Effects of Zn and P addition on the microbial biomass in a Zn deficient calcareous soil amended with glucose

A 35-day laboratory incubation experiment at 25A degrees C was carried out to investigate the effects of Zn and P addition on microbial biomass C, N, and P in a Zn deficient calcareous soil, sampled at 15-40 cm depth in Central Anatolia, Turkey, amended with glucose. The underlying hypothesis was that P, but also Zn addition leads to a decrease in the microbial biomass C/N ratio. In the glucose-amended soil, the microbial biomass C/N ratio was not affected by the addition of P at day 5. At day 35 in this treatment, the significant P addition x day interaction revealed a significant decrease in the microbial biomass C/N ratio from 11.3 to 8.9. In the glucose-amended soil, Zn addition also had generally significant negative effects on microbial biomass C in comparison with the pure glucose treatment. A similar tendency was observed for microbial biomass N and consequently the microbial biomass C/N ratio remained unaffected. No evidence was found in the present incubation experiment that the microbial community suffered from Zn deficiency.