Freshwater algae as a garden nutrient

I adapted my canoe into a sailboat and I was sailing on a lake near my house.  I noticed that my rudder was smothered in algae.  I pulled it off and before throwing it back into the lake, thought, Why don't I use this? I had been waiting for the rare occasion in which I am at the ocean beach.  I try to see if I have time to gather seaweed when it is there, which is not often.  This time,  I put the algae in my canoe.  They have cordoned off parts of the lake to warn boaters not to go there, as it will get stuck in your propeller, or rudder.  On a cursory search to see if it would work as well, it seems to have a lot of the same nutrients, and you don't have to wash off the salt.  There is so much algae in that lake that I feel like I am doing them a favor.  Many people live near shallow lakes and slow rivers but not near the ocean.  I know that some people use it directly as a nutrient, but I was planning on using it as part of my biochar inoculation.  Do you see any reason why I shouldn't use it in the garden?

Thanks,
JOhn S
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Seaweed is a saltwater algae, so I don't see why a freshwater algae wouldn't be just as good for macronutrients. I suspect that you will miss out a bit on the micronutrients that are present in sea water, like Iodine for example. But there is plenty of goodness in the freshwater algae. I've got some algae growing in my water terraces and I am meaning to fish it out to mulch around my blueberries there.

Using that algae is a great idea.

It sounds like a problem for boaters on the lake so why not talk to the folks in charge about getting a permit to harvest that algae.

That could also be a business opportunity.

Here's an observation to support your theory John.
My dog's wading pool is in mostly full sun (UV 10 out of 11) under a very productive Bing cherry tree. The 7" diameter trunk of the semi-dwarf tree is 18" from the pebble driveway. The pool is atop the driveway. When I drag the hose around to water, the pool get's topped off. The algae grows, and grows until it floats at the surface of the pool. After a week or so, I take a firm bristle push-broom and wildly scrub the algae off the pool surfaces so the water sloshes over the sides. Eventually, enough water and algae are slopped around under the tree so I can dump the remaining pool water and green algae into the driveway where the green water infiltrates through the pebbles. I place the pool on top of the algae film. Then I fill up the pool and the algae-growing process begins again.
That algae-watered 12' tall Bing produced well over 130 lbs of cherries this season without any fertilizer in mostly silt-sand soil. This is pretty rare in the desert.

Fresh water marine weeds/algae are magnificent stuff for nutrients. And when you pull them out into a pile, they instantly create a giant, vile, anaerobic compost bomb that offends the nose of anybody within half a mile downwind.  

That means it's the right stuff!! Put it into a rot barrel, and harvest the vile liquid for a biochar soak. It's a match made in heaven!

one of my local parks has a pond weed problem. every so often they haul them all out and dump them in a corner of the park, where the most magnificent weeds grow (jerusalem artichokes that reach the sky, practically, plantains with huge leaves, enormous dandelions-- I go there to score food for my rabbits when my garden is looking sad).
What a great resource for you! and oh darn, while you're down there you might have to go sailing/canoeing.

Im convinced that aquatic plants could be the best source of localized animal free fertilizer.
Consider netting some fish as well.
Do you have good source of carbon to add to the algae?

Wood. Trees grow like crazy here. People are always trying to give away wood.
JohN S
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I'll echo that this sounds like a great use of the algae in the pond. I've often wondered why more of the invasive water plants aren't used for fertilization on land. Let that water chestnut and milfoil feed soil while clearing out lakes and ponds. Some of it might even be useful as animal feed.

I'm sure the labor involved is the limiting factor at scale, but in your setup it feels like a great inoculant for char!

Mike, I think you are onto something.
Mixing the aquatic plants with char could be a way to prompt their decay while mitigating the funk of decomposition and charging the char.
I bet corn would like the resulting material.

Douglas Alpenstock wrote:Fresh water marine weeds/algae are magnificent stuff for nutrients. And when you pull them out into a pile, they instantly create a giant, vile, anaerobic compost bomb that offends the nose of anybody within half a mile downwind.  

That means it's the right stuff!! Put it into a rot barrel, and harvest the vile liquid for a biochar soak. It's a match made in heaven!

I live in a densely populated suburb, Douglas, so your post got me nervous.  
We have been very hot for a week and over 100 F for 3 days.  I laid it out flat on the soil. It dried pretty well. Then I flipped it over and let any moist part be spread out again.  Now it's bone dry. It has never smelled bad.  It weighs so much less now! I think it should store well now.

John S
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