Nitrogen rate drives the effectiveness of 3,4-Dimethylpyrazole phosphate (DMPP) in reducing N2O emissions from limed soil subjected to temporary waterlogging

Soil pH, moisture, and nitrogen (N) rate may affect the effectiveness of the nitrification inhibitor 3,4-Dimethylpyrazole phosphate (DMPP) in mitigating N 2 O release. Thus, the present study raised the question: do soil pH and N rate regulate the effect of DMPP on mitigating N 2 O production and promoting N 2 O reduction to N 2 from soils subjected to temporary waterlogging? This was studied in a greenhouse experiment under semi-controlled conditions in which wheat was cultivated under aerobic conditions for 30 days, followed by a temporary waterlogging period of 5 days. The study investigated the factors of soil pH, which was manipulated by liming (unlimed and limed), application of the nitrification inhibitor DMPP, and N application rate (60 and 180 mg N kg soil −1 ), referred to as N60 and N180. The N source was ammonium sulfate. DMPP reduced the relative abundance of nitrifying bacteria such as Nitrospira and Nitrosospira and, therefore, suppressed nitrification in all treatments. After waterlogging, DMPP efficiently mitigated N 2 O-N release from unlimed soil (80 %), probably by suppressing fungal ( Cladosporium , Chaetomium , and Fusarium ) and bacterial ( Bradyrhizobium ) denitrifiers due to DMPP-induced lower NO 3 − concentrations. In addition, DMPP reduced cumulative N 2 O-N release by 94 % at the N180 rate but was ineffective at the N60 rate in the limed soil. In conclusion, DMPP was confirmed as an excellent mitigation measure for N 2 O release from unlimed soils subjected to waterlogging. However, our study demonstrated that relatively low N rates can lead to DMPP ineffectiveness in reducing N 2 O release from limed soil subjected to temporary waterlogging.