(Mishnah): If a furrow that passes through a vineyard is 10 Tefachim deep and 4 Tefachim, R. Eliezer ben Yaakov says that if it passes end to end, it looks like two separate vineyards and one may plant in it.

If there's a wine press in a vineyard that is 10 Tefachim deep and 4 Tefachim wide, R. Eliezer permits planting in it and the Chachamim prohibit it.

If there's a guard's mound 10 Tefachim tall and 4 Tefachim wide, one may plant in it; but if the vine branches became entwined and grew there, it is prohibited.

If a vine is planted in a winepress or in a pit, it's given work access (6 Tefachim) and he may plant in the rest of it.

(R. Yosi): If there aren't four Amos there, he shouldn't bring another seed there.

It is permitted to plant (a different species) within a house in a vineyard.

(Gemara) Question: (The Mishnah taught that R. Eliezer ben Yaakov says that if it passes end to end, it looks like two separate vineyards.) Must it run along the entire length of the vineyard with an additional 4 Amos work access space on each side?

Answer (Baraisa): 'The Chachamim agree to R. Eliezer ben Yaakov that even though it is forbidden to plant in a furrow that passes from end to end, if it runs along the entire length of the vineyard with its work access space, it is permitted.' This shows that R. Eliezer ben Yaakov reasons that even without that, it is permitted.

When do they disagree? When there were two rows (meaning a vineyard) on each side, but if there were only one on each side (so that both rows are needed to create a vineyard), it is considered that there is no vineyard and he may plant even outside the area of the furrow.

Baraisa: (If there's a wine press in a vineyard that is 10 Tefachim deep and 4 Tefachim wide, R. Eliezer permits planting in it and the Chachamim prohibit it.) If it is less than this it is prohibited.

Question: Why does the Baraisa need to teach that phrase? Certainly, according to the Chachamim, if it is smaller than ten Tefachim it would be prohibited!

Answer: Rather, what's the meaning of 'less than this'? Less than 4 Tefachim wide.

(But isn't that also obviously prohibited?) Since it's narrow and one could step over it, one might have thought that it's considered closed up and therefore permitted.

Question: But why not say that it is permitted in that case? Didn't a Tosefta teach that when the roots of a Piah plant enter into a field (under the ground) within 4 Amos of a vineyard, if they are more than 3 Tefachim below the ground, they are permitted...?

Answer: (A furrow is different since it is not covered on top and) the air of the vineyard surrounds them.

(R. Eliezer to Chachamim): Don't you agree that depth is like height (that it creates a separate domain)? (Since you permit planting on a guard's mound, you should also permit planting inside a wine press?!)

It's logical to say that R. Eliezer (who permits planting inside a wine press) agrees with R. Eliezer ben Yaakov (who permits planting in a furrow), but R. Eliezer ben Yaakov would not agree that one may plant in a wine press.

Explanation: R. Eliezer agrees with R. Eliezer ben Yaakov that depth is like height; but R. Eliezer ben Yaakov doesn't agree with R. Eliezer than the air of the vineyard surrounds.

(R. Chiya citing R. Yochanan): (The Mishnah permitted planting on a guard's mound) only if there is a space of 4 by 4 Tefachim there (for the guard).

(Rav Shmuel bar Rav Yitzchak): That's in the case of a round mound, since otherwise it will look like it was naturally there. But if it's a square mound, it's permitted even without 4 by 4 for the guard.

(R. Chalafta ben Shaul): There must be 3 Tefachim of earth on top (to contain the roots and prevent them from entering into the mound itself).

(R. Yosi): This is the case when the mound is round, but if it's square, it does not require 3 Tefachim of topsoil.

(The Mishnah taught that it's permitted to plant (a different species) within a house in a vineyard (as it's considered to be a separate domain).) The Mishnah is referring to when its airspace is between 3 and 4 Tefachim. If it's less than three, it is considered to be closed up (and one may not plant a different species). But if it is between three and four, the walls complete the required four Tefachim separation and one may plant in the house without any other separation.

(R. Avin citing Shmuel): This is alluded to in the pasuk that states (Yishayahu 42:22), "(lit.) they are hidden in (Batei Kilayim) dungeons" - it is expounded to refer to seeds of other species that are shielded from the prohibition (of Kilayim) because they are planted in houses.