Learn to Measure Water Potential at a Bodentag

One of the best parts of my job is the opportunity I get to teach others about the science and technique of measurement. For more than 10 years, I have participated in seminars and workshops all over the world to do just that.  But, a couple of months ago, I had my first opportunity to work with my good friend Georg von Unold (METER Ag) to do a Bodentag workshop, German-style.  I learned a lot from my experience, and I think the participants did as well.

UMS’s Georg von Unold with his backhoe, digging a permanent soil observation pit in the Black Forest

A Bodentag (meaning “soil day” in German) is an unusual opportunity for the attendees to get practical hands-on teaching and training from the people who understand soil and environmental instrumentation.  In a typical conference, you will not get a chance to do things under field conditions.  Instead of sitting in a conference room all day, a Bodentag starts with presentations to set the stage with the theory and principles of measurement, but quickly moves to the lab and field to get the participant’s hands dirty.  With the diversity of measurements required for today’s multidisciplinary research, there is great value in structured field installation familiarity.

Our trip to Freiburg was a great example of how a Bodentag works.  Preparation started early in the morning the day before as Georg used his large Mercedes Sprinter van full of equipment to tow his Bobcat excavator for more than five hours on our drive from Munich.  When we got there, we were directed to a nearby site in the Black Forest where we used the excavator to dig a permanent soil observation pit (Georg’s gift to the institute there), complete with a stairwell that allowed people to go and inspect the pit face and install sensors. We prepared other stations to get people to install soil sensors with minimum impact, cut out intact soil columns for a field lysimeter, and remove intact soil cores.

Georg standing in the finished soil observation pit

The day of Bodentag, participants listened to two hours of lecture/presentations in the morning followed by both lab and field practicum sessions. During the field practicum, attendees could do actual installations of sensors into pit faces. This was useful because there were several researchers there who had Black Forest research sites, and they could look at and ask questions about the challenges of the rocky soil pervasive in that region. We used augers to dig holes to install Decagon sensors so everyone could see how that was done. Georg had one of his Smart Field Lysimeters out there and did a half-field installation. He showed them how to dig the Smart Field Lysimeter down into the soil, scrape the soil off, and actually collect a monolith right there.

After the outdoor practicum session, we went back to the lab where we broke up into small groups. There, people had an opportunity to go see laboratory instrumentation while learning some best practices for making measurements. In mine, people were using the WP4C water potential instrument to figure out the permanent wilting point of the soil that we brought. Attendees also got some careful training on the Hyprop to measure the wet end of the moisture release curve as well as learning about the KSAT, a METER instrument which measures saturated hydraulic conductivity. Because Bodentag is an opportunity to share ideas, we also got a chance to see the multi-step outflow instrumentation developed over the past 20 years by the Forest Research Center there in Freiburg that they use to create soil moisture characteristic curves.

2014 Bodentag attendees

At the end of the day, everyone was exhausted, and we still had a five-hour drive left to get back to Munich.  But, everyone had a great time, and the students and researchers who were there learned enough so they could be confident when using an instrument to get the data they need in an experiment. It was a unique opportunity for me to see how to put together a great educational experience, and I am excited to try one here in the U.S. sometime soon: especially if I can run the excavator again!

Download the “Researcher’s complete guide to water potential”—>

Download the “Researcher’s complete guide to soil moisture”—>

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