Commento su Levitico 25:16

תרבה מקנתו THOU SHALT INCREASE THE PRICE THEREOF — i. e. you may sell it at a high price

תרבה מקנתו, you will buy it at a higher price than would have been the case if you had only rented it. The reason why the seller is entitled to a proportionately better price is that over a period of years any investment the owner makes in building on such property will be worth his while, and will be amortized over many years, whereas a rental agreement does not permit the renter to make such changes.

כי מספר תבואות until the Jubilee year is what he is selling you, as opposed to the actual soil.

Lessen its price. Because תרבה or תמעיט מקנתו implies to increase or decrease the [number of the] field’s sales, which is not the verse’s meaning. Therefore Rashi explains, “’You shall increase its purchase price,’ sell it at a high price,” and “’You shall decrease its purchase price,’ lessen its price.” Rashi says, “’You shall increase its purchase price,’ sell it at a high price (תמכרנה ביוקר),” instead of saying “increase its price” (תרבה בדמיה) as he said “lessen its price” (תמעיט בדמיה), so that you do not think that one should increase and lessen its price more than it is worth. The expression תמכרנה ביוקר, however, does not imply selling for more than its worth, but rather [implies] that it is worth a lot. Re’m

תמעיט מקנתו — You shall offer a lower price.

תמעיט מקנתו, that you do not have to pay a price as if you had only rented it. Naturally, if the sale is for a few years only, such considerations are taken into account. כי מספר תבואות הוא מוכר לך, for when you buy the land for a few years only, the only use you can make of it is the harvests which it will yield. Shortness of tenure does not permit the owner to invest in superstructure on the field and to amortize his investment. The purchaser also cannot grow the kind of crop which weakens the soil such as flax, as by the time he has to return the field to the original owner it must be returned in a condition similar to the one when he had bought it. Baba Metzia 109 states specifically that if someone purchased a piece of land for a few years only, he is not permitted to grow flax on it.