Enter any of the following codes during gameplay: 

Free Money
     During the game hold shift and type "corn".

$1,000,000
     Grow  oranges near New York City for five seasons and ignore crop
failures.

Display version number
     Type "v" during game and press [Enter].

Donate $10,000 to the mayor
     Type "fund" during game and press [Enter].

Fill water trough
     Using  the Hand icon, place an empty water trough under a bale of
hay.  Then set the Speed option to "Ultra". After about 15 seconds the
trough should be full of water.

Laughing llama
     Type "llama" during game and press [Enter].

Natural fence
     Instead  of  costly  fences, use irrigation ditches to quarantine
your livestock.

Test mode
     Type "t" during game and press [Enter].

Three cows in perfect health
     Type "poultry" during game and press [Enter].