You can 'cancel' a cultivation of a crop when it fails just by reloading your previous save.
This goes the same for contests. You can save the game before you enter a crop for competition, and when you lose the competition, you could reload the previous save. (although this can save you from losing a competition/letting you choose another, you would lose up to 1 month's worth of gameplay if you don't use boosts)
You can earn money from investments - Dynamite - after the first time you use a dynamite, the next time you research the dynamite, it will give you money instead of requiring you to pay.