Fig. 1. Components of the soil microcosm system used in an incubation study with six soils: (1) thermometer; (2) redox potential (E_H) electrode; (3) pH electrode; (4) dispersion tube for N₂; (5) dispersion tube for O₂; (6) stirrer; (7) sampling tube; (8) microcosm vessel; (9) temperature control by a thermostat and water circulation; (10) data logger for E_H, pH, and temperature; (11) automatic redox regulation by N₂ and O₂ valves; (12) control computer for data logger, pump, and valve system (gas sampling), and gas chromatograph (start signal); (13) gas chromatograph (GC) with flame ionization detector/electron capture detector for trace gas measurements (CO₂, CH₄, and N₂O); and (14) computer for GC control and GC data storage.