(1) Scientifically what are the nutrients that are being absorbed from a potted plant with a hole when it is above the ground.
(2) what does rashi see in clay to say that the boat is made from clay and therefore it absorbs the nutrients. scientifically what does rashi see to say this halacha. or maybe rashi holds diffrently see minachos 44b last rashi.
(3) tosfos. gitten 7b says that it appears to him that wood absorbs more nutrients than clay and the plant grows better. A-scientifically is this true? if so what is rashis shita? B-tosfos brings a zachir to this that the gemara says that they would cover the vegetables with clay so it should not grow, how is this a hint of a proof to tosfos/rashbam since of course they didnt grow plants need sunlight, and the clay blocked it this does not even suggest that clay absorbs less nutrients than wood.
(4) what is the rambam shita in regards to clay and wood? it seems from the radvas that it has something to do with the air-space around the boat. scientifically how does this work? halachicly how does this work?
Thanx in advance.
L. sternbach, balmitore md usa
(1) It seems to me that the nutrients refer to the water from the ground that creates a moist environment directly under the plant, thereby nurturing the plant. According to most opinions that the hole must be on the bottom of the plant (not on the sides, see Me'iri Shabbos 95a), it is possible that this is considered to be more directly nurturing the plant, as it goes more directly into the plant, than a pot which might be able to get some nourishment through evaporated liquids despite the fact that it does not have a hole in the bottom of the pot. [See Shevet ha'Levi 9:243 who says that he argued with the Chazon Ish regarding whether an Atitz Nakuv is considered physically connected to the ground as if it was sitting on the ground (Chazon Ish), or just that it "grows" from the ground and is therefore considered to have a Halachah of being ground.]
(2) The Me'iri explains that Rashi understands earthenware as more naturally absorbing water. Being that it is from the earth, it more naturally absorbs moisture.
(3) Obviously, Rashi and Tosfos each held that they were right. Although I haven't done any scientific tests, I would like to suggest that they were possibly both right in their scientific calculations. There are many varieties of wood, and I am quite sure that some are more absorbent than others. It is possible that Rashi was assuming that the case of the Gemara dealt with a type of wood which generally is not as absorbent as earthenware, while Tosfos understood the opposite.
(4) There is much discussion among the Acharonim regarding the Rambam's position regarding clay and wood. The Mahari Kurkas (Hilchos Bikurim 2:9 quoted by Derech Emunah ibid., see at length) seems to understand that the Rambam did not see a difference in practical Halachah between clay and wood according to the way he Paskens (like Rebbi Yochanan), and therefore did not codify this difference. However, the Mishneh l'Melech (ibid.) understands that the Rambam holds like Rabeinu Tam that wood is more absorbent than clay.
All the best,
Yaakov Montrose