Inverted Triangle

Inverted Pyramid by sylvain.collet via Compfight

2016 is turning out to consist of a number of elegant sets of threes, and thus I’m officially declaring 2016 the Year of the Triangle – at least for myself. In the next three (get it?) blog posts, I will explore three different sets of threes under which my year in research can be organized. In part 1 (below), I will report on my sabbatical visit to New Zealand and how it evolved into a three-way collaboration between labs in New Zealand, the US and Canada. In part 2 (coming soon), I’ll describe one conceptual framework that the Powell Center working group on soil carbon came up with to guide our thinking about the next generation models for soil carbon cycling. And in part 3 (coming soon), I’ll describe the triangulation of data, code and results, and how we are using these in ongoing projects.

Part 1: How a trip to New Zealand brought me back to Canada

With the support of the America-New Zealand Soil Science Professional Exchange Award from the Soil Science Society of America, I spent six weeks of my recent sabbatical in Christchurch, New Zealand working with colleagues at Plant & Food Research (PFR) in Lincoln. During my stay, Drs. Mike Beare, Denis Curtin and I discussed a number of ongoing PFR projects, and how I might contribute to them. One of my current research goals is to explore the connections between the biogeochemical stability of soil organic matter and its thermal stability as measure by thermal analysis during ramped combustion. This is an evolving field of study and there are few research groups applying this approach, so there is still much to be learned on whether thermal stability can indeed be used as a proxy for assessing soil organic matter’s resistance to decomposition.

In a recent study (published here), Denis and others examined the biodegradability of soil organic matter by comparing laboratory incubation assays to a different thermal analysis technique called RockEval. RockEval was originally developed to characterize oil-bearing sedimentary rocks, but has recently been applied to the study of soil organic matter. It uses a combination of ramped pyrolysis (burning in the absence of oxygen) and combustion (burning in the presence of oxygen), while the techniques that I typically used consist only of combustion. The lead author on the study was someone that I’ve known for a long time, Dr. Ed Gregorich from Agriculture & Agri-Food Canada (AAFC). Ed has made a number of research visits to New Zealand to work with Denis and Mike.

So between the three nodes at PFR in New Zealand, AAFC in Canada and myself at Penn in the U.S., we are exploring the possibility of a three-way collaboration that would explore a wide range of possible ways to express thermal analysis data on soil organic matter from both ramped combustion and RockEval, with laboratory incubation data. I’ve done this kind of correlation before (published here and here), but the comparison with RockEval and the larger and more diverse set of soils from New Zealand and Canada provide a novel and potentially more robust test of the possible link between thermal and biogeochemical stability of soil organic matter.