3.3 Microbial biomass and qCO2 responses influenced by land management
According to the RM-ANOVA (Table 2), MBC was explained well by treatment (83.9 %). The average MBC of each cultivation period was 84.5, 94.8, 103.2, and 103.0 mg C kg−1 (first-year), 87.3, 93.0, 117.1, and 113.3 mg C kg−1 (second-year), and 79.4, 87.3, 115.5, and 119.1 mg C kg−1 (third-year) in the C, B, M and BM treatments, respectively (Fig. 2a-c and Table 3). In all cultivation periods, there were no significant differences in MBC between the C and B treatments, while MBC in the M and BM treatments were significantly higher than that in the C and B treatments in most cultivation periods.
In the first year, qCO2 tended to be high during the first half of the cultivation period, whereas it was high during the latter half of the cultivation period in the second year (Fig. 2d-e). In the third year, qCO2 fluctuated over the whole cultivation period (Fig. 2f). As for MBC, during all cultivation periods, there were no significant differences in qCO2between the C and B treatments, while qCO2 in the M and BM treatments were significantly higher than that in the C and B treatments in most cultivation periods (Table 3). Only during the cultivation period of the first year, qCO2 in the BM treatment was significantly lower than that in the M treatment. During the period when there was a significant difference in qCO2 between the M and BM treatments (Fig. 2d), qCO2 in the BM treatment (9.3–19.1 µg CO2-C mg MBC−1 h−1) was 30% lower than that in the M treatment (15.1–29.4 µg CO2-C mg MBC−1 h−1), while qCO2 in the M and BM treatments showed a similar fluctuation during the second and third cultivation periods. As with the CO2 efflux rate, a significant interaction effect between biochar application and FYM application on qCO2was shown during the cultivation period of the first year (Table S2). In the C treatment, the MBC was independent of soil moisture (data not shown), while qCO2 was significantly correlated with soil moisture (Fig. S2b).