WATERING GRASS WITHOUT INTENT [Davar she'Eino Miskaven: watering]
Gemara
91b (Shmuel): A voluntary Korban of wine is sprinkled on the fire (on the Mizbe'ach).
Question: The wine will (partially) extinguish the fire (where it lands). This is forbidden!
Answer: Shmuel holds like R. Shimon, who permits Davar she'Eino Miskaven (something he does not intend for).
Shabbos 75a (Beraisa): If one hunts a Chilazon (a fish whose blood is used to make Techeiles) and bruises (or presses) it with his hands to extract its blood, he is liable only once.
Question: He should be liable also for killing!
Answer #1 (R. Yochanan): The case is, he bruises it after it died.
Answer #2 (Rava): We can even say that he bruises it while it was alive. He is Mis'asek regarding killing it (he is engaged in something else).
Question: Abaye and Rava both say that R. Shimon agrees about a Pesik Reishei (an inevitable result, for it is as if he intended)!
Answer: Here is different. He prefers that it stay alive, for then the blood makes a clearer dye.
81b (Rav Huna): On Shabbos, one may not eliminate (move his bowels) in a plowed field (that is ready to be planted).
We are concerned lest he take (rocks to clean himself) from a high place and return it to a depression. Rabah taught that one is liable for this!
103a (Beraisa): If one pruned (moist, edible) reeds for people to eat, he is liable for the volume of a fig. If he did so to improve (the ground), he is liable for any amount.
Question: In any case, he improves the ground!
Answer #1 (Rabah and Rav Yosef): The Reisha discusses a swamp (there is no benefit from the improvement).
Answer #2 (Abaye): It discusses even a field. The case is, he does not intend to improve it (therefore, he is exempt for improving).
Question: Abaye and Rava both say that R. Shimon agrees about a Pesik Reishei (an inevitable consequence, for it is as if he intended)!
Answer: It discusses another's field (the one who pruned does not benefit).
Rishonim
Rambam (Hilchos Shabbos 8:2): Watering vegetation and trees on Shabbos is a Toldah of seeding. One is liable for any amount.
Hagahos Maimoniyos (2): In Mo'ed Katan 2b, we say that one is liable for watering (on Shabbos) both for seeding and for plowing. Therefore, one must be careful not to cast water on vegetation on Shabbos. Even though we hold like R. Shimon, who permits Davar she'Eino Miskaven, R. Shimon admits that a Pesik Reishei is forbidden. Here, it is impossible that they will not grow. Re'em forbids also urinating on them. The Aruch permits a Pesik Reishei d'Lo Nicha Lei (he does not want the result). If so, one may eat in another's garden, for he does not benefit from the growth. Shabbos 103a supports this. Sefer ha'Terumah says that this is not a proof. Even though he is exempt, it is forbidden! One can distinguish our case (watering) from pruning. I bring a proof for the Aruch from 75a. Here, it (it seems that the Beis Yosef's text said 'wine' - PF) is permitted even in his own garden for it does not help the vegetation grow. Rather, it burns it! Sefer ha'Terumah permitted also urinating, unlike Re'em.
Hagahos Maimoniyos (3, citing Re'em): One must be careful not to cast seeds in a yard in a place where rain falls, for they will ultimately sprout. If he casts to chickens, he must be careful to cast only an amount that they will eat in one or two days. If people walk there, they will not sprout, so it is permitted.
Tif'eres Yisrael (Kalkalas Shabbos (before Seder Mo'ed), Melachah 1 (Zore'a)): Therefore, one should be careful not to eat Peros or drink in a garden, for it is very hard to beware not to cast seeds or spill drinks there.
Tosfos (103a DH Lo): The Aruch permits l'Chatchilah to cut Tzara'as along with the foreskin during Bris Milah, for he has no Hana'ah from this. There is no Isur even mid'Rabanan. If a barrel of wine was corked with flax, Rebbi permitted to remove the cork to take wine. Even though it is a Pesik Reishei that he will squeeze the flax, since the wine falls to the ground and he does not benefit from this, it is permitted. I disagree. Bursting a scab to remove the pus would have been forbidden if not to alleviate pain, even though he does not benefit at all from the opening in the scab, and he does not intend for an opening at all. He just wants to puncture it! The Rashba similarly brought that we permit using a needle to remove a thorn (splinter) according to R. Shimon, who exempts Melachah she'Einah Tzerichah l'Gufah, due to pain. Even though he does not benefit from the wound, it would be forbidden if not for pain. Our Gemara answered that in his Chaver's land he is not Chayav Chatas. It is forbidden. In Zevachim, we say that R. Shimon, who permits Davar she'Eino Miskaven, permits throwing wine on the Mizbe'ach. He permits in a way that is not a Pesik Reishei, e.g. he throws small drops or on limbs, so it is possible that he will not extinguish. In Sukah (33b), Tana'im argue about whether one may remove berries on myrtle (to make it Kosher). We said that R. Elazar b'Rebbi Shimon permits when he takes them to eat; Davar she'Eino Miskaven is permitted. We ask that even R. Shimon forbids a Pesik Reishei, and answer that he has (enough Kosher) myrtle. This connotes like the Aruch, who permits when he does not benefit. Do not say that since he has extra myrtle, he does not fix at all. If so, why did we say that R. Elazar holds like his father R. Shimon, who permits Davar she'Eino Miskaven?! However, we can say that it is a small Tikun which is forbidden only mid'Rabanan, and Chachamim did not decree when he does not benefit.
Tosfos (103a DH b'Ar'a): In another's land it is Melachah she'Einah Tzerichah l'Gufah.
Poskim
Shulchan Aruch (OC 336:3): Those who eat in gardens may not wash their hands over vegetation, for this waters them. Even though they do not intend for this, it is a Pesik Reishei.
Beis Yosef (DH Aval ha'Ochlim): Semag, Semak, the Mordechai and Hagahos Maimoniyos say so. Sefer ha'Terumah (235) says that one should avoid eating on Shabbos in a place of vegetation, for it is very hard to be careful that water not fall while drinking or during Netilas Yadayim. According to the Aruch, it is permitted in another's garden, but surely those who argue with the Aruch forbid.
Magen Avraham (6): Sefer ha'Zichronos says that the lenient opinion permits only in a Nochri's garden. Then, he is not pleased with the growth. The Gemara connotes unlike this; it says his 'Chaver's (friend's) garden. See what I wrote in 307:7. (In one answer, the Ran says that we are more stringent about extinguishing, for if it is Melachah she'Tzerichah l'Gufah, one is liable for it.)
Mishnah Berurah (27): Some permit a Pesik Reishei d'Lo Nicha Lei l'Chatchilah, so it is permitted in a garden that does not belong to him and not to someone he likes. Many forbid Pesik Reishei d'Lo Nicha Lei l'Chatchilah.
Kaf ha'Chayim (26): Mateh Yehudah (or Mateh Yosef) says that the Shulchan Aruch holds like those who forbid a Pesik Reishei d'Lo Nicha Lei. However, Sefer ha'Zichronos forbids mid'Oraisa in the garden of another Yisrael, and mid'Rabanan in a Nochri's garden. The Magen Avraham says that the Gemara connotes unlike this. Eliyahu Rabah says that the Gemara discusses when we know that it is Lo Nicha Lei, and Stam, we say that even in the garden of another (Yisrael) it is Nicha Lei.
Kaf ha'Chayim (27): It seems that it is a Pesik Reishei only if the grass is visible. If not, even if the soil grows vegetation, we forbid only if he intends to help it grow. If he knows that there are seeds under the ground, e.g. he plowed over them, even though they did not sprout yet he may not wash over them, for surely they will sprout. We also forbid washing in a place of trees. Even though they would grow even without this water, it helps them to grow branches and fruits.
Kaf ha'Chayim (28): A case occurred in which one did not notice grass between rocks near the well, and washed there. The grass is useless. Lev Chayim said that he did not sin and needs no atonement, for several reasons.
Kaf ha'Chayim (29): If before Shabbos a tree or vegetation was watered all it needs, or a Nochri watered it on Shabbos, and a Yisrael watered on Shabbos with intent for the vegetation, he is exempt, for extra water only harms.
Shulchan Aruch (ibid.): They may urinate there or spill other liquids that do not make things grow.
Beis Yosef (DH Aval Mutar): Sefer ha'Terumah, the Mordechai and Hagahos Maimoniyos permit wine and urinating, for these hinder growth. Re'em forbids.
Birkei Yosef (Shirei Berachah 3): Sefer ha'Zichronos asked that one may not urinate on the ground, for he makes a hole! We can say that he urinates against a wall, and the urine flows to the vegetation.
Tif'eres Yisrael (ibid.): Agriculturists say that urine is a good fertilizer. We must say that nature changed. One who fertilizes is liable for plowing.
Bi'ur Halachah (DH Oh): Hagahos Maimoniyos brought that one who waters is liable for plowing (it softens the soil). If so, why do we permit wine and other liquids that do not help vegetation grow? Perhaps it is considered plowing only when it helps also the vegetation. When it harms the vegetation, it does not improve the land. Ma'amar Mordechai says like this, but this is difficult. This requires investigation. Tif'eres Yisrael forbids urinating; people are not careful about this at all. Shabbos 81b refutes him. One who eliminates will surely urinate; the Gemara did not forbid for this reason.
Note: One who urinated one minute ago can eliminate without urinating. However, if urinating was a problem, surely we would decree against eliminating, since normally one urinates at the time. However, Tif'eres Yisrael said that nature changed. If so, the Gemara does not refute him!
Kaf ha'Chayim (31): Pesach ha'Dvir says that this explains why the Re'em forbids urinating on grass. In practice, he leans to forbid.
Mishnah Berurah (29): Wine does not make things grow, for it is strong and burns the vegetation. The same applies to similar liquids. The Magen Avraham (27) says that one should be careful even for other liquids; Eliyahu Rabah says that wine is strong, so one need not be careful about it at all. The Pri Megadim says that mead and beer have water; surely, they make things grow.
Kaf ha'Chayim (32): Eliyahu Rabah permits strong wine, and all the more so whiskey.
Rema: It is good to be careful not to eat in gardens if he uses water, for it is hard to be careful that water not fall.
Mishnah Berurah (30): The Taz says that a garden more than (5000 square Amos, i.e. each side is a bit more than) 70 Amos is a Karmelis (a place where mid'Rabanan, one may not carry on Shabbos). No enclosure can permit it. In any case one must be careful not to carry four Amos. This applies even in another's Chatzer.