Simulating Potato Growth and Nitrogen Uptake in Eastern Canada with the STICS
Morissette, R., Jégo, G., Bélanger, G., Cambouris, A. N., Nyiraneza, J., & Zebarth, B. J. 2016. Simulating Potato Growth and Nitrogen Uptake in Eastern Canada with the STICS Model. Agronomy Journal, 108(5), 1853-1868.
Plain language summary
A soil-crop mathematical model called STICS was used to simulate the potato growth and nitrogen (N) uptake under the conditions of eastern Canada. In this study, two main objectives were defined. The first one was to calibrate and validate the model with crop data for two cultivars widely used in eastern Canada, Shepody and Russet Burbank. The second objective was to evaluate the model performance with a specific calibration of the parameters that drive plant’s N uptake. The data sets used for calibration of the model were mainly composed of the entire plant mass and N content and tuber mass and N content. They were collected in different locations (Charlottetown, PE; Fredericton, NB; and Québec, QC) with various fertilization rates, soils characteristics, and climatic conditions. In crop modeling, the calibration process is more robust when data covers a wide range of crop management, climate conditions and soil types. Following calibration, the model performed well to simulate the plant and tuber mass. The simulation of N uptake by the plant and tuber was better with the specific calibration of model’s parameters related to N uptake than with default values. Thus, it is recommended to use this specific calibration for assessing the N budget of potato cropping systems. This work represents a great advance in terms of the future possibilities for potato crop modeling in eastern Canada such as the refinement of the optimum N fertilization rate or the evaluation of the impact of climate change on potato yield.
The ability of process-based soil–crop models to simulate potato (Solanum tuberosum L.) yield and N uptake for a range of N fertilization under the conditions of eastern Canada has never been tested. Our objectives were (i) to calibrate and evaluate the performance of the STICS model for the Shepody and Russet Burbank cultivars with cultivar-specific critical N concentration dilution curves, and (ii) to quantify the gain in model performance with cultivar-specific N concentration curves rather than a generic curve. Data sets including measurements of leaf area index (LAI), total and tuber biomass, and total and tuber N uptake for several N rates (0–280 kg N ha–1) collected at Charlottetown, PE; Fredericton, NB; and Québec, QC, Canada were used. Calibration was done with one data set from Charlottetown for Shepody and one data set from Québec for Russet Burbank, while all the other data sets were used to evaluate model performance. Following calibration, the STICS model generally performed well, with a normalized root mean square error (NRMSE) < 30% and a normalized mean error (NME) ranging from –8% to 23%, for LAI and biomass. Model performance was slightly worse for total and tuber N uptake, although cultivar-specific N concentration curves for Shepody and Russet Burbank improved model performance compared with a generic curve with a lower NRMSE (18–50% vs. 21–63%) and NME (–9 to 23% vs. –14 to 23%). Cultivar-specific critical N concentration curves should therefore be used for assessing the N budget of potato cropping systems.