Compost & Composted Dirt!
Compost is made from a large quantity of any vegetable at a brewery.
A single compost can be used to 'upgrade' an existing fertile tile to 105% fertility, at the cost of a reasonable amount of wealth.
4 compost can be spent to lay down a tile of composted dirt where there previously was only stone - a much higher-value square of dirt with the same 105% fertility.
