Search results for " nitrogen"
showing 10 items of 319 documents
How does pea (Pisum sativum) recover from water deficit?
2020
International audience
A priori parameterisation of the CERES soil-crop models and tests against several European data sets
2002
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…
Quantification des flux d’azote induits par les cultures de légumineuses et étude de leurs déterminants : comparaison de 10 espèces de légumineuses à…
2019
In the context of agroecological transition, the reintroduction of legume crops should play a key role in cropping system sustainability by allowing a reduction of nitrogen (N) inputs. But few references are available concerning the agronomical and ecological services provided by a wide range of legume crops, particularly within crops succession scale. Thus, the main objective of our study is to quantify the N fluxes during and after the legume crops taking into account 10 legume crops (peas, lupin, faba bean, soybean...). Our experiment consists in i) quantifying symbiotic N fixation depending on the amount of soil inorganic N, the mineralisation of N present in legume crop residues after …
Légumineuses et prairies temporaires : des fournitures d'azote pour les rotations
2015
Intervention présentée aux Journées de l'AFPF, "La fertilité des sols dans les systèmes fourragers", les 8 et 9 avril 2015; Les atouts des légumineuses (fixation symbiotique, diversité fonctionnelle...) leur permettent de contribuer à la fertilité des sols, à l'amélioration de la durabilité de l'agriculture et de l'autonomie protéique des systèmes alimentaires. Il convient donc de mieux connaître leurs rôles, directs et indirects, dans les flux d'azote des rotations.Les légumineuses fourragères (en culture pure ou dans des couverts multispécifiques) représentent une grande part des apports azotés symbiotiques. Il existe une grande diversité d'implication des légumineuses dans les rotations.…
Legacy effects of contrasting water and N-availability patterns on plantmicrobial response to rewetting
2019
National audience; Introduction. Shifts in the frequency and magnitude of rain events (precipitation regime) associated with climate change may affect plant morphological and physiological strategies as well as soil microbial activity.Objectives. The objective of this study was to determine i) how precipitation history shapes the response dynamics of soil bacterial and fungal communities to rewetting, as well as plant-microbial competition for N, and ii) how the N status of the system may modulate the effect of precipitation regime.Materials & methods. The legacy effects of 12 weeks of contrasting precipitation (frequent or infrequent watering, equal total water input) and N inputs was asse…
How does pea (Pisum sativum) recover from water deficit?
2019
International audience; Pea (Pisum sativum), like other legumes, has the unique ability to fix atmospheric dinitrogen (N2) via symbiosis with soil bacteria known as rhizobia in root nodules. This particular feature makes the pea crop an essential component of sustainable cropping systems because of the reduction of nitrogen fertilizers it affords. However symbiotic nitrogen fixation (SNF) is very susceptible to abiotic stresses and particularly to water deficit, which is becoming an increasingly common threat in the current context of climate change. Water deficit impacts negatively SNF (Prudent et al., 2016), affecting both nodule number and growth (i.e. structural components of SNF) and t…
Zinc isotopes in Late Pleistocene fossil teeth from a Southeast Asian cave setting preserve paleodietary information
2020
Significance Dietary habits, especially meat consumption, represent a key aspect in the behavior and evolution of fossil hominin species. Here, we explore zinc (Zn) isotope ratios in tooth enamel of fossil mammals. We show discrimination between different trophic levels and demonstrate that Zn isotopes could prove useful in paleodietary studies of fossil hominin, or other mammalian species, to assess their consumption of animal versus plant resources. We also demonstrate the high preservation potential of pristine diet-related Zn isotope ratios, even under tropical conditions with poor collagen preservation, such as the studied depositional context in Southeast Asia. However, assessing the …
Distribution and sources of bulk organic matter (OM) on a tropical intertidal mud bank in French Guiana from elemental and isotopic proxies
2014
International audience; The mobile French Guiana coast is a shoreface region downdrift of the Amazon River, where enormous quantities of inorganic and organic materials are exchanged with the Atlantic Ocean. The rapid accumulation of these materials forms highly unstable shore-attached mud banks, which can be temporally emerged and then rapidly colonized and stabilized by microphytobenthos and opportunistic mangroves (i.e. Avicennia germinans). Mud banks are preferential sites for the accumulation and significant remineralization of organic matter (OM) due to intense erosion/deposition cycles and potential biological colonization. The distribution and sources of bulk sedimentary OM were cha…
Development of an aerobic digestion model for the assessment of greenhouse gases production (AeDMG1): Calibration and validation
2015
The increasing interest in greenhouse gas emissions from WWTPs has been leading to new tools for their designing and managing. The activated sludge models have been modified in order to consider on – site emissions from nitrification and denitrification, in particular. The biological nitrogen removal processes have been mainly assessing due to nitrous oxide (N2O) production as intermediate. The IPCC suggests that N2O contributes to climate change because it has a global warming potential 298-fold stronger than carbon dioxide. Even if the mathematical modelling is wide regarding the activated sludge models for greenhouse gases, a model for aerobic digestion is still not available. In this pa…
Reacciones de ciclación de compuestos quirales poliinsaturados fluorados catalizadas por metales de transición
2022
En el presente trabajo de Tesis se ha llevado a cabo la síntesis de compuestos nitrogenados quirales cíclicos de estructura compleja mediante reacciones de cicloadición catalizadas por metales de transición empleando como sustratos de partida 4-aza-1,7-eninos y 5,10-diaza-1,7,13-triinos quirales que, en la mayor parte de los casos, contienen átomos de flúor o agrupaciones fluoradas en su estructura molecular. La preparación de estos compuestos se basa en la utilización de homopropargilamidas quirales como sustrato común en la estructura de todos ellos. Los elementos de quiralidad y la presencia de átomos de nitrógeno y agrupaciones fluoradas en los sustratos de partida son importantes en cu…