Our dam used to have lots of azolla, before we got geese. I was missing it. Azolla is a really valuable plant. It’s a rampant native waterweed, that is symbiotic with a nitrogen fixing bacteria, so, like legumes, it is capable of harvesting nitrogen out of the air and putting it into a form that plants can use as a fertilizer.
And it’s a potent fertilizer. There’s good science saying that fertilizing with azolla is better in terms of yield than fertilizing with chemical sources of nitrogen like urea or ammonium nitrate. I know that in compost, it works as well as any animal manure as a source of nitrogen – I can get “hot” compost very reliably using just azolla as the nitrogen source. It thrives in water that has too much phosphorus, and since we’re already past “peak phosphorus“, it’s a good idea not to let any of it get away.
And there’s another reason to love azolla. Urea, ammonium sulphate, ammonium nitrate, anhydrous ammonia – all the forms of nitrogen fertilizer, are made by a process called the Haber-Bosch process, which uses natural gas as it’s main raw material. A significant percentage of the world’s natural gas production is used in the process, making it a significant contributor to greenhouse gases, and a big market driver for coal seam gas mining. I really really really don’t want to give any dollars, directly or indirectly, to Metgasco.
So happily, I’ve found a neighbour’s dam that is chokka with azolla. It’s a nice 1 kilometre walk away, making it the perfect distance for my morning walk. I have been collecting a wheelbarrow load every few days for the chooks. They scratch through it looking for bugs accidentally scooped up with it, and mix it with the wheelbarrow load of mulch from the mulch mountain I give them on the other days, their own manure, and the household scraps and garden weeds they get routinely.
When I move them to the next bed, in a couple of weeks, I will have a beautiful bed of sheet compost to plant straight into.
PS. You can see the chook roost in the picture. The piece of pipe at the bottom is donged into the ground and there is one like it in the centre of each bed. The roost just slides into it. The chooks fly up to the lower rungs then climb right up as high as they can under the cone, the top of the pecking order at the top and the rooster keeping guard at the bottom.
The big carpet snake spent two weeks sleeping off a bandicoot dinner just metres away, but no chooks have been murdered in their beds yet. It could get into the fence – I’ve never found a way to effectively fence snakes out, and so could a determined fox or quoll I imagine, but the chooks can just fly up out of reach, and the barbed wire round the leg has so far been effective at stopping the snake climbing.