Umm shouldn't the upside turf be inbetween the ground and the pond liner ? Or edging the pond?
Normal soil and ponds don't normally give good results, most plants go in with specially prepared aquatic soil which has less nutrients. Tho I could be wrong. Better though I think with normal liner bottom and popping your plants in aquatic pots, the escaped soil and odd bit of gravel give bottom dwelling creatures some terratory. I did mine like this and it's thriving. Good luck.