Soil nutrient cycles as a nonlinear dynamical system
- 1Department of Civil and Environmental Engineering, Duke University, 127 Hudson Hall, Durham, NC 27708, USA
- 2Department of Environmental Sciences, University of Virginia, 291 McCormick Road, Charlottesville, VA 22904, USA
- 3Dept. di Idraulica Trasporti e Infrastrutture Civili, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
- 4Department of Civil and Environmental Engineering, Princeton University, Olden Street, Princeton, NJ 08544, USA
Abstract. An analytical model for the soil carbon and nitrogen cycles is studied from the dynamical system point of view. Its main nonlinearities and feedbacks are analyzed by considering the steady state solution under deterministic hydro-climatic conditions. It is shown that, changing hydro-climatic conditions, the system undergoes dynamical bifurcations, shifting from a stable focus to a stable node and back to a stable focus when going from dry, to well-watered, and then to saturated conditions, respectively. An alternative degenerate solution is also found in cases when the system can not sustain decomposition under steady external conditions. Different basins of attraction for "normal" and "degenerate" solutions are investigated as a function of the system initial conditions. Although preliminary and limited to the specific form of the model, the present analysis points out the importance of nonlinear dynamics in the soil nutrient cycles and their possible complex response to hydro-climatic forcing.