Intercropping affects genetic potential for inorganic nitrogen cycling by root-associated microorganisms in Medicago sativa and Dactylis glomerata

Zhao, Ming; Jones, Christopher M.; Meijer, Johan; Lundquist, Per-Olof; Fransson, Petra; Carlsson, Georg; Hallin, Sara

doi:10.1016/j.apsoil.2017.06.040

Cited by 51 publications

(36 citation statements)

References 46 publications

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“…We observed a clear rhizospheric effect on denitrification, with the denitrification rates in the rhizosphere soils being lower than those in the bulk soils, regardless of fertilizer treatment and soil type, as a consequence of the higher redox conditions in the bulk soils, which aligns with the findings of previous studies (55,62). The abundance of the efficient N 2 O-reducing nosZ clade II was demonstrated to be higher in the bulk soil than in the rhizosphere soil (38), which may further explain the higher N 2 production in the bulk soil. However, our findings contradict those of Zhao et al (38), who observed that the abundance of nosZ clade I associated with the roots of legume crops was higher than that in the bulk soil.…”

Section: Discussionsupporting

confidence: 89%

“…The abundance of the efficient N 2 O-reducing nosZ clade II was demonstrated to be higher in the bulk soil than in the rhizosphere soil (38), which may further explain the higher N 2 production in the bulk soil. However, our findings contradict those of Zhao et al (38), who observed that the abundance of nosZ clade I associated with the roots of legume crops was higher than that in the bulk soil. Recent studies have demonstrated that anammox can account for up to 41% of the total N 2 production from rice paddies (7,55).…”

Section: Discussionmentioning

confidence: 89%

“…The DNRA rate and the nrfA gene abundance were not affected by the rhizospheric zone, which suggests that DNRA is not regulated by differences in chemical characteristics between the rhizosphere and bulk soils (3). There are no studies investigating the effect of rhizospheric zones on DNRA and the nrfA gene abundance in rice paddies, and the results from the few studies which have looked into the nrfA gene abundance in the roots of other arable crops are contradictory (38,39). The rhizosphere soil in rice paddies receives considerably higher OC from root exudates than from the bulk soil, which should support higher DNRA rates in the rhizosphere soil than the bulk soil, but we did not observe such an effect in our study.…”

Section: Discussionmentioning

confidence: 98%

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Nitrogen Addition Decreases Dissimilatory Nitrate Reduction to Ammonium in Rice Paddies

Pandey

Suter

et al. 2018

Appl Environ Microbiol

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Dissimilatory nitrate reduction to ammonium (DNRA), denitrification, anaerobic ammonium oxidation (anammox), and biological N fixation (BNF) can influence the nitrogen (N) use efficiency of rice production. While the effect of N application on BNF is known, little is known about its effect on NO partitioning between DNRA, denitrification, and anammox. Here, we investigated the effect of N application on DNRA, denitrification, anammox, and BNF and on the abundance of relevant genes in three paddy soils in Australia. Rice was grown in a glasshouse with N fertilizer (150 kg N ha) and without N fertilizer for 75 days, and the rhizosphere and bulk soils were collected separately for laboratory incubation and quantitative PCR analysis. Nitrogen application reduced DNRA rates by >16% in all the soils regardless of the rhizospheric zone, but it did not affect the gene abundance. Without N, the amount and proportion of NO reduced by DNRA (0.42 to 0.52 μg g soil day and 45 to 55%, respectively) were similar to or higher than the amount and proportion reduced by denitrification. However, with N the amount of NO reduced by DNRA (0.32 to 0.40 μg g soil day) was 40 to 50% lower than the amount of NO reduced by denitrification. Denitrification loss increased by >20% with N addition and was affected by the rhizospheric zones. Nitrogen loss was minimal through anammox, while BNF added 0.02 to 0.25 μg N g soil day We found that DNRA plays a significant positive role in paddy soil N retention, as it accounts for up to 55% of the total NO reduction, but this is reduced by N application. This study provides evidence that nitrogen addition reduces nitrogen retention through DNRA and increases nitrogen loss via denitrification in a paddy soil ecosystem. DNRA is one of the major NO reduction processes, and it can outcompete denitrification in NO consumption when rice paddies are low in nitrogen. A significant level of DNRA activity in paddy soils indicates that DNRA plays an important role in retaining nitrogen by reducing NO availability for denitrification and leaching. Our study shows that by reducing N addition to rice paddies, there is a positive effect from reduced nitrogen loss but, more importantly, from the conversion of NO to NH, which is the favored form of mineral nitrogen for plant uptake.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 98%

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Nitrogen Addition Decreases Dissimilatory Nitrate Reduction to Ammonium in Rice Paddies

Pandey

Suter

et al. 2018

Appl Environ Microbiol

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“…Following this, it was shown that nitrification inhibitors can lead to a decline of up to 90% in ammonia oxidation rates in Brachiara pasture and a lower abundance of both archaeal and bacterial ammonia-oxidizing microorganisms (Subbarao et al, 2009). Such a decrease in the abundance of ammonia oxidizers on plant roots compared to the bulk soil has also been reported for two forage crops, Medicago sativa and Dactylis glomerata (Zhao et al, 2017). These results have been nicely complemented by laboratory-based studies, which demonstrated the presence of secondary metabolites released into soil via root exudates, such as methyl 3-(4 hydrophenyl) propionate or cyclic diterpene, that block the ammonia-monooxygenase and hydroxylamine oxidoreductase in the nitrification pathway, a phenomenon called biological nitrification inhibition (BNI) (Subbarao et al, 2009;Zakir et al, 2008).…”

Section: Pl Ants Limit N Loss E S To Con S Erve Avail Ab Le Nmentioning

confidence: 70%

A plant perspective on nitrogen cycling in the rhizosphere

et al. 2019

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Nitrogen is the major nutrient limiting plant growth in terrestrial ecosystems, and the transformation of inert nitrogen to forms that can be assimilated by plants is mediated by soil micro‐organisms. The last decade has witnessed many significant advances in our understanding of plant–microbe interactions with evidence that plants have evolved multiple strategies to cope with nitrogen limitation by shaping and recruiting nitrogen‐cycling microbial communities. However, most studies have typically focused on the impact of plants on only one, or relatively few, processes within the nitrogen cycle. This review synthesizes recent advances in our understanding of the various routes by which plants influence the availability of nitrogen via an array of interactions with different guilds of nitrogen‐cycling micro‐organisms. We also propose a plant trait‐based framework for linking plant nitrogen acquisition strategies to the activities of nitrogen‐cycling microbial guilds. In doing so, we provide a more comprehensive picture of the ecological relationships between plants and nitrogen‐cycling micro‐organisms in terrestrial ecosystems. Finally, we identify previously overlooked processes within the nitrogen cycle that could be targeted in future research and be of interest for plant health or for improving plant nitrogen acquisition, while minimizing nitrogen inputs and losses in sustainable agricultural systems. A plain language summary is available for this article.

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“…The primer pairs and reaction conditions used are shown in Supplementary Table S1. Primer pairs selected have been consistently used to date in the literature for qPCR amplification of the different denitrifier groups (Jones et al, 2013;Domeignoz-Horta et al, 2015;Zhao et al, 2017…”

Section: Dna Extraction and Community Analysesmentioning

confidence: 99%

Effect of model root exudate on denitrifier community dynamics and activity at different water-filled pore space levels in a fertilised soil

Langarica-Fuentes

Manrubia

Giles

et al. 2018

Soil Biology and Biochemistry

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Although a "rhizosphere effect" on denitrification rates has been established, a clear understanding of the effects of exudate addition on denitrifier community dynamics remains elusive. A microcosm experiment was designed to explore the interaction between exudate addition and soil moisture on community dynamics and denitrification rates. Artificial root exudate at 5 different carbon concentrations was added daily to soil microcosms at contrasting target WFPS (50, 70 and 90%). After a 7-day period, total denitrification and N 2 O emission rates were measured and community dynamics assessed using molecular methods. The response of denitrifier genes to exudate addition was different, with nirS and nosZ-I showing a stronger effect than nirK and nosZ-II. Distinct community structures were observed for nirS and nosZ-I at 90% target WFPS when compared to 50% and 70%. NirS denitrifier population size showed a ca. 5-fold increase in gene copy number at 90% WFPS when exudate was added at the highest C input. Significant total denitrification and N 2 O emission rates were observed only at 90% WFPS, which increased with C input. Our study improves the understanding of the complex interaction between microbial communities, the abiotic environment and process rates which can inform management practices aimed at increasing complete denitrification and controlling greenhouse gas production from agriculture.

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Intercropping affects genetic potential for inorganic nitrogen cycling by root-associated microorganisms in Medicago sativa and Dactylis glomerata

Cited by 51 publications

References 46 publications

Nitrogen Addition Decreases Dissimilatory Nitrate Reduction to Ammonium in Rice Paddies

Nitrogen Addition Decreases Dissimilatory Nitrate Reduction to Ammonium in Rice Paddies

A plant perspective on nitrogen cycling in the rhizosphere

Effect of model root exudate on denitrifier community dynamics and activity at different water-filled pore space levels in a fertilised soil

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