Simulation modeling of soil and plant nitrogen use in a potato cropping system in the humid and cool environment

With rising environmental concerns for current practices of fertilizer N management in the humid and cool areas, we simulated soil N dynamics and plant N use in the potato (Solanum tuberosum L.) cropping system using the software Stella. The objectives were to predict in-season N requirements by the potato crop, tuber yield, N uptake, N partitioning within root, leaf, stem and tuber, and N loss in the plant–soil system, and to examine the accuracy of using model predictions for N management in potato. The first-order linear and S-shaped growth processes were used in the simulation. The model was unidimensional and used a daily time step. Sensitivity analysis indicated that N inflow in the system was the key trait affecting potato N uptake and tuber yield. The model was validated by comparisons of the predictions with field study datasets at four sites conducted across Quebec, Canada. The simulated daily N uptake by the potato followed a S-growth pattern from the early vegetative stage to full bloom, and a plateau of N uptake appeared at late tuberization. The predicted maximum daily N uptake rate (4.46 kg ha−1 day−1) occurred at early bloom whereas the predicted maximum N transfer from stems and leaves to tubers (4.31 kg ha−1 day−1) occurred 3 weeks after the peak of N uptake. Simultaneously, high daily N uptake occurred when N concentrations in the root zone ranged between 90 and 120 kg ha−1. The predicted N uptake and potato tuber yield values were correlated to N inflows in the model (R2 = 0.91). The model estimated loss of N was 34% of the field measurements. Using model balancing the amounts of N needed by crops would lead to optimize plant growth and N use efficiency and to minimize N lost to the environment.