Table 2. Nitrate- and ammonium-N concentrations, pH and Eh of soil/biochar mixtures after incubation, with Eh values corrected to pH = 7 (s.e.m. in parentheses, n = 3).
| Biochar (%) | 0 |
1 |
5 |
100 | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| WFPS (%) | 12 | 39 | 54 | 12 | 39 | 54 | 12 | 39 | 54 | 6 |
| NH4 + -N (mg kg−1) | 24.7 (0.33) a*c**** | 72.5 (1.50) a*b* | 95.3 (0.67) b*c****j* | 23.3 (0.33) d***f**** | 73.0 (1.15) d***e**k* | 94.0 (0.00) e**f****n* | 24.0 (0.58) g****h** | 77.7 (1.20) g****k* | 79.7 (3.18) h**j*n* | <0.3 |
| NO3−-N (mg kg−1) | 0.2 (0.03) a**b** | 1.2 (0.35) | 1.9 (0.56) | 0.5 (0.01) a**c** | 0.9 (0.24) | 1.7 (0.26) c** | 0.5 (0.01) b** | 1.3 (0.51) | 0.9 (0.29) | <0.20 |
| pH | 5.8 (0) a#b** h#j# | 6.0 (0) a#n* q** | 6.1 (0.03) b**r* t**** | 6.1 (0) c*d* h#k# | 6.3 (0.03) c*n* p**** | 6.4 (0.07) d*r*s** | 6.7 (0) e**g** j#k# | 7.0 (0.03) e**f** p****q** | 7.4 (0.03) f**g** s**t**** | 9.7 (0.1) |
| EhpH7 (mV) | 454 (3.8) a**f* g*h** | 382 (7.0) f* | 404 (5.8) a** | 515 (4.5) b**c** g*j** | 405 (6.9) b** | 414 (11.6) c** | 621 (12.0) d**e*** h**j** | 428 (4.0) d** | 429 (14.0) e*** | 499 (13.3) |
Within rows, means accompanied by the same letter are significantly different (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, #p = 0).