# Effects of Manure Waste Biochars in Mining Soils
## Results
### CO\({}_{2}\) Emissions and qCO\({}_{2}\) Quotient in Amended Mining Soils  
Figure 2 shows the cumulative CO\({}_{2}\) emissions of the control soils and the soils amended with different biochars of the three studied areas after 180 days of the incubation experiment. The variation of CO\({}_{2}\) emissions of different treatments with respect to control soils adopted the following sequences in the different areas:  
* For the Zarandas-Andalusia area (Figure 2a): Soil Z1: Z1 (81 mg-100 g\({}^{-1}\)) \(<\) Z1 + BPL600 (+69%) \(<\) Z1 + BRM600 (125%) \(<\) Z1 + BRM450 (232%) \(<\) Z1 + BPL450 (+281%); Soil Z2: Z2 (90 mg-100 g\({}^{-1}\)) \(\approx\) Z2 + BPL600 \(\approx\) Z2 + BRM600 \(\approx\) Z2 + BRM450 \(<\) Z2 + BPL450 (+145%); Soil Z3: Z3 + BPL600 (-30%) \(\approx\) Z3 + BRM600 (-32%) \(<\) Z3 (141 mg-100 g\({}^{-1}\)) \(<\) Z3 + BRM450 \(\approx\) Z3 + BPL450 (+34%). * For the Mijarojos-Cantabria area (Figure 2b): Soil M1: M1 (347 mg-100 g\({}^{-1}\)) \(\approx\) M1 + BRM600 \(\approx\) M1 + BRM450 \(<\) M1 + BPL450 (+26%); Soil M2 (264 mg-100 g\({}^{-1}\)): there was no significant difference among treatments for soil M2; Soil M3: M3 (340 mg-100 g\({}^{-1}\)) \(\approx\) M3 + BRM600 \(\leq\)\(\leq\) M3 + BPL600 (+15%) \(\approx\) M3 + BRM450 \(\leq\) M3 + BPL450 (+40%). * For the Portman-Murcia area (Figure 2c): Soil P1: P1 (279 mg-100 g\({}^{-1}\)) \(\approx\) P1 + BRM600 \(<\) P1 + BPL600 (+38%) \(<\) P1 + BRM450 (77%) \(\approx\) P1 + BPL450; Soil P2: P2 (261 mg-100 g\({}^{-1}\)) \(\approx\) P2 + BPL600 \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & **pH** & \multicolumn{2}{c}{**EC**} & **Cr** & **Cu** & **Ni** & **Fe** & **Zn** & **Cd** & **Pb** \\ \cline{3-10}  & & **dS m\({}^{-1}\)** & **mg kg\({}^{-1}\)** & **kg kg\({}^{-1}\)** & **mg kg\({}^{-1}\)** & **mg kg\({}^{-1}\)** \\ \hline
**M1** & 7.91a ** & 0.90a & 0.20a & 0.08 ab & 2.98a & 4.20c & 1.97b & 4.93c & 8.35b \\
**M1** + **BPL450** & 7.96a & 3.11b & 0.854 & 0.04a & 3.12a & 2.09b & 0.28a & 1.46a & 6.85b \\
**M1** + **BPL600** & 7.59a & 3.14b & 0.96d & 0.14 ab & 6.56b & 1.99b & 0.43a & 1.10a & 5.19a \\
**M1** + **BRM450** & 7.49a & 3.05b & 0.54c & 0.16b & 7.37b & 1.43a & 0.30a & 2.94b & 1.657d \\
**M1** + **BRM600** & 7.43a & 2.43b & 0.40b & 0.15b & 5.65b & 1.05a & 0.55a & 2.50 ab & 14.38c \\ \hline
**M2** & 8.23a & 0.40a & 0.31a & 0.08a & 5.45 ab & 3.81b & 3.37b & 0.40a & 6.43b \\
**M2** + **BPL450** & 9.30e & 1.80b & 0.37a & 0.16b & 5.64b & 2.74 ab & 0.20a & 0.37a & 6.34b \\
**M2** + **BPL600** & 8.88b & 1.72 ab & 0.39 ab & 0.38d & 3.43a & 1.71a & 0.50a & 0.28 ab & 4.00a \\
**M2** + **BRM450** & 9.04c & 2.13b & 0.61c & 0.19b & 4.39a & 1.58a & 0.16a & 0.23b & 15.73c \\
**M2** + **BRM600** & 9.18d & 1.73 ab & 0.47b & 0.26c & 7.23b & 3.56b & 0.40a & 0.34a & 15.33c \\ \hline
**M3** & 7.24a & 0.53a & 0.31a & 0.12b & 4.87a & 1.55 bc & 0.41a & 0.33a & 7.10b \\
**M3** + **BPL450** & 8.57b & 2.44d & 0.37a & 0.37c & 3.78a & 1.10 ab & 0.32a & 0.26a & 5.95 ab \\
**M3** + **BPL600** & 8.05 ab & 2.70e & 0.39a & 0.09 ab & 6.75b & 0.86a & 0.35a & 0.13b & 7.63b \\
**M3** + **BRM450** & 7.71 ab & 1.58b & 0.61b & 0.05a & 8.80c & 1.64c & 0.30a & 0.21a & 4.86a \\
**M3** + **BRM600** & 8.67b & 1.73c & 0.43a & 0.07 ab & 7.34b & 2.70d & 0.27a & 0.27a & 7.61b \\ \hline \hline \end{tabular}
\end{table} 
Table 6: pH, electrical conductivity (EC), and mobile metal content in control soils and biochar/soil mixtures from Mijarojos area after 180 incubation days. \(\approx\) P2 + BRM450 \(<\) P2 + BRM600 (+25%) \(\approx\) P2 + BPL450; Soil P3: P3 (295 mg:100 g\({}^{-1}\)) \(<\) P3 + BPL450 (+21%) \(<\) P3 + BRM600 (+44%) \(<\) P3 + BRM450 (62%) \(\approx\) P3 + BPL600; Soil P4: P4 + BPL600 (\(-\)33%) \(\leq\) P4 + BRM600 (\(-\)28%) \(<\) P4 + BRM450 (\(-\)17%) \(<\) P4 (291 mg:100 g\({}^{-1}\)) \(<\) P4 + BPL450 (+27%). The data of CO\({}_{2}\) emissions in the Zarandas-Andalusia area showed that the four biochars increased the CO\({}_{2}\) emissions in both Z1 and Z2 soils by more than 69% and 145%, respectively.