Fertile Soil treats the targeted Farming patch with Super compost and 18 farming experience is granted. Super compost is not needed and the spell can be cast even after the farming patch has something growing in it; however once the plants have fully grown, the spell can no longer be cast, and players will instead receive the message, "Composting it isn't going to make it get any bigger." As with all Lunar spells, the quest Lunar Diplomacy must be completed to cast this spell. It is strongly suggested to use an earth staff when casting the spell. If you use the spell on anything but a farming patch, your character will say "Um..I don't want to fertilise that!"

This spell cannot be cast on the jade vine patch. Horacio will say "Oi! Don't you be fiddling with Magic in my garden! I'm an organic gardener, me!"

Attempting to cast this on a compost bin will yield the following message "No, that would be silly."

Casting Fertile Soil on a farming patch near Seers' Village is one of the Seers' Village Elite Tasks.

Fertile Soil costs 674 coins for each cast, or 509 coins for each cast when using an earth staff.

This spell is more expensive than a bucket of supercompost by 172 coins, assuming the caster is wielding an earth, lava, or mud staff.