Abstract: To investigate the effects of compound inoculation on interannual changes of bioactivity of Pinus sylvestris var.mongolica rhizosphere soil, a pot experiment was carried out to examine the interannual variations of soil enzyme activities (catalase, urease, and alkaline phosphatase), the quantity of microorganisms (bacteria, fungi, and actinomycetes), and soil nutrient concentrations (total nitrogen, available phosphorus and available potassium) in the rhizosphere of P. sylvestris var. mongolica seedlings after inoculated with ectomycorrhizal fungi Suillus luteus N94 and Trichoderma virens T43. The results showed that the compound inoculation of N94 and T43 exhibited a synergistic effect, with the soil enzyme activities, microbial quantity, and soil nutrients of rhizosphere being enhanced. All measured variables (except for total soil nitrogen in 2013) performed better in the compound inoculation treatment than in the single inoculation treatment. Such better performance consisted, but with significant interannual variations. Our results provide a reference for improving soil biological activity of probiotics and the growth of seedlings.

Key words: PPCPs, algae, ecological risk, toxicity mechanism, surface water