Summary
This foundational work used 15N-labelled ammonium and soil fumigation to quantify nitrogen mineralization and immobilization processes in soil, comparing fumigated and unfumigated controls. The authors demonstrated that measurements of organically-bound 15N provided more reliable estimates of immobilization than measurements based on label disappearance from soil solution. The study proposes a standardised procedure for calculating soil microbial biomass nitrogen from the flush of mineral nitrogen following fumigation, contributing an important methodological advance for soil biological assessment.
Regional applicability
This was a UK-based laboratory study that established a widely-adopted methodological approach for measuring microbial biomass nitrogen. The fumigation-incubation method described remains relevant to soil assessment practice in the United Kingdom and internationally, particularly for monitoring soil biological activity and organic matter turnover in managed agricultural soils.
Key measures
Nitrogen immobilization (μg N g−1 soil), gross mineralization rates (μg N g−1 soil), organically-bound 15N content, extractable inorganic 15N, soil microbial biomass nitrogen (BN)
Outcomes reported
The study measured nitrogen immobilization and gross mineralization rates in fumigated versus unfumigated soil using 15N isotope tracing, and developed a method for calculating soil microbial biomass nitrogen from the mineral nitrogen flush caused by fumigation.
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