Nitrous oxide emissions from soil amended with glucose, alfalfa, or corn residues
2000
Shelp, M.L. | Beauchamp, E.G. | Thurtell, G.W.
Nitrous oxide (N2O) emissions result from the nitrification and denitrification processes, the latter strongly affected by soil organic carbon (C) derived from plant residues. This study addressed two questions: (1) does plant residue C become less available to denitrifiers after a period of aerobic incubation, and (2) do plant residues with smaller particle sizes provide C for higher rates of N2O production due to a faster decomposition rate? Nitrous oxide fluxes from soil amended with alfalfa or corn residues, or glucose were measured in the laboratory using a gas flow-through chamber system. Soil amended with these C substrates was also subjected to a 5-d aerobic preincubation treatment. The significance of particle size on C availability was studied by comparing N2O released from soil amended with ground (particle size <1 mm) and large pieces (5-cm lengths) of alfalfa residues. A 5-d aerobic preincubation of soil amended with plant residues resulted in reduced N2O production during a subsequent anaerobic period. Results suggested that, due to consumption of the most available substrate, remaining C in plant residues is less available to denitrifiers after a period of aerobic incubation. Higher N2O losses were found with large alfalfa particles than with ground alfalfa.
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