I have been working in the Agroecology Lab for almost a year now researching the movement of nitrogen through the soil profile and into cover crops. In this time, I have installed instrumentation in the field, processed data using a combination of R and excel, and collected over a thousand soil and plant samples.
Our instrumentation includes lysimeters and Time-Domain Reflectometers (TDR). Lysimeters are used to collect porewater samples, which we use to quantify nitrate and ammonia concentrations 60 cm down the soil profile. This will give us an idea of how much nitrate-N is leaching out of the system. Our TDR’s are used to measure soil temperature, volumetric water content, bulk relative permittivity, electrical conductivity, and soil pore water electrical conductivity at 0-10 cm, 20-30 cm, and 50-60 cm down the soil profile. The TDR’s were installed for approximately 4 months and collecting data every 10 minutes yielding 252, 870 data points. This forced me to quit using excel all together and familiarize myself with R Studio. Data processing in R Studio has been a wonderful, rewarding experience.
Over 900 soil samples sounds quite intimidating. However, we processed all of our soils shortly after the collection date, so it was quite manageable. Unfortunately, some sources of contamination are entirely unexpected and are left undiscovered until the data processing stage. Four of our sampling dates had unusually high levels of ammonia. Contamination is part of working in a lab and is something we are all very careful about. After a while we discovered the potential source of contamination: our filter papers. I rummaged through my archived soils and began the process all over again. Luckily, with the help of our amazing lab crew: Cullen, John, Gabe, and Tony we were able to complete all 900+ extraction in seven days!
- By Josh Gaimaro
Dr. Kate Tully
Kate is an Assistant Professor of Agroecology at the University of Maryland.