Designing Rhizotrons

I’ve been designing rhizotrons. Sketches of plans are in my notebooks and on loose sheets of paper on my floor, desk, coffee table, nightstand, and kitchen counter. I’ve tried conceptualizing all sorts of materials and dimensions. Some of my ideas are very cool, and I’d love to build them. A constraint exists, however. My rhizotron needs to be cheap because I need to build a fleet of them.

With some sadness and reluctance I discarded a PVC-framed design due to cost. It would have been an elegantly simple yet devastatingly stylish rhizotron. Instead I turned to a cheap wood frame. This means the frame will be boxier (a loss of style points) and prone to decomposition (but should easily survive long enough for my purposes). And less cool.

Here are some sketches:

Figure1. A simple rhizotron design.

Figure 2. The side.


The rhizotron is composed of two 12″x24″ sheets of plexiglass with a 1.5″ thick wooden frame between them (I am considering making it 2″). Bolts run through the frame and plexiglass, with wing nuts holding the glass in place. The rhizotron will be filled with soil and two firs will be planted in it. Pieces of foil-covered foam insulation will be placed over the glass to block the light and buffer the temperature. To encourage the roots to grow to the glass the rhizotron will be held at a 30° angle. After root developemnt occurs I’ll be incorporating flooding treatments of varying lengths.

Right now my estimated cost for the design above is less than $20 per rhizotron. My current task is to figure out just how many I need.

Figure 3. All is well in the rhizotron.

I’m confident I won’t be able to see clear pictures of fir root systems like I sketched above. I’ll see bits and pieces. Many of the roots will be shy.

Developing an idea based upon theory, speculation, and anecdotal evidence is a bit scary. Especially when it is linked to my ability to graduate. The behavior of fir roots in flooded soils is not well-studied or documented. It seems that differences in morphology and physiology should be apparent following flooding. One question that is fascinating is why do vast differences in flooding tolerance exist between different species of firs? Another is how quickly does permanent damage caused by flooding occur in Fraser fir? I hope to explore these questions this summer.

Designing rhizotrons is the easy part. Experimental design and procedure will be trickier. My journey in the wilderness of research continues. . .


Filed under Horticulture

3 responses to “Designing Rhizotrons

  1. Paul B

    Nice beard.

    • I wasn’t sure if anyone actually looked at the site header or not, good catch.
      I am currently sporting a “wilderness of research” beard, so I adjusted my graphic accordingly.

  2. Anonymous

    Thank you so much. I want to seed turf in different kind of soil and demonstrate how do the roots and I did not know how to do it. Now, I think you helped me a lot!

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