Nitrous oxide flux from poultry-manured erosion plots and grass filters after simulated rain

Adding carbon-rich materials to fields, like manure, may enhance denitrification. Grass filters, which are used to trap surface runoff from these fields, may also provide a carbon-rich environment that favors water infiltration and denitrification. Nitrous oxide (N₂O) may be evolved in these settings. It is a radiatively important trace gas and intermediate in the denitrification pathway and several other microbial processes. We measured N₂O flux, after simulated rain, using a soil cover technique in poultry-manured plots and grass filters receiving their runoff. Intact soil cores were used to relate the N₂O flux to the denitrification potential of the plots. Nitrous oxide fluxes were smaller in grass filters than in manured plots, even though more denitrifying bacteria were present. The average N₂O flux in the three most dynamic erosion plots was 755 μg N₂O-N m^-2h^-1, which was 39% of the maximal denitrification rate measured in acetylene- blocked, NO₃/^--amended soil cores. Nitrous oxide flux immediately after rainfall was greater than N₂O flux measurements reported for similar agricultural settings.