Didier Stilmant - Academia.edu (original) (raw)

Papers by Didier Stilmant

Farming systems based on products of roughage feeders are a vital part of the EU agricultural pro... more Farming systems based on products of roughage feeders are a vital part of the EU agricultural production. Up to the CAP reform in 2003 the EU promoted these systems via a wide variety of measures. This paper highlights the different impacts European, national and regional support measures have on the utilization of pastoral resources across the EU-25. Based on an expert survey and a literature review the paper summarizes the expected developments of pastoral farming systems across the EU.

Fourrages, 2007

Une enquete realisee en region wallonne aupres d’exploitants agricoles et portant sur leurs prati... more Une enquete realisee en region wallonne aupres d’exploitants agricoles et portant sur leurs pratiques de gestion et d’entretien des prairies montre l’importance de la pression exercee par Rumex obtusifolius L. qui represente un probleme pour 40% d’entre eux ; la complementation et l’epandage de lisier et de fumier de bovins sont correles avec la difficulte exprimee par les eleveurs. Une revue complete des traitements chimiques est effectuee selon la nature du couvert et l’âge de la prairie. Diverses methodes de lutte alternatives sont egalement presentees (faux semis, type de travail du sol, gestion du pâturage...) ainsi que leur efficacite sur les jeunes plantules et sur les repousses de plantes de rumex.

Miscanthus and switchgrass are promising perennial lignocellulosic crops in the field of bioenerg... more Miscanthus and switchgrass are promising perennial lignocellulosic crops in the field of bioenergy and biorefinery owing to their high fiber content, high biomass yield, high dry matter content and low input needs for their growth. The optimal valorization of their cellulosic and hemicellulosic components in lignocellulose-based biorefineries requires a good knowledge of their available biomass contents, and of their molecular composition. The main chemical components (cellulose, hemicelluloses, lignin, total soluble sugars, starch, proteins and mineral compounds) and more specifically the monosaccharidic composition of cellulose and hemicelluloses (cellulosic glucan, xylan, arabinan, mannan, galactan and hemicellulosic glucan) were analyzed in two perennial lignocellulosic crops: miscanthus giganteus (Miscanthus x giganteus J.M.Greef & Deuter ex Hodk. & Renvoize ; cultivar: Bical) and switchgrass (Panicum virgatum L. ; cultivar: Cave-in-rock). Both crops were grown at Tinlot (Belgi...

Biotechnologie, Agronomie, Société et Environnement, 2013

Le Programme de Gestion Durable de l'Azote en agriculture (PGDA), transposition de la Directi... more Le Programme de Gestion Durable de l'Azote en agriculture (PGDA), transposition de la Directive Nitrates (91/676/CEE), doit prochainement faire l'objet d'une revision. En vue de contribuer a celle-ci, des scientifiques wallons (Universite catholique de Louvain - UCL, Centre wallon de Recherches agronomiques CRA-W, Universite de Liege - ULg, Gembloux Agro-Bio Tech) et francais (Institut National de Recherche Agronomique - INRA) se sont reunis du 28 mai au 1er juin 2012 a l'occasion du deuxieme Atelier "Nitrate – Eau". A la lumiere de resultats d'experimentations scientifiques presentes lors de cet Atelier, des modifications au programme actuel sont recommandees. Celles-ci portent sur la gestion de la fertilisation (organique et minerale) pour les cultures et prairies, l'interculture, le controle du reliquat azote au debut de la periode de lixiviation du nitrate, la gestion du retournement des prairies permanentes et la norme de production d'azote...

Biofuels can offer an alternative to fossil fuels in the context of climate change and fossil res... more Biofuels can offer an alternative to fossil fuels in the context of climate change and fossil reserves depletion. Plant biomass consists mainly of structural polysaccharides (cell wall), but contains also reserve polysaccharides (starch, polyfructans) and soluble carbohydrates, that can be converted by micro-organisms. So, agricultural residues and herbaceous biomasses offer the opportunity to be converted to second-generation bio-ethanol. Suitable conversion process requires a good knowledge of the available carbohydrates. We adapted and optimised a method to monitor the principal mono- and di-saccharides found in biomass (fructose, glucose and sucrose) simultaneously with soluble oligosaccharides (oligofructans, oligoglucans, dextrins). The method is also suitable to monitor the carbohydrate that can be released by the hydolysis of structural polysaccharides or starch (xylose, arabinose, mannose, galactose, cellobiose, maltose). Soluble carbohydrates are first extracted from the biomass with hot water (70°C/20min.). This extraction proved to be more effective than the extraction with ethanol or methanol. After filtration at room temperature, samples are eluted by HPLC at a flow rate of 1 mL/min through a Prevail Carbohydrate ES column (5µ, 250 x 4.6mm) with a acetonitrile (A): water-acetonitrile (95:5, v/v) (B) gradient. The ratios of solvent flows were as follows: 80_A/20_B to 50_A/50_B in 15 min., to 0_A/100_B in 10 min., plateau for 5 min., then back to 80_A/20_B in 5 minutes. An evaporative light scattering detector (ELSD) was used. The response of the ELSD follows the relationship [Area] = a.[concentration]b . On the basis of many analyses, we were able to set b= 1.5 for fructose, glucose and sucrose and oligofructans. This allowed to reproducibly calibrate the a value for each analysed carbohydrates. Calibration of the a-value for oligofructans was tentatively performed after determining the total oligofructan concentration in the analysed samples. The latter concentration was obtained by subtracting the identified carbohydrates from the total soluble carbohydrate determined by the Luff-Schorrl method. Results of this calibration will be presented in the poster.

-Miscanthus and switchgrass are promising perennial lignocellulosic crops in the field of bioener... more -Miscanthus and switchgrass are promising perennial lignocellulosic crops in the field of bioenergy and biorefinery owing to their high fiber content, high biomass yield, high dry matter content and low input needs for their growth. The optimal valorization of their cellulosic and hemicellulosic components in lignocellulose-based biorefineries requires a good knowledge of their available biomass contents, and of their molecular composition. The main chemical components (cellulose, hemicelluloses, lignin, total soluble sugars, starch, proteins and mineral compounds) and more specifically the monosaccharidic composition of cellulose and hemicelluloses (cellulosic glucan, xylan, arabinan, mannan, galactan and hemicellulosic glucan) were analyzed in two perennial lignocellulosic crops: miscanthus giganteus (Miscanthus x giganteus J.M.Greef & Deuter ex Hodk. & Renvoize ; cultivar: Bical) and switchgrass (Panicum virgatum L. ; cultivar: Cave-in-rock). Both crops were fertilized with 0, 80 or 160 kgN ha-1 and harvested in October or March. Cellulose and hemicelluloses contents range respectively from 32.0 to 47.6 and from 24.0 to 34.3 g (100gDM)-1 while lignin, total soluble sugars, proteins and mineral compounds contents range from 6.1 to 12.8, 0 to 2.2, 0.6-5.6 and 0.8 to 6.2 g (100gDM)-1, respectively The main hemicellulosic components and their corresponding range expressed in g (100gDM)-1 were by order of decreasing importance : xylan (18.0 to 27.8), arabinan (1.90 to 3.88), hemicellulosic glucan (0.93 to 2.74), galactan (0.26 to 1.50) and mannan (0 to 0.92). Plant species and harvest period has the most significant influence on main chemical components and structural polysaccharide composition, while the influence of nitrogen fertilization is only rarely significant except on the protein content

Journal of environmental management, Jan 15, 2016

Producing biogas via anaerobic digestion is a promising technology for meeting European and regio... more Producing biogas via anaerobic digestion is a promising technology for meeting European and regional goals on energy production from renewable sources. It offers interesting opportunities for the agricultural sector, allowing waste and by-products to be converted into bioenergy and bio-based materials. A consequential life cycle assessment (cLCA) was conducted to examine the consequences of the installation of a farm-scale biogas plant, taking account of assumptions about processes displaced by biogas plant co-products (power, heat and digestate) and the uses of the biogas plant feedstock prior to plant installation. Inventory data were collected on an existing farm-scale biogas plant. The plant inputs are maize cultivated for energy, solid cattle manure and various by-products from surrounding agro-food industries. Based on hypotheses about displaced electricity production (oil or gas) and the initial uses of the plant feedstock (animal feed, compost or incineration), six scenarios...

Agriculture and Agricultural Science Procedia, 2015

Peer-review under responsibility of the Centre wallon de Recherches agronomiques (CRA-W)

Biotechnologie Agronomie Societe Et Environnement, 2010

Détermination de la cellulose, des hémicelluloses, de la lignine et des cendres dans diverses cul... more Détermination de la cellulose, des hémicelluloses, de la lignine et des cendres dans diverses cultures lignocellulosiques dédiées à la production de bioéthanol de deuxième génération"

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Biotechnology, Agronomy, Society and Environment

The efficiency of the energy recovery potential of lignocellulosic crops as solid biofuel depends... more The efficiency of the energy recovery potential of lignocellulosic crops as solid biofuel depends on various characteristics. One of the main characteristics in this field is the higher heating value. It is defined as the amount of heat emitted by the combustion of a fuel, including the heat coming from the condensation of the water vapor. Its value depends on the content of main components of the lignocellulosic crops. Two models predicting the higher heating value have been built based on the content of main components of the following lignocellulosic crops: miscanthus (Miscanthus x giganteus J.M.Greef & Deuter ex Hodk. & Renvoize), switchgrass (Panicum virgatum L.), Jerusalem artichoke (aerial part) (Helianthus tuberosus L.), fiber sorghum (Sorghum bicolor (L.) Moench), fiber corn (Zea mays L.) and hemp (Cannabis sativa L.) [trials made at Libramont (Belgium) in 2007 and 2008]. The first model predicts the higher heating value of the lignocellulosic crops based on sum of the prod...

Biofuels can offer an alternative to fossil fuels in the context climate change and fossil reserv... more Biofuels can offer an alternative to fossil fuels in the context climate change and fossil reserves depletion. Plant biomass consists mainly of structural (cell wall) polysaccharides, but contains also reserve polysaccharides (starch, polyfructans) and soluble carbohydrates, that can be converted by micro-organisms. So agricultural residues and herbaceous biomasses offer the opportunity to be converted to second-generation bio-ethanol. In this study, we examined the composition of Jerusalem artichoke stalks and leaves, as well as tubers, to check their suitability for a dedicated ethanol conversion process. We investigated the influence of fertilization, crop density and harvest period for several years. All harvested samples were dried at 60°C and stored until analysis. Soluble carbohydrates were extracted from the dried biomass samples by water at 70°C. Total soluble sugars were determined by Luff-Schoorl method. Individual soluble carbohydrates Fructose, Glucose, Sucrose (FGS) and oligofructans to a degree of polymerisation DP11 were analysed by HPLC-ELSD with Carbohydrate Prevail column. Total polyfructans were determined by subtracting FGS from total soluble carbohydrates. Structural polysaccharides cellulose and hemicelluloses were determined after acid hydrolysis of isolated fractions and HPLC-CAD. For two harvest years (2009-2010), the aerial part of Jerusalem artichoke show a maximum content of 40 to 85 gFGS/kgDM (8 to 30 gFGS/kgFM) in late summer to mid fall. There is a decrease in the content polyfructans, possibly due to the translocation of polyfructans stored in the aerial parts to the tubers. The tubers reach contents of 700g/kgDM (90 g/kgFM) polyfructans. The direct fermentation of soluble carbohydrate availables in the aerial part can lead to ethanol concentration of maximum 30 to 50 gEtOH/lliquor. During the plant development, the amount of fibers (cellulose, hemicelluloses and lignin) increases and the amounts of protein and mineral compound decrease. In the hemicelluloses, the proportion of xylan increases while glucan, mannan and arabinan decrease.

Weed Research, 2011

Determining seed quality parameters is an integral part of cultivar improvement and germplasm scr... more Determining seed quality parameters is an integral part of cultivar improvement and germplasm screening. However, quality tests are often time consuming, seed destructive, and can require large seed samples. This study describes the development of near-infrared spectroscopy (NIRS) calibrations to measure moisture, oil, fatty acid profile, nitrogen, glucosinolate, and chlorophyll content in six species from the Brassicaceae family. Rapeseed and similar oilseeds are potential feedstocks for producing hydrotreated renewable jet fuel. Screening samples with NIRS would allow cultivars with desirable characteristics to be quickly identified. A total of 367 samples of six species (Brassica napus, Brassica carinata, Brassica juncea, Brassica rapa, Sinapis alba, and Camelina sativa) were scanned with NIRS. Global calibrations for all six species were developed using modified partial least squares regression with reference values obtained through wet chemistry techniques. Comparing predicted values to reference data, the coefficients of determination (r 2) and ratios of performance to deviation (RPD) varied, with some calibrations performing better than others. The calibration equations for seed oil content (r 2 = 0.98, RPD = 7.3) and nitrogen (r 2 = 0.98, RPD = 5.3) performed very well while the equations for seed moisture (r 2 = 0.93, RPD = 3.8) and total glucosinolate content (r 2 = 0.92, RPD = 2.3) were more qualitative. Large variation was observed for chlorophyll content (0-390 mg/kg) so two calibration equations were developed, one for the higher and one for the lower range of values. When combined, these calibrations also showed very good performance (r 2 = 0.99, RPD = 14). The performance of the calibrations for the fatty acids was more varied, with some performing very well, such as the calibration for C 18:3 (r 2 = 0.99, RPD = 9.9), and others, such as C 22:0 (r 2 = 0.69, RPD = 1.9), showing poor correlation.

Oecologia, 2008

Generalists and specialists use different cues to find their habitat and essential resources. Whi... more Generalists and specialists use different cues to find their habitat and essential resources. While generalists have the advantage of exploiting a wider range of resources, they are predicted to be less efficient in using one particular resource compared to specialists. The level of specialization of parasitoids can be either at the habitat or at the host level; strategies used by either type are expected to differ. We examined interactions between three aphid parasitoid species that are a habitat specialist Aphidius rhopalosiphi, a habitat generalist Aphidius ervi, and a host generalist Praon volucre on three cereal aphids, Sitobion avenae, Metopolophium dirhodum and Rhopalosiphum padi. We compared total parasitism rate across behavioral and physiological variation in a non-choice test. Next, we addressed total parasitism in two phases to examine: (1) the response of parasitoids to different hosts through the behavioral sequence from antennation through oviposition, and (2) the physiological suitability of different hosts for oviposition and larval development. Parasitization typically involved the following behavioral steps: (1) antennal contact, (2) abdominal bending, and (3) ovipositor insertion (acceptance). A. rhopalosiphi had the same number of antennal contacts with the three aphids but showed fewer instances of abdominal bending towards R. padi. Pre-contact host preference was found for A. ervi but it did not correspond to the level of acceptance. The number of antennal contacts by P. volucre corresponded to the parasitization level of the aphid species but more mummies were produced on M. dirhodum than on R. padi. These results suggest that parasitoid species that are habitat specialists react similarly to the different host species present in the same habitat, whereas generalist species exhibit clear preferences during host selection. Preferences were, however, not always related to host suitability.