1) GROWING PLANTS IN THE UPPER FLOOR OF A HOUSE IN ERETZ YISRAEL
OPINIONS: The Gemara discusses the laws of an Atzitz Nakuv, which is considered attached to the ground underneath it, and the laws of an Atzitz she'Eino Nakuv (or an Atzitz Nakuv which is separated from the ground by a partition), which is not considered part of the ground and is exempt mid'Oraisa from Terumos and Ma'aseros. Mid'Rabanan, however, even an Atzitz she'Eino Nakuv is considered attached to the ground (Mishnah, Shabbos 95a) and is obligated in Terumos and Ma'aseros mid'Rabanan.
What is the Halachah in the case of a person who fills the upper story of his house with soil and grows plants there? If a person takes an Atzitz Nakuv to the upper story of his house, what grows in the Atzitz Nakuv clearly is not obligated in Terumos and Ma'aseros (ROSH, Gitin 2:22). Does the same Halachah apply when a person fills the upper story with soil and grows plants in that soil?
(a) The ROSH (Teshuvos 2:4) writes that only a portable pot of earth (like an Atzitz or a boat) is exempt mid'Oraisa from Terumos and Ma'aseros when it is not perforated (Nakuv), because it is not considered "Tevu'as Zar'echa ha'Yotzei ha'Sadeh Shanah Shanah" (Devarim 14:22), the produce of the ground that is produced year to year, which grows the way that plants normally grow. In contrast, if a person plants inside a non-portable item (such as in the upper story of his home), he is considered as though he planted on the ground of Eretz Yisrael, because the house is considered attached to the ground regardless of the amount of space that separates the upper story from the ground floor, since the upper story is attached to the ground floor by the support beams that hold it up. Therefore, what grows in the upper story is obligated mid'Oraisa in Terumos and Ma'aseros. (See TOSFOS to Bava Metzia 88a, DH Ba'al ha'Bayis, who also might be of this opinion.)
(b) However, the VILNA GA'ON (in the Shulchan Aruch) rejects the opinion of the Rosh and rules that whether or not the object is portable, if it is separated from the earth of Eretz Yisrael by a solid partition it is considered an Atzitz she'Eino Nakuv and, mid'Oraisa, it is not obligated in Terumos and Ma'aseros. This also seems to be the opinion of TOSFOS (7b, DH Ha). Tosfos asks that if the plants which a person grows in soil in an upper story of a house in Eretz Yisrael are exempt from Terumos and Ma'aseros, why does a Shali'ach not have to say "b'Fanai Nichtav" when he brings a Get from there?
If Tosfos follows the view of the Rosh, it is obvious why the upper story is considered part of Eretz Yisrael; plants which a person grows in soil in the upper story are obligated in Terumos and Ma'aseros. (It is interesting to note that the Rosh himself asks the question of Tosfos, despite what he writes in the Teshuvah.)
However, there is another reason to exempt what is planted in an upper story (or anywhere in a house for that matter) from Ma'aser. The Yerushalmi (Orlah 1:2, cited by the Mishneh l'Melech, beginning of Hilchos Shevi'is) states that a tree planted inside of a house is exempt from Ma'aser because the verse (Devarim 14:22) obligates only produce "ha'Yotzei ha'Sadeh Shanah Shanah" -- which grows from a field -- in Ma'aser. A house is not considered a field.
The RAMBAM records this Halachah in Hilchos Terumos (1:10). However, he writes that what grows in a house is nevertheless obligated in Ma'aser mid'Rabanan, like fruits picked from a tree in the yard ("Chatzer," which is not a field), which are obligated in Ma'aser (when one picks two or more fruits at a time).
(c) The RA'AVAD there argues that what grows in a house is exempt from Ma'aseros even mid'Rabanan. Accordingly, what grows in an upper story also should be exempt even mid'Rabanan, because it does not grow in a "field" ("Sadeh").
The CHAZON ISH asks, according to the Rambam and Ra'avad, why does the Gemara here insist that what grows in a boat is obligated mid'Oraisa in Ma'aser? It grows in a boat and not in a field, and thus it should be exempt!
The Chazon Ish answers that only when it grows in a covered area is it not considered to grow in a field. If it grows in an open area, it is considered to grow in a field. The boat is uncovered and therefore the plants are obligated mid'Oraisa in Ma'aser.
According to the Chazon Ish, a tree which grows in a Chatzer is obligated in Ma'aser, mid'Oraisa, since it is exposed to the elements there and is considered to be in a field ("Sadeh"). When the Rambam writes that what grows in a house is no less obligated than what grows in a Chatzer, he means that what grows in a house is not exempt from Ma'aser because it did not enter the house, but it grew there, just as what grows in a Chatzer is not exempt from Ma'aser because it did not enter the Chatzer, but it grew there (Berachos 25b, Gitin 81a).
RAV CHAIM KANIEVSKY shlit'a (in his footnotes to the Rambam) suggests that perhaps the Rambam does not distinguish between a covered house and an uncovered house; neither one is considered a field. Rather, the reason why what grows in the boat is obligated in Ma'aser, mid'Oraisa, is that the Mishnah is discussing a person who covered the floor of the boat with earth and plowed it, thereby transforming it into a field. (See Rambam, Hilchos Ma'aseros 4:14.)
(Rav Chaim notes that the Rambam and Yerushalmi write that what grows in the house is exempt only from Ma'aser. Perhaps it is obligated in Terumah since the laws of the obligation of Terumah are not identical to the laws of Ma'aser. See Rambam, Hilchos Terumos 2:6).
2) THE NORTHERN BOUNDARY OF ERETZ YISRAEL
QUESTION: The Gemara teaches that the northern boundary of Eretz Yisrael is "Turei Amnon" (the mountains of Amanah or Amanus). How is this Gemara to be reconciled with the Gemara on the previous page which implies that the northern-most part of Eretz Yisrael is the city Keziv?
(a) The MAHARAM SHIF points out that according to Rashi (7b),who explains that Ako and Keziv are in the northeast corner of Eretz Yisrael, perhaps Turei Amnon is the northwest border.
However, as the Rishonim point out, this answer does not conform with the location of Ako as it is known today, and it does not conform with the Midrashim which describe Ako as situated on the coast. The RAMBAN (7b), in fact, suggests that Rashi writes that Ako is in the east only to explain the Gemara's initial understanding of the Beraisa about Ako. According to the Gemara's conclusion, though, even Rashi agrees that Ako and Keziv are in the northwest corner of Eretz Yisrael (on the same side as Turei Amnon).
(b) The RAMBAN (7b) explains that Keziv demarcates only the northernmost part along the path that leads northward from Ako. The border of Eretz Yisrael, however, is north of Keziv, at Turei Amnon. The area to the east of this path is definitely Chutz la'Aretz, as the Gemara says, but only until the path reaches Keziv. The reason why the area to the east of the path is no longer Chutz la'Aretz once the path passes Keziv is either because the path turns westward to the coast when it reaches Keziv, or because the strip of Eretz Yisrael which connects Ako to Turei Amnon widens at that point, at Keziv.