Yanjiang Cai Weixin Ding Jiafa Luo. Nitrous oxide emissions from Chinese maize-wheat rotation systems: a 3-year field measurement. Atmospheric Environment 2012 http://dx.doi.org-10.1016-j.atmosenv.2012.10.038.

Abstract

Nitrous oxide (N₂O) fluxes were measured over a 3-year period (2004-2007) in a long-term experimental field. The objectives of the study were to evaluate the interannual variation of N₂O emissions from a maize-wheat rotation under different fertilizer regimes and to determine the key controlling factors. The study involved four treatments: compost (OM) half compost-N plus half inorganic fertilizer-N (HOM) inorganic fertilizer-N (NPK) and control (CK) where no N application. The mean annual N₂O emission over a 3-year period was 0.30±0.11 kg N₂O-N ha⁻¹ in the CK treatment but increased to 1.61±0.10 kg N₂O-N ha⁻¹ in the HOM treatment 2.13±0.15 kg N₂O-N ha⁻¹ in the OM treatment and 2.76±0.19 kg N₂O-N ha⁻¹ in the NPK treatment. Differences were significant among treatments. The N₂O emission factors of the applied OM NPK and HOM were 0.61±0.02 0.82±0.10 and 0.44±0.04% respectively at a rate of 300 kg N ha⁻¹ year⁻¹ indicating that the combined application of compost with inorganic fertilizer significantly reduced N₂O emission. Over a maize-wheat rotation year more than 65% of the annual N₂O emission occurred during the maize growing season. There was a large interannual variation in N₂O emission in all treatments albeit not significant either during the maize growing season or at an inter-year scale. This interannual variation was mainly attributable to differences in soil moisture after basal fertilizer application and irrigation and-or heavy rainfall events immediately following basal fertilization could induce more N₂O production than pre-irrigation before plowing. The HOM treatment had higher N-fertilizer use efficiency and lowest yield-scaled N₂O emissions compared with the OM and NPK treatments. We therefore argue that the combined application of half compost-N plus half fertilizer-N will mitigate N₂O emissions from soils in the North China plain.