Don't bother with turnips. I tried them in north central Iowa. They grew alright, but turnips are a bitter taste and not edible until after a freeze. The deer did not touch mine at all even after a good freeze. Deer tracks right through the plot, no sign of the deer even trying them. I have to believe the deer did try them because they try everything at least once. Obviously they learned the turnips were not good to eat. The following spring I did not see any evidence the deer were even trying the turnip bulbs that were still in the ground. Bust.
The Iowa DNR planted some large plots of turnips on some public hunting area I hunt a few years ago, I saw the plots. The next year they plots were planted to alfalfa. Based on my experience I have to assume the DNR felt turnips were not worth it. I read an article by Doctor Deer, a deer biologist, who said in effect turnips were not a good food plot crop in this climate. Sorry, I do not have a link or reference to share. I am going with clover blend in my next food plot. Do yourself a favor and skip the turnips.