Revisiting the Effectiveness of Nitrification Inhibitors Under Different Soil Moisture Conditions and Mineral Nitrogen Extraction Methods: Further Experimental Work Considering the Pasda et al. (2023) Opinion Paper

ABSTRACT Background In a recent opinion article, Pasda et al. indicated that the findings from our previous study (Guo et al.) were misleading due to the inappropriateness of the experimental work. The mentioned study focused on the effectiveness of four nitrification inhibitors (NIs) in reducing nitrous oxide (N 2 O) emissions as affected by temperature and moisture. Aims We assessed to what extent the issues raised by Pasda et al. impact the findings presented by Guo et al. The points considered were (1) the lack of distinction between pure NIs, commercial formulations, and NI‐treated fertilizers, (2) unsuitable application rates of nitrogen (N) and NIs, and (3) inappropriate soil NH 4 + ‐N extraction method. Methods We conducted an incubation experiment to evaluate the efficacy of dicyandiamide (DCD), 3,4‐dimethylpyrazole phosphate (DMPP) (pure NIs), ENTEC (DMPP‐treated fertilizer), and PIADIN (commercial NI formulation) under 60% and 80% water‐holding capacity (WHC). Application rates of N and NIs followed Guo et al. but were adjusted according to Pasda et al. comments. The measurements included periodic monitoring of soil NH 4 + ‐N and NO 3 − ‐N concentrations, as well as N 2 O‐N emissions. We compared 0.0125 M CaCl 2 and 1 M KCl extraction solutions to assess the effectiveness of NIs in regulating soil mineral N concentrations. Results The control treatments at the both 60% and 80% WHC exhibited highest N 2 O‐N emissions; however, emissions were higher at 80% WHC compared to 60%. NIs effectively reduced N 2 O emissions although the efficiency was slightly lower 80% WHC. Furthermore, NI treatments also retained higher NH 4 + ‐N levels and suppressed NO 3 − ‐N accumulation. KCl extractions consistently yielded higher amount of NH 4 + ‐N as compared to CaCl 2 . Conclusions The study proves that the dilution of ENTEC significantly affected Guo et al.’s results. In the current study, ENTEC effectively reduced N 2 O emissions, performing similar to DMPP, DCD, and PIADIN. The high efficiency of these inhibitors remains consistent and in line with the earlier findings. Although the KCl extraction is more precise for NH 4 + ‐N measurement, CaCl 2 can still detect NI effects and may be suitable depending on the specific context of study.