Table 2.
Components in unwashed and washed rice husk biochar (n = 1)
| Components | Unwashed biochar | Washed biochar |
|---|---|---|
| pH | 10.5 | 10.1 |
| EC (mS cm−1) | 0.771 | 0.371 |
| Ash (%) | 53.5 | 57.2 |
| Water content (%) | 9.8 | 3.1 |
| Total N (%) | 0.23 | 0.30 |
| Total P2O5 (%) | 0.17 | 0.15 |
| Total K2O (%) | 0.70 | 0.66 |
| Total CaO (%) | 0.26 | 0.17 |
| Total MgO (%) | 0.06 | 0.07 |
| Organic C (%) | 31.3 | 33.9 |
| Total C (%) | 31.5 | 33.9 |
| C/N ratio | 136 | 113 |
| Na (%) | < 0.1 | < 0.1 |
| Al (%) | < 0.1 | < 0.1 |
| Mn (%) | 0.03 | 0.02 |
| Fe (%) | < 0.01 | 0.01 |
| As (mg kg−1) | 1 | < 1 |
| Cd (mg kg−1) | < 0.5 | < 0.5 |
| Hg (mg kg−1) | < 0.1 | < 0.1 |
| Ni (mg kg−1) | < 5 | < 5 |
| Cr (mg kg−1) | 16 | 15 |
| Pb (mg kg−1) | < 1 | < 1 |
| Water-soluble phenols (mg L−1)a | < 0.05 | < 0.05 |
aWater-soluble phenols was measured in water extract of unwashed and washed biochar