Fertile Soil is a Lunar spell that can treat any targeted farming patch with supercompost. Doing so grants 87 Magic experience and 18 Farming experience. As with all Lunar spells, completion of the Lunar Diplomacy quest is required to cast this spell.
Players who have read the ash covered tome can have the spell treat a patch with ultracompost instead by casting the spell while having two volcanic ash in their inventory, which it consumes. The ash covered tome can be purchased from Petrified Pete's Ore Shop for 40,000 Volcanic Mine reward points.
Just like using compost normally, the spell can be used on a patch before or after planting the seeds and at any growth stage.
- If used on a patch that is finished growing, the player will get a chatbox message saying, "Composting it isn't going to make it any bigger."
- If used on a compost bin, the player will get a chatbox message saying, "No, that would be silly."
- If used on anything other than a farming patch or compost bin, the player will say, "Um... I don't want to fertilize that!"