Regulators of N2O Production and Emissions

The release of N2O to the atmosphere from wetlands is enhanced by alternating flooding and drainage cycles. The wetting enhances mineralization of organic matter with resultant pulses in nitrification, and creates (local) anaerobic conditions that favor denitrification. Under these conditions, the production of N2O may exceed the reduction of N2O to N2. 

Denitrification generally increases when the oxygen is depleted in the soil. Prolonged flooding can limit denitrification by restricting nitrification that produces the nitrate for denitrification such conditions may prevail in permanently flooded soils. 

FIGURE 16.9 The effect of redox potential on relative production of nitrous oxide and nitrogen gas during denitrification. (From Kralova et al., 1992.) 

Redox zone with little methane or nitrous oxide formation 

FIGURE 16.10 Soil redox zone where methane and nitrous oxide denitrification occur. (Modified from data by Yu and Patrick, 2003.) 

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