It includes two crop tiles: Cactus ("Opuntia ficus-indica") and The Lake ("Lacus Ludus" - literally 'Game Lake'), together with a token used with the Cactus tile. They can be added to the existing crop tiles to give more variety at game setup.
It also includes fertilizer tokens. These add a new mechanic to the game where fertilised crop tiles yield more return.
The rules are listed on the last page of the rule book of the (kickstarter) base game.