Answer #3 (Beraisa - R. Shimon): There is no Shi'ur (that can be Batel in a mixture) for any Davar she'Yesh Lo Matirin (there is a time, place or way in which the Isur is permitted), such as Tevel, Ma'aser Sheni, Hekdesh, and Chadash (new grain before the Omer is offered);

For every Davar she'Ein Lo Matirin, such as Terumah, Terumas Ma'aser, Chalah, Orlah, and Kil'ei ha'Kerem, Chachamim fixed a Shi'ur (how much Heter is needed for Bitul).

Chachamim: Shemitah is never permitted, yet it is never Batel!

(Mishnah): Any amount of Shemitah produce forbids b'Minah (if it became mixed with Heter of the same species, or if sixth year produce grew additionally in Shemitah).

Version #1 (our text, Rosh) R. Shimon: (In that Mishnah) I said only regarding Bi'ur (if a bulb of Shishis grew in Shemitah, the growth is not Batel and the onion must be disowned);

Regarding eating (if Peros Shemitah were mixed with Heter), if they do not give taste to the mixture, they are Batel (since Ein Lo Matirin).

Version #2 (Ran's text) R. Shimon: That Mishnah applies only to (before) Bi'ur (Shemitah produce is permitted before Bi'ur, so it is Yesh Lo Matirin and it is not Batel);

Regarding eating (a mixture after Bi'ur), if the Shemitah produce does not give taste to the mixture, it is Batel (since Ein Lo Matirin). (end of Version #2)

Rejection: Perhaps here also we are stringent to say that the bulb is not Batel!

Answer #4 (Mishnah): If onions were in the ground in Shemitah and rain fell and they sprouted:

If the leaves are dark, they are forbidden. If they are green, they are permitted;

R. Chanina ben Antigonus says, if they can be uprooted by the leaves, they are forbidden;

Regarding Shemitah onions which resumed growing in Sheminis, if the leaves grew this amount [the new growth is the majority], the onions are permitted.

Inference: A forbidden bulb is Batel in permitted growth!

Rejection: Perhaps the Mishnah discusses onions that were mashed (they are insignifcant, therefore they are Batel in the added growth).

Answer #5 (Beraisa): One who this out (prunes) with a Kusi in Chasayos (this will be explained) may eat from them (before tithing) Arai (haphazardly). One tithes them like Vadai Tevel (before eating Kavu'a);

R. Shimon ben Elazar says, (if he was weeding) in Sheminis he may eat Chasayos of a Yisrael suspected of transgressing Shemitah.

Inference: The added growth in the eighth year nullifies the bulb (of Shemitah)!

Suggestion: This is no proof. Perhaps R. Shimon permits species in which the seed disintegrates!

Rejection (Beraisa): Chasayos are species like lupines, garlic, and onions (in which the seed remains).

Suggestion: This is no proof. Perhaps the case is, the produce was ground up (Ran - before it was planted; Rosh - after it was harvested, and it was mixed with Heter)!

Rejection: The Beraisa discusses one suspected of transgressing Shemitah. He would not bother to grind up the produce!

Suggestion: This is no proof. Perhaps the produce was mixed up with Heter!

Rejection: The Beraisa allows one to eat while weeding, when it is not mixed up!

Suggestion: This Beraisa refutes R. Yochanan and R. Yonasan (57b).

Rejection (R. Yitzchak): Shemitah is different. Since the Isur comes through land, the Isur can be Batel even while attached to the land.

Question: The Isur of Ma'aser comes through land, but it is not Batel while attached!

(Beraisa): If Terumas Ma'aser was not separated from a Litra of Ma'aser Rishon, and it was planted, and it is now 10 Litras, Ma'aser and Shemitah apply to the produce;

Tithes on the initial Litra must be separated from other produce.

Answer: The obligation to tithe does not come from the land, rather from Miru'ach (final processing).