Table 3. Soil bulk density (BD), SOC contents, the estimated mean SOC sequestration rate (SSR) and mean ΔSOC sequestration rate (ΔSSR) during the 29-years period, for all treatments.
| Treatment | 1982 | 2011 | SSR (ton/ha/yr) | ΔSSR (ton/ha/yr) | ||||
| BD (g/cm3) | SOC (g/kg) | SSOC (ton/ha) | BD (g/cm3) | SOC (g/kg) | SSOC (t/ha) | |||
| CK | 1.45 | 5.86 | 16.99 | 1.44±0.03a | 5.08±0.17e | 14.63±0.79e | −0.08±0.03e | - |
| NPK | 1.45 | 5.86 | 16.99 | 1.38±0.01a | 8.24±0.07d | 22.74±0.47d | 0.20±0.02d | - |
| NPKW1/2 | 1.45 | 5.86 | 16.99 | 1.21±0.02b | 11.66±0.46c | 28.22±1.58c | 0.39±0.05c | 0.19±0.03 |
| NPKW | 1.45 | 5.86 | 16.99 | 1.19±0.02b | 13.23±0.55b | 31.49±1.84b | 0.50±0.06b | 0.30±0.04 |
| NPKPM | 1.45 | 5.86 | 16.99 | 1.18±0.02b | 13.46±0.42b | 31.77±1.53b | 0.51±0.05b | 0.31±0.03 |
| NPKCM | 1.45 | 5.86 | 16.99 | 1.11±0.01c | 20.36±0.32a | 45.20±1.12a | 0.97±0.04a | 0.77±0.02 |
CK: no fertilizer; NPK: mineral fertilization; NPKW1/2: mineral fertilizer combined with 2.5 ton/ha/yr of wheat straw; NPKW: mineral fertilizer combined with 5.0 ton/ha/yr of wheat straw; NPKPM: mineral fertilizer combined with pig manure; NPKCM: mineral fertilizer combined with cattle manure. Data are presented as means (n = 4), and those designated with the same letter are not significantly different (P<0.01).