## 3 Results
### Experiment Termination
#### 3.2.4 Soil Lead  
Available Pb concentrations were similar between the treatments at the beginning of the experiment and ranged from 83.5 mg kg\({}^{-1}\) in COMP to 88.5 mg kg\({}^{-1}\) in BIOC (Figure 3). Available Pb concentrations at the end however, differed depending on treatment. The greatest available Pb concentrations were in INF planted to radish and lettuce (100.9 mg kg\({}^{-1}\) and 96.3 mg kg\({}^{-1}\), respectively) and the lowest available Pb concentrations were observed in BIOC planted to radish (76.9 mg kg\({}^{-1}\)). Negative correlations between soil available Pb and soil pH, TOC, and C:N ratio were observed using data from all groups (radial, lettuce, and Lab Inc) and treatments (Table 5). Soil pH measurement included radial and lettuce samples only (Figure 4). The observed relationship between pH and available Pb was driven by BIOC within the high range of pH values and by INF and COMP at the low end of pH values. Comparing data by individual treatment (Table 6), available Pb was positively correlated with available Fe in both BIOC and INF (Figure 5). Available Pb in BIOC was positively correlated with DON (Figure 6a), negatively correlated with PMN (Figure 6b), and positively correlated with INN (Figure 6c). In contrast, available Pb in INF showed negative correlations with DON and INN, but a positive correlation with PMN, just like Pb in UNAM. Considering radish only, available Pb was correlated with soil TOC (Figure 7a), yet negatively correlated with soil DOC in BIOC and COMP (Figure 7b). Figure 3: Available lead (Pb) concentrations in soils amended with biochar (BIOC), compost (COMP), inorganic fertilizer (INF), and unamended control (UNAM) at the beginning of the experiment (Begin) presented next to a stepwise comparison of final concentrations for soils planted to radish, lettuce, and lab-incubated (Lab Inc). Lower case letters represent statistically significant differences across all treatments and life forms. Asterisks indicate a significant difference within each treatment in concentrations between Begin and end (Lab Inc, Radish, and Lettuce). Statistical tests were performed using a two-way Analysis of Variance (ANOVA) or Kruskal-Wallis if data could not be normalized. [PERSON] and [PERSON]’s test (non-normal data) were used to determine treatment significance at a \(p\leq 0.05\). Figure 2: Soil available nutrient concentrations: **(a)** available phosphorus (P) and (b) iron (Fe) in soils amended with biochar (BIOC), compost (COMP), inorganic fertilizer (INF), and unamended control (UNAM) at the beginning of the experiment (Begin) presented next to a stepwise comparison of final concentrations for soils planted to radish, lettuce, and lab-incubated soil (Lab Inc). Lower case letters represent statistically significant differences across all treatments and groups. Asterisks indicate a significant difference within each treatment in concentrations between Begin and end (Lab Inc, Radish and Lettuce). Statistical tests were performed using a two-way Analysis of Variance (ANOVA) or Kruskal-Wallis if data could not be normalized. Tukey HSD and [PERSON]’s test (non-normal data) were used to determine treatment significance at a \(p\leq 0.05\).