SOM6 Notes

The SOM6 workshop consisted of around 100 people, with a good spread among late and early-career scientists. I only met one other person who hadn’t delved pretty deeply into their PhD work, so I was among the earliest in career. I think it was all academic scientists from national labs or universities, with one representative from the USDA NIFA funding agency. There was a strong sense of continuation from previous SOM workshops over the past decade or so. However, oral sessions highlighted work from “Young Invesitgators,” mostly late PhD students, and these were among my favorite presentations:
-Charlotte Riggs from U MN talked about the effect of N additions in a grassland on SOM fractions. This was part of a larger network of replicated factorial additions of N, P and K around the world– the Nutrient Network– but apparently the story was still an N story from an SOM standpoint. Charlotte looked at 5 different grassland sites in the US and found that in general N addition increased the fast pool decay rate, and decreased the slow pool decay rate. However there was also large intra-site differences that she had not yet accounted for. For example, a shortgrass prairie in CO had oposite trends than all other (rainier) sites, and the Konza prairie reserve in KS had more macroaggregates by an order of magnitude than all other sites.
-Cynthia Kallenbach from Stuart Grandy’s UNH lab talked about her incubation of a microbial community on sterile sand. Cynthia called this a proof of concept to look at what kinds of molecules are synthesized by microbes which are provided with simple substrates: glucose, syringol, biocellulose (I think). They compared 1:1 clay and 2:1 clay and found some differences in the proportion of various organic compounds synthesized in these two environments– possibly aggregation was occuring and microsites for specific communities were emerging? Although we all know that microbes are synthesizing complex molecules, it was exciting to see that laid out so clearly in this experiment.

There were also some gorgeous images showing real hotspots in C processing around roots, and plenty of modelling and including microbial populations in modelling. Carlos Sierra gave an excellent little workshop on SoilR, which is an R package which includes many common models like RothC or Century (as well as dozens of models people have published and added) as R functions. There are also basic one-pool or two-pool functions which you can adapt to your data. This seems like a fantastic tool which is very accessible.

I got good responses to my poster and enjoyed talking about my work to people who think about SOM all the time. There was other work presented at the conference (Rota Wagai, in particular) showing that C associated with the mineral fraction is very young, and I used that to explain my positive correlation between stilt and clay SOM and yield. The paradigm of mineral association being the oldest, strongest association seems to be shifting. In general my work was more applied than most of the other work presented there. Though I found the theoretical work exciting I was also satisified to represent an agricultural, applied context.