Search results for "fertilisation"
showing 10 items of 105 documents
Adjustment time and offset of a system for spatially variable rate fertilisation
2005
The aim of this research is to measure the adjustment time and offset of a cheap system for spatially variable rate fertilisation, designed, developed and set up by the Mechanics Section of I.T.A.F. Department. In order to test the system, a centrifugal fertiliser spreader, working by gravity, was modified connecting an actuator with the two hopper shutter slides. Two different actuator types were tested, in order to measure the accordingly variable adjustment time and offset. The adjustment offset of the centrifugal spreader increases with increasing machine average forward speed and decreases with increasing fertiliser rate, considering the same rate variation. The main components of the …
The rise of thermophilic sea urchins and the expansion of barren grounds in the Mediterranean Sea
2011
Recent ecological studies have shown a strong relation between temperature, echinoids and their grazing effects on macro-algal communities. In this study, we speculate that climate warming may result in an increasingly favourable environment for the reproduction and development of the sea urchin Arbacia lixula. The relationship between increased A. lixula density and the extent of barren grounds in the Mediterranean Sea is also discussed.
The influence of pulsed redox conditions on soil phosphorus
2010
Abstract. The effects of eleven pulsed reduction-oxidation cycles (20 and 2 days, respectively) on soil phosphorus (P) dynamics are compared for 12 soils having contrasting properties and overfertilised with respect to P. Incubation conditions simulated transient waterlogging of the soil profile and involved repeated sampling and analysis of both the solution and solid phase P forms. An initial increase in P concentration occurred upto and including the fourth full cycle was followed by a sharp decline in concentration for all but one soil. Accompanying changes in the main extractable forms of P, which appeared to be cumulative, could be summarised as a general decline in the organic P frac…
Functional ecology for evaluating and predicting the aptitude of permanent grassland to provide services
2013
National audience; Applying the principles of functional ecology helps better predict the services which can be provided by permanent grassland. Farming practices and environmental characteristics influence the functional composition of grassland. Functional plant types have a generic effect on forage services which can be assessed. 13 types of grassland composed of distinct functional types were defined based on 1,283 sample grassland fields located on 8 sites. This approach was validated by checking 8 Ellenberg indicator values (used to evaluate environmental characteristics and farming practices) against climatic data and descriptive data for farming practices. The interest of a function…
La régulation des adventices dans les systèmes de culture moins dépendants des herbicides : quels rôles de la fertilisation azotée et des caractérist…
2020
National audience; Is it possible to use nitrogen fertilization for weed control? Use of herbicides and mineral fertilizers must be reduced to make cropping systems more sustainable. These changes could lead to the development of a residual weed flora and an increased competition for resources, including nitrogen, between weeds and crops. This project aims at identifying which fertilization techniques and cultivar traits contribute to the biological regulation of weeds by modulating plant‐plant competition for nitrogen and thus help to reduce herbicide use, using a modelling approach (FLORSYS). The first step of the PhD project aimed at introducing plant‐plant competition for nitrogen into …
Changements à court terme de la composition des communautés de champignons mycorhiziens à arbuscules et des populations de Rhizophagus irregularis en…
2014
La mycorhize à arbuscule a un important potentiel d’amélioration de la nutrition minérale des plantes, fort utile dans le contexte agricole. Cependant, certaines pratiques culturales sont connues pour avoir un effet néfaste sur la diversité des champignons mycorhiziens à arbuscules (Glomeromycètes). Il est donc nécessaire de mieux comprendre les dynamiques de leurs communautés et populations pour pouvoir préserver et gérer le potentiel symbiotique. Dans cette étude, nous avons étudié les effets séparés et conjoints du retournement du sol et des fertilisations phosphatée et azotée du sol sur la structure des communautés des Glomeromycètes et sur les populations de l’espèce Rhizophagus irregu…
Effect of timing of grassland destruction on nitrogen mineralization kinetics.
2007
International audience
En direct de l’essai patrimonial des 42 parcelles d’INRAE à Versailles : impacts de fertilisations centenaires en profondeur du NEOLUVISOL de lœss
2020
International audience; Après l’étude d’évolutions pédologiques et géochimiques dans l’horizon de surface (van Oort et al., 2016, 2017a), ce nouveau volet du projet de valorisation du dispositif des 42 parcelles de l’Inra de Versailles présente les effets d’apports continus de matières fertilisantes à l’échelle du solum, pour une dizaine de traitements : ammoniacaux, engrais-Na et/ou K, phosphatés, CaCO$_3$, fumier et témoins. Pour chaque traitement, les profils de teneur en éléments (0-120 cm) ont été comparés avec le bilan 1929-2014 en surface (0-25 cm), afin de raisonner la pertinence d’études des impacts d’activités anthropiques, restreintes à l’horizon de surface. En l’absence de végét…
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…
Fixation symbiotique et effet précédent : toutes les légumineuses ne se valent pas
2018
National audience; [pas de résumé]