Processes and factors controlling N₂O production in an intensively managed low carbon calcareous soil under sub-humid monsoon conditions
Ju, X.; Lu, X.; Gao, Z.; Chen, X.; Su, F.; Kogge, M.; Römheld, V.; Christie, P.; Zhang, F.
Environmental Pollution 159(4): 1007-1016
ISSN/ISBN: 1873-6424 PMID: 21251741 DOI: 10.1016/j.envpol.2010.10.040
An automated system for continuous measurement of N₂O fluxes on an hourly basis was employed to study N₂O emissions in an intensively managed low carbon calcareous soil under sub-humid temperate monsoon conditions. N₂O emissions occurred mainly within two weeks of application of NH₄(+) based fertilizer and total N₂O emissions in wheat (average 0.35 or 0.21 kg N ha⁻¹ season⁻¹) and maize (average 1.47 or 0.49 kg N ha⁻¹ season⁻¹) under conventional and optimum N fertilization (300 and 50-122 kg N ha⁻¹, respectively) were lower than previously reported from low frequency measurements. Results from closed static chamber showed that N₂O was produced mainly from nitrification of NH₄(+)-based fertilizer, with little denitrification occurring due to limited readily oxidizable carbon and low soil moisture despite consistently high soil nitrate-N concentrations. Significant reductions in N₂O emissions can be achieved by optimizing fertilizer N rates, using nitrification inhibitors, or changing from NH₄(+)- to NO₃(-)-based fertilizers.