Fig. 5. Soil N₂O production rates and NH₄⁺ and NO₃^– concentrations in soil suspensions under different redox potential (E_H) conditions in a microcosm incubation study with six soils. Additional NO₃^– was amended when E_H > 0 mV. Soil E_H occasionally fluctuated beyond the desired level, especially during the period before NO₃^– was added, where measurements were also conducted.