Back before the days of circle irrigators on every other 40 up there, I wouldn't have been so sure bueller. If you could have got an 8' cutting buried 7' in that sand, just the depth of your water table might have been enough for those willows to do fine, even this late or later. Since the upper level sands of that whole aquifer get sucked dry every summer now irrigating corn instead of supplying deep rooted trees with water, I think you are correct, you would have no chance.