Domesticating Duckweed – The Food of the Future
Duckweed MAY be the food of the future. There is no doubt about that. Grown under ideal conditions, duckweed ranges between 25% and 45% protein and doubles its growth every 36 hours, and OUR TILPAIA love to eat it.
We do not profess to be experts at growing farm-raised duckweed to feed our fish. In fact, quite the opposite is true. We have grown duckweed in kiddy-pools, large and small containers and even open-air tanks off-and-on for many years and we have not always been successful in our efforts to maintain our duckweed farms, but we keep trying and we continue to experiment to find the answers to pass along to you.
Duckweed seems to overgrow in places that people do not want it to grow – like ponds, rivers and lakes, but it’s been difficult for us to raise it in tubs for more than a few weeks before it dies. If duckweed covers the surface of a body of water, there is an oxygen depletion which kills fish in the ponds, rivers or lakes. (Feed tilapia only enough for them to eat. The remnants are picked off over time.)
Our latest experiments for growing duckweed suggests putting pvc pipes or pvc fittings in the water in the tanks for the duckweed to grow around it (which makes sense) so we’re going to try that and we’ll keep you posted.
If you plan to raise enough farm-raised duckweed to feed your fish for a commercial sized-farm, we recommend you speak with a local botanist in your area that might be able to guide you better than we can. There is a vast amount of scientific research and available information on the Internet about duckweed.
Here’s a close-up photo of duckweed on our fingertips
Fun fact: “People asked us for a long time what duckweed tasted like. One day our construction engineer said, “Well, I guess you ought to taste it so you can tell them.” So I did. It tastes like watercress. Tangy, peppery and very clean tasting. – Thought you’d like to know. – Colle
{Also, starch that comes from duckweed can quickly be changed into ethanol, which it can used instead of corn for ethanol. Farmers from large-scale hog farms, rid their waste through large duckweed “lagoons.” It helps manage their animal wastes through biological treatment and can even ‘clean’ hog-waste water and makes the water potable by running the water through enough duckweed. Interesting, eh?}
Here are a few links for you to study duckweed and its benefits and complexities:
http://www.fishfarming.com/duckweed.html
http://www.lrrd.org/lrrd7/1/3.htm
http://en.wikipedia.org/wiki/Lemna
http://www.mobot.org/jwcross/duckweed/Fish.htm
Duckweed in kids 8’ kiddy pools
In fact, here is a link to a technical working paper by researchers for the World Bank, Duckweed Aquaculture, A New Aquatic Farming System for Developing Countries, by Paul Skillicorn, William Spira and William Journey – Emena Technical Department, Agricultural Division. http://www.p2pays.org/ref/09/08875.htm#Morphology
Advice for ridding unwanted duckweed from ponds from the Royal Horticultural Society in London:
Non-chemical controls: Complete control is impossible and growth should be controlled before it reaches nuisance levels. Try the following for control and prevention of duckweed:
- On small ponds repeated raking or netting will keep the weed under control. Continuous removal is usually necessary
- On larger pools use a floating boom to sweep from end to end. Sweep at intervals from early in the season and continue until winter dormancy
- You can compost the removed weed
- Fit stop-boards at any upstream inlets to prevent duckweeds entering ponds or lakes
- Weed-eating water birds, such as domestic and ornamental ducks, moorhens and coots will provide some degree of control
- Grass carp will eat Lemna species
- Shading can reduce duckweed growth. This can be achieved by planting on the south side of the pond. Waterlilies and other plants with floating leaves can also substantially reduce the level of duckweed. The use of a fountain to disturb the surface may also help
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4 comments
Joe Kaemerer says:
2011/10/11 at 11:13 am (UTC -5 )
Have you tried an aquarium air pump to keep the duck weed pool with a continuous supply of air?
Have either any State or Federal Department of Agriculture issued any bans or warnings on farming duckweed seeing as it is very invasive to lakes and streams?
portfarms says:
2011/10/11 at 11:24 am (UTC -5 )
Joe,
We have tried the aeration and it seemed to make it worse. Duckweed likes still water or very slowly moving water and aeration moves the water. Duckweed is indigenous to every state in the US and banning it has never been even considered as far as we can ascertain. Yes, it can be invasive, but only when the water is nutrient contaminated by sloppy agricultural or food processing practices does it become a problem. Duckweed is a fantastic fish food and many people have been very successful all over the world in raising it for that purpose.
Colle Davis, Inventor, Portable Farms™ Aquaponics Systems
Tamra Fakhoorian says:
2012/03/17 at 11:56 am (UTC -5 )
I’ve found that innoculating my duckweed beds every month or so with a new batch seems to help with consistent cropping far into the fall. It likes a high nitrogen nutrient load, but don’t forget the micro nutrients. I’ll mix in a few pinches of unrefined sea salt in my kiddie pools. A little goes a long way. Great post. Duckweed is going to have its day in the sun within two years in this country because it’s got so much to offer.
portfarms says:
2012/03/18 at 7:35 am (UTC -5 )
Tamra,
Thanks for the tip. That is one method we have not tried or even heard of before. When we set up our next duckweed pools we’ll see how that works and let everyone know of our success or non success. LOL
Love the duckweed information on your website. Keep up the great work. It’s so needed in today’s world.
Colle Davis, Inventor