DESIGNING MIXED HORTICULTURAL SYSTEMS

The necessary ecologization of agriculture in the developed countries has recently resulted in the research of innovative systems that are both economically viable and environmentally friendly, with sustainable objectives at mid and long terms. The sylvoarable systems, mixing trees and crops on the same plot, are ecologically intensive systems that allow a better use of natural resources, hence increase production on the same land area. The vegetable orchard is a sylvoarable system mixing fruit trees and vegetable crops that disappeared in the 1950’s for economic reasons. Its possible reintroduction becomes a new research topic for ecological purposes, with agronomic bases to ensure its viability. The vegetable orchards’ agronomic bases are a combination of scientific results and feedback from farmers on the interactions between fruit trees and vegetable crops. These bases are the common knowledge to be harnessed during vegetable orchards’ co-design processes, especially for developing decision-support tools, such as models. A proof of concept is built for modelling the vegetable orchard with constraint satisfaction problems (CSP), proposing layouts of fruit trees and vegetable crops that take maximum advantage of a set of interactions between them. This proof of concept is the core of a more exhaustive model to be built, with CSP formalism or another, which could be used to support the design of systems mixing trees and crops

Performances de reproduction et d'élevage des brebis romanov finnoises et croisées: premier bilan des résultats obtenus en france dans les troupeaux expérimentaux de l'INRA et dans quelques troupeaux d'étude

International audienc

ELABORATING INNOVATIVE SOLUTIONS WITH EXPERTS USING A MULTICRITERIA EVALUATION TOOL. THE CASE OF SOIL BORNE DISEASE CONTROL IN MARKETGARDENING CROPPING SYSTEMS

International audienceMarket-gardening cropping systems in protected cultivation are very sensitive to soil-borne pests and diseases. Their productivity used to rely on pesticides, but alternative systems have now to be found for environmental, societal and health reasons. Many cultural techniques are known to provide some control of soilborne diseases, but are only partially efficient. The aim of the project is to design alternative systems with professionals, by improving the efficiency of the present techniques and/or imagining more innovative systems. The research project takes place in two steps. The first one consists in building a tool to assess the resistance or resilience of a given cropping system to soil-borne pests; the second one consists in using the tool with professionals in order to build alternative cropping and farming systems in cooperation. The model built for evaluation is a qualitative multicriteria tool. As scientific knowledge is not available for each technique or combination of techniques, empirical knowledge collected from growers and technical advisers is used to fill the gaps. The model is already built for root-knot nematodes and under construction for the other fungi. The second step will consist in using the tool with technical advisers and growers to redesign cropping systems and select the promising ones that should be put into trial in R&D stations. Co-building farming systems with stakeholders appears as an absolute necessity, to imagine solutions both efficient and acceptable for growers. The presentation will enable to discuss how combining expert and scientific knowledge may not only fill the knowledge gap, but also enable to build innovative solutions thanks to the diversity of experts' standpoints

An alternative well-posedness property and static spacetimes with naked singularities

In the first part of this paper, we show that the Cauchy problem for wave propagation in some static spacetimes presenting a singular time-like boundary is well posed, if we only demand the waves to have finite energy, although no boundary condition is required. This feature does not come from essential self-adjointness, which is false in these cases, but from a different phenomenon that we call the alternative well-posedness property, whose origin is due to the degeneracy of the metric components near the boundary. Beyond these examples, in the second part, we characterize the type of degeneracy which leads to this phenomenon.Comment: 34 pages, 3 figures. Accepted for publication in Class. Quantum Gra

Variations génétiques de la fertilité des brebis mérinos d'arles

International audienc

Development and evaluation of an automated prototype for the fertigation management in a closed system

In France, in order to prevent imbalances and accumulation of nutrients in the plant root zone, most of the soilless crops in glasshouses are cultivated in open drainage systems, which leads to water and fertilizer losses. The goal of the EU project CLOSYS (CLOsed SYStem for water and nutrient management) was to build a prototype which delivers water and nutrients according to the plant needs in a recirculating system. This prototype aimed at controlling production and quality as well as reducing nutrient accumulation or shortage in the root zone in a closed system and avoiding pollution of the environment. This paper deals with the development and the evaluation of the prototype in comparison with a classical closed system for a sweet pepper crop. This prototype includes: substrate and plant models incorporated in an expert system, using substrate and plant sensors, and a real time controller. Technical details and results of each module will be presented. The plant model provided proper simulations of growth and development parameters, nutrient concentrations in the plant organs, plant nutrient and water consumption. The expert system enabled the coupling between plant and substrate models, thus ensuring the system to take into account the weather forecasts. The real time controller managed to control relative water content and electric conductivity in the substrate slabs. A Leaf Area Index sensor was used to calibrate the plant model according to the real crop area development. As a conclusion, the CLOSYS system led to a lower nutrient consumption, lower sodium and chloride accumulation and a proper electric conductivity control in comparison with the classical closed system, while maintaining production and quality

EBIO-Network: a web-based platform for knowledge sharing on functional agrobiodiversity in organic apple production.

The web-based platform "EBIO-Network" (European Biodiversity Orchards Network),created within the framework of the CoreOrganic plus project EcoOrchard, will provide an interactive communication tool between stakeholders in European organic fruit production at different levels (practice, science, advisory etc.). The website will offer the opportunity to share, extract and use stakeholder knowledge in Europe in a participatory approach. As an outcome of this ongoing exchange, the aim is to provide technical information how to create, keep and assess functional agrobiodiversity (FAB) in apple production

Influence of the heating method on greenhouse microclimate and energy consumption

The influence of the heating system method on greenhouse microclimate was investigated overnight, using an experimental greenhouse tunnel with a tomato crop. The heating system consisted of plastic heating pipes located close to the gutter holding the growing substrate and an air heater, located 2.6 in above the ground. All the measurements were performed during two periods: (a) a period when only pipe heating was used; and (b) a period with pipe and air heating together. Heating pipes only could maintain the desired inside air temperature up to a temperature difference between inside and outside air of 10 degrees C, whereas this difference was increased to 15 degrees C with the addition of the air heater. Energy consumption with a system combining heating pipes and an air heater was 19% higher. The use of the air heater enhanced the vapour pressure difference and thus the crop transpiration. For both cases crop temperature was lower than air temperature but this difference was larger with the air heater and resulted in an increase in crop aerodynamic conductance. The use of the air heater for dehumidification purposes was also investigated. It was shown that with the air heater, although the mass transfer conductance to the cover was higher, condensation flux was smaller which resulted in less condensation at the inner surface of the cover. These results indicate that the use of a mixed system is favourable in greenhouse tunnel conditions since the use of the air heater, although increasing slightly the energy consumption, improves the control of both air temperature and humidity, particularly by keeping the inside air dew point temperature lower than the cover temperature and preventing the occurrence of condensation on the plastic films. (c) 2005 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd