Shalom u'Vrachah,
(Rava): One who damages Ziburis, if he pays for this with land, he pays Idis. If he damages the edge of the field by the river, even if the field is Idis, he pays Beinonis. (The river floods it, so one cannot grow crops. It is mere pasture, so one who grazed his animals there is like a borrower, even if the owner did not consent.)
This a very speculative interpretation, by a minority of rishonim. It should indicate such.
(Rava): One who damages Ziburis, if he pays for this with land, he pays Idis. If he damages the edge of the field by the river {according to some rishonim), even if the field is Idis, he pays Beinonis. (The river floods it, so one cannot grow crops. It is mere pasture, so one who grazed his animals there is like a borrower, even if the owner did not consent.)
We usually explain based on RAshi. Tosfos asked some questions on Rashi, and his Perush fits the words better, so
we also brought Tosfos' explanation as version 2. I do not feel it is necessary to mention whether or not other Rishonim
disagree with Tosfos. The outlines are not intended to bring all the Perushim.
Pesach Feldman