Nitrifier‐induced denitrification is an important source of soil nitrous oxide and can be inhibited by a nitrification inhibitor 3,4‐dimethylpyrazole phosphate

Abstract

Soil ecosystem represents the largest contributor to global nitrous oxide (N O) production, which is regulated by a wide variety of microbial communities in multiple biological pathways. A mechanistic understanding of these N O production biological pathways in complex soil environment is essential for improving model performance and developing innovative mitigation strategies. Here, combined approaches of the N- O labelling technique, transcriptome analysis, and Illumina MiSeq sequencing were used to identify the relative contributions of four N O pathways including nitrification, nitrifier-induced denitrification (nitrifier denitrification and nitrification-coupled denitrification) and heterotrophic denitrification in six soils (alkaline vs. acid soils). In alkaline soils, nitrification and nitrifier-induced denitrification were the dominant pathways of N O production, and application of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) significantly reduced the N O production from these pathways; this is probably due to the observed reduction in the expression of the amoA gene in ammonia-oxidizing bacteria (AOB) in the DMPP-amended treatments. In acid soils, however, heterotrophic denitrification was the main source for N O production, and was not impacted by the application of DMPP. Our results provide robust evidence that the nitrification inhibitor DMPP can inhibit the N O production from nitrifier-induced denitrification, a potential significant source of N O production in agricultural soils.

Nitrification inhibitors effectively target N2O‐producing Nitrosospira spp. in tropical soil

“…The limitation of Nitrosospira but not Nitrososphaera by DCD has been shown also in a paddy field soil and in microcosms of Nitrosospira multiformis but not Nitrososphaera viennensis (Shen et al, 2013;Fu et al, 2018). In studies of nitrification in agricultural soils, DMPP inhibited AOB expression under neutral pH conditions (Shi et al, 2016(Shi et al, , 2017. In a Chinese vegetable soil, DMPP rather than DCD was revealed to be the more effective inhibitor of N 2 O-producing AOB rather than AOA, although the N source urea was also amended with manure (Kou et al, 2015).…”

“…In a Chinese vegetable soil, DMPP rather than DCD was revealed to be the more effective inhibitor of N 2 O-producing AOB rather than AOA, although the N source urea was also amended with manure (Kou et al, 2015). In studies of nitrification in agricultural soils, DMPP inhibited AOB expression under neutral pH conditions (Shi et al, 2016(Shi et al, , 2017. The different success of the nitrification inhibitors appears to be a function of temperature, Cu-levels, and variation in abundance, genetic potential and/or expression levels of the targeted nitrifiers (Ruser and Schulz, 2015).…”

Nitrosospira sp. Govern Nitrous Oxide Emissions in a Tropical Soil Amended With Residues of Bioenergy Crop

“…In this process, AOB possess machinery that reduces NO 2 – to N 2 O via a nitric oxide (NO) intermediate ( Ritchie and Nicholas, 1972 ; Shaw et al, 2006 ). Shi et al (2017) showed that nitrifier denitrification is an important pathway leading to high N 2 O production (10.5–54.5%) in alkaline cropping soils (pH 7.2); however, heterotrophic denitrification accounted for a the largest proportion of total N 2 O production (∼83%) in acid soils (pH 4.9). Recently, Caranto et al (2016) demonstrated another direct enzymatic pathway from NH 2 OH to N 2 O under anaerobic conditions, which is mediated by cytochrome P460.…”

Sources and sinks for N2O, can microbiologist help to mitigate N2O emissions?

“…This would involve slow release ammonium fertilizers, possibly combined with selective inhibitors. To reduce the N 2 O emission from nitrifier coupled denitrification (Shi et al ., ), any measure that enhances the activity of N 2 O reductase activity (see below) will be effective. These considerations are also relevant for understanding the N 2 O emission from industrial waste water treatment plants, in which nitrification/nitritation reactors are the strongest emitters of N 2 O, and their emission is enhanced by incomplete aeration (Kampschreur et al ., ).…”