Influence de la dégradation des matières organiques et du couvert végétal sur la composition isotopique du carbone organique dissous : le cas des alocrisols forestiers du Morvan

National audience; Pour étudier les processus de production et de transfert des matières organiques dissoutes (MOD) dans les sols et dans les hydrosystèmes, il est essentiel de définir des traceurs de l’origine des MOD. La composition en isotopes stables du carbone (13C/12C) est un marqueur potentiel des processus producteurs de MOD. De fait, des études récentes ont montré que la composition isotopique du carbone organique dissous (COD) dans des solutions de sols forestiers en région tempérée présentaient un enrichissement en 13C de 1 à 2 ‰ par rapport à la composition isotopique des MOS, en fonction des saisons et/ou du type de couverture végétale (Kaiser et al., 2001 ; Andreux et al., 200…

Influence de différentes pratiques agricoles (culture, forme de fertilisant) sur les émissions de N2O par le sol

New insights into the use of rhizobia to mitigate soil N2O emissions

Agriculture is a major anthropogenic source of the greenhouse gas N2O, which is also involved in stratospheric ozone depletion. While the use of rhizobial inoculants has already been reported as an emerging option for mitigating soil N2O emissions, this study presents an in situ abatement of 70% of soil N2O emission using the strain nosZ+ G49 vs. nosZ− USDA138 in association with soybean. Therefore, we consider that the choice of the inoculant strain of a leguminous crop should take into account the capacity of strains to reduce nitrous oxide in addition to their N fixation capacity. This study also clearly suggests that this mitigation option could be considered not only for soybean but al…

13C differentiation of dissolved organic carbon pool during carbon mineralization in soil from a native deciduous forest and a coniferous plantation

International audience

13C Differentiation between Dissolved and Solid Organic Carbon in Soils as Induced by Substitution of a Native Deciduous Forest by a Coniferous Forest

International audience

Mécanismes de production, régulation et possibilités de limitation des émissions de N2O à l'échelle agronomique

Influence of15N enrichment on the net isotopic fractionation factor during the reduction of nitrate to nitrous oxide in soil

5 pages; International audience; Nitrous oxide, a greenhouse gas, is mainly emitted from soils during the denitrification process. Nitrogen stable-isotope investigations can help to characterise the N(2)O source and N(2)O production mechanisms. The stable-isotope approach is increasingly used with (15)N natural abundance or relatively low (15)N enrichment levels and requires a good knowledge of the isotopic fractionation effect inherent to this biological mechanism. This paper reports the measurement of the net and instantaneous isotopic fractionation factor (alpha(s/p) (i)) during the denitrification of NO(3) (-) to N(2)O over a range of (15)N substrate enrichments (0.37 to 1.00 atom% (15)…

Modelling nitrous oxide emissions from cropland at the regional scale

Arable soils are a large source of nitrous oxide (N2O) emissions, making up half of the biogenic emissions worldwide. Estimating their source strength requires methods capable of capturing the spatial and temporal variability of N2O emissions, along with the effects of crop management. Here, we applied a process-based model, CERES, with geo-referenced input data on soils, weather, and land use to map N2O emissions from wheat-cropped soils in three agriculturally intensive regions in France. Emissions were mostly controlled by soil type and local climate conditions, and only to a minor extent by the doses of fertilizer nitrogen applied. As a result, the direct emission factors calculated at …

Laboratory kinetics of soil denitrification are useful to discriminate soils with potentially high levels of N2O emission on the field scale

Les emissions de N 2 O, gaz a effet de serre, ont ete mesurees au cours d'essais au champ, sur des sols cultives dont un Rendzic Leptosol, un Eutric Leptosol, un Haplic Calcisol, un Haplic Luvisol et deux Gleyic Luvisols, et sur des sols cultives et en prairie, dont un Haplic Fluvisol et deux Gleyic Cambisols. En parallele, les cinetiques de production et de consommation de N 2 O au cours de la denitrification ont ete etudiees au laboratoire sur des suspensions de sol, au cours d'incubations anaerobies avec apport de NO 3 - et de N 2 O, en presence et en absence d'acetylene. Les sols qui emettent le plus de N 2 O « in situ », c'est-a-dire les Gleyic Luvisols cultives et les sols de prairie,…

Différenciation isotopique (13C) du carbone organique dissous (COD) au cours de la dégradation des matières organiques dans les sols forestiers : influence de la végétation

National audience

Conserver les potentialités de stockage du carbone dans les forêts et les sols

Parlons de l’environnement !

Nitrous oxide emission : a comparison of field measurements and model predictions

National audience

Organisation du séminaire Pivots

National audience

Fiche projet SOLGES. https://www.agrisource.org/fr/7_113/1509/solges-.html

Etude et gestion des processus biogéochimiques couplant les cycles du carbone et de l'azote à l'origine de la libération de composés polluants, du sol vers les compartiments eau et air de l'environnement

Procédé de réduction du gaz à effet de serre N2O en N2 par des couples symbiotiques légumineus-rghizobia, sélectionnés conjointement pour application dans des sols à faible aptitude vis-à-vis de cette fonction

13C differentiation of the dissolved organic carbon pool during carbon mineralization in soil from a native deciduous forest and a coniferous plantation

International audience

Modelling mitigation scenarios on a landscape in Central France

Modelling mitigation scenarios on a landscape in Central France. 20th European Nitrogen Cycle Meeting, ENC2018 Conference

Impacts of Integrated Weed management in cropping systems on N2O emissions from soils

International audience

Le traçage isotopique pour étudier la production par les microorganismes du sol d'oxyde nitreux, gaz à effet de serre.

Domaine SCIENCES DE L’ALIMENT ET AGRO-ENVIRONNEMENT

Dynamics and identification of soil microbial populations actively assimilating carbon from 13C-labelled wheat residue as estimated by DNA- and RNA-SIP techniques.

International audience; This work is the first report on the use of DNA-, RNA-SIP approaches to elucidate the dynamics and the diversity of bacterial populations actively assimilating C derived from plant residues labelled at more than 90% (13)C. Wheat-residues, were incorporated and incubated into soil microcosms for 28 days. At the end of the incubation time, no more than 55% of the total CO(2) released was (13)C-labelled, suggesting the occurrence of an important priming effect process. After 7 days, more than 30% of the whole DNA extracted were labelled, allowing an efficient separation of labelled from unlabelled DNA using density gradient centrifugation. The genetic structure of bacte…

Inhibitory capacities of acetylene on nitrification in two agricultural soils

Abstract Acetylene is currently used to distinguish between the relative contribution of nitrification and denitrification to soil emissions of the greenhouse gas, N 2 O. The basis of this method is that acetylene at low partial pressures inhibits nitrification without affecting N 2 O reduction. This paper reports experiments where low acetylene partial pressures were insufficient to totally inhibit nitrification in an hypercalcareous rendosol at water potentials higher than −3.5 MPa while they were always sufficient in a redoxic luvisol.

Devenir de l'azote des eaux résiduaires de féculerie après épandage sur un sol cultivé

Emissions and spatial variability of N2O, N2 and nitrous oxide mole fraction at the field scale, revealed with 15N isotopic techniques.

Abstract The accurate measurement of nitrous oxide (N 2 O) and dinitrogen (N 2 ) during the denitrification process in soils is a challenge which will help to estimate the contribution of soil N 2 O emissions to global warming. Oxygen concentration, nitrate concentration and carbon availability are generally the main factors that control soil denitrification rate and the amount of N 2 O or N 2 emitted. The aim of this paper is to present a database of the N 2 O mole fraction measured at the field scale, and to test hypotheses concerning its regulation. A 15 N-nitrate tracer solution was added to 36 undisturbed soil cores on a 20 m×20 m cultivated field plot. Fluxes of CO 2 , N 2 O and N 2 f…

Questionnaire d’enquête sur les rotations de culture en Région Centre. Septembre 2016

Predicting in situ soil N2O emission using NOE algorithm and soil database

This paper presents a new algorithm, Nitrous Oxide Emission (NOE) for simulating the emission of the greenhouse gas N2O from agricultural soils. N2O fluxes are calculated as the result of production through denitrification and nitrification and reduction through the last step of denitrification. Actual denitrification and nitrification rates are calculated from biological parameters and soil water-filled pore space, temperature and mineral nitrogen contents. New suggestions in NOE consisted in introducing (1) biological site-specific parameters of soil N2O reduction and (2) reduction of the N2O produced through nitrification to N2 through denitrification. This paper includes a database of 6…

A priori parameterisation of the CERES soil-crop models and tests against several European data sets

Mechanistic soil-crop models have become indispensable tools to investigate the effect of management practices on the productivity or environmental impacts of arable crops. Ideally these models may claim to be universally applicable because they simulate the major processes governing the fate of inputs such as fertiliser nitrogen or pesticides. However, because they deal with complex systems and uncertain phenomena, site-specific calibration is usually a prerequisite to ensure their predictions are realistic. This statement implies that some experimental knowledge on the system to be simulated should be available prior to any modelling attempt, and raises a tremendous limitation to practica…

Quantifying the contribution of nitrification and denitrification to the nitrous oxide flux using 15N tracers.

8 pages; International audience; Microbial transformations of nitrification and denitrification are the main sources of nitrous oxide (N2O) from soils. Relative contributions of both processes to N2O emissions were estimated on an agricultural soil using 15N isotope tracers (15NH4+ or 15NO3-), for a 10-day batch experiment. Under unsaturated and saturated conditions, both processes were significantly involved in N2O production. Under unsaturated conditions, 60% of N-N2O came from nitrification, while denitrification contributed around 85-90% under saturated conditions. Estimated nitrification rates were not significantly different whatever the soil moisture content, whereas the proportion o…

Simulation of nitrous oxide emissions from wheat-cropped soils using CERES

Estimation of nitrous oxide (N2O) emissions from arable soils, in relation to crop fertilization, is essential to devise strategies to mitigate the impact of agriculture on global warming. This paper presents the development and test of a N2O model resulting from the linkage of a dynamic soil-crop simulation model (CERES) with two sub-models of N2O production and reduction in soils. These sub-models (NOE and NGAS) account for both the nitrification and denitrification pathways. The resulting models (CERES–NOE and CERES–NGAS) were tested against experimental data collected on three contrasting wheat-cropped soils representative of the Beauce agricultural region in France. Although the input …

La dénitrification en zone humide de fonds de vallée

National audience

Effect of integrated weed management in cropping system on soils, microbial activity and N2O fluxes

National audience

N2O emissions during and after legume crops cultivation

International audience

Production et devenir des matières organiques dissoutes dans les milieux faiblement anthropisés

Rapport de fin de projet, programme FAST (compte-rendu de projet international)

Legume inoculants to reduce soil emissions of nitrous oxide

Nitrous oxide (N2O) is a potent greenhouse gas involved in depletion of the ozone layer and mainly arising from the soil and from agricultural activities. Within this framework, INRA teams inoculated soybean plants with natural strains of Rhizobia bacteria. Convincing results regarding the consumption of N2O greenhouse gases were obtained.

Émissions du gaz à effet de serre, N2O, au cours du fonctionnement du cycle de l’azote dans différents compartiments de notre environnement

Déterminisme de la capacité des sols à réduire le gaz à effet de serre N2O et implications pour la gestion des émissions

Loss in microbial diversity affects nitrogen cycling in soil

International audience; Microbial communities have a central role in ecosystem processes by driving the Earth's biogeochemical cycles. However, the importance of microbial diversity for ecosystem functioning is still debated. Here, we experimentally manipulated the soil microbial community using a dilution approach to analyze the functional consequences of diversity loss. A trait-centered approach was embraced using the denitrifiers as model guild due to their role in nitrogen cycling, a major ecosystem service. How various diversity metrics related to richness, eveness and phylogenetic diversity of the soil denitrifier community were affected by the removal experiment was assessed by 454 s…

Sources et puits de gaz à effet de serre (CO2, CH4, N2O) en prairie pâturée et stratégies de réduction

National audience

Les émissions de protoxide d'azote dans différentes situations agronomiques : mécanismes en jeu, régulation et simulation à l'échelle agronomique

National audience

An approach to map nitrous oxide emission risk by soils at regional scale based on soil properties

Options for reducing greenhouse gas emissions from the agricultural sector: abatement potential and cost of technical measures

National audience

Isotopic Differentiation (13C) of Dissolved Organic Carbon and CO2 During Organic Matter Degradation in Forest Soils: Influence of Vegetation

International audience

Influence of organic matters on the bacterial AsIII oxidation in polluted soils

International audience; The global bacterial AsIII-oxidizing activity tends to decrease As toxicity in soils and its transfer toward underlying aquifers. The influence of different types of organic matters on arsenic speciation by pure strains and soils microflora was determined. Experimental results show that the presence of organic matter has a negative effect on the specific rate of AsIII oxidation by pure strains presenting different metabolisms. In parallel, experiments are performed with various soils from different types of polluted sites: former mining and industrial sites, forest and agricultural soils impacted by mining activities. The effect of yeast extract on the AsIII-oxidizin…

Microbial community structure in soils with decomposing residues from plants with genetic modifications to lignin biosynthesis

Lignin is a major determinant of the decomposition of plant materials in soils. Advances in transgenic technology have led to the possibility of modifying lignin to improve the pulping properties of plant materials for papermaking. Previous studies have shown that lignin modifications also affect the rate of plant material decay in soil. The aim of this work was to investigate short-term changes in soil microbial community structures when tobacco residues with reduced activity of enzymes in the monolignol pathway decompose. The residues from lignin-modified plants all decomposed faster than unmodified plant materials. The relative proportions of some of the structural groups of microbial ph…

La dénitrification et la production de N2O dans la rhizosphère de maïs : diversité et activité des populations bactériennes impliquées

Sol et changement climatique

Les émissions de protoxyde d'azote (N2O) sous culture de colza

N2O and NO emissions by agricultural soils with low hydraulic potentials

N2O and NO production were studied on five agricultural soils with low hydraulic potentials. All experiments were performed in a laboratory under standard incubation conditions to limit any intrinsic soil heterogeneity. The mechanisms involved in NO and N2O production was investigated using the inhibitory properties of acetylene on nitrification and N2O reduction. This work confirmed that N2O and NO could be produced by soils under aerobic conditions. Nitrification seemed to be the only process involved in NO production and the main process involved in N2O production by the five studied soils when the water content was low. Nevertheless, aerobic denitrification with N2O release was observed…

Nitrous oxide emission by agricultural soils: a review of spatial and temporal variability for mitigation

CT3 ; EnjS4; International audience; This short review deals with soils as an important source of the greenhouse gas N2O. The production and consumption of N2O in soils mainly involve biotic processes: the anaerobic process of denitrification and the aerobic process of nitrification. The factors that significantly influence agricultural N2O emissions mainly concern the agricultural practices (N application rate, crop type, fertilizer type) and soil conditions (soil moisture, soil organic C content, soil pH and texture). Large variability of N2O fluxes is known to occur both at different spatial and temporal scales. Currently new techniques could help to improve the capture of the spatial va…

Influence de l'apport d'amendements organiques sur les émissions de N2O et de N2 par les sols, au cours de la dénitrification, révélée par le traçage isotopique 15

International audience

Questionnaire d’enquête sur les rotations de culture en Région Centre. Février 2016

Les émissions de protoxyde d'azote (N2O) d'origine agricole : évaluation au niveau du territoire français

National audience

N2O emissions from cropping systems with integrated weed management

International audience; Integrated weed management (IWM) in cropping systems aims to lower the reliance on herbicides of the crops, by introducing new combinations of agricultural practices in the system development (Munier-Jolain et al, 2009). These combinations may greatly change from a system to another and include a large variety of practices, such as false seed beds, late sowing, mechanical weeding, reduced tillage, specific crop rotations that alternate spring and winter crops, the choice of crop varieties and the use of pesticides with low ecotoxic impacts. Several implemented agricultural practices are likely to alter soil biogeochemical cycles and different components of the greenh…

La Plate-forme PESAa, PF pour les échanges Sols-Atmosphère dédiée aux sols agricoles

National audience

Modélisation du bilan environnemental d'une culture de colza

National audience

Emissions de N2O pendant et après la culture de légumineuses

National audience

Utiliser les symbiotes des légumineuses pour favoriser la réduction du gaz à effet de serre, N2O dans les sols

EA; CT3

Utiliser les symbiotes des Légumineuses pour favoriser la réduction du gaz à effet de serre N2O dans les sols

Nitrous oxide emissions from cultivated soils in France

International audience

Bayesian calibration of the nitrous oxide emission module of an agro-ecosystem model

1. NitroEurope Open Science Conference on Reactive Nitrogen and the European Greenhouse Gas Balance ; Ghent (Belgique) - (2008-02-20 - 2008-02-21) / Conférence; Nitrous oxide (N2O) is the main biogenic greenhouse gas contributing to the global warming potential (GWP) of agro-ecosystems. Evaluating the impact of agriculture on climate therefore requires a capacity to predict N2O emissions in relation to environmental conditions and crop management. Biophysical models simulating the dynamics of carbon and nitrogen in agro-ecosystems have a unique potential to explore these relationships, but are fraught with high uncertainties in their parameters due to their variations over time and space. H…

NatAdGES : a project dedicated to the mitigation of greenhouse gas emissions (N2O) by soils

International audience

Modélisation du bilan environnemlental d'une culture de colza

International audience

Mitigation of GHG emissions: Management of soil organic carbon and of soil N2O emissions and interactions. Experimental results from litterature

International audience

Some insights in sources and processes of production of N2O by surface water in a watershed dominated by cropland in France thanks to isotopic analysis with a Picarro G5131-i spectrometer.

International audience

Soil organic carbon storage capacity of old and modern wheat varieties

Despite the possible mitigation of carbon emissions by favoring carbon transfer to terrestrial carbon sinks, little is knownabout the capacity of different crop genotypes to enhance soil carbon sequestration. We hypothesize that carbon sequestrationpotential linked to old wheat varieties (released before 1960) is higher than the one linked to modern ones while old varietiesare known to develop bigger and deeper root systems. Moreover, modern varieties are often cultivated using syntheticchemical inputs known to modify soil carbon dynamics. We conducted a field experiment by cultivating four modern andfour old wheat varieties, with and without chemical inputs (nitrogen, herbicide and fungici…

Loss in microbial diversity affects nitrogen cycling in soil

National audience; Microbial communities have a central role in ecosystem processes by driving the Earth’s biogeochemical cycles. However, the importance of microbial diversity for ecosystem functioning is still debated. Here, we experimentally manipulated the soil microbial community using a dilution approach to analyze the functional consequences of diversity loss. A trait-centered approach was embraced using the denitrifiers as model guild due to their role in nitrogen cycling, a major ecosystem service. How various diversity metrics related to richness, eveness and phylogenetic diversity of the soil denitrifier community were affected by the removal experiment was assessed by 454 sequen…

Diversity of denitrifying community in three soils and ability to reduce nitrous oxide

International audience

Membre du comité d'organisation scientifique et logistique du Séminaire de restitution des projets SOLGES et PUIGES

National audience

Fiche projet PUIGES https://www.agrisource.org/fr/7_113/1505/puiges--culture-puits-de-n2o.html

National audience

NEMIS, a predictive model of denitrification on the field scale

Influence de la qualité biochimique des résidus végétaux sur les processus de minéralisation et les communautés bactériennes impliquées

Effects of integrated weed management in cropping systems on soils, microbial activity and N2O fluxes

International audience; Cultivated soils have been widely highlighted as a major source of nitrous oxide (N2O) emissions. This suggests that greenhouse gas emissions should be taken in account when evaluating the impact of new cropping systems. The development of integrated weed management in cropping systems introduces new agricultural practices (combinations of crop rotation, soil management, fertilization, and mechanical and chemical weed control, etc.), which may affect the microbial processes responsible for N2O production in soils. However, the effect of those practices remains to be assessed. Thus, the main objectives of our study is to provide (i) an accurate estimation of the inten…

16S rDNA analysis for characterization of denitrifying bacteria isolated from three agricultural soils

Bacteria capable of denitrification are spread among phylogenetically diverse groups. In the present investigation, molecular methods (amplified ribosomal DNA restriction analysis (ARDRA) and partial 16S rDNA gene sequencing) were used to determine the genetic diversity of culturable denitrifying soil bacteria. The purpose of this work was to study the microbial density and diversity of denitrifying communities isolated from two luvisols and a rendosol. The denitrifying bacterial density was significantly higher in the two luvisols (3x10(6) and 4x10(6) bacteria g(-1) dry soil) than in the rendosol (4x10(5) bacteria g(-1) dry soil). Denitrifying isolates from soils were grouped according to …

Effect of temperature on soil microbial structure and fractionation during C mineralisation

International audience; Microbial carbon mineralization in soils leads to the production of different gaseous or dissolved components that have environmental impacts. Our study deals with the influence of soil temperature on the production of gaseous and dissolved carbon components during carbon mineralization in forest soils in France. After an incubation of soil samples for 42 days at 4 different temperatures, we determined both size and 13C isotopic signature of dissolved organic carbon and CO2 pools. We also characterised the soil microbial community structure (PLFA profiles). While temperature clearly increases the CO2 production, a low decrease of the dissolved organic carbon pool was…

Membre du comité d'organisation du Séminaire de lancement du projet NatAdGES

National audience