Estimating phosphorus availability for microbial growth in an emerging landscape

S. K. Schmidt, C. C. Cleveland, D. R. Nemergut, S. C. Reed, A. J. King, P. Sowell

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Estimating phosphorus (P) availability is difficult-particularly in infertile soils such as those exposed after glacial recession-because standard P extraction methods may not mimic biological acquisition pathways. We developed an approach, based on microbial CO2 production kinetics and conserved carbon:phosphorus (C:P) ratios, to estimate the amount of P available for microbial growth in soils and compared this method to traditional, operationally-defined indicators of P availability. Along a primary succession gradient in the High Andes of Perú, P additions stimulated the growth-related (logistic) kinetics of glutamate mineralization in soils that had been deglaciated from 0 to 5years suggesting that microbial growth was limited by soil P availability. We then used a logistic model to estimate the amount of C incorporated into biomass in P-limited soils, allowing us to estimate total microbial P uptake based on a conservative C:P ratio of 28:1 (mass:mass). Using this approach, we estimated that there was <1μg/g of microbial-available P in recently de-glaciated soils in both years of this study. These estimates fell well below estimates of available soil P obtained using traditional extraction procedures. Our results give both theoretical and practical insights into the kinetics of C and P utilization in young soils, as well as show changes in microbial P availability during early stages of soil development.

    Original languageEnglish
    Pages (from-to)135-140
    Number of pages6
    JournalGeoderma
    Volume163
    Issue number1-2
    DOIs
    StatePublished - Jun 15 2011

    Keywords

    • Biological weathering
    • Phosphorus limitation

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