Evaluation of water and nutrient dynamics in soil-crop systems using the eco-hydrological catchment model SWIM

摘要

The process-based eco-hydrological spatially distributed catchment model SWIM (Soil and Water Integrated Model) was used to model water and nutrient dynamics in soil-crop systems. SWIM integrates hydrological processes, vegetation/crop growth, erosion, soil carbon, phosphorous and nitrogen dynamics at the river basin scale. A module for the turnover of soil organic matter was recently added by integrating the soil organic matter module of the forest growth model 4C into SWIM. As part of the model evaluation exercise described in this paper, SWIM was evaluated against data on soil temperature, soil hydrology, crop yield, soil nitrogen and long-term soil organic matter dynamics at the plot scale. The model was run predominantly without calibration except for parameterization data provided for the field plots (e.g. soil physical parameters). Soil temperature and soil water were simulated well, with modelling efficiency index (IA) 0.87-0.96 for soil temperature and 0.54—0.92 for soil water. Simulatedcrop yield compared satisfactory well to measured yield, with IA values ranging from 0.37 to 0.87. Some problems occurred for long-term simulations (51 years) due to the fact that SWIM does not consider technical management changes such as seed quality improvements. Soil nitrogen dynamics were represented satisfactory under the different crop rotation and fertilization regimes at the measurement sites. Modelling efficiency index varied between 0.18 and 0.79. The simulation of long-term soil carbon dynamics resulted in a good representation of the measurements under the different fertilization treatments. The long-term trend of soil organic carbon (SOC) could be successfully represented by SWIM with a modelling efficiency index between 0.46 and 0.69. Although SWIM was not designed as a plot or field scale agro-ecosystem model, it was able to reproduce the measured data for different plots, representing different edaphic, climatic and management conditions, in their temporal dynamics and magnitudes.