I am trying to find a way to build floating gardens/islands for our sloughs. I want to help the ducks and other beneficial wildlife that comes to the farm (to increase our chance of mosquito control at least until we have poultry).
Has anybody built anything that's floating and can be planted?
Garden Therapy has an article on floating planters: https://gardentherapy.ca/floating-planter/ However, I don't like to use plastics and I don't know if they would support the weight of wildlife.
Google "foamed concrete" or "aircrete" or "lightweight cellular concrete". You can make planters in any shape you want and lightweight concrete will float. I've made it, it's pretty strong and you can alter your mix design to change the density to suit your needs.
So, instead of a man made material, why not give willow or some other lower density logs a try? Bind them together into a raft, leaving enough space between logs to allow some water plants to potentially establish themselves in the cracks. Anchoring them if possible may also be helpful.
Seems like the basic idea is to use dry material to build a woven mat with bamboo or other woody material for support and extra flotation. Compost material is added on top of this and then soil at the very top. Then you can plant into the soil and let the plants grow. The site suggested the beds could last for up to two years before sinking.
The site is based in a tropical environment but it seems like a temperate version could be constructed. Hope that helps!
I like the chinampas idea. How large are you looking for these islands to be?
I wonder if two specific ideas would help.
One, what about incorporating something like straw bales for both structural integrity and weight? I was thinking that you might seal a layer, or the perimeter sections, of the base of a raft made of straw bales. My thinking was EPDM, but you don't like plastics. I do think, though, that in the context of a multi-season project like this, the use of pond liner could be justified. It would probably extend the life of the island, and the liner might survive to see a second use.
In any case, even if they aren't used for flotation, they could easily stand in for many years accumulation of dead reeds, and serve as structure for many individual plantings that you start in the straw bales, using straw bale gardening methods. You could prepare the whole top of the straw bale layer to accept plants, and then seed it with everything you want for duck habitat and forage, and still be able to have room and structure to accept more elaborate garden bed plantings that you could section off from your ducks, either perennials for their feed, or yours.
The second idea is to incorporate wicking layers, at least one on the bottom and one under the mulch layer, to maintain and regulate moisture throughout the bed.
Either way, I like the floating softwood and/or reed raft idea. I don't really like the foamed concrete idea, although I agree it would work. I just hear the idea about floating foamed concrete planters and I think about water working its way through poured concrete foundations designed to withstand that action with weeping channels because water infiltration and saturation is otherwise unavoidable. I don't like the idea of the air bubbles in the concrete filling with water over time, which might in itself cause such a structure to sink. I also don't like the idea of one of these saturated structures not sinking and continuing to pass water through the concrete into the garden bed, carrying with it whatever is in the concrete.
I also wonder why you need them to float. I understand the need for access, but there could be advantages to fixed islands built on pilings or some sunken wooden structure upon which you would then build your land base (for which I would again suggest the straw bales, just to simulate built up dead reeds).
Lets say your slough was a long trough. If you had arms of anchored island jutting out perpendicularly to the direction of flow, alternating sides, you could lengthen the path the water travels by making it zig zag. This could be really good if you're interested in trapping sediment, making use of the islands to plant more reeds and other filtering species, shelter and habitat for wildlife, both aquatic and otherwise, and probably a bunch of other benefits having to do with increasing edge habitats and cleaning water.
However you decide to proceed, I think it's awesome that you're doing this. If you don't mind providing more information, advice could be better tailored to your specific situation. Updates are also appreciated, because I love seeing these kinds of plans in action.
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
-Robert A. Heinlein
I use a system I developed and can be easily cpioed.
I cut and glued 100mm/ 4 onch plastic sewerage pipes to form a frame which looks like the letter E with the open side filled in.
Then I wired on thin timber to the frame, and placed sa small house on it.
Mine is about 1M x 2M and it niht it can have 4 -6 ducks on it.
Because its a safe place from foxes.
I have cut a hole to allow a pot to hang in the water and items grow in that.
Its been working for 15 years
John Daley Bendigo, Australia
The Enemy of progress is the hope of a perfect plan