Lost in the Corn: The Search for Lysimeters

Today’s guest blog post was provided by summer student intern Laura Lacquement. A native Iowan, Laura grew up south of Des Moines, and went to school at Martensdale-St. Mary’s. She started her college career at Valparaiso University, and later transferred to ISU, where she is now a senior studying Environmental Science.  

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I enjoy travelling across the State of Iowa with Water Rocks! and Iowa Learning Farms. The location and events vary, while the field work remains consistent. One of the projects I’ve helped with all summer long is ILF’s cover crop mixtures project. Each week we travel to three of Iowa State University’s research farms to collect water samples from lysimeters located in plots of corn and soybeans.  Each block of plots contains 12 lysimeters placed between rows of corn or soybeans.

Lysimeters measure the movement or storage of water in the ground.  The lysimeters that the ILF team uses are composed of a tube two inches in diameter and two feet (24”) deep.  The bottom of the tube is composed of a porous ceramic cup that allows the movement of water into the lysimeter from the soil around it. Using a vacuum pump, we create suction inside the tube that pulls water inside.  Each week, we extract the water by using a flask that is connected to the vacuum pump on one side and a straw connected to its lid and inserted into the tube to its full depth.  Using the pump and flask, we pull water from the lysimeter into a small bottle, where it will later be analyzed for the amount of nitrates present. Each lysimeter tube is installed so it’s flush with the ground. To protect the lysimeter, a four inch PVC drainage pipe plug and small pipe is placed above it.

Most of our plots are located close to each other, with the exception of the plots at the ISU Northern Research and Demonstration Farm in Kanawha, Iowa. Finding the lysimeters there can be quite an adventure! At the start of the internship, all we could see of corn and soybeans in our plots were little sprouts an inch tall.  In just a couple weeks, the corn grew past our knees to over our heads.  I not only watched this growth, but experienced it firsthand by struggling to carry our devices and tools over and through the corn and soybeans to each lysimeter.

On Friday, June 30, I traveled to Kanawha, Iowa, with Elizabeth to extract water samples from lysimeters there. As I mentioned, the plots here are not located right next to each other, but in completely different fields separated by a grass driveway.  After we collected samples from the soybeans, we entered the corn in search of our small buried lysimeters in the shoulder-height corn.  We walked inside each row looking for our lysimeters … for an hour or so. Our ILF plots happen to be in the middle of a much larger field, and the challenge is that there’s no easy way to flag or label the plots once the corn is this tall! We eventually ventured a bit south of our current location, where we recognized our plots and finally spotted a lysimeter only a short distance away. Small victories!

Friday, July 7, I returned to Kanawha with Kaleb to collect more samples. This time, I knew exactly where to go to find the plot, but not the precise location of the lysimeters. In just one week, the corn had grown from the height of my shoulders to the height of me. I could no longer see over the corn.  As I finished extracting each water sample, Kaleb would move to the next lysimeter.  He may be the tallest of us interns, yet I still could not see him over the corn.  To find him and the next lysimeter, I followed the sound of corn rustling and looked for his bright red shirt through the corn.  If we do not wear bright colored shirts, a game of Marco Polo may be necessary!

After these experiences, I’m now very confident where ILF’s plots at Kanawha are located, plus how to find the other lysimeters and interns in corn taller than me. Each time I take samples from the lysimeters, I have learned a little more about corn and soybean cropping systems, as well as water quality issues in Iowa!

Laura Lacquement