Current concepts in nitrogen dynamics for mesoscale catchments

The study of global change impacts on nitrogen dynamics in mesoscale catchments remains an important topic. The primary mechanisms of change can be grouped broadly into those focused on land management, land use, climatic change, as well as on N deposition patterns. The current state of mesoscale studies of N dynamics is outlined in an effort to present the potential tools and methods available to researchers, as well as to outline future directions for additional research. This review focuses on a comparison of the common model approaches that are used to simulate the N cycle in catchments. The review is not meant as an exhaustive list of all models that might include N cycling, but instead outlines a classification framework as a means of better understanding key differences between common modelling strategies. We conclude with a blueprint of what hydro-biogeochemical models should be capable of, and which additional efforts should be considered in the course of model development and verification.