## 3 Results and Discussion
### Phase I: Greenhouse Column Study  
#### 3.2.1 Cu Distribution in Plants (Camelina and Field Pennsylvania)  
Cu concentration (uS/g) in roots of camelina and field pennycress (Figure 1A) was significantly higher at low rates of compost (2.5% and 5%) as compared to those of the higher rates (10% and 20%). In the case of camelina, Cu concentration in roots was higher than that of field pennycress at all rates of compost and significantly higher at the compost rate of 2.5%.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Properties** & **Stamp Sand** & **Compost** \\ \hline pH & 8.2 & 6.9 \\ Electrical Conductivity (uS/cm) & 83 & 1840 \\ Organic matter (\%) & 0.5 & 84 \\ Sand (\%) & 95 & NA \\ Silt (\%) & 2.5 & NA \\ Clay (\%) & 2.5 & NA \\ Cu (mg/kg) & 719 & 54 \\ Fe (mg/kg) & 6200 & BDL \\ Al (mg/kg) & 2300 & BDL \\ Plant Available P (mg/kg) & 0.70 & 1009 \\ Total P (mg/kg) & 800 & 2090 \\ Total N (g/kg) & 1.81 & 388 \\ \hline \hline \end{tabular} where NA= Not Available; BDL = Below Detection Limit.  
\end{table}
Table 1: Physicochemical properties of soil and compost.  
Similarly, Cu concentrations (\(\upmu\)g/g) in stems of amelina (Figure 1B) were significantly higher at low rates of compost (2.5% and 5%) compared to those of the higher rates (10% and 20%). In case of field penhycress, Cu concentrations in stems (Figure 1B) were similar at compost rates of 2.5%, 5%, and 10% but were significantly higher than at the maximum compost rate (20%). In stems of amelina, Cu concentration was significantly higher than in stems of field penhycress at all rates of compost.  
Cu concentrations (\(\upmu\)g/g) in leaves of amelina (Figure 1C) were similarly higher at low rates of compost (2.5% and 5%) than high rates of compost (10% and 20%). Cu concentration in leaves of amelina at the maximum compost rate was significantly less than in amelina leaves at other rates of compost (2.5%, 5%, and 10%). In the case of field penhycress, Cu concentrations in leaves (Figure 1C) at low compost rates (2.5% and 5%) were significantly higher than in leaves at high compost rates (10% and 20%). In leaves of amelina, Cu concentration was significantly higher than in leaves of field penhycress at all rates of compost.  
Cu concentrations (\(\upmu\)g/g) in pods of amelina (Figure 1D) were significantly higher in low rates of compost (2.5% and 5%) than high rates of compost (10% and 20%). In the case of field penhycress, Cu concentrations in pods (Figure 1D) were almost same at compost rates of 2.5%, 5%, and 20% but Cu concentration was higher at the compost rate of 10%. In pods of amelina, Cu concentration was significantly higher than in pods of field penhycress at low rates of compost (2.5% and 5%).  
Cu concentrations (\(\upmu\)g/g) in seeds of amelina (Figure 1E) were significantly higher at lower rates of compost (2.5% and 5%) than at higher rates of compost (10% and 20%). Cu concentration in seeds of amelina at the lowest rate of compost was significantly higher than at other compost rates. In the case of field penhycress, Cu concentrations in seeds (Figure 1E) were almost the same at compost rates of 5%, 10%, and 20% but Cu concentration was higher in compost rate of 2.5%. In seeds of amelina, Cu concentration was significantly higher than in seeds of field penhycress at all rates of compost except 10%. Overall, Cu concentration was highest in roots, closely followed by leaves in amelina and field penhycress. Pods, seeds and stem in amelina and field penhycress contained very low levels of Cu. Overall, metal uptake in both plants declined with increasing compost rates, which is similar to previous reports [21].