Mark,
I don't think your urea evaporated but it probably did something
similar. If left in sunlight, it will decompose into carbon dioxide and
water. If left in the open, not in direct sunlight it can also decompose
but at a slower rate. If you are going to fertilize anything, you really
should till it into the soil. Watering it in would have been a good choice
too. If you were to leave 10-10-10 (or any fertilizer), sunlight will
liberate any chemically-bound water and the wind will scatter it about.
I had a question about using Urea on the pecan tree I want to graft. I have
obtained some scion wood and plan to try to graft it early this summer. I
bought 50lbs of Urea 48-0-0 to fertilize the tree so that it will grow more
vigorously this spring. The tree has been very slow growing and you
suggested some N might help. About a month ago I used about 2 cups (dry
measure) around the tree. But it didn't rain for quite a while and the
crystals seemed to evaporate. I'm wondering if it did any good? Also would
it hurt to dose it again this spring.