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New Duckweed Test Site

May 11, 2013

Adjusting the liningIt looks like I’m trying to climb out, but actually, I’m “kneeing” the plastic into place on a newly dug duckweed pond on my friend’s nearby farm. This is a test pond that measures 14 ft wide by 90 ft long and two feet deep. It took a couple of days to fill via a well pump and two really heavy spring downpours. The plastic is UV treated, 4 mil greenhouse plastic. Hopefully it should last four years or more. My friend is interested in growing duckweed as cattle feed supplements. I have been wanting to do a more controlled growth pond specifically for Lemna minor so it’s going to be a fun project. Many thanks to Gina McCord and family!

While it was filling, I did a bioprospecting run up to Southern Illinois and harvested 7 gallons of Lemna minor from one of my favorite finds- a little pond alongside a back country road.  The owners of this pond are really nice folks and have been letting me harvest duckweed for about three years in a row now.  Last year, I used 100 pounds of their duckweed to dry for a bioenergy project and did some fresh feeding tests with chickens and a few peacocks. This year, I am using their strain to seed this shallow, new pond seventy miles south of theirs. As we’ve had a really cool spring, the wild duckweed populations in my region are delayed in growth- down by 90% in volume over last year ths time. Also, certain strains that usually are predominant this time of year are nearly non-existent. (Wolffia and Spirodela polyrhiza)

I got back to two days heavy rain and didn’t get to release my new duckweed until the third day. It sat outside in a couple of ten gallon containers and stayed moist under the trees. It looked perfectly healthy when I finally did let it go in its new home. Below is a pic of the pond half-filled. I am going to plant tons of sunflowers on all sides to act as windbreaks. My initial fertilizer was some 20-20-20. I am transitioning to manure for this pond as soon as I can get a set-up for it.

New test pond

7 Comments leave one →
  1. June 24, 2013 7:46 am

    ”I am going to plant tons of sunflowers on all sides to act as windbreaks. My initial fertilizer was some 20-20-20 ”
    May I ask what do you mean exactly by 20-20-20 ?


    • June 24, 2013 7:55 am

      20-20-20 is an general purpose soluble plant fertilizer. It comes under many brand names and contains 20% by weight of each of the following: nitrogen, phosphorus, and soluble potash.


  2. Susan Munroe permalink
    May 23, 2013 7:53 pm

    It probably doesn’t matter if waterfowl bring in other varieties of duckweed. Just as long as they don’t bring in something like water hyacinth or water lettuce to contaminate it. And I certainly don’t know how you would keep them out!

    Our last frost date last year was in the last week of May. The farmers around here don’t plant anything before June 1… and for good reason, I guess.

    Don’t worry about the Lemna yet. I looked in a concrete bowl that wintered outdoors, and it looks like some Lemna is popping to the surface. I’ll fish it out and put it in a safe place (out of reach of the ducks, which I thought it was, but it wasn’t).



    • May 23, 2013 8:20 pm

      Sue, as this pond is very manageable, I can fish out any odd ducks, so to speak. So you’ve got turions that are popping up. Very cool! Keep me posted as to whether your real ducks outsmart you and eat all the duckweed.


  3. May 13, 2013 7:41 pm

    HI Sue, We had a mild winter but prolonged cold spell well into late April where it froze even three weeks after our last frost date. The past three years, our last frost would be in early March and I’d take advantage of a whole extra month of gardening. Wolffia tried and gave up. Lemna minor is moping along even now except for my chicken barn pond. That is chock full of Lemna and I’ve been harvesting it right and left for seeding other ponds.
    The new trial pond… I may string white polyspun material over portions of it to give it a bit of shade but am going to let the birds land it they want to. It’s about real life situations as opposed to totally controlled settings. (other than shade and a sunflower windbreak)
    I am going to plant ground cover plants close to the edges and hope to cover the horizontal plastic as best I can with either plants or dirt. Thanks for the thoughts on that.
    Want some Lemna minor? I can send you some more if you like.


  4. Susan Munroe permalink
    May 12, 2013 4:43 am

    p.s. All my Lemna is dead. I had two bowls sitting by the window in the bathroom, one with Lemna and the other with Spirodela. The water dried up in the Lemna one. I caught the cats drinking out of that one a couple of times, despite having their own water bowl filled fresh daily. I should have kept a closer eye on it. I guess I’ll have to depend on the Wolffia for my supply.



  5. Susan Munroe permalink
    May 12, 2013 4:39 am

    “…certain strains that usually are predominant this time of year are nearly non-existent. (Wolffia and Spirodela polyrhiza).”

    Well, now, isn’t that odd! I can’t even find Lemna around here, but I stopped to check the Wolffia down in Kalama, and the stuff was 3″ thick! It was there all winter. So I wonder what the problem was down there? What do you call “cool”? I was still using the wood stove two weeks ago. Is there something growing in its place that could be choking it out?

    Nice trial pond! Are you planning to try to keep passing waterfowl out of it to avoid contamination? Once covered with water and duckweed, the plastic may last longer than four years, esp if you cover the edges against the sun.



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