3,230. Produce From Which Terumah Must Be Taken
Terumos 1:26
Nowadays, even in parts of Israel that were settled by the Jews returning from Babylonia, even in the time of Ezra (when the land was re-sanctified), the obligation of terumah is rabbinic rather than Biblical. This is because the Biblical obligation of terumah applies only in Israel and only when the whole nation resides there, as per Numbers 15:18, “When you enter....” It is only when the whole nation enters the land, as they did when they first took possession of it and as they will in the future when they take possession of it again. However, the possession of the land in the time of Ezra was effected only by a portion of the nation, with the result that terumos were not made obligatory under Biblical law. The Rambam opines that it seems that the same applies to maaseros (tithes), which likewise are a rabbinic obligation nowadays.
Terumos 2:1
We must take terumah from food that is intended for human consumption, that is guarded by its owners and that grows from the ground. There is a Torah obligation to separate the first part of these things for a kohein as per Deuteronomy 18:4: “You shall give him the first of your grain, your wine and your oil.” Just like grain, wine and oil are intended for human consumption, grow from the ground and are guarded by their owners – as we see from the fact that the Torah says “your grain” – we must take terumos and maaseros from any produce that meets these criteria.