Ducks eating fallen bird seed, killing grass.

In my back yard we have a bird feeder that the ducks like to eat the fallen seed under. I have no problem with this except the grass all dies (or is eaten with the seed?) and we are left with a mud or dirt spot. My mother has stated she wants to put down concrete slabs under the feeder. But I would think that wouldn't be great for the ducks' beaks. Does anyone have any ideas what could be put down that would be safe for the ducks? Would fake grass be okay? Thank you for any ideas!

I'm sure the ducks would be even happier if the seed fell in shallow water rather than on land.

I'll second Roy's suggestion to move the bird feeder so it hangs over the water. I believe it won't take long for that grass to recover and the bare spot to disappear. No need to spend money on concrete or fake grass! If you do move the feeder, spread a little straw over the bare spot to help keep the sun from baking it, and that will help speed up the grass recovery process.

The ducks are probably eating the grass when they eat the seeds. I've found that a really good way to eliminate weeds/grass in certain areas is to put my ducks' feed on it. They end up eating the plant just to eat the seeds.

Woodchips might be a great solution to your problem. They look nice, are easy to weed, and they don't hurt the ducks. In fact, my ducks love digging through woodchips to eat the woodlice, slugs, and other bugs that live in the chips.

Thank you for the ideas guys! I like the idea of putting it over water, but the space we own in the water is actually super deep. We'd have to get a much longer pole (or make one). But the idea of a small circle of wood chips sounds nice too! We will probably go with that and see how that works.
Thank you again!

Could you put the feeder through a plank of wood. Secure one end of the wood to the land and have the other end just enough inches into the water to prevent seed falling on the grass. The part that is in the water should have a square or circle of wood as a platform around or below the waterlevel to catch the seeds in shallow water that the duka could also stand on?

First I would toss some of your seed on the water and see if and for how long it floats. They might be fine with that.

It would be very simple to drive a 3/4 in pipe into the ground,  screw a tee on the top and have equal length arms off the tee. One for the feeder and the other for a counterweight. Depending on the length of the arms you could rotate it to a different place each time or even hang it over the water.
Instead of a chicken tractor you could have a duck carousel.