Abstract: Plant extract cyclopentanone (CCO) has dual effects in inhibiting urease activity and nitrification, with potential as an environmentally friendly and efficient novel inhibitor. In this study, a ¹⁵N labeled field microcosm experiment was conducted to investigate the effects of CCO application on maize yield and soil greenhouse gas (CO₂, CH₄, and N₂O) emissions. The sources of N₂O production were quantified and the abatement effects of CCO on N₂O emissions were evaluated. There were four treatments in the experiment: (1) blank control (CK); (2) urea treatment alone (U); (3) NBPT (N-(N-butyl)thiophosphorictriamide) and DMPP (3,4-dimethylpyrazole-phosphate) with urea (ND); and (4) CCO (2-cyclopenten-1-one) with urea (CCO). Each treatment was replicated for three times. The results showed that CCO had a greater potential to increase maize yield than NBPT and DMPP, with yield increasing by 77.3% and 12.7% compared to CK and the U treatment, respectively. CH₄ uptake under the CCO treatment was significantly increased compared to that under U treatment, with cumulative emission reductions of CO₂ and N₂O of 9.9% and 12.8%, as well as better emission reductions than that of ND. Combined global warming potential (GWP) and greenhouse gas emission intensity (GHGI) were reduced by 14.8% and 24.2%, respectively. N₂O derived from fertilizer nitrogen was reduced by 35.1%. In conclusion, CCO combined with urea can synergistically increase crop yields and reduce greenhouse gas emissions from farmland, while reduce the loss of fertilizer nitrogen in the form of N₂O.

Key words: maize, inhibitor, 2-cyclopenten-1-one (CCO), yield, N₂O, greenhouse effect, ¹⁵N