Emission of nitrous oxide (N 2 O) from soils is the net result of N 2 O-producing and consuming processes within the soil, and studying the regulation of these processes in the real soil environment is essential to the understanding of the factors governing N 2 O emission. In this study, microscale distributions of O 2 and N 2 O in the soil were investigated to describe how N 2 O production within, and emission from, soils are regulated by anoxic volumes created by injection of liquid manure. An application device simulating field injection methodology was developed and liquid pig manure was injected at a depth of 5 cm into boxes containing soil. Microsensors with <0.12 mm tip diameter were used to measure high-resolution vertical N 2 O and O 2 concentration profiles though the centre of the horizontally positioned soil-manure core and up to 4 cm laterally away from the centre. Both microsensor measurements and N 2 O emission rate determinations, with a closed chamber, were performed daily. Injected manure filled the original air-filled pore space of a 6-cm-wide cylindrical core and created anoxia. Nitrous oxide was detected in the anoxic part of the core, indicating N 2 O production by denitrification in the entire anoxic volume. Although anoxia was present in the core during all 3 days of the experiment, a peak rate of net N 2 O production was detected after 1 day, with a maximum N 2 O accumulation of 500-700 Pa in the core. Comparison of the cumulated N 2 O net production and emission revealed a delay of N 2 O emission, as N 2 O was trapped inside the saturated core.
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