Changes in the fungal-to-bacterial respiratory ratio and microbial biomass in agriculturally managed soils under free-air CO2 enrichment (FACE) – A six-year survey of a field study

摘要: Abstract In soil ecology, microbial parameters have been identified as sensitive indicators of changes in the environment. The Braunschweig FACE project provided opportunity to study effects elevated CO 2 (550 μmol mol −1 ) compared ambient (370 μmol mol on total biomass (C mic ), C -to-C org ratio and fungal-to-bacterial respiratory together with , N t C:N pH over a six-year period. Field management followed typical crop rotation system this region either crop-related full nitrogen supply (N100) or 50% reduced (N50). responded treatment varying intensities time spans. was most parameter responding an highly significant differences -treated control plots third year fumigation. After six years bacterial activity had increased ascending order 34% FACE-treated (N50 N100) plots. Soil more slowly increases >12% after fourth very late last two increase >7.0% only N100 variant. Total were slightly but significantly under around 10.0% tendency starting second treatment. No could be recorded for pH. These results suggest that community will occur. our superior bioindicators reflecting organic matter composition.