*2.7. Data Visualization and Statistics*

Data visualization was performed using the RStudio ggplot2 and emmeans packages. Analyses of variance with the *post hoc* Tukey HSD test were computed using the mixed procedure (nlme library) (RStudio Team, 2020). A natural logarithmic transformation was used when needed to respect the normality and homogeneity of variance assumptions.

#### **3. Results**

#### *3.1. Yield (Fresh Mass)*

Lettuce fresh mass decreased by 35% in the miscanthus-amended treatment and by 14% in the willow-amended treatment, although these differences were not statistically significant (Figure 3, Table 3).

**Figure 3.** Lettuce fresh mass per plant as a function of soil amendment. Different letters indicate significance at *p* < 0.05 using the *post hoc* Tukey HSD test.

