Corn has to be grown very close together for good pollination.
The tassles at the top produce the pollen, which must fall down onto the silks below for pollination to occur. Each silk is attached to a corn kernel. Corn is wind pollinated, although honeybees can help with pollination. It's best to sow corn in blocks of (minimum) four to take advantage of wind direction.
I'm doing this from memory, I haven't grown corn for over thirty years!