 23:10-11 commands the fallow so that "the poor of your people may eat, and what they leave the beasts of the field shall eat". Leviticus 25:1-7 frames it as "a sabbath of solemn rest for the land, a sabbath to the LORD". Deuteronomy 15:1-11 adds the remission of debts, together with a warning against the mean calculation of refusing a loan because the seventh year is near. Produce that grows of itself is ownerless and available to anyone.
Rabbinic law developed both halves, and both produced characteristic legal instruments for their difficulties. Hillel's prosbul, recorded in the Mishnah, assigns outstanding debts to the court so that they are not released, and the Mishnah states the reason plainly: people had stopped lending as the seventh year approached, which is exactly what Deuteronomy had warned against (Shevi'it 10:3-4). The instrument is often cited as the clearest case of rabbinic legislation designed to preserve a law's purpose by altering its operation.
The fallow year became a practical question again with the revival of Jewish agriculture in Ottoman and then British Palestine. The heter mekhira, a temporary sale of the land to a non-Jew for the duration of the year, was authorised as an emergency measure, most influentially by Rabbi Abraham Isaac Kook, and remains the arrangement used by the Israeli Chief Rabbinate. Haredi authorities reject it as a fiction that empties the commandment, and rely instead on the otzar beit din, under which a court administers the harvest, or on produce grown outside the land or without soil. The dispute recurs in full every seven years and involves the state, the rabbinate, farmers and importers.
How to read the institution is contested in a second and quieter way. Some treat it primarily as a law of the land's sanctity and of Israel's dependence on God, the fallow being an enacted acknowledgement that the land is not simply property. Others emphasise the explicit provision for the poor and for the beasts and read it as social and ecological legislation. Both readings have direct textual warrant, since the two accounts in Exodus and Leviticus supply different reasons, and modern Jewish environmental and economic thought has drawn heavily on the second.