Arjun Chakrawal

SSS Soil System Sciences

The 2019 Outstanding Student Poster and PICO (OSPP) Award is awarded to Arjun Chakrawal for the poster/PICO entitled:

How does soil spatial heterogeneity affect decomposition kinetics? (Chakrawal, A.; Herrmann, A.; Koestel, J.; Jarsjö, J.; Nunan, N.; Kätterer, T.; Manzoni, S.)

Click here to download the poster/PICO file.

Arjun Chakrawal is a Ph.D. student at the Department of Physical Geography, Stockholm University. His research focuses on the effects of micro-scale heterogeneity posed by the soil structure on the soil carbon cycling and upscaling approaches that account for this heterogeneity in macro-scale models.
An accurate representation of soil organic matter (SOM) decomposition dynamics in large scale Earth system models is required for a better prediction of carbon storage and its fluxes. Often, the dynamics of soil carbon decomposition are simplified – assuming soils as well-mixed homogeneous compartments of varying substrate quality and microorganisms. However, soils are naturally heterogeneous. This heterogeneity results in a non-uniform spatial distribution of substrate carbon as well as microorganisms inhabiting it. In this poster, we introduce a methodology to account for spatial heterogeneities in soil carbon cycling models and discuss the limitations of using traditional models that neglect spatial variability. We use scale transition theory to analytically link micro- and macro-scale dynamics in a two-dimensional spatially heterogeneous medium. Using scale transition theory, we show that the higher-order spatial moments of substrate and microorganisms should be included in a macro-scale carbon model because these moments exhibit a dynamic behavior that alters the mean dynamics of SOM decomposition.