This plot is on its 3rd. year of no-till. The first year I did a "throw and mow", the second year was a "throw and mow, then roll". This year was "throw and roll" (no mowing at all). Results have improved each year. It seems that the better the thatch/mulch build up, the better the results. I suspect two things come into play - it hides seed from the birds and it holds moisture much better than tilled soil.