Emissions de composés organiques volatils par des sols amendés par des PRO: évolution saisonnière et lien avec la diversité microbienne

National audienc

Microbial volatiles organics compounds (mvocs) emitted from soils amended with organic wastes

EABIOmEAGROSUPVolatile organic compounds (VOCs) have a central role in environmental pollution. They influence the chemistry and the composition of the atmosphere. In particular, biogenic volatile organic compounds (bVOCs) contribute 90% to global VOCs emissions1. Microorganisms contribute to bVOCs emissions and their emissions could be affected by different type of organic waste in soil2. The aim of this study is focused on determining the effect of organic wastes on VOC emitted by microorganisms in soils. The technique used for mVOC detection is the Proton Transfer Reaction-Time of Flight-Mass Spectrometry*(PTR-TOF-MS). PTR-TOF-MS technique provides on-line detection of VOC with two mains advantages: rapidity and the detection limit as low as 0.1 ppt by volume3. Five sample of the same soil with 4 different organic waste contributions were analyzed: (1) Municipal solid waste, (2) Green waste and sludge, (3) bio-waste, (4) farmyard manure and a control sample without organic waste. We also compared dry and humid conditions for each sample. Results show that VOC emissions are higher in humid samples than dry ones. Different VOCs such as acetone, Methyl Ethyl Ketone, acetaldehyde, toluene, ethanol and monoterpenes contribute between 60% and 80% of total emissions. Furthermore, other compounds emitted in smaller quantities are analyzed in order to identify a VOC profile belonging to each type of organic waste in soil. Finally, perspectives concerning the study of the correlation between mVOC emissions profiles with microorganism diversity and activity in soil will be discussed. Also analysis of soils genetic content and manipulation of genetic diversity of soils will be performed. 1 Roger Atkinson, ‘Atmospheric Chemistry of VOCs and NOx’, Atmospheric Environment, 34.12–14 (2000), 2063–2101 . 2 Mallard P. et al., ‘Impacts environnementaux de la gestion biologique des déchets : bilan des connaissances’ (2005). 3 Christos Soukoulis and others, ‘PTR-ToF-MS, A Novel, Rapid, High Sensitivity and Non-Invasive Tool to Monitor Volatile Compound Release During Fruit Post-Harvest Storage: The Case Study of Apple Ripening’, Food and Bioprocess Technology, 6.10 (2012), 2831–43 . *Financed by ANAeE France <http://www.anaee.com/

Investigating sources and sinks for ammonia exchanges between the atmosphere and a wheat canopy following slurry application with trailing hose

Ammonia exchanges between the atmosphere and terrestrial ecosystems are composed of several pathways including exchange with the soil, the litter, the plant surfaces (cuticle) and through the stomata. In this study, the fate of nitrogen in the different pools (soil and plant) was analyzed with the aim of determining the sources and sink of atmospheric ammonia after slurry application on a wheat canopy. To do this, we measured ammonia exchanges between a winter wheat canopy and the atmosphere following cattle slurry application with a trailing hose. From 12 March to 8 April in Grignon near Paris, France, the ammonia fluxes ranged from an emission peak of 54,300 NH3 ng m−2 s−1 on the day of slurry application (with a median during the first 24 h of 5990 NH3 ng m−2 s−1) to a deposition flux of −600 NH3 ng m−2 s−1 (with a median during the last period of −16 NH3 ng m−2 s−1). The ammonia compensation points were evaluated for apoplasm, foliar bulk, root bulk and litter bulk tissue, as well as for soil surface. Ammonia emission potentials defined by the ratios between the concentration in [NH4+] and [H+] for each N ecosystem pool were in the same order of magnitude for the plant decomposed in apoplastic liquid, green leaf bulk tissue and cuticle, respectively, averaging at 73, 160 and 120; in green leaf bulk tissues, the emission potential decreased gradually from 230 to 78 during the period after slurry application, while in the dead leaf bulk tissues considered as litter, the emission potential reached a maximum of 50,200 after application stabilized at around 20000. The dynamic of the emission potential for roots was similar to the ammonium concentration in the first two centimeters of the soil, with a maximum of 820 reached two days after application and a minimum of 44 reached three weeks later. The surfatm-NH3 model interpreted the emission and deposition fluxes by testing soil surface resistance. We conclude that emission of the first day application was driven by climatic conditions and ammonia concentration at the soil surface, with no surface resistance and with only soil surface emission potential. On the next three days, the ammonia emission originated from the soil surface with the growth of a dry surface layer inducing surface resistance and regulated by slurry infiltration. The following days need a more detailed description of soil surface processes and the integration of vegetation exchanges (stomatal and cuticle pathways), particularly in the last period, in order to explain the ammonia deposition

Effect of senescence on biogenic volatile organic compound fluxes in wheat plants

International audienc

Modelled and measured greenhouse gases emissions from a typical Île-De-France crop rotation between 2005 and 2013. Influence of climatic conditions and sensitivity to nitrogen exchange with the atmosphere

Modelled and measured greenhouse gases emissions from a typical Île-De-France crop rotation between 2005 and 2013. Influence of climatic conditions and sensitivity to nitrogen exchange with the atmosphere. Open Science Conference: Greenhouse Gas Management in European Land Use System

Effets de l’apport de produits résiduaires organiques sur le stockage de carbone, les émissions de gaz à effet de serre et la lixiviation du nitrate dans les sols agricoles périurbains

The PROSTOCK project develops within the context of peri-urban agriculture and the aim of recycling organic waste of either agricultural or urban origin (or exogenous organic matter, EOM) in keeping with the perspective of restoring soil organic carbon stocks (SCS) in agricultural areas. Its main objective was to spatially assess the potential of EOM recycling for improving SCS over these areas. The secondary objective was to assess the resulting possible impacts of EOM use on greenhouse gas emissions (CO2, N2O in this project) and nitrate leaching. Moreover, PROSTOCK included a methodological aim oriented towards the feasibility assessment of monitoring SCS variations using spectroscopy and remote sensing in the visible near and shortwave infrared range (NIRS). The spatial level considered was that of small peri-urban agricultural regions, where waste management and its resulting effects on water and soil quality operate. The Versailles Plain and the Alluets Plateau, a peri-urban region covering 221 km² (of which 100 km² are croplands), unique in terms of available data, spatial and thematic representativeness and references on EOMs, was chosen as study region. A database of field and lab measurements (reflectance, roughness, bulk density, moisture, physico-chemical analysis…) and observations (soil surface conditions, amendment practices and cultural operations) with unprecedented size was collected and structured from more than 250 point locations spread over the cropped areas. Some fifteen remote sensing images from varied satellite and airborne sensors were acquired over the course of 3 field campaigns of field measurements synchronous with sensor acquisitions in 2011, 2012, 2013. This project enabled considerable progress in using imaging data related to field spectral measurements, for the purpose of estimating topsoil organic carbon content (SOC) from soil reflectance spectra. The accuracy that is expectable from such method not only depends on sensor type, but also on atmospherical and angular conditions of imaging, and cultural operations, which influence the performance of image atmospheric correction into reflectance units. Conversely to predictions obtained from lab or even field reflectance spectra, multispectral satellite images with medium spatial resolution do not enable to discriminate changes in SOC resulting from EOM applications over a large 15 years-duration, but they result in a rough mapping of SOC over large extents. This project also enabled to demonstrate the potential of optical/radar synergy for detecting cultural operations, which otherwise can hardly be spatially surveyed from interviews to farmers. In the same prospect of facilitating surveys, this project favoured ongoing studies about very high resolution Pleiades images showing their potential for mapping crop types and phenological stages, as well as for locating those fields having recently received EOM application. More, PROSTOCK enabled to parameterize the CERES-EGC agro-environmental model which was chosen for the purpose of simulating SCS dynamics according to various EOM applications. This parameterized model succeeds in retrospectively predicting temporal trends of SCS as observed over the course of 10 years for the QualiAgro Experiment. The inventory of actually of potentially available EOMs over the study region reveals multiple agronomical scenarios of amendment practices with EOM, depending on either their stocking or their fertilizing properties, through their proportion of easily available N: nitrogen mineralization and CO2, N2O emissions dynamics were characterized in this project for the main EOMs identified. The main N2O-emitter soils are now identified according to the EOMs applied. All required elements are therefore ready for the spatial modeling of simulations, to anticipate future evolutions. The PROSTOCK project paves the way for numerous related questions addressing the validity domain of agri-environmental models when soil types and cultural operations vary at the scale of a small agricultural region. It relied on both support and commitment from the study area farmers and appears to be rich in further developments for their common benefit, that the large size of collected data permits to anticipate. It could be continued and add value to its results with the prospect of spatially assessing soil ecosystem services according to the effects of EOM application.Le projet PROSTOCK s’inscrit dans le contexte d’une agriculture péri-urbaine visant le recyclage des matières organiques résiduaires d’origines agricole, urbaine et de loisirs (ou produits résiduaires organiques, PRO) dans une perspective vertueuse de restauration des stocks de carbone organique (SCO) de ses sols agricoles. Son objectif principal était d’évaluer spatialement la possibilité d’accroître le SCO des sols agricoles par le recyclage des PRO. L’objectif secondaire visait à en évaluer les impacts potentiels, au même niveau d’organisation spatiale, sur les risques d’émission de GES et de lixiviation du nitrate. En outre, PROSTOCK comportait un objectif méthodologique visant à évaluer la faisabilité du suivi des variations de stocks de carbone organique des sols agricoles par imagerie de télédétection et/ou spectroradiométrie visible proche infrarouge (NIRS). Le niveau d’organisation spatiale retenu est celui de petites régions agricoles périurbaines, où se jouent la gestion des déchets et ses effets sur la qualité de l’eau et des sols. La Plaine de Versailles et du Plateau des Alluets, région périurbaine vaste de 221 km² (dont environ 100 km² de surface agricole utile), unique en termes de données disponibles, de représentativité spatiale et thématique et de références sur les PRO, a ainsi été choisie comme territoire de l’étude. Une base de données de mesures (réflectance, rugosité, masse volumique apparente, humidité, déterminations analytiques) et d’observations (états de surface du sol, pratiques d’amendement et opérations culturales) d’ampleur inédite a été recueillie et structurée et concerne plus de 250 localisations ponctuelles réparties sur la zone agricole. Une quinzaine d’images de divers capteurs satellitaires et aéroportés ont été acquises lors de 3 campagnes printanières de mesures de terrain synchrones des prises de vue de télédétection, en 2011, 2012 et 2013. Le projet a permis des avancées significatives sur l’utilisation de données imagées en lien avec les mesures spectrales au sol, pour l’estimation des teneurs en carbone organique (CO) du sol à partir de la réflectance du sol. La précision que l’on peut en espérer dépend non seulement du type de capteur, mais aussi des conditions atmosphériques et angulaires de la prise de vue, et des opérations culturales, qui affectent la performance de la correction atmosphérique des images en réflectance. Contrairement aux prédictions issues de spectres de réflectance de laboratoire ou même de terrain, les données multispectrales satellitaires de résolution moyenne haute ne permettent pas de distinguer des changements liés à des apports de PRO sur une durée de 15 ans, mais contribuent à une cartographie sommaire des teneurs en CO sur de vastes superficies. Le projet a par ailleurs permis de mettre en évidence l’intérêt de la synergie optique/radar pour la détection des opérations culturales, qui sont difficiles à répertorier spatialement par le biais d’enquêtes. Dans la même perspective d’alléger les enquêtes sur les pratiques agricoles, les travaux en cours sur les images de très haute résolution spatiale Pléiades montrent l’apport de ces images à la cartographie des types de cultures et de leurs stades phénologiques ainsi qu’au repérage des parcelles ayant récemment fait l’objet d’un épandage de PRO. Par ailleurs, le projet a permis de paramétrer le modèle agro-environnemental retenu pour simuler les stocks de C sous l’effet des apports de PRO (CERES-EGC), qui restitue fidèlement et rétrospectivement les évolutions temporelles des SCO observées sur 10 ans du dispositif expérimental QualiAgro. L’inventaire des PRO actuellement ou potentiellement disponibles réalisé sur le territoire fait ressortir une multiplicité de scenarii agronomiques d’utilisation des PRO selon leurs propriétés stockantes ou bien fertilisantes, via leur disponibilité en azote : les dynamiques de minéralisation de l’azote, d’émission de CO2 et de N2O ont été caractérisées pour les principaux PRO répertoriés dans le cadre de ce projet. On connaît désormais quels sont les sols principaux émetteurs de N2O selon les PRO qu’on leur apporte. Tous les éléments sont donc en place pour mettre en oeuvre ces simulations au niveau spatial, afin d’anticiper des évolutions futures. Le projet PROSTOCK ouvre la voie à de nombreuses questions connexes qui portent notamment sur le domaine de validité des modèles agri-environnementaux lorsque les types de sols et les opérations culturales varient à l’échelon d’une petite région agricole. Il s’est fait en lien et avec l’engagement des agriculteurs du territoire et s’avère fécond en possibles approfondissements au service de ces derniers, que permet d’envisager l’ampleur inédite des données recueillies. Il pourrait donner lieu à une suite qui valoriserait les résultats en cours dans la perspective de l’évaluation spatialisée des services écosystémiques des sols sous l’effet de l’apport des PRO

Comparative study of biogenic volatile organic compounds fluxes by wheat, maize and rapeseed with dynamic chambers over a short period in northern France

Biogenic volatile organic compounds (BVOC) are mainly emitted from vegetation. However there is still little information on BVOC exchanges with crops. In this study we measured fluxes of BVOC from wheat, maize and rapeseed crops near Paris at the plant level during a full-week period for each species. We used dynamic automated chambers coupled to a Proton Transfer Reaction, Quadrupole ion guide, Time of Flight mass spectrometer (PTR-Qi-Tof-MS) instrument for online measurements of BVOC. Our results confirm the hypothesis that many unexplored compounds contribute to BVOC exchanges between crops and the atmosphere, although for all plant species methanol was dominating the emissions (55–85% of the sum of the BVOC exchanges fluxes on a mass basis) followed by acetone and acetaldehyde. The 10 most exchanged compounds, excluding methanol, contributed more than 50% of the summed fluxes and the 100 most exchanged contributed to more than 90%. The summed BVOC emission and deposition presented large interspecies variations, but limited intra-species variability, with a summed net flux of 0.11 ± 0.02 μgBVOC gDW−1 h−1 for maize, 1.5 ± 0.7 μgBVOC gDW−1 h−1 for wheat, and 9.1 ± 2.4 μgBVOC gDW−1 h−1 for rapeseed. The 10 most emitted compounds were mostly emitted during the day and were correlated with both photosynthetically active radiation and temperature and anti-correlated with relative humidity. This study provides the first evaluation so far of the biosphere-atmosphere fluxes for several BVOC. In particular we provide a first evaluation of standard emission factor for isoprene and monoterpene for wheat and rapeseed at their respective growth stages. This study is however limited to a week period at a given stage for each species and at the plant level