Time-series analysis of phosphorus-depleted microbial communities in carbon/nitrogen-amended soils

The mineralization of organic phosphorus (P) in soil is mainly driven by extracellular phosphatases secreted by soil microbes. Previous studies have suggested that microbial phosphatase production is regulated by soil nutrient stoichiometry and, thus, promoted by carbon and nitrogen (CN) amendment. However, the mechanism leading to increased phosphatase activity after nutrient amendment to soil is unclear, and it is not known how long the effect of the nutrient amendment lasts. To address these questions, we performed a 24-day time-series analysis of full-factorial soil microcosms with CN amendment. Phosphatase activity as well as that expressed per unit of beta-D-glucosidase activity, increased sharply and significantly in response to the CN amendment. This suggests that the microbial community shifted their resource allocation after the nutrient amendment and preferentially produced phosphatases rather than beta-D-glucosidase. This shifted resource allocation pattern was maintained throughout the 24-day incubation period, and copiotrophic microbes dominated soils that received CN amendment. These results indicate that the effect of the CN amendment on soil microbial resource allocation lasted for > 24 days. Together, our results highlight the importance of high-resolution time-series observations that complement long-term studies for which frequent observation is often difficult.