Building an Edible Floating Island

Aquaculture, Dams, Fish, Land, Plant Systems — by Erik Klockemann May 30, 2013

Here we are! We are underway with our Ten Week Internship with Geoff Lawton at the Permaculture Research Institute, Zaytuna Farm, in The Channon, New South Wales, Australia. We are a small group of only six interns, two teacher assistants and Mr. Geoff Lawton. The team has really formed a synergy and we feel great with some of the projects we have been able to complete.

The first project was in our first week of the internship and we built a floating edible island. Artificial floating islands and floating gardens have been used for ages — most famously would be the floating islands of the Uros on Lake Titicaca. Then you have the floating gardens of Mexico City which are in fact chinampas and do not float. However there was a time the “floating gardens” were actually “floating” due to Lake Texcoco flooding the valley of Mexico City in June 1629. The city was flooded by three feet and remained flooded for five years. The fields were underwater, so necessity pushed the people of the city to rely upon floating gardens to simply avoid famine.

Our edible floating island is probably much different than the floating gardens of Mexico City during the last great flood. The design of our modern edible island is simple and effective. It’s a small raft held up with an inner pvc pipe frame and is reinforced with bamboo. A plastic net and shade house cloth are ziptied to the frame to make a bottom. We then filled it with semiaquatic, edible plants. These include Aethionema cordiolum (Lebanese Watercress), which looks like rounded celery leaves and tastes just like it. It is used as a flavor additive to salads, soups or stir frys. Also Ipomoea aquatica, otherwise known as Kang Kong or Chinese Water Spinach, widely eaten as a stir fry vegetable and is the fastest growing leaf crop in the world. A relative of sweet potato, it is much healthier for you than lettuce in way of nutrient value. You can find it in supermarkets and it is used throughout Southeast Asia in many dishes.

Both plants were grown in pots and then transplanted with the soil to the net. There were concerns about keeping them from frosting over the winter if they remained in pots on the dams edge. So the floating edible island build is a floating experiment with the hope that the thermal mass of the dam will keep them from frosting.

Other than being an edible island, it is also intended as an additional underwater edge for life to live. We imagine fish feeding under its canopy and it being a hotspot for frogs and turtles. Hopefully when the roots have really developed it will also be a means for additional water filtration, aeration and increase the waters clarity.

Finally we launched the island and anchored it to the bottom of Paradise Dam. It sits as a splendid view from the dining area and I have enjoyed seeing the Kang Kong’s white morning glory flowers bloom and increase. I look forward to the first harvest and some stir fry!