The Baraisa (above daf 47 (j)) taught that they may not extend the Seventh year etc. R. Mana said that this applied originally when the years were in order, but now that they are not, the Seventh year is the same as any other year.

Baraisa: The House of Rabban Gamliel immediately extended the Eighth year.

(R. Avin): One cannot use that Baraisa to prove that Beis Din can exempt from Maaseros - that Baraisa is based on the pasuk that states (Devarim 16:1), "Guard the month of Aviv (spring, meaning the month of Nisan)" - guard it, that it should always fall in the spring season (by sometimes adding a second month of Adar so that Nisan is delayed until after the winter).

From where did we learn that Beis Din can render someone's property Hefker? From the case (in our Mishnah that said - (daf 46 (a)) of "If a heap of grain was made from which Leket had not yet been gathered"...

(R. Mana citing R. Shimon ben Lakish): That case is according to Beis Shammai who say that Hefker just for the poor is considered Hefker; but Beis Hillel say that the poor must separate Maaser and then eat.

(R. Yosi to R. Mana): We have heard that all agree that it is exempt from Maaseros because there is a penalty by Beis Din that makes it Hefker.

(R. Zeira/ R. Abahu citing R. Yochanan): (What does Rabban Shimon ben Gamliel (in the Mishnah daf 46 (c)) mean by "He should give the poor the usual amount that falls"?) Four Kav per Kur.

Question (R. Zeira to R. Abahu): Is that four Kav per Kur harvested or per Kur planted?

Answer (R. Abahu to R. Zeira): Per Kur planted.

(Mishnah in Bava Metzia): (If a sharecropper received a field and it did not sufficiently produce - and the sharecropper does not want to continue working with it as it is not profitable - if it produced enough grain to make a pile, he must continue to work it.) R. Yehuda said - if there is 'the amount that falls'.

(R. Abahu): (What is the meaning of 'the amount that falls'?) Enough seeds that he can sow the field the following year. On the other hand, here, the explanation of 'the amount that falls' was the usual amount that falls during harvesting.