Microdialysis fluxes of inorganic nitrogen differ from extractable nitrogen by minimising disturbance of mineral-associated sources

•We examine how sampling methods affect detecting inorganic N in 21 soils.•In situ microdialysis sampled proportionately less ammonium than soil extractions.•Ammonium was highest in salt extracts and correlated with soil properties.•Nitrate was correlated across methods implying minimal impact by disturbance.•Measurement of inorganic N is biased by methods-related soil disturbance.