Siman 168

Our sages, of blessed memory, said that in Eretz Yisrael, if a river washed away Reuven's olive trees and planted them within the field of his fellow, and Reuven says, "I am taking my olive trees," we do not listen to him because of the settlement of Eretz Yisrael. They assessed that Reuven will certainly plant others since he already possessed olive trees, whereas his fellow, since he did not have them until now, if they are taken from him, he will not plant others; therefore, they shall remain in their place. Regarding the division of the fruit: if the river uprooted them with their clumps of earth in a manner that they are capable of surviving through them—and consequently orlah does not apply to them—the owner of the field and the owner of the olive trees shall divide the fruit during the first three years. For if not for Reuven's trees being with their clumps, the owner of the field would not have eaten at all if he had planted olive trees because of orlah; and since Reuven's clods of earth also caused the fruit to be edible, they shall divide them between them. After three years, everything belongs to the owner of the field, for had he planted then, he would be eating all the fruit now. One should not ask that if so, why does he eat half during the first three years when, if he had planted, he would not have eaten at all? For it can be said that even if he would not have eaten the fruit, nevertheless, since the saplings would have been thin, he would have sown small things beneath them and would have benefited from them, whereas when the trees are thick, it is impossible to sow beneath them. Only after the three years must he give the owner of the olive trees the value of his trees as they were worth at the beginning when the river washed them away. Some say he must pay immediately [Taz]. It is not similar to a lost object washed away by a river, which is permitted without payment as written in siman 259, for with a lost object one certainly despairs, whereas with trees it is not the way to despair, for sometimes the water carries them to a nearby place; this is not like the one who disagrees in this matter. If they were not uprooted with their clumps, and their law is like saplings to which orlah applies, the owner of the olive trees has no share in this, and he takes the value of his olive trees as they stand to be sold for planting. All this applies if it is the will of the landowner to retain them, but if he says, "Take your trees," we listen to him, for we do not have the power to coerce him. In the Diaspora, if the owner of the olive trees comes to take his olive trees, whether within three years or after three years, he has the right to do so.

One who sells his olive trees for wood, if he stipulated with him that he should cut them down immediately, all the fruit that they produce until the cutting belongs to the owner of the land, because they grew from his land. And if he stipulated with him to cut them down whenever he desires, all the fruit they produce belongs to the owner of the trees, for since he permitted him to cut them down when he desires, the nourishment is in his domain. And if he sold them without specification: if they produced less than a revi'it per se'ah—which are poor olives that do not yield a revi'it of oil per se'ah beyond the expenses—these belong to the owner of the olives, for it is not the way of the owner of the land to be particular about them. And if they produced a revi'it per se'ah beyond the expense, they shall divide them, for they are like partners: the land belongs to this one and the olives belong to that one. And regarding other trees that produce fruit, one should also estimate according to this value: that if they produced a small amount that the owner of the field is not particular about, the fruit belongs to the owner of the tree; and in an explicit sale, their law is like that of olives.