are you going to hunt it? if not, the quickest way to get ducks into your pond would be to dump a bunch of corn in there... it can provide good hunting too
I would look at a crop like barley or, if you want low maint. try some *** millet, or smart weed...
hell dont even bother planting anything other than the corn. Just leave some standing in the depression and then flood it. that will bring in some birds