The first line of the description reads: "With Soil Appreciation II, tending a Patch takes half as much time AND more XP each time, plus more chance of extracting Loam from delicious Dirt Piles."
It should read "takes half as much time AND gives/grants/offers more XP each time"
The way it's written now makes it sound like you lose XP each time you tend a patch with this skill ;)