An experimental determination of the scale length of N2O in the soil of a grassland

Authors:
  • ANAlbrecht Neftel
    Albrecht Neftel
  • ABAndreas Blatter
    Andreas Blatter
  • BLBernhard Lehmann
    Bernhard Lehmann
  • STSergei V. Tarakanov
    Sergei V. Tarakanov
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Abstract
Concentration profiles of N2O in a grassland soil and dynamic response curves to disturbance of the soil concentration (relaxation curves) were measured with a new membrane tube technique. Diffusive properties of the soil were derived from 222Rn measurements. The mathematical analysis of the relaxation curves yielded N2O uptake rates U soil diffusivities Ds, scale lengths z*, and production rates P at different levels under the surface. The following ranges were found during 2 days of measurements: Ds = (0.4–5) × 10−7 m2 s−1, U = (1–20) × 10−4 s−1, z* = 0.7–2.8 cm, and P = 0.02–4.4 ppb s−1. These values were used to reproduce the measured N2O concentration profiles with a one‐dimensional diffusive transport model of N2O in the soil air‐filled pore space and to deduce flux profiles. Bidirectional fluxes occurred with small deposition fluxes up to a few ppt ms−1 during intensive growing phases of the grass. Uptake rates were high enough that N2O produced at greater depth did not reach the atmosphere.

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