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Spring temperature responses of oaks are synchronous with North Atlantic conditions during the last deglaciation
Paleoclimate proxies based on the measurement of xylem cell anatomy have rarely been developed across the temperature range of a species or applied to wood predating the most recent millennium. Here we describe wood anatomy-based proxies for spring temperatures in central North America from modern bur oaks (Quercus macrocarpa Michx.). The strong coherence of temperature signals across the species range supports the use of these proxies across thousands of years of climatic change. We also used 79 subfossil oak log cross sections from northern Missouri, ÂčâŽC-dated to 9.9-13.63 ka (ka is 1000 cal yr BP), to assess the frequency of oak deposition into alluvial sediments and a subset of these oaks for a wood anatomy-based reconstruction of spring paleotemperatures. Temperatures during the Younger Dryas cold period (YD) were up to 3.5 degrees C lower than modern temperatures for that region, equivalent to or lower than those experienced at the northern edge of the modern species range. Compared to extant oaks growing at much higher [COâ], subfossil oaks had greater vessel frequencies. Besides very low theoretical (or estimated) xylem conductivity near the beginning of the oak record near 13.6 ka, vessel frequencies greater than modern trees compensated for reduced vessel dimensions so that theoretical xylem conductivity was consistently above that of modern trees at the cold northern sites. Significant correlations were found between the frequency of ÂčâŽC-dated oaks and either delta ÎŽÂčâžO from the NGRIP (North Greenland Ice Core Project) ice core or from the Cariaco grayscale marine-sediment record from the southern Caribbean sea. Oak deposition into alluvial sediments during the YD was significantly lower than expected given the average sample depth of oaks from 9.9 to 13.6 ka. Reduced oak deposition during the YD suggests that an abrupt shift in climate reduced oak populations across the region and/or changed the rates of channel movement across drainages.Keywords: Pleistocene, Quercus macrocarpa, Holocene, Pre-Boreal, Younger Dryas, Radiocarbon, Wood anatomy, Great Plains\, USA, Phenology, Bolling-Allerod, Xylem, Bur oa
Optimising Exogenous Organic Matter use in cropping systems of a francilian region : evolution of soil organic carbon stocks and substitution of mineral fertiliser
Lâutilisation des Produits RĂ©siduaires Organiques (PRO) par lâagriculture peut permettre de substituer une partie des engrais minĂ©raux et augmenter les niveaux de matiĂšre organique des sols. Elle peut Ă©galement gĂ©nĂ©rer des pollutions azotĂ©es via la lixiviation de nitrate ou des Ă©missions gazeuses. Mieux connaitre le devenir du carbone (C) et de lâazote (N) aprĂšs applications de PRO sur les sols agricoles contribue Ă amĂ©liorer les bĂ©nĂ©fices de cette pratique et Ă en limiter les impacts environnementaux. Cette thĂšse a pour objectif: (i) de prĂ©dire les dynamiques du C et du N en cas dâapplications de PRO sur les sols agricoles, (ii) dâĂ©tudier les effets de scenarios dâapports de PRO sur les stocks de carbone dans les sols, la substitution des engrais azotĂ©s et les pollutions azotĂ©es dans le contexte du territoire de la Plaine de Versailles, en prenant en compte la diversitĂ© des sols, de leurs teneurs en C et des successions culturales, (iii) dâamĂ©liorer ces bĂ©nĂ©fices Ă lâĂ©chelon du territoire via une distribution optimale des PRO. Le modĂšle CERES-EGC a Ă©tĂ© utilisĂ© pour simuler les effets de 13 ans dâapports de PRO sur les dynamiques de C et de N dans le systĂšme sol-plante-atmosphĂšre de lâexpĂ©rimentation QualiAgro, situĂ©e au cĆur du territoire dâĂ©tude. Le sous-modĂšle NCSOIL a Ă©tĂ© paramĂ©trĂ© Ă partir de cinĂ©tiques de minĂ©ralisation de C et N mesurĂ©es en conditions contrĂŽlĂ©es de laboratoire. Le transfert de ces paramĂštres dans CERES-EGC a permis de simuler correctement les Ă©volution des stocks de carbone dans les sols, les rendements et les prĂ©lĂšvements de N par les cultures ainsi que lâĂ©volution des stocks de N minĂ©ral dans les sols. Les dynamiques de minĂ©ralisation de C et N des 18 PRO disponibles sur le territoire ont Ă©tĂ© dĂ©terminĂ©es. NCSOIL a Ă©tĂ© paramĂ©trĂ© Ă partir des caractĂ©ristiques analytiques et des rĂ©sultats de fractions biochimiques des PRO. Les types de sol du territoire nâont pas impactĂ© significativement le paramĂ©trage. Les PRO ont Ă©tĂ© classĂ©s selon 4 types : (1) composts stables, (2) composts moins matures restant plus rĂ©actifs et les fumiers stables, (3) des fumiers trĂšs rĂ©actifs correspondant Ă des fumiers de chevaux, (4) des PRO trĂšs rĂ©actifs tels que des boues et des fientes pouvant plutĂŽt ĂȘtre utilisĂ©s comme fertilisants. De nombreux scenarios dâapport de PRO, contraints par les flux de phosphore et de N apportĂ©s, ont Ă©tĂ© simulĂ©s sur 20 ans dans tous les contextes de sols, successions culturales et teneurs en C organique des sols du territoire. Le type de sol a impactĂ© le plus le stockage de C et les lixiviations de nitrate tandis que les successions culturales Ă©taient prĂ©pondĂ©rantes sur la substitution des engrais. Des composts ont permis de stocker 1.1 t C ha- 1 an-1 allant jusquâ63% du C apportĂ©. Des substitutions de 74 kg N ha-1 an-1 ont Ă©tĂ© atteintes avec une boue mais aussi un compost en prenant en compte la substitution des engrais liĂ©e aux augmentations de matiĂšre organique dans les sols. La substitution des engrais a pu atteindre plus de 90% du N apportĂ© par les PRO, ceci Ă©tant liĂ© aux arriĂšres-effets sur le stockage de matiĂšre organique dans les sols et dĂ©pendant des hypothĂšses de calcul de la substitution des engrais azotĂ©s. Un modĂšle dâoptimisation a Ă©tĂ© dĂ©veloppĂ© pour sĂ©lectionner les scenarios dâapports de PRO pour chaque ilot du territoire (sol x succession de culture x teneur en C organique initiale x surface) tenant compte de la disponibilitĂ© des PRO et avec pour objectif de maximiser le stockage de C ou les substitutions en engrais azotĂ©s ou de minimiser la lixiviation de nitrate au niveau du territoire. En apportant prĂ©fĂ©rentiellement les PRO les plus stables sur les sols Ă fort potentiel de stockage de C (fortes teneurs en argile et calcaire), jusquâĂ 0.47 t C ha-1 an- 1 pourrait ĂȘtre stockĂ©. En appliquant prĂ©fĂ©rentiellement les PRO fertilisants sur les successions Ă maĂŻs, et les PRO amendants sur les successions Ă colza jusquâĂ 53 kg N ha-1 an-1 de N de synthĂšse pourrait ĂȘtre Ă©conomisĂ©s.The use of Exogenous Organic Matter (EOM) in agriculture could be an efficient way to substitute mineral fertilisation and increase soil organic matter (SOM) enhancing soil fertility and storing carbon (C). It could also cause nitrogen (N) pollutions such as nitrate leaching and gas emissions. Better understanding of C and N fate after EOM applications on cropped soils would allow improving these benefits while limiting environmental impacts. This thesis aims at: (i) predicting EOM impacts when applied on cropped soils, (ii) studying the effects of various scenarios of EOM applications in terms of C storage, synthetic N saving and N pollutions in the context of the Plain of Versailles region (221 kmÂČ) and taking into account soil diversity, crop successions and soil organic C contents, (ii) studying the potential for improving these benefits at the regional scale with an optimal distribution of EOM. The CERES-EGC crop model was used to simulate the effects of repeated applications of EOM over 13 years on both soil C and N dynamics in the soil-crop-water-air system of the long-term field experiment QualiAgro located within the region. The sub-model NCSOIL was parameterised from C and N mineralisation kinetics of EOM measured in laboratory conditions. When transposing the parameters into the CERES-EGC model, C storage at the field scale was well simulated, together with crop N uptake and yields, as well as soil mineral N contents. The kinetics of C and N mineralisation of the 18 EOM available in the region were used along with EOM biochemical fractionations for parameterising the NCSOIL model. The soil type did not significantly change EOM parameters. Four groups of EOM were distinguished based on their C and N dynamics: (i) stable composts, (2) more reactive and less mature composts and stable manures, (3) manures with reactive OM corresponding to horse manures and (4) very reactive EOM as sludges, litters that should be used as fertilisers. Numerous scenarios of EOM applications, constrained on the phosphorus and N quantities they bring (and limiting the input in trace elements), were simulated for 20 years in all regional contexts of soil, crop successions and soil organic C contents. The soil type was the main factor controlling C storage and N leaching while it was crop successions for N saving. Some composts allowed C storage up to 1.1 t C ha-1 yr -1 reaching 63% of C applied. N saving of 74 kg N ha-1 yr -1 were possible with a dried sewage sludge and a compost. N substitution could reach more than 90% of N applied with EOM, these high percentages being related with the indirect effect of EOM on soil OM and the hypothesis made for N substitution An optimisation model was developed to select EOM application scenario for each crop plot (soil x crop succession x initial soil OC content x area) accounting for EOM availability in the region with the objectives of maximising C storage or synthetic N saving or minimising N leaching at the regional scale. Applying preferentially the most stable EOM on soils with the highest potential for C storage i.e. with the highest calcareous and clay contents, up to 0.47 t C ha-1 yr-1 could be stored. Applying preferentially fertilising EOM on crop succession with maize and amending EOM on succession with rapeseed, up to 53 kg N ha-1 yr -1 could be saved
Optimisation de l'insertion des Produits Résiduaires Organiques dans les systÚmes de cultures d'un territoire francilien : évolution des stocks de carbone organique et substitution des engrais minéraux
The use of Exogenous Organic Matter (EOM) in agriculture could be an efficient way to substitute mineral fertilisation and increase soil organic matter (SOM) enhancing soil fertility and storing carbon (C). It could also cause nitrogen (N) pollutions such as nitrate leaching and gas emissions. Better understanding of C and N fate after EOM applications on cropped soils would allow improving these benefits while limiting environmental impacts. This thesis aims at: (i) predicting EOM impacts when applied on cropped soils, (ii) studying the effects of various scenarios of EOM applications in terms of C storage, synthetic N saving and N pollutions in the context of the Plain of Versailles region (221 kmÂČ) and taking into account soil diversity, crop successions and soil organic C contents, (ii) studying the potential for improving these benefits at the regional scale with an optimal distribution of EOM. The CERES-EGC crop model was used to simulate the effects of repeated applications of EOM over 13 years on both soil C and N dynamics in the soil-crop-water-air system of the long-term field experiment QualiAgro located within the region. The sub-model NCSOIL was parameterised from C and N mineralisation kinetics of EOM measured in laboratory conditions. When transposing the parameters into the CERES-EGC model, C storage at the field scale was well simulated, together with crop N uptake and yields, as well as soil mineral N contents. The kinetics of C and N mineralisation of the 18 EOM available in the region were used along with EOM biochemical fractionations for parameterising the NCSOIL model. The soil type did not significantly change EOM parameters. Four groups of EOM were distinguished based on their C and N dynamics: (i) stable composts, (2) more reactive and less mature composts and stable manures, (3) manures with reactive OM corresponding to horse manures and (4) very reactive EOM as sludges, litters that should be used as fertilisers. Numerous scenarios of EOM applications, constrained on the phosphorus and N quantities they bring (and limiting the input in trace elements), were simulated for 20 years in all regional contexts of soil, crop successions and soil organic C contents. The soil type was the main factor controlling C storage and N leaching while it was crop successions for N saving. Some composts allowed C storage up to 1.1 t C ha-1 yr -1 reaching 63% of C applied. N saving of 74 kg N ha-1 yr -1 were possible with a dried sewage sludge and a compost. N substitution could reach more than 90% of N applied with EOM, these high percentages being related with the indirect effect of EOM on soil OM and the hypothesis made for N substitution An optimisation model was developed to select EOM application scenario for each crop plot (soil x crop succession x initial soil OC content x area) accounting for EOM availability in the region with the objectives of maximising C storage or synthetic N saving or minimising N leaching at the regional scale. Applying preferentially the most stable EOM on soils with the highest potential for C storage i.e. with the highest calcareous and clay contents, up to 0.47 t C ha-1 yr-1 could be stored. Applying preferentially fertilising EOM on crop succession with maize and amending EOM on succession with rapeseed, up to 53 kg N ha-1 yr -1 could be saved.Lâutilisation des Produits RĂ©siduaires Organiques (PRO) par lâagriculture peut permettre de substituer une partie des engrais minĂ©raux et augmenter les niveaux de matiĂšre organique des sols. Elle peut Ă©galement gĂ©nĂ©rer des pollutions azotĂ©es via la lixiviation de nitrate ou des Ă©missions gazeuses. Mieux connaitre le devenir du carbone (C) et de lâazote (N) aprĂšs applications de PRO sur les sols agricoles contribue Ă amĂ©liorer les bĂ©nĂ©fices de cette pratique et Ă en limiter les impacts environnementaux. Cette thĂšse a pour objectif: (i) de prĂ©dire les dynamiques du C et du N en cas dâapplications de PRO sur les sols agricoles, (ii) dâĂ©tudier les effets de scenarios dâapports de PRO sur les stocks de carbone dans les sols, la substitution des engrais azotĂ©s et les pollutions azotĂ©es dans le contexte du territoire de la Plaine de Versailles, en prenant en compte la diversitĂ© des sols, de leurs teneurs en C et des successions culturales, (iii) dâamĂ©liorer ces bĂ©nĂ©fices Ă lâĂ©chelon du territoire via une distribution optimale des PRO. Le modĂšle CERES-EGC a Ă©tĂ© utilisĂ© pour simuler les effets de 13 ans dâapports de PRO sur les dynamiques de C et de N dans le systĂšme sol-plante-atmosphĂšre de lâexpĂ©rimentation QualiAgro, situĂ©e au cĆur du territoire dâĂ©tude. Le sous-modĂšle NCSOIL a Ă©tĂ© paramĂ©trĂ© Ă partir de cinĂ©tiques de minĂ©ralisation de C et N mesurĂ©es en conditions contrĂŽlĂ©es de laboratoire. Le transfert de ces paramĂštres dans CERES-EGC a permis de simuler correctement les Ă©volution des stocks de carbone dans les sols, les rendements et les prĂ©lĂšvements de N par les cultures ainsi que lâĂ©volution des stocks de N minĂ©ral dans les sols. Les dynamiques de minĂ©ralisation de C et N des 18 PRO disponibles sur le territoire ont Ă©tĂ© dĂ©terminĂ©es. NCSOIL a Ă©tĂ© paramĂ©trĂ© Ă partir des caractĂ©ristiques analytiques et des rĂ©sultats de fractions biochimiques des PRO. Les types de sol du territoire nâont pas impactĂ© significativement le paramĂ©trage. Les PRO ont Ă©tĂ© classĂ©s selon 4 types : (1) composts stables, (2) composts moins matures restant plus rĂ©actifs et les fumiers stables, (3) des fumiers trĂšs rĂ©actifs correspondant Ă des fumiers de chevaux, (4) des PRO trĂšs rĂ©actifs tels que des boues et des fientes pouvant plutĂŽt ĂȘtre utilisĂ©s comme fertilisants. De nombreux scenarios dâapport de PRO, contraints par les flux de phosphore et de N apportĂ©s, ont Ă©tĂ© simulĂ©s sur 20 ans dans tous les contextes de sols, successions culturales et teneurs en C organique des sols du territoire. Le type de sol a impactĂ© le plus le stockage de C et les lixiviations de nitrate tandis que les successions culturales Ă©taient prĂ©pondĂ©rantes sur la substitution des engrais. Des composts ont permis de stocker 1.1 t C ha- 1 an-1 allant jusquâ63% du C apportĂ©. Des substitutions de 74 kg N ha-1 an-1 ont Ă©tĂ© atteintes avec une boue mais aussi un compost en prenant en compte la substitution des engrais liĂ©e aux augmentations de matiĂšre organique dans les sols. La substitution des engrais a pu atteindre plus de 90% du N apportĂ© par les PRO, ceci Ă©tant liĂ© aux arriĂšres-effets sur le stockage de matiĂšre organique dans les sols et dĂ©pendant des hypothĂšses de calcul de la substitution des engrais azotĂ©s. Un modĂšle dâoptimisation a Ă©tĂ© dĂ©veloppĂ© pour sĂ©lectionner les scenarios dâapports de PRO pour chaque ilot du territoire (sol x succession de culture x teneur en C organique initiale x surface) tenant compte de la disponibilitĂ© des PRO et avec pour objectif de maximiser le stockage de C ou les substitutions en engrais azotĂ©s ou de minimiser la lixiviation de nitrate au niveau du territoire. En apportant prĂ©fĂ©rentiellement les PRO les plus stables sur les sols Ă fort potentiel de stockage de C (fortes teneurs en argile et calcaire), jusquâĂ 0.47 t C ha-1 an- 1 pourrait ĂȘtre stockĂ©. En appliquant prĂ©fĂ©rentiellement les PRO fertilisants sur les successions Ă maĂŻs, et les PRO amendants sur les successions Ă colza jusquâĂ 53 kg N ha-1 an-1 de N de synthĂšse pourrait ĂȘtre Ă©conomisĂ©s
Apport des images satellitaires de trÚs haute résolution spatiale PLEIADES à la caractérisation des cultures et des opérations culturales en début de saison
This study is part of several projects aiming at spatially monitoring the effects of exogenous organic matter apply on soil organic carbon sequestration, and necessitating for this purpose the gathering of spatial data about cropping systems. The aim of this study was to assess the contribution of very high spatial resolution (VHR) PlĂ©iades images to both early season crop identification and mapping and changes in bare soil surface characteristics due to cultural operations. The study region covering 4000 ha including 2100 ha-croplands is located west of the peri-urban territory of the Versailles plain and the Alluets plateau (Yvelines, France). About 100 cropped fields were observed on the ground synchronously with two PlĂ©iades images of 3 and 24 April 2013 and one SPOT4 image of 2 April 2013. The GIS structuring of these field data was used for delimitating both training and test zones for the support vector machine classifier with polynomial function kernel (pSVM). For the single date-images, the pSVM was computed on the 4 spectral bands while for the bitemporal PlĂ©iades image, it relied on the 8 spectral bands and the two NDVI bands. For the single-date classifications of crops, the overall accuracy reached 87% for the SPOT4 image of 2 April (6 classes), 79% for the Pleiades image of 3 April (6 classes) and 82% for that of 24 April (7 classes). For the bi-temporal PlĂ©iades image, the overall accuracy was about 80% (7 classes), winter crops, grasslands and fallows being very well detected while confusions occured between spring barley at initial stages (2-3 leaves) and bare soils prepared for other spring crops. At the earlier date (2-3 April), the PlĂ©iades image very well discriminated cultural operations (>77%, userâs or producerâs accuracies) as well as fallows and grasslands, and brought unique information about within-field spatial heterogeneity of crop development stages, while winter cereals and rapeseed were better discriminated by the SPOT4 image winter cereals (>70%, userâs or producerâs accuracies). Pleiades images therefore bring information complementary to multispectral images with high spatial resolution.Cette Ă©tude s'inscrit dans des programmes de recherche visant Ă surveiller spatialement lâeffet des apports de produits rĂ©siduaires organiques sur les stocks de carbone des sols, et nĂ©cessitant pour cela le recueil de donnĂ©es spatialisĂ©es sur les systĂšmes de culture. L'objectif de cette Ă©tude est celui d'Ă©valuer, au niveau d'organisation spatiale des parcelles culturales, l'apport des images satellitaires de TrĂšs Haute RĂ©solution Spatiale (THRS) PlĂ©iades Ă l'identification des cultures Ă des stades de dĂ©veloppement prĂ©coce dâune part, Ă la dĂ©tection des changements d'Ă©tat de surface des sols nus liĂ©s aux opĂ©rations culturales, dâautre part. La rĂ©gion dâĂ©tude, vaste dâenviron 4000 ha, dont 2100 ha de surface agricole utile, est situĂ©e Ă lâouest du territoire pĂ©riurbain francilien de la Plaine de Versailles et du Plateau des Alluets (PVPA) (Yvelines). Environ 100 parcelles culturales ont fait lâobjet dâobservations de terrain synchrones des prises de vue des deux images PlĂ©iades acquises les 3 et 24 avril 2013 et dâune image SPOT4 acquise le 2 avril 2013. La structuration gĂ©omatique de ces donnĂ©es acquises sur le terrain a servi Ă dĂ©limiter des zones susceptibles de servir Ă lâentraĂźnement ou la validation des rĂ©sultats de classification assistĂ©e par machine Ă support de vecteurs Ă noyau polynomial (pSVM). La classification pSVM a Ă©tĂ© mise en Ćuvre sur les 4 bandes spectrales assorties du NDVI pour les images monodates, et pour les 8 bandes spectrales assorties de 2 bandes NDVI pour lâimage bi-temporelle PlĂ©iades. Pour les classifications monodates des cultures, la prĂ©cision totale atteint 87% pour lâimage SPOT4 du 2 avril (6 classes), 79% pour lâimage PlĂ©iades du 3 avril (6 classes) et 85% pour celle du 24 avril (7 classes). Pour la classification bitemporelle (7 classes), la prĂ©cision totale est de prĂšs de 80%, avec des cultures dâhiver trĂšs bien discriminĂ©es tandis que les confusions opĂšrent entre lâorge de printemps aux stades 2-3 feuilles et les sols nus prĂ©parĂ©s pour les autres cultures de printemps. A la date la plus prĂ©coce (2-3 avril), lâimage PlĂ©iades discrimine bien les opĂ©rations culturales (prĂ©cisions utilisateur et producteur >77%), les jachĂšres et les prairies et renseigne sur lâhĂ©tĂ©rogĂ©nĂ©itĂ© spatiale des stades de dĂ©veloppement des cultures, tandis que les cĂ©rĂ©ales dâhiver et le colza sont mieux dĂ©tectĂ©s sur lâimage SPOT4 (prĂ©cisions utilisateur et producteur >70%). Les images PlĂ©iades apportent donc des informations complĂ©mentaires Ă celles des images multispectrales de haute rĂ©solution spatiale.Cette Ă©tude s'inscrit dans des programmes de recherche visant Ă surveiller spatialement lâeffet des apports de produits rĂ©siduaires organiques sur les stocks de carbone des sols, et nĂ©cessitant pour cela le recueil de donnĂ©es spatialisĂ©es sur les systĂšmes de culture. L'objectif de cette Ă©tude est celui d'Ă©valuer, au niveau d'organisation spatiale des parcelles culturales, l'apport des images satellitaires de TrĂšs Haute RĂ©solution Spatiale (THRS) PlĂ©iades Ă l'identification des cultures Ă des stades de dĂ©veloppement prĂ©coce dâune part, Ă la dĂ©tection des changements d'Ă©tat de surface des sols nus liĂ©s aux opĂ©rations culturales, dâautre part. La rĂ©gion dâĂ©tude, vaste dâenviron 4000 ha, dont 2100 ha de surface agricole utile, est situĂ©e Ă lâouest du territoire pĂ©riurbain francilien de la Plaine de Versailles et du Plateau des Alluets (PVPA) (Yvelines). Environ 100 parcelles culturales ont fait lâobjet dâobservations de terrain synchrones des prises de vue des deux images PlĂ©iades acquises les 3 et 24 avril 2013 et dâune image SPOT4 acquise le 2 avril 2013. La structuration gĂ©omatique de ces donnĂ©es acquises sur le terrain a servi Ă dĂ©limiter des zones susceptibles de servir Ă lâentraĂźnement ou la validation des rĂ©sultats de classification assistĂ©e par machine Ă support de vecteurs Ă noyau polynomial (pSVM). La classification pSVM a Ă©tĂ© mise en Ćuvre sur les 4 bandes spectrales assorties du NDVI pour les images monodates, et pour les 8 bandes spectrales assorties de 2 bandes NDVI pour lâimage bi-temporelle PlĂ©iades. Pour les classifications monodates des cultures, la prĂ©cision totale atteint 87% pour lâimage SPOT4 du 2 avril (6 classes), 79% pour lâimage PlĂ©iades du 3 avril (6 classes) et 85% pour celle du 24 avril (7 classes). Pour la classification bitemporelle (7 classes), la prĂ©cision totale est de prĂšs de 80%, avec des cultures dâhiver trĂšs bien discriminĂ©es tandis que les confusions opĂšrent entre lâorge de printemps aux stades 2-3 feuilles et les sols nus prĂ©parĂ©s pour les autres cultures de printemps. A la date la plus prĂ©coce (2-3 avril), lâimage PlĂ©iades discrimine bien les opĂ©rations culturales (prĂ©cisions utilisateur et producteur >77%), les jachĂšres et les prairies et renseigne sur lâhĂ©tĂ©rogĂ©nĂ©itĂ© spatiale des stades de dĂ©veloppement des cultures, tandis que les cĂ©rĂ©ales dâhiver et le colza sont mieux dĂ©tectĂ©s sur lâimage SPOT4 (prĂ©cisions utilisateur et producteur >70%). Les images PlĂ©iades apportent donc des informations complĂ©mentaires Ă celles des images multispectrales de haute rĂ©solution spatiale
Early-season mapping of crops and cultural operations using very high spatial resolution Pléiades images
The aim of this study was to assess the contribution of very high spatial resolution (VHSR) PlĂ©iades images to both early season crop identification and the mapping of bare soil surface characteristics due to cultural operations. The study region covering 21 km2 is located west of the peri-urban territory of the Versailles plain and the Alluets plateau (Yvelines, France). About 100 cropped fields were observed on the ground synchronously with two PlĂ©iades images of 3 and 24 April 2013 and one SPOT4 image of 2 April 2013. The GIS structuring of these field data along with vector information about field boundaries was used for delimitating both training and test zones for the support vector machine classifier with polynomial function kernel (pSVM). The pSVM was computed on the spectral bands and NDVI for both single-date PlĂ©iades and the bi-temporal PlĂ©iades pair. For the single-date classifications of crops, the overall per-pixel accuracy reached 87% for the SPOT4 image of 2 April (6 classes), 79% for the PlĂ©iades image of 3 April (6 classes) and 82% for that of 24 April (7 classes). At the earlier date (2â3 April), the PlĂ©iades image very well discriminated cultural operations (>77%, userâs or producerâs accuracies) as well as fallows and grasslands, while winter cereals and rapeseed were better discriminated by the SPOT4 image winter cereals (>70%, userâs or producerâs accuracies). As PlĂ©iades images revealed within-field spatial variations of early phenological stages of winter cereals that could be critical for adjusting management of zones with delayed development during the growing season, they brought information complementary to multispectral images with high spatial resolution. For the bi-temporal PlĂ©iades image, the overall per-pixel accuracy was about 80% (7 classes), winter crops, grasslands and fallows being very well detected while confusions occurred between spring barley at initial stages (2â3 leaves) and bare soils prepared for other spring crops. Using an additional validation field set covering âŒ1/3 of the study area croplands, the crop map resulting from the bi-temporal PlĂ©iades pair achieved correct crop prediction for about 89.7% of the validation fields when considering composite classes for winter cereals and for spring crops. Early-season PlĂ©iades images therefore show a considerable potential for anticipating regional crop patterns and detecting soil tillage operations in sprin
Contribution of VSHR Pléiades images to the assessment of agricultural systems over a peri-urban region near Paris, France
Contribution of VSHR Pléiades images to the assessment of agricultural systems over a peri-urban region near Paris, France. Pléiades Day
Modelling the long-term effect of urban waste compost applications on carbon and nitrogen dynamics in temperate cropland
The recycling in agriculture of Exogenous Organic Matter (EOM) issued from organic waste treatment is a promising way to restore soil organic matter (SOM) content in intensively managed soils. EOM applications to crop fields may also be used as substitute to synthetic fertilisers. The CERES-EGC mechanistic model was used to simulate the effects of repeated applications of urban waste composts and manure over 13 years on both soil carbon (C) and nitrogen (N) dynamics in the soilâcropâwaterâair system of the long-term field experiment QualiAgro. Several EOMs were considered: a farmyard manure, FYM; a municipal solid waste compost, MSW; a bio-waste compost, BIO; a co-compost of green waste and sewage sludge, GWS. Each EOM application brought the equivalent of 220â400 kg N haâ1. The sub-model NCSOIL was parameterised from C and N mineralisation kinetics of EOMs measured during incubations of soilâEOM mixtures in controlled conditions. The simulation correctly reproduced the experimental kinetics. When transposing these parameters into the CERES-EGC model, C storage at the field scale was well simulated, together with crop N uptake and yields, as well as soil mineral N contents despite a slight overestimation. The GWS compost generated the highest C storage over the 13 y-period and MSW the lowest with 65% and 36% of the Exogenous Organic Carbon (EOC) applied incorporated into the soil organic C, respectively. The GWS and MSW had the highest potential of N loss because of high mineral N content and a high potential of N mineralisation, respectively in contrast to FYM and BIO. MSW had also the highest apparent N use efficiency (48.8%) thanks to a high potential of mineralisation (76.3% of organic N applied). The achieved CERES-EGC parameterisation offers promising prospects for predicting the effects of a larger panel of EOMs, and for further using this soilâplantâwaterâatmosphere model to manage EOM application practices at the regional scale in compliance with crop production and environmental aims
Simulation with the NCSOIL model of carbon and nitrogen dynamics in a loamy soil after various compost applications
INRA Unités EGC et PESSAC, Veolia EnvironnementSimulation with the NCSOIL model of carbon and nitrogen dynamics in a loamy soil after various compost applications. 15. International Conferences of RAMIRAN (Network on R ecycling of Agricultural, Municipal and Industrial Residues in Agriculture