In this study, MBC data did not show a consistent relationship between two treatments during both growing seasons. However, a significant (P ≤0.05) negative correlation occurred between available P and MBC in the M treatment, but not in the B treatment.
Therefore, we infer that more serious competition for soil available P existed between crop and soil microorganisms in the M treatment than the B treatment (Li et al., 2004; Fontaine et al., 2003). More soil microorganisms in the M treatment would impair P availability for crop growth.