Gross N2O Production Process, Not Consumption, Determines the Temperature Sensitivity of Net N2O Emission in Arable Soil Subject to Different Long-Term Fertilization Practices

Abstract

Chronic amendment of agricultural soil with synthetic nitrogen fertilization and/or livestock manure has been demonstrated to enhance the feedback intensity of net N 2 O emission to temperature variation (i.e., temperature sensitivity, TS). Yet few studies have explored the relevance of changes in underlying gross N 2 O production and consumption processes toward explaining this phenomenon, in particular for the latter. Furthermore, the microbe-based mechanisms associated with the variation of N 2 O consumption process remain largely unexplored. To address this knowledge gap, a temperature-(15, 25, and 35 • C) and moisture-controlled (50% water holding capacity) microcosm incubation experiment was established using an arable soil subject to longterm addition of synthetic fertilizer (NPK), a mixture of synthetic fertilizer with livestock manure (MNPK), or with no fertilizer treatment (CT). Over the incubation time period, the C 2 H 2 inhibition method was adopted to monitor reaction rates of gross N 2 O production and consumption; the population sizes and community structures of nosZIand nosZII-N 2 O reducers were analyzed using quantitative PCR (Q-PCR) and terminal restriction fragment length polymorphism (T-RFLP). The results indicated that only NPK significantly increased the TS of net N 2 O emission, and gross N 2 O consumption process consistently occurred under all treatment combinations (temperature and fertilization) at each sampling time point. The responses of gross N 2 O production and consumption processes to temperature elevation exhibited fertilization-and sampling time-dependent pattern, and the higher net N 2 O production TS in the NPK treatment was underlain by its higher TS of gross production process and insensitivity of gross consumption process to temperature. The size and structure of nosZII-N 2 O reducers, as well as the community structure of nosZI-N 2 O reducers, were positively correlated with variation

Plants Mitigate Nitrous Oxide Emissions from Antibiotic-Contaminated Agricultural Soils

“…Semedo et al showed that tetracycline exposure increased N 2 O release in soil by simultaneously enhancing N 2 O production and inhibiting N 2 O reduction. We applied C 2 H 2 inhibition to discriminate between gross N 2 O production and consumption processes, , and found different results. ENR inhibited both gross N 2 O production and consumption processes, particularly in the bare soil (Figure ), which was likely associated with the decrease in almost all the detectable functional genes involved in nitrification and denitrification after elevating the ENR concentration (Figure a).…”

“…A microcosm study was applied to investigate the legacy effect of growing vegetables and ENR treatment on soil and their roles in changing soil N 2 O flux. Gross N 2 O production and consumption rates were determined using the C 2 H 2 inhibition method following the procedure as described by Yin et al Briefly, soil samples collected on days 7 and 44 from the pot experiment were selected for the microcosm study. Three treatments were designed for each soil sample with three replicates, namely, 0 Pa of C 2 H 2 (net N 2 O production), 10 Pa of C 2 H 2 (inhibits nitrification), and 10 kPa of C 2 H 2 (inhibits both nitrification and N 2 O reduction).…”

“…The detailed information of this experiment is provided in Supporting Information, S1. The following equations (eqs and ) were used to estimate the gross N 2 O production ( R pro ) and consumption ( R con ) rates where, R 0Pa , R 10Pa , and R 10kPa are the net N 2 O production rates under 0 Pa, 10 Pa, and 10 kPa C 2 H 2 treatments, respectively.…”

Assembly of root-associated N2O-reducing communities of annual crops is governed by selection for nosZ clade I over clade II

“…Most organisms with nosZ clade II are nondenitrifying N 2 O reducers, whereas denitrifiers with N 2 O as an intermediate dominate clade I (Graf et al 2014 ). The soil N 2 O sink capacity has been explained by the abundance and diversity of clade II in arable soils (Jones et al 2014 , Domeignoz-Horta et al 2015 , Yin et al 2020 ) and nondenitrifying N 2 O reducing bacteria can lower the net N 2 O production from soil (Domeignoz-Horta et al 2016 ). Both clades I and II are abundant in soils and rhizosphere (Hallin et al 2018 ), but little is known if plants select for specific N 2 O-reducing communities and the underlying ecological processes governing the colonization of roots by N 2 O-reducers.…”

N2 and N2O mitigation potential of replacing maize with the perennial biomass crop Silphium perfoliatum—An incubation study

“…Interestingly, a higher N 2 Oi (+0.23 ± 0.17 and +0.19 ± 0.24 higher N 2 Oi in maize and S5). This suggests that in both systems, gross N 2 O production exceeds consumption at high WFPS, probably due to high NO − 3 availability (Yin et al, 2020). Although WFPS was 79.5 ± 3.2% and 84 ± 3.3% in cup plant and maize soils, respectively, which is at the upper limit of the optimum range (70%-80% WFPS) for most soils for N 2 O formation during denitrification (Butterbach-Bahl et al, 2013), the N 2 Oi results implied that soil moisture in the high WFPS treatments was, in fact, not above optimum conditions for N 2 O formation.…”