Journal
SOIL BIOLOGY & BIOCHEMISTRY
Volume 69, Issue -, Pages 38-45Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.soilbio.2013.10.034
Keywords
Fertilization; Microbial community structure; PLFA; Bacteria; Fungi; Microbial biomass; GC-C-IRMS; Herbicide; Management
Categories
Funding
- Ministry of Science and Culture of Lower Saxony
- Niedersachsisches Vorab
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In permanent grassland the influence of NPK fertilizer addition and sward composition (proportion of plant functional groups) on soil microorganisms and the incorporation of C-13 labelled glucose into microbial tissue were studied for 52 weeks. Microbial biomass was analysed by chloroform fumigation -extraction (CFE), soil microbial community structure by phospholipid fatty acids (PLFAs) and incorporation of labelled glucose into microorganisms by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). C-13 incorporation into PLFA biomarkers suggested that after two and six weeks fungi most efficiently captured glucose C compared to later sampling dates, whereas in bacteria it remained at a similar level for 52 weeks, suggesting that microbial residues are processed predominantly by bacteria not by fungi. Further the fungal-to-bacterial atom percent excess ratio of PLFA concentrations after two and six weeks exceeded one, indicating that in relative terms initially fungi are more efficient in capturing low molecular weight C compounds entering the soil in pulses than bacteria. NPK fertilizer decreased soil microbial biomass and changed microbial community structure but did not affect the fungal-to-bacterial PLFA ratio. In fertilized swards the fungal-to-bacterial C-13 ratio increased, while bacterial C-13 incorporation remained at the same level, suggesting that NPK fertilizer addition increases the efficiency of resource capture by fungi. Sward composition little affected microbial community composition and glucose C incorporation. (C) 2013 Elsevier Ltd. All rights reserved.
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