Fertilizers inclusion with nitrification inhibitors alleviate soil CO2 emissions: a meta-analysis study

PurposeExcessive application of nitrogen (N) fertilizers in croplands induces serious N pollution and environmental consequences. Nitrification is the primary driver of soil acidification, leading to the consumption of soil inorganic carbon (C) and massive carbon dioxide (CO2) emissions from calcareous soils. Previous studies have shown that N fertilizer with nitrification inhibitors (NIs) can reduce CO2 emissions; however, the underlying mechanisms and factors influencing these reductions remain unclear.Materials and methodsWe conducted a comprehensive meta-analysis under different experimental types (incubation and field experiments). The effect of NI amendment on soil CO2 emissions was investigated using data from 57 peer-reviewed scientific articles (172 paired observations), and a machine learning model was used to identify the primary factors influencing this process.Results and discussionThe addition of NIs significantly reduced the CO2 emissions by 19.19% and 7.97% under the incubation and field experimental scenarios, respectively. NIs applied to soils with high pH, low soil organic carbon and total nitrogen content, and coarse texture could mitigate soil CO2 emissions under both the experimental types. CO2 emissions can be considerably reduced by using 3,4-dimethyl pyrazole phosphate (DMPP) or NIs amended with urea or by adopting an N subsurface or single-dose application method.ConclusionsNI amendment has a high potential to reduce the CO2 emissions during N fertilization, and a suitable NI product, soil conditions, and fertilization regimes should be considered to further improve its efficacy.