Duckweed as fertilizer? You bet!
Check out this close up shot from one of my ponds:
The larger plant is some kind of native duckweed… the tiny light-green plants are another type, and the frilly dark-green plants are azolla.
Duckweed and azolla are loaded with protein, which means… NITROGEN!
Azolla has the additional benefit of being a nitrogen-fixer, which means it makes nitrogen out of thin air. Er, water. Or something.
Anyhow, if you have a place to grow these tiny floating plants, you can use them as fertilizer in your garden. Simply scoop them out with a net and side-dress your vegetables with sloppy clumps of duckweed/azolla, or add them to your compost heap. Once they’re out of the water they break down quickly, giving your food plants a kick of nutrition.
For lots and lots more on duckweed, including duckweed as fertilizer, check out this gal’s site. Plenty of food for thought there.
You should also check out my homesteading video; in it, I cover using ponds as sources for compost.