Search results for "Nitrogen"
showing 10 items of 1200 documents
How does pea (Pisum sativum) recover from water deficit?
2020
International audience
Mise en évidence du rôle de la diversité dans la dynamique des communautés d'adventices et des interactions adventices/cultures
2020
The main challenge of 21st century agriculture is to provide sufficient food for a growing to identify cropping systems which maintain crop productivity, minimize reliance on synthetic herbicides and nitrogen fertilizers, and promote weed diversity. We hypothesized that cropping system diversification, either at the annual scale through the introduction of cover crops, or at the plurennial scale through a diversification of the crop sequence and associated weed management tools, could be a viable means to reach these objectives. More specifically, we hypothesized that cropping system diversification could (i) contain weed abundance and thereby, allow a reduction of herbicide use and an incr…
Typology of exogenous organic matters based on chemical and biochemical composition to predict potential nitrogen mineralization
2010
Our aim was to develop a typology predicting potential N availability of exogenous organic matters (EOMs) in soil based on their chemical characteristics. A database of 273 EOMs was constructed including analytical data of biochemical fractionation, organic C and N, and results of N mineralization during incubation of soil–EOM mixtures in controlled conditions. Multiple factor analysis and hierarchical classification were performed to gather EOMs with similar composition and N mineralization behavior. A typology was then defined using composition criteria to predict potential N mineralization. Six classes of EOM potential N mineralization in soil were defined, from high potential N minerali…
Synchronie entre l'offre et la demande dans le cycle des nutriments: apprendre des écosystèmes naturels pour construire des agrosystèmes durables
2023
Redesigning agrosystems with more ecological regulations can help feed a growing population, preserve soils for future productivity and reduce environmental impacts. However, guidelines for redesigning agrosystems from natural systems are limited. Reviewing the last knowledge of ecosystem functioning, we outlined four ecological systems synchronizing the supply of soluble nutrients by soil biota to fluctuating plant nutrient demand. This synchrony limits deficiencies and excesses of soluble nutrient, which usually penalize both production and regulating services of agrosystems such as nutrient retention and soil carbon storage. We detail how ecological systems promoting synchrony can be ins…
Study of nitrogen requirements of non-Saccharomyces yeasts during winemaking : impact on sequential fermentations
2019
Study of the interaction between the non-Saccharomyces yeast and Saccharomyces cerevisiae. This study aims to describe changes in the flavor profile of the wine on one hand and reducing percentage of alcohol on the other hand. For this, control of non-Saccharomyces yeast is required. Thus, the main aromatic molecules must be measured according to the conditions of cultures (pure culture - sequential culture) and their effects on the organoleptic properties will be evaluated. In parallel, their sugar, nitrogen, oxygen and vitamins requirements will be determined to decrease the percentage of alcohol in the wine.
Ecology of N2O reducing bacteria in arable soils
2016
Nitrous oxide (N2O) is an important greenhouse gas (GHG) and the main ozone depleting substance. Agricultural soils are the main anthropogenic-induced source of this GHG. The concentration of N2O in the atmosphere is steadily increasing, but we still lack knowledge on the factors controlling its production and consumption in soils. The reduction of N2O to N2 by microorganisms harboring the N2O reductase gene (nosZ) is the only known biological process able to consume this GHG. Recent studies revealed a previously unknown clade of N2O-reducers which was shown to be important to the N2O sink capacity of soils. This thesis seeks to gain a greater understanding on the ecology of N2O-reducers in…
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…
Dependence of seed nitrogen concentration on plant nitrogen availability during the seed filling in pea
1999
Abstract The final seed nitrogen (N) concentration of the pea ( Pisum sativum L.) varies greatly with environment. These variations seem to be related to N availability in the plant. To understand such an effect, the pattern of seed N concentration during seed filling was analysed at a given node as the ratio of seed N accumulation rate and seed dry matter accumulation rate. Three experiments were conducted in the field and glasshouse. Pea genotypes ‘Solara’, ‘Frisson’ and its non-nodulating mutant ‘P2’ were grown and different treatments were applied to manipulate N availability during seed filling. Treatments included N supply (addition of N fertiliser), depodding (removal of pods) and de…
Assessing non-chemical weeding strategies through mechanistic modelling of blackgrass (Alopecurus myosuroides Huds.) dynamics
2010
; Because of environmental and health safety issues, it is necessary to develop strategies that do not rely on herbicides to manage weeds. Introducing temporary grassland into annual crop rotations and mechanical weeding are the two main features that are frequently used in integrated and organic cropping systems for this purpose. To evaluate the contribution of these two factors in interaction with other cropping system components and environmental conditions, the present study updated an existing biophysical model (i.e. AlomySys) that quantifies the effects of cropping system on weed dynamics. Based on previous experiments, new sub-models were built to describe the effects on plant survi…
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 …