English: “Year by year” — this teaches that one may not tithe from one year for another.
On the daf / in context: Produce of one year may not be used to fulfill the tithing obligation of produce of a different year; each year’s crop is tithed separately.
Type of Learning
Derash on the verse (Sifrei) — years may not be mixed for tithing.
What Is Learned
One may not tithe the produce of one year on behalf of the produce of another year.