Your subject is certainly a light color and your background may have been white, but your lighting makes it difficult to see. It also looks as though it is a black and white which doesn't help bring out the white in this shot.
what ever that gunk is on the right of the ball, it sure hurts the shot. well framed and the lighting is perfect, but my eye just loops back to the left, is it dirt, is it some odd logo? of course most of the shots in this challenge have a flaw or two is it might fly yet .
I like how this shot is composed. Nice close-up on the golf ball. I do think that, for this challenge, there's a bit too much emphasis on the shadow. But the shadow definitely adds a nice dimension to it.