Soil and Crops

We plant continuous corn in ponds that we flood in the fall to attract waterfowl for hunting. The ponds we plant tend to be wet and the soil is heavy. Would it be OK if we let the weeds come up in the spring, spray them with Roundup, surface spread fertilizer and then plant the corn? Any distrubance of the ground results in poor germination. The emerging corn is picked off by blackbirds. Will planting deeper help us with this? Will the sprayed weeds assist in keeping the blackbirds out? We have a John Deere no-till planter with fertilizer boxes. Would it be better to run the fertilizer through these boxes instead of broadcasting? These ponds are from 2 to 5 acres in size.
Submitted on behalf of Jim Scheer, La Grange, IL