≡ Menu

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.



The dam is full of azolla – a little water weed that I encourage because it is symbiotic with a nitrogen fixing bacteria.  Like legumes, it can grab nitrogen out of the air and stabilize it in a form that feeds soil and plants that are not so handily endowed with an in-built fertilizer factory.

My partner, who is a bit more enthusiastic about cold water than I am, decided that collecting it was a good excuse for a swim.  In a few minutes with a little swimming pool net he had scooped up several feed bags full of it (still leaving plenty for this little frog to live in).

So of course with this supply, it had to be a compost making morning.

I don’t make a lot of compost – most of my soil building is done in-situ.  But three or four times a year, I decide it is worth the effort to create a batch of high-value plant food mostly used for raising seedlings.  I have written an item before about the theory behind compost making, and it really helps avoid failures if you get the idea behind the system.

Here’s today’s method for applying the theory:

Pick a spot with some stubborn weeds that need to be cleared.  Good compost composts the weeds growing under a pile – too good an opportunity for weeding without digging to waste.

Line up  five or six feed bags full of something that has a very high level of nitrogen, in this case, azolla.  Other options though include horse, cow or goat manure or a green legume.

Do a couple of hour-long sessions of mowing mediation to get two ute-loads of mulch.  I have a nice bit of community centre lawn that I like to mow because it has a good variety of soft meadow weeds in the grass, and some big angophoras (apple gums) that tend to drop lots of nutrient rich leaves.  So my mowing yields mulch with a good variety of nutrients and a good carbon to nitrogen ratio, (as well as a nice big lawn area for cricket games).

Mix the lot together either in layers or randomly, wetting as you go to give a texture like a wet sponge.  That is, it should be moist enough for the aerobic bacteria that will do the compost making to really enjoy the environment, but not drown.  Think air-breathing life form with no skin.

Wait for the pile to heat up to a temperature too hot to comfortably leave your hand inside it.  In something like a week to a fortnight’s time, when the pile has peaked in temperature and has started to cool down again, use a pitchfork to turn the pile, turning the outside to the middle and wetting it down again as you go.  You may have to do this more than once, depending on the weather and just how nice a breeding environment you have provided for the compost bacteria.

Within a few weeks you will have a pile of lovely stuff like this:

Expensive in labour, but oh so worth it!