A P-33 tracing model for quantifying gross P transformation rates in soil

作者：Mueller Christoph; Buenemann Else K

来源：Soil Biology and Biochemistry, 2014, 76: 218-226.

DOI：10.1016/j.soilbio.2014.05.013

• P-33 tracing model
• Gross transformations
• Isotopic dilution
• Organic phosphorus
• Mineralization
• Immobilization

Due to rapid sorption of phosphate released by mineralization processes, in most soils net organic P mineralization rates cannot be derived from changes in extractable inorganic P over time. Besides, a mechanistic understanding is only obtained if the individual gross P transformation rates are known. Available techniques for the quantification of gross P transformation rates rely on isotopic dilution principles. To unambiguously analyse the full dynamics and quantify all relevant simultaneously occurring P transformation rates in soil, we developed a numerical P-33 tracing model. The tracing model combines a process-based numerical model with a parameter optimization routine to estimate gross P rates. Each rate can follow either zero-order, first-order or Michaelis-Menten kinetics. The tracing model was used to analyse a previously published dataset by Bunemann et al. (2012). The model was able to simulate the observed dynamics. However, gross organic P mineralization rates were lower than previously published. Net organic P mineralization rates tended towards zero, confirming the overriding dominance of microbial immobilization and re-mineralization processes in the studied grassland soil. The P tracing model presented in this study removes the need for the baseline of isotopic dilution due to physicochemical processes. The dynamic P-33 tracing model, which takes into account simultaneous dilution and enrichment, presents an important advancement over the conventional estimation of gross P transformations in isotopic dilution experiments.

• 出版日期2014-9