BF, LF and CF represent balanced fertilization, low fertilization and conventional fertilization, respectively. NS, no-tillage rotated with subsoiling in alternating years; SP, subsoiling rotated with ploughing in alternating years; PN, ploughing rotated with no-tillage in alternating years; PP, ploughing applied every year. Different lowercase letters in the same columns stand for statistical difference (at 5% level) among different treatments. ns, not significant.

TABLE 2 SOC lability (L), SOC lability index (LI), C pool index (CPI) and C pool management index (CMI) under different treatments.