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Nitrification inhibitors (NIs) affect nitrogen (N) cycle and crop yield, but how the combinations of NIs influence N transformation and maize yield remains unclear. An outdoor pot experiment was performed to explore the effect of three NIs (nitrapyrin (CP), 3, 4-dimethylpyrazole phosphate (DMPP) and dicyandiamide (DCD)) and their combinations on mineral N transformation, yield and N use efficiency (NUE) of maize in a brown soil and a cinnamon soil from northeast China. Higher yield and NUE were obtained in the brown soil than that in the cinnamon soil. All treatments with NIs significantly increased NH4+-N content, grain yield and NUE in both soils, especially for NIs combination (DMPP + DCD in the brown soil and CP + DCD in the cinnamon soil). These two treatments significantly increased yield and apparent nitrogen recovery by 1.84 and 2.31 times, 10.24 and 6.39 times, respectively, compared with N fertilizer treatment. They also showed lower apparent nitrification rates (17.2% and 53.7%, respectively) compared with single NIs treatments. Considering both the inorganic N supply and agronomic effect of NIs, DMPP + DCD and CP + DCD are the best strategies for the application of NIs in the brown soil and cinnamon soil. [ABSTRACT FROM AUTHOR]

Returning corn stalks to the field is an important and widely used soil management practice which is conducive to the sustainable development of agriculture. In this study, the effects of corn stalks and urea on N2O production in corn field soil were investigated through a 21-day incubation experiment. This study showed that increasing amounts of urea added to soil with a history of corn cultivation leads to increasing overall N2O emissions, by increasing both the intensity and the duration of emissions. Although N2O production was affected primarily by urea-derived NH4+-N and NO3−-N, its main source was native soil nitrogen, which accounted for 78.5 to 94.5% of N2O. Returning corn stalk residue to the field reduced the production of N2O, and the more urea was applied, the stronger the effect of corn residue on reducing N2O emissions. Combining the application of corn stalks and urea could reduce the concentration of NH4+-N and NO3−-N derived from urea, and then reduce the substrate required for N2O production in nitrification and denitrification processes. In addition, the combined application of corn stalks and urea could effectively inhibit the abundance of key N2O-producing genes AOA amoA, nirS and nirK. [ABSTRACT FROM AUTHOR]

The application of nitrification inhibitors (NIs) is considered to be an efficient way to delay nitrification, but the effect of NIs combinations on soil nitrification and ammonia (NH3) volatilization are not clear in soils with different pH values. In this study, we explored the effect of nitrapyrin (CP) and its combinations with 3, 4-dimethylepyrazole phosphate (DMPP), dicyandiamide (DCD) on the transformation of nitrogen, potential nitrification rate (PNR), and ammonia (NH3) volatilization in a 120-day incubation experiment with three different pH values of black soil. Treatments included no fertilizer (Control), ammonium sulfate (AS), AS+CP (CP), AS+CP+DMPP (CP+DMPP), and AS+CP+DCD (CP+DCD). The application of NIs significantly decreased NO3−-N contents and potential nitrification rate (p < 0.05), while significantly increased NH4+-N contents (p < 0.05), especially CP+DCD and CP+DMPP were the most effective in the neutral and alkaline soils, respectively. In the acid soil, CP significantly increased total NH3 volatilization by 31%, while CP+DCD significantly reduced by 28% compared with AS. However, no significant difference was found in NH3 volatilization with and without NIs treatments (p > 0.05) in the neutral and alkaline soils. In conclusion, the combined nitrification inhibitors had the better efficiency in all three tested soils. CP+DCD and CP+DMPP are the most effective in inhibiting soil nitrification in the clay soils with higher pH value and lower organic matter, while CP+DCD had the potential in mitigating environment pollution by reducing N loss of NH3 volatilization in the loam soil with lower pH value and higher organic matter. It provided a theoretical basis for the application of high efficiency fertilizer in different soils. Further studies under field conditions are required to assess the effects of these nitrification inhibitors. [ABSTRACT FROM AUTHOR]