Torn, what you have suggested is exactly what I do as well (with the suggestion by Gary to use a cell that is meaningful such as planting date). Except, I would use SUMIFS instead of SUMIF. Down the road, that will allow multiple conditions which always seem to come up eventually. So, maybe you only want corn fields planted before May 1 using Pioneer seed. With SUMIFS, that is possible to do.

As far as the idea of using macro programming, I would stay far away from that. My fear is that each version of Excel seems to deal with colours differently. I wouldn't want an upgrade to Excel to break the colour counting.