Monday, 27 April 2015

Duckweed update

It's been a couple of weeks of experimentation and observation. Actually it's been a lot of fun and has made me quite content to do nothing other than watch plants grow and things decompose.

The idea is to have a sustainable egg production. Sounds simple, but actually requires a bit of work. The farmer is agreeing to contained poultry - and that's what's making it more work. If they were free range then it would be all rather natural and easy. Instead they will be relying solely on humans for food and water. That's a shame really, but I think over time I'll be able to let them out. The plant man just needs reassurance that the feathered ones won't destroy the orchard. Patience.

So even though it's another month and a half until they arrive, and even though the site hasn't been fully cleared or the coop / run built, food production is under way.

We've planted spinach, pumpkin, pidgeon pea, moringa and a local green (chickens love it, no-one has a name for it) for fodder. Early days, but everything is coming up and looking good. Weather has been co-operating with sun and rains.

I have 3 tubs on the deck with duckweed and azolla. One tub has lots of leaf litter and tadpoles and gets about 4 hours of sun a day, one tub has just leaf litter and is in the shade, another tub contains Orinoco (my betta splendens) and is in more shade with indian almond leaf which makes the water soft and slightly acidic.

So far the tadpole tank is doing the best in terms of duckweed production. This is also the only tank with azolla, which is also doing well. We're not talking dense mats, but it is growing. I'd say doubling every 4 days. The azolla is slower, but also growing. Thus far I'm not at all confident that it will be the major green stuff in the birds' food. I need better production.

In all the research I've been doing there seems to be several "limiting factors", or variables: sunlight, nutrients in the water, temperature, hours of daylight. I'd also add munchers - something ate half my azolla when it was at ground level. Duckweed - it is said, prefers some shade, though in this case, it prefers a few hours of direct sun. The tadpole tub has probably the best nutrient rich water - both from the large number of tadpoles and the decaying leaf matter.

Initially I tried tubs with no leaf litter, no wildlife (that I could see), and added fermented pee to the water. Too much it seems. Not good. Since researching more it needs only 20mg of urine a liter, so my initial enthusiasm all but killed the plants. Unless I build a large tank I don't think the pee is an efficient idea, much as I like it.

I've also been reading that the effluent from black soldier fly larvae is also great for duckweed. It so happens that I have such an effluent, so another tub will in all likelihood get set up today to try that out.

I'd like to make a small duckweed pond by the coop, we'll have to wait til all the construction work is done for that.

I'm almost delighted that the most natural tank - with lots of leaf mulch and tadpoles, is the most successful. "Almost" delighted in that it's the one that requires the least participation, but of course quite delighted to see that Nature is always ultimately the most efficient, sustainable and long term winner.


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thanks for sharing!