Yes, you can rotate in clover or alfalfa. Maybe something like a corn/soybean/clover for 3 years, top seeded with rye or oats. You also may be able to sneak another year of corn in, just watch your soil for signs of erosion. Topsoil takes years to replace naturally.

Excuse me about the ph, I meant to say basic. Corn tends to lower the soil ph, requiring lime to bring the ph back up into a suitable range. If you plan to plant clover I would suggest a ph of 6.2 or higher, and for alfalfa 6.4 or higher.

I have never heard of corn being broadcasted. My best bet would be to use a corn planter if at all possible to plant the corn. If you broadcast the corn it may be the case that the corn will grow in clumps, kind of like volunteer corn and produce smaller cobs, or no cobs at all. The closer the plants are planted to one another the smaller the cobs will be. Same situation occurs when soybeans are drilled rather than planted with a corn planter.

One additional note, don't forget to add the innoculant to the soybeans. And no need to rush getting the corn seeds in the ground, It sprouts when the soil temp. is 52 degrees.

Good Luck