Nitrogen fertiliser-induced changes in N2O emissions are attributed more to ammonia-oxidising bacteria rather than archaea as revealed using 1-octyne and acetylene inhibitors in two arable soils

Abstract

Nitrification is believed to be one of the major sources of N 2 O production emitted from soil. Previous studies showed that both ammonia-oxidising bacteria (AOB) and archaea (AOA) can produce N 2 O via nitrification but their relative contributions are still poorly defined. Here, we used acetylene, an inhibitor of AOB and AOA ammonia monooxygenase (AMO), and 1-octyne, a selective inhibitor that specifically inhibits AOB AMO, to investigate how AOB versus AOA contribute to N 2 O emissions in two distinct arable soils. Soil amended with ammonium (NH 4 + ) increased N 2 O emissions to a greater extent than nitrate (NO 3 − ), and acetylene had a greater impact on N 2 O emissions in NH 4 + -treated soils than that in NO 3 − -amended soils, which indicated that nitrification was the dominant N 2 O emitting process in these two arable soils. In the alluvial and red soil, the percentage of evolved N 2 O after application of NH 4 + by AOB were 70.5~78.1 % and 18.7~19.7 % by AOA, respectively. Quantitative PCR revealed that NH 4 + addition stimulated AOB growth, and the growth could be significantly inhibited by acetylene or 1-octyne in the two soils. The stimulation of N 2 O emissions by NH 4 + and the relative suppression by inhibitors paralleled fluctuations in the AOB growth. In addition, cumulative N 2 O emissions were not correlated with AOA abundance in the two soils. Our results revealed that AOB could contribute more to soil N 2 O production than AOA in the NH 4 + -amended arable soils.

Ammonia‐oxidizing bacteria are the primary N2O producers in an ammonia‐oxidizing archaea dominated alkaline agricultural soil

“…All data types, which included gene and transcript abundance, isotopic signatures, and responses to a suite of selective inhibitors, were consistent with nitrification by the AOB as the dominant source. This result is consistent with analyses of other soil systems, reporting a greater contribution of AOB to N 2 O emissions (Hink et al, 2017;Wang et al, 2016). In addition to the isotopic and molecular signatures, the absence of nitrous oxide production in the presence of acetylene was consistent with denitrification being only a minor source.…”

The interactive effects of dolomite application and straw incorporation on soil N2O emissions

“…Dolomite application increased the soil pH, and consequently increased the rate of mineralization, which produced more exchangeable NH 4 + -N in soil. Nitrification can play a vital role in N 2 O emissions when NH 4 + -N is converted into NO 3 − -N in soil (Wang et al, 2016a). Despite greater exchangeable soil NH 4 + -N and nitrification, surprisingly, dolomite application showed a decrease in soil N 2 O emission.…”

Physiological and genomic analysis of “Candidatus Nitrosocosmicus agrestis”, an ammonia tolerant ammonia-oxidizing archaeon from vegetable soil

“…In general, the AOA species were reported to have low ammonia tolerance (only up to 1-20 mM) (Table 1) while AOB species were able to tolerate 7-50 mM (Prosser and Nicol, 2012) even up to 400 mM (Hunik et al ., 1992). Then, AOB groups were usually regarded as the main contributor who was responsible for the N 2 O emission in agricultural fields after fertilizing with ammonium nitrogen (Wang et al ., 2016; Hink et al ., 2017; Meinhardt et al ., 2018). However, the AOA groups were still observed to have a small contribution (10-20%) to the N 2 O emission (Wang et al ., 2016; Hink et al ., 2017; Meinhardt et al ., 2018).…”

“…Then, AOB groups were usually regarded as the main contributor who was responsible for the N 2 O emission in agricultural fields after fertilizing with ammonium nitrogen (Wang et al ., 2016; Hink et al ., 2017; Meinhardt et al ., 2018). However, the AOA groups were still observed to have a small contribution (10-20%) to the N 2 O emission (Wang et al ., 2016; Hink et al ., 2017; Meinhardt et al ., 2018). Moreover, in some agricultural soils, the ammonia oxidation and N 2 O production of AOA would not be suppressed by the fertilization with high ammonium (Schauss et al ., 2009; Stopnišek et al ., 2010; Lu et al ., 2015; Duan et al ., 2019).…”