there are places in the world, *china or viatnam i beleave* that have used this idea for years for growing there rice, wheat and other crops, by gathering the floating vegatation from the lake they live on, and make small 4'x4' floating islands and connecting them with srting so they dont float away, and pile some compost on it from last years crop to grow, so the crops get all the nutes they need and the roots dangle below in the lake water.

ill try and find some more information maby some links so you can check it out its prity genious if you ask me.