Before us is Mishnah 5 in the eighth chapter of Tractate Bava Metzia - another Mishnah in the series of Mishnayos dealing with disputes between buyers and sellers.
"Ha'mocher zeisav la'etzim" - one who sells his olive trees for wood:
This refers to a person who has olive trees growing in his field, and the olive trees stopped yielding a crop that economically justifies their maintenance. It is worth noting that otherwise it would be forbidden to cut them down, since it is forbidden to cut down a fruit tree; but since the tree's output does not cover the cost of its maintenance, it is permitted to cut it down. The owner of the field therefore sells the trees to a third party for firewood, and the buyer is about to cut them down.
"Ve'asu pachos mi'revi'is la'se'ah" - and they produced less than a revi'is per se'ah: The trees did indeed yield olives, but their yield is meager: from every se'ah of olives, less than a revi'is of oil is produced. To calculate the measurements:
A revi'is is a quarter of a log.
There are four lugin in a kav.
There are six kavin in a se'ah.
It turns out that only one ninety-sixth of the volume of the olives turns into olive oil - an extremely small amount.
Therefore, the Mishnah states: "Harei elu shel ba'al hazeisim" - they belong to the owner of the olives: The olives belong to the buyer who purchased the trees for firewood. The logic is that since the value of the crop is so tiny, the owner of the land relinquishes them and walks away from them, and he has no interest in them.
"Asu revi'is" - if they produced a revi'is:
When the olives are economically worthwhile, meaning that the trees produce at least a revi'is of oil for every se'ah of olives, there is no longer any relinquishment here, and the two sides disagree about who the olives belong to:
"Zeh omer zeisai gidlu" - this one says, "My olives grew": The owner of the trees claims: These are my trees, and they are the ones that yielded the olives, and therefore they are mine.
"Ve'zeh omer artzi gidlah" - and this one says, "My land grew them": The owner of the land claims: The olives grew from the nourishment of my soil, and therefore they are mine.
The Mishnah rules: "Yachloku" - they divide them: They divide the olives equally between them. We must carefully note: This is not the "yachloku" we saw in the previous Mishnayos. There it was the "yachloku" of Sumchos, who holds that property whose ownership is in doubt is divided because of the doubt. Here the division is done out of justice and fairness, since the claims of the two men are equal to one another, and not because we do not know how to handle the property.
The Gemara's Clarification - The Time of the Chopping:
The Gemara explains that the Mishnah is dealing with a case where no prior condition was made regarding when the buyer must cut down the trees. We have three situations before us:
If the landowner stipulated that the buyer must cut down the trees immediately and clear them from his field, and the buyer delayed - all the olives belong to the landowner.
If the landowner told him that he may cut down the trees whenever he wishes - everything growing on the tree belongs to the owner of the trees.
If the matter was stated without specification and no time was defined - they divide them half and half, since this is the fair rule.
"Shatav nahar zeisav" - if a river washed away his olive trees:
The Mishnah continues with a similar case, but here we are not dealing with a business transaction at all. A river that overflowed its banks and flooded the field uprooted the olive trees, "unesanom lesoch sedeh chavero" - and deposited them into his fellow's field - the trees were washed away and replanted in his neighbor's field. The one who had olive trees no longer has trees in his field, and the trees are now standing in another's land. To whom do the olives growing on them belong?
"Zeh omer zeisai gadlu, vezeh omer artzi gadlah" - this one says, my olives grew, and this one says, my land grew them - the two claims return exactly: the owner of the trees claims that his trees are producing the olives, and the landowner claims that the trees are taking up space in his land and it is what produces the fruit. The Mishnah rules: "yachaloku" - they divide them.
The law of Orlah and transplanting with a clod of earth:
This matter requires explanation. An olive tree, as well as any fruit tree, has its fruit completely forbidden due to the laws of Orlah for the first three years. This law applies not only to a new sapling, but even to a replanted tree: transplanting a tree and planting it in a new location resets the count of years, and for the next three years the fruits are forbidden as Orlah. However, if the tree was moved from place to place with a 'clod' - a clod of earth surrounding its roots, which has the ability to sustain the tree without the need for replanting in the near future - the count of years does not reset, since the tree is considered as if it is already planted and standing, and its fruits are permitted immediately.
The case before us is therefore about an olive tree that was uprooted with a clod of earth attached to it and ended up in another's field. Now the two claims come into sharper focus:
The new landowner: The nourishment comes from my field, and therefore the fruit belongs to me.
The original owner of the trees: If not for the clod of earth that came from my field, you would not be able to eat from the fruit at all for three years.
Therefore, the Mishnah rules, "yachaloku" - they divide them between themselves.
After three years:
This division applies only during the first three years. Afterward, the original owner of the tree no longer has any claim to the olives, since all the nourishment certainly comes from the field of the current landowner, and he also cannot claim that without him the fruit would not be fit to eat - since after three years they would be fit in any case. Furthermore, if his trees were not standing in that spot, the landowner could have planted other trees there, so it turns out that the trees are taking up his space. Therefore, the landowner acquires all the fruit after three years.
Nevertheless, the landowner must pay the original owner of the trees for the value of his trees, since he never paid for them: he must pay the value of the trees at the time they were first transferred into his field. However, he does not need to share the fruit that grows on the trees with him after the first three years.
In summary: In this Mishnah we learned of two cases where the owner of the trees and the owner of the land are at odds. Regarding one who sells his olive trees for wood - if the yield is less than a revi'is per se'ah, the landowner disregards it and the olives belong to the buyer; but if it reaches a revi'is per se'ah, they divide them out of a sense of justice and fairness, provided no time was stipulated for chopping them down. And regarding a case where a river swept his olive trees into his friend's field - they share the produce during the first three years because of the benefit of the clump of earth which allowed the fruit to be permitted immediately, and afterward the landowner acquires all the fruit, and pays the owner of the trees their value at the time of the transfer.