Fertilization regimes impact CO₂ emission of rainfed maize field in an acidic luvisol

Addition of nitrification inhibitor (NI) to nitrogen fertilizer is an effective way to mitigate N₂O emission. However, the impacts of applying NI with pig manure and inorganic fertilizer on soil CO₂ emissions in Northeast China are poorly documented. The objective of this study was to assess the effects of NI with pig manure and inorganic fertilizer on soil CO₂ emissions for four consecutive years (2012–2015), in an acidic luvisol of a maize cropping system in Northeast China.

The experiment included three treatments: (1) inorganic fertilizer (NPK), (2) NPK plus pig manure (NPKM), (3) NPKM plus nitrification inhibitor 3,4-Dimethylpyrazole phosphate (NPKMI). Soil CO₂ fluxes were measured using static closed chamber method.

The maize yield in NPKM was significantly increased (p < 0.05) in 2015 compared with NPK. NPKM significantly increased soil CO₂ emission by 23.5% (p < 0.05) in 2015/2016 compared with NPK, while NPKMI has little effect on soil CO₂ emission compared with NPKM. NPKM and NPKMI showed no significant effects (p > 0.05) on bacterial abundance compared to NPK, respectively. Temperature sensitivity of soil respiration (Q₁₀) was significantly enhanced by 7.6% (p < 0.05) after manure application. Soil depth of 15 cm was more appropriate for calculating Q₁₀ of CO₂ emission than that in the 0 cm, 5 cm and 10 cm.

The integrated application of manure and inorganic fertilizer may increase the soil C loss through CO₂ emissions over time, while additional application of DMPP has little impact on soil CO₂ emissions.