关键词: 土壤养分, 植物养分, 石漠化, 灌丛生态系统

Abstract: The reuse of reclaimed water is a significant measure to solve the urban water crisis, but few studies have examined the effect of reclaimed water on the soil and soil microorganisms. Taking irrigation with tap water as the control, the effect of reclaimed water irrigation on soil physicochemical properties and microbial community diversity was studied by a variety of soil index measurement and microbial dilution separation. The results showed that the soil pH, soil moisture, organic matter (OM), total nitrogen (TN), total potassium (TK), available nitrogen (AN) and available phosphorus (AP) contents all showed a tendency of increase, especially TK, while the values of soil total phosphorus (TP), carbon/nitrogen (C/N) and available potassium (AK)  were lower under irrigation with reclaimed water than under the control treatment. A total of 62 strains of bacteria were separated from sampling sites, which belong to 20 species (genera). Bacillus was the dominant group in the soil irrigated with reclaimed water while Pseudomonas was dominant in the control treatment. Differences in the level of microbial diversity existed between the differently irrigated soils. Soil microbial evenness index (J_sw) and the probability of interspecific encounter (PIE) were higher, while Shannon index (H′), Pielou evenness index (J_si), Margalef richness index (R₁) and Patrick richness index (R₂) were lower in the soil irrigated with reclaimed water. By correlation analysis, the close relationship among diversity index, richness index and evenness index reflected the consistency of microbial community characteristics. By hierarchical scaling analysis, the spatial pattern of the microbial community was described. The microbial community was separated into four clusters: reclaimed water-B (RW-B), reclaimed water-J (RW-J), reclaimed water-C (RW-C) and tap water (DW). RW-B, RW-J and RW-C were of the lowest similarity, while RW-B and RW-J shared the highest similarity. Canonical correspondence analysis between the microbial community of each site and environmental factors showed that microbial community structures were correlated with OM, TN and TP (P<0.05). TP had a great impact on Xanthomonas, Cellulomonas, Listeria murrayi and Corynebacterium fascians.

Key words: shrub ecosystem, rocky desertification, plant nutrient, soil nutrient.