3.1 Soil total organic C and labile C fractions
The SOC significantly increased with increasing bio-fertilizer rates in both years, especially in 2018. The highest SOC was read in BF100, followed by BF70, BF50, BF30 and BF0 (Fig. 1A). BF30, BF50, BF70 and BF100 significantly increased SOC by 12.0%, 43.2%, 69.3% and 71.2% in 2018, of which no significant difference was observed between BF70 and BF100; BF30 had no significant effect on SOC but BF50, BF70 and BF100 increased it by 44.0%, 66.5% and 68.2% in 2019.
Bio-fertilizer application affected four types of labile organic fractions, while had no effect on BR (Fig. 1B, C, D, E and F). As to MBC, bio-fertilizer irrespective of application rates significantly increased MBC in both 2018 and 2019. Of which, MBC of treatments BF50, BF70 and BF100 showed no difference, though MBC of BF50 was slight high. Bio-fertilizer had no significant effect on EOC in 2018, while variable effects were observed in 2019. EOC was significantly increased by 24.3% in BF50 and was significantly decreased by 3.2% and 2.7% in BF70 and BF100, but no difference was recorded between BF0 and BF30 in 2019. The WSOC was significantly increased by bio-fertilizer, and showed a similar tendency in 2018 and 2019. The highest WSOC was read in BF50 in both years, while there was no difference between BF30, BF70 and BF100. Bio-fertilizer significantly increased the KMnO4-C in both years, but no difference was observed among treatments applied with bio-fertilizer. The BR was generally decreased by bio-fertilizer application, with an order of BF0 > BF30 > BF50 > BF70 > BF100 in both years.