Effect of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on N-turnover, the N2O reductase-gene nosZ and N2O:N2 partitioning from agricultural soils

• Published in: Scientific reports Vol. 10; no. 1
• Main Authors: Friedl, Johannes, Scheer, Clemens, Rowlings, David W., Deltedesco, Evi, Gorfer, Markus, De Rosa, Daniele, Grace, Peter R., Müller, Christoph, Keiblinger, Katharina M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12-02-2020; Nature Publishing Group
• Subjects: 38; 38/22; 38/77; 704/106/694/682; 704/47/4112; Abundance; Denitrification; Fertilization; Greenhouse gases; Horticulture; Humanities and Social Sciences; multidisciplinary; Nitrates; Nitrification; Nitrous oxide; Pasture; Reductase; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-59249-z

Nitrification inhibitors (NIs) have been shown to reduce emissions of the greenhouse gas nitrous oxide (N
2
O) from agricultural soils. However, their N
2
O reduction efficacy varies widely across different agro-ecosystems, and underlying mechanisms remain poorly understood. To investigate effects of the NI 3,4-dimethylpyrazole-phosphate (DMPP) on N-turnover from a pasture and a horticultural soil, we combined the quantification of N
2
and N
2
O emissions with
15
N tracing analysis and the quantification of the N
2
O-reductase gene (
nosZ
) in a soil microcosm study. Nitrogen fertilization suppressed
nosZ
abundance in both soils, showing that high nitrate availability and the preferential reduction of nitrate over N
2
O is responsible for large pulses of N
2
O after the fertilization of agricultural soils. DMPP attenuated this effect only in the horticultural soil, reducing nitrification while increasing
nosZ
abundance. DMPP reduced N
2
O emissions from the horticultural soil by >50% but did not affect overall N
2
 + N
2
O losses, demonstrating the shift in the N
2
O:N
2
ratio towards N
2
as a key mechanism of N
2
O mitigation by NIs. Under non-limiting NO
3
−
availability, the efficacy of NIs to mitigate N
2
O emissions therefore depends on their ability to reduce the suppression of the N
2
O reductase by high NO
3
−
concentrations in the soil, enabling complete denitrification to N
2
.