Rashi on Leviticus
וכל מעשר הארץ AND ANY TITHE OF THE LAND… [BELONGETH TO THE LORD] — Scripture is speaking here of the “second tithe”.
Siftei Chakhamim
Second tithe. Because here it is written is written “sacred to Hashem,” and regarding second tithe it is written (Devarim 26:13) “I have divested my estate of sacred material.” Thus we derive one from the other [through the common words] “sacred,” “sacred.” This excludes first tithe which is completely non-sacred as it is written (Bamidbar 18:27), “Your terumah-gift will be considered the same as grain from the granary.”