CrunchREWT, a coupled root exudation and reactive transport model for Critical Zone biogeochemical dynamics

Abstract:

Roots both directly and indirectly influence the active root zone (ARZ) of all vegetation-bearing ecosystems, including the transport, deposition, and potential destabilization of organic matter. Root-soil-microbe interactions are inextricably linked with our understanding of and ability to model the transport and transformation of carbon (C) and other nutrients in the Critical Zone (CZ). CrunchREWT is a novel software coupling which merges the principal multi-component geochemical features of the reactive transport model CrunchFlow with the spatially heterogeneous transport framework of the root exudation model REWT (Root Exudation in Watershed-scale Transport) [1]. This coupled framework uniquely links high-resolution, process-based simulation of dynamic root properties, such as root exudation, and the transport and transformation of ARZ C and nutrients according to stoichiometrically-balanced reaction networks. We present CrunchREWT simulations for an intensively managed landscape in the US Midwest and for a steep, forested landscape in the Northern California Coast. Preliminary results demonstrate the role of root exudation in the promotion and alteration of biogeochemical cycling in both ecosystems. In the intensively managed landscape, root-soil-microbe interactions alter nitrate and other solute exports compared to model simulations where root exudation was not considered. In the forested ecosystem, root-rock-microbe interactions alter solute flux in the weathered regolith.

[1] doi: 10.1029/2019WR026606