Effect of K2SO4 concentration on extractability and isotope signature (δ13C and δ15N) of soil C and N fractions |
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| Authors: | M I Makarov T I Malysheva O V Menyailo N A Soudzilovskaia R S P Van Logtestijn J H C Cornelissen |
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| Institution: | 1. Soil Science Department, Moscow State University, Leninskie Gory 1‐12, Moscow, Russia;2. Department of Biogeochemistry, Institute of Forest SB RAS, Akademgorodok, Krasnoyarsk, Russia;3. System Ecology, Department of Ecological Sciences, Faculty of Earth and Life Sciences, Vrije Universiteit, Amsterdam, the Netherlands |
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| Abstract: | Determination of the labile soil carbon (C) and nitrogen (N) fractions and measurement of their isotopic signatures (δ13C and δ15N) has been used widely for characterizing soil C and N transformations. However, methodological questions and comparison of results of different authors have not been fully solved. We studied concentrations and δ13C and δ15N of salt‐extractable organic carbon (SEOC), inorganic (N–NH4+ and N–NO3?) and organic nitrogen (SEON) and salt‐extractable microbial C (SEMC) and N (SEMN) in 0.05 and 0.5 m K2SO4 extracts from a range of soils in Russia. Despite differences in acidity, organic matter and N content and C and N availability in the studied soils, we found consistent patterns of effects of K2SO4 concentration on C and N extractability. Organic C and N were extracted 1.6–5.5 times more effectively with 0.5 m K2SO4 than with 0.05 m K2SO4. Extra SEOC extractability with greater K2SO4 concentrations did not depend on soil properties within a wide range of pH and organic matter concentrations, but the effect was more pronounced in the most acidic and organic‐rich mountain Umbrisols. Extractable microbial C was not affected by K2SO4 concentrations, while SEMN was greater when extracted with 0.5 m K2SO4. We demonstrate that the δ13C and δ15N values of extractable non‐microbial and microbial C and N are not affected by K2SO4 concentrations, but use of a small concentration of extract (0.05 m K2SO4) gives more consistent isotopic results than a larger concentration (0.5 m ). |
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