Fig. 6

Relationships between actual observations of forage N, P and K and optimal model simulations for different grassland growth periods: (a) N in July, (b) N in September, (c) N in November, (d) P in July, (e) P in September, (f) P in November, (g) K in July, (h) K in September, and (i) K in November (the size and color of the circles in the figure are related to the actual observations of forage N, P, and K). The red line indicates the linear fit of the model-simulated values to the actual observations. The red line shows the results of the linear fit between model simulations and actual observations, and the gray area represents the 95% confidence interval