The Summer Soil Institute is a rare and immersive opportunity to study soil science both in the lab and outdoors. Centered at Colorado State University, the program takes students to the short grass steppe and Borden Memorial Forest ecosystems, where soil samples are collected and analyzed by participants. An array of techniques is then employed to process the samples over the course of two weeks. Techniques span soil pedology, SOM chemistry, fractionation, stable isotopes, fauna, microbial ecology, and gas flux. In-depth lab protocols are provided to students, in addition to hands on instruction by CSU faculty and grad students. Sampling and lab work are supplemented with intensive lectures in soil science. These experiential resources prove invaluable to participants, as they go on to apply them to research at their own universities.
SSI was initiated by a lecture in soil health by Dr. Stuart Grandy from the University of New Hampshire. Grandy discussed SOM dynamics and their connection to biological communities and physical processes. He described the evolution of society’s relationship with soil, which progressed in focus from soil fertility (<1960), to soil tilth (1960-1985), soil quality (1985-2005), and soil health (2005-present). Soil health is broadly defined as qualities that facilitate both sustainable ecosystems and human communities. Grandy’s presentation opened discussion on the need for a more exact definition of soil health to guide research in this field.
We ventured into the short grass steppe to collect sample cores and gas flux measurements the next day. Sample collection was followed by a trip to CSU’s Agricultural Research, Development and Education Center, where research was being conducted on organic matter amendments and their impact on corn production. Treatments included corn cob, bamboo stalk, and biochar (from pyrolyzed wood) amendments. Plots spanned an unaltered control, as well as corn cob and bamboo stalks addition with and without biochar. Gas flux was measured using an intricate automated system that sealed gas chambers, extracted samples, and transmitted them to an on-site PICARRO analyzer to quantify CO2, CH4 and N2O between sites.
Samples were also taken at the Borden Memorial Forest site, on a mountainside near Horseshoe Dam, the next day. The forest site had endured episodic fire events that impacted the surrounding vegetation. Soil samples without trees were labeled “clear cut,” while their vegetated counterparts were labeled “still standing.” Data analysis entailed comparing results between these site conditions. Gas flux samples were taken using sealed collars that relayed emissions from the soil to portable LI-COR and PICARRO instruments. Participants were debriefed on sample processing methods—for soil fauna analysis and sieving—at the end of each respective day.
The rest of the week was split into lectures and lab work. Participants chose between a soil chemistry and pedology lab and a soil organic matter and isotope fractionation lab. I chose the latter, which focused on tracking the fate of C in the soil matrix. The first lecture gave a comprehensive run-down on soil pedology; it was clearly and concisely delivered by Dr. Suellen Melzer, who had accompanied us for field sampling. This was followed by a thorough lecture on soil organic carbon dynamics by Dr. Francesca Cotrufo, which I will discuss in detail in another follow-up post. Dr. Thomas Borch proceeded to deliver two lectures on the chemistry and analysis of soil organic matter. Lectures on isotopes in soil ecology and greenhouse gas efflux were delivered by Dr. Cotrufo and Dr. Joe von Fischer respectively. Finally, students voluntarily presented ignite talks on their research projects and interests to hone their public speaking skills throughout the week. This was an engaging way to prepare participants to deliver their research at future research conferences.