Lars, I don’t have much experience planting plots in the Spring. However, my plots in the fall do just fine when I prepare them the way I do and don’t have hardly any weeds in them. I’m guessing the Spring plantings will be different and have more competition from weeds. What I have heard that works is after you plant your plot, give the plot a few weeks to sprout and start to grow and then find the right herbicide and spray your plot to kill any competing weeds.
As far as fertilizing I usually do that when I disc when I’m preparing the plot. My normal food plot process is: Spray plot with round up, wait a week, Disc Plot, fertilize/lime plot, disc plot again, drag plot to firm/level the seed bed, broadcast seed on plot, then culitpack or tamp plot. Then if I can, I water or pray for rain. In the Spring, I would then wait a few weeks for the plot to sprout and then spray herbicide on it. I guess, I don’t see the harm and fertilizing again if you wanted??????
I hope this helps.