| bodhranist |
It doesn't look like anyone has, but if I were doing it, I'd rule that it takes a gallon or so of water to change a square foot of normal earth into wet earth (the equivalent of 1.5 inches of rain, plus it makes for convenient calculations). A 5th level druid creates 10 gallons of water per casting, and there are 100 square feet in each 10x10 foot square, so it would take that druid a full minute (10 rounds) of casting create water for each 10 foot square to soften, so five full minutes of casting to dampen the entire area of his soften earth spell.