My third Ph.D. dissertation chapter has been published in Environmental Science and Technology. I am feeling pretty proud, and am happy to be getting the work I did at Cornell off my desk (two more papers to go, with the one on three-source partitioning with two stable isotopes almost ready to submit). I presented this work at the SOM6 conference while I was working on the revisions, and had some helpful feedback from conference participants.
Briefly, I used (what I think is) a cool approach to manipulate the level of mineralizability of soil C (i.e., how easy it is to decompose) by pre-incubating the soils for different lengths of time (6 months vs. 24 hours), and then mixing it with pyrogenic organic matter (or “PyOM”, or “charcoal”, or “biochar“) with increased or decreased amounts of easily-available C (i.e., water-soluble), to see how relative amounts of easily-mineralizable C affected decomposition in the soil and the PyOM.
I found that the 6-month pre-incubated soil was more susceptible to increased C losses with PyOM additions, over the first few days of the incubation, although both soils eventually experienced net decreases in C losses with PyOM additions. Also, more PyOM-C was lost in the 6-month pre-incubated soil, possibly because portions of the PyOM were relatively more appealing than the soil C or because the 6-month pre-incubation had more available nitrogen, which helps decompose the PyOM.
This could help us predict which soils will be at risk for increased C losses with biochar applications, with soils where C is already depleted being more likely to experience losses with PyOM additions, especially if the PyOM is similar to the 350°C maple wood char I used in the study.