Planting time is usually not a good time to fertilize anything. Seeds have what they need to germinate inside of them. Seedlings being transplanted from pots need to take their time getting established before they get a shot of nutrients that stimulates new growth.
So the best strategy for corn at planting time is to just be sure that you're starting with good soil, working in plenty of compost or sphagnum peat moss into the soil before planting. Then plant the corn seed.Once the corn has germinated and is about one foot high, fertilize. Then fertilize a second time when the ears begin to produce tassels.