Nürtingen, FH, Diplomarb., 2005. / Betreuer: Jan Sneyd.

This thesis investigates the cost of producing miscanthus in Ontario as an energy crop for the Ontario greenhouse industry. To determine the breakeven price of growing miscanthus an enterprise budget was developed and applied to three different life cycle scenarios to determine the effect of stand life on the breakeven price. The base case breakeven price of producing miscanthus ranged from $74.74/t to $80.22/t. Sensitivity analysis was conducted to assess the effect of assumptions (stand yield, rhizome cost, harvest method and discount rate) on the breakeven price. Price of energy from miscanthus ranged from $2.87/GJ to $8.63/GJ with an average price of $5.51/GJ. The Ontario greenhouse industry`s willingness to pay for bioenergy from miscanthus is based on the prices of fuels currently in use. Ontario farmer‘s willingness to produce miscanthus is based on its profitability compared to other crops and the time it takes to pay off the initial investment.

Winter losses challenge the adoption of Miscanthus as a biomass crop in northern regions. This study was conducted to investigate the winter survival and yield potential of Miscanthus in Ontario. Twenty Miscanthus entries representing diploid M. sacchariflorus x M. sinensis hybrids, triploid M. x giganteus hybrids and diploid M. sinensis were established in 2008 at three locations in Ontario. First year winter survival ranged from 8-100% in Leamington, 0-100% in Elora and 0-89% in Kemptville. No difference in winter survival potential of the three species groups was observed in Leamington or Elora, but a diploid hybrid was significantly greater than all others in Kemptville. Establishment year culm height and basal circumference, and second year spring regrowth timing and biomass yield were associated with winter survival. Overall, winter severity increased from Leamington to Kemptville. The diploid hybrids were most winter hardy, followed by M. x giganteus types, followed by M. sinensis, though all had equivalent survival potential in Leamington and Elora. / Mendel Biotechnology

Face à l’épuisement du pétrole, l’Europe s’oriente vers la production de bioéthanol 2ème génération à partir de biomasse végétale. L’espèce Miscanthus x giganteus est prometteuse de par son fort rendement et ses faibles impacts environnementaux. Cependant, sa diversité génétique est faible et sa composition de biomasse pas forcément optimale pour produire du bioéthanol 2ème génération. Cette thèse explore donc différentes espèces de Miscanthus pour définir des idéotypes et des pistes en sélection afin d’améliorer le miscanthus pour ce débouché. Trois approches ont été menées : une étude bibliographique, une étude expérimentale au champ et des tests en pilote industriel. L’étude bibliographique montre une forte variabilité environnementale et génotypique pour les caractères associés à la production et à la composition de biomasse. L’analyse des données expérimentales révèle des caractères antagonistes : une forte production de biomasse est associée à de fortes teneurs en cellulose et lignines, mais à de faibles teneurs en hémicelluloses, solubles et cendres. De fortes teneurs en lignines contribuent également à réduire l’efficacité de la transformation de la biomasse en bioéthanol 2ème génération. Enfin, des outils de phénotypage ont été définis : la hauteur de végétation et le volume aérien de la plante permettent de prédire la production de biomasse des stades adultes à partir des stades jeunes. La spectroscopie proche infra-rouge permet aussi de prédire la composition de la biomasse. Ce travail contribue à la définition d’idéotypes de miscanthus pour une valorisation en bioéthanol 2ème génération en proposant des critères, des outils et des perspectives en sélection. / In front of the depletion of oil resources, Europe is moving towards the 2nd-generation bioethanol production from plant biomass. The Miscanthus x giganteus species is promising due to its high biomass production and its low environmental impacts. However, the genetic diversity of this species is low and its biomass composition is not necessary optimal for the 2nd-generation bioethanol production. This thesis therefore aims to explore several Miscanthus species in order to define ideotypes and to propose guidelines to target miscanthus breeding for 2nd-generation bioethanol production. It was based on three approaches: a literature review, an experimental field study, and tests in pilot at industrial scale. The review of literature showed a strong environmental and genotypic variability for traits related to biomass production and composition. Moreover, the experimental data analysis showed antagonisms between the traits of interest: a high biomass production was associated with high cellulose and lignin contents, but low hemicellulose, soluble, and ash contents. High biomass lignin content also reduced the efficiency of the biomass conversion to 2nd-generation bioethanol. Lastly, breeding tools were defined: canopy height and aboveground plant volume enabled to predict the biomass production of mature crops from early stages. The near infrared spectroscopy also provided accurate prediction of the miscanthus biomass composition. This contributes to the definition of miscanthus ideotypes for 2nd-generation bioethanol production by providing selection criteria, breeding tools, and breeding prospects.

La nécessité de maîtriser les émissions de GES (CO2, NO), la raréfaction et la hausse du prix des carburants fossiles conduisent à envisager la substitution du C fossile par du C « renouvelable » c'est-à-dire issu de la biomasse végétale. Cette stratégie de substitution doit être durable. En particulier l’exportation massive de biomasse végétale privant le sol des restitutions de résidus végétaux (par exemple pour les pailles de céréales) ; et l’implantation de nouvelles cultures notamment des plantes pérennes (par exemple le miscanthus) interrogent sur les pratiques culturales, notamment les dates et les fréquences d’exportation, indispensables pour le maintien de la fertilité des sols et une bonne gestion des cycles biogéochimiques. Miscanthus×giganteus, plante pérenne à rhizome est une des plantes « candidate » pour la production des carburants de seconde génération, en raison de son fort potentiel de production de biomasse, y compris en conditions tempérées. Dans ce contexte l’objectif principal de ce travail de thèse était de quantifier et caractériser les litières végétales recyclées vers le sol sous culture de Miscanthus, plus précisément les feuilles sénescentes,les racines et rhizomes de Miscanthus et d’étudier la minéralisation du C et N au cours de leur décomposition. Ce travail s’est appuyé sur un essai au champ de Miscanthus×giganteus, âgé de 3 à 5ans, implanté depuis 2006 à Estrées-Mons (Nord de la France), et croisant 2 dates de récolte (une récolte précoce avant l’hiver et une récolte tardive après l’hiver en fin de cycle annuel) et 2 niveaux de fertilisation azotée (0 kg N ha-1 et 120 kg N ha-1). Tout d’abord sur les litières prélevées sur cet essai,nous avons quantifié, caractérisé biochimiquement et étudié la minéralisation en conditions contrôlées des feuilles sénescentes, rhizomes et racines. Ensuite la dynamique de chute des feuilles au cours de la sénescence, leur accumulation sous forme de mulch à la surface du sol et les cinétiques de décomposition ont été étudiées au champ pendant deux années. Enfin nous avons étudié les effets de la disponibilité de l’azote sur la dynamique du C et N, la dynamique microbienne et des fonctions enzymatiques au cours de la décomposition de ces feuilles, en conditions contrôlées. La disponibilité en N a été modulée soit en apportant de l’azote minéral, soit en apportant des quantités croissantes de feuilles pour une quantité d’azote donnée. Nous montrons que le C stocké dans les trois " compartiments " recyclés potentiellement au sol est considérable : feuilles sénescentes (1à 3 t C ha-1 par an), racines (1 à 2 t C ha-1) et rhizomes (7 à 10 t Cha-1). Les rhizomes, ont une teneur en soluble-NDS de 25 à 35% et une teneur en lignine de 11 à 15% selon les prélèvements précoces ou tardifs, et une teneur en N élevée (0.7-1.5%). On observe en 263jours à 15 °C, une minéralisation des rhizomes représentant 61±8% du C apporté, supérieure à celle observée pour les racines (36±8%) et les feuilles sénescentes (53±4%). Nous montrons l’importance des feuilles sénescentes de Miscanthus dans le recyclage de matière organique vers le sol : le scénario de récolte précoce prive le sol d’un recyclage annuel de 1-3 t C ha-1 ; d’autre part qualitativement, la faible dégradabilité observée au laboratoire pour les feuilles est confirmée au champ, ce qui conduit à la formation d’un mulch important en épaisseur (2 à 4cm) et en quantité (équivalent à 6 à 7 t C ha-1).Enfin, une forte disponibilité en N accélère la vitesse de minéralisation du C à court terme. Ceci se traduit aussi par une augmentation du C microbien et de l’ergostérol, marqueur fongique, ainsi que des activités enzymatiques liées à la dégradation du C et N (xylanase, leucine aminopeptidase). En revanche, cette disponibilité forte en N réprime l’activité laccase. Nous montrons aussi que diminuer la disponibilité relative en N pour les décomposeurs, par ajout de quantités croissantes de feuilles dans le sol conduit à ralentir la croissance microbienne et fongique. Cette situation favorise très tôt l’installation de la biomasse fongique (augmentation du rapport ergostérol/C microbien) et son activité(laccase).Ce travail montre que la culture de Miscanthus permet potentiellement une forte accumulation de C organique, ce qui est favorable au maintien de la fertilité des sols à long terme. Il est maintenant essentiel de pouvoir prédire le devenir du C des parties souterraines de Miscanthus, dans la perspective de changement dans l’utilisation des terres. / To control emissions of greenhouse gases (CO2, NO), fossil fuels scarcity and their rising prices lead to consider the substitution of fossil C by the "renewable" C from plant biomass. This alternative strategy must be sustainable. In particular the massive export of plant biomass depriving soil of plant residues (eg cereal straws), and the growing of new crops specially perennial crops (eg miscanthus)questioned the cultural practices (dates and frequency of biomass export) essential for maintaining soil fertility and good management of biogeochemical cycles. Miscanthus × giganteus, a rhizomatous perennial grass is dedicated to second-generation fuels production, because of its high potential biomass production.In this context the main objective of this work was to quantify and characterize Miscanthus plant litter recycled to soil, more precisely senescent leaves, roots and rhizomes of Miscanthus, and to study the C and N mineralization during decomposition of these litters. This work was performed on 3 to 5 years old Miscanthus stands established since 2006 in Northern France (Estrées Mons), either fertilized with120 kg N ha−1 year−1 or unfertilized. The sampling of litters was performed in autumn (maximal biomass production) and winter (maturity). Firstly we quantified and biochemically characterized Miscanthus senescent leaves, rhizomes and roots. Then we studied their decomposition in soil under controlled conditions (15°C, -80 kPa) during 263 days. We also investigated in the field for two years the dynamics of leaf fall during senescence, their accumulation in the form of mulch on soil surface and the kinetics of decomposition. Finally we investigated under controlled conditions the effects of nitrogen availability on C and N dynamics, microbial dynamics and enzymatic functions during the decomposition of these leaves. N availability was modulated either by adding inorganic nitrogen, or by adding increasing amounts of leaves for a given amount of nitrogen in soil.Our results showed that the C stored in the three "compartments" recycled to soil is potentially considerable: senescent leaves (1 to 3 t C ha-1 year), roots (1 to 2 t C ha-1) and rhizomes (7 to 10 t C ha-1). The rhizomes had a high NDS soluble content (25 to 35%), a high N content (0.7 to 1.5%) and low lignin content (11 to 15%) depending on early or late harvest dates. we observed after 263 days of decomposition at 15°C a higher carbon mineralization from rhizomes 61 ± 8%, than that observed for roots (36 ± 8%) and senescent leaves (53 ± 4%). We also showed the importance of senescent leavesin the recycling of organic matter in the soil: the early harvest scenario deprives the soil of an annual leaves of 1-3 t C ha-1. Qualitatively, the low degradability observed in the laboratory experiment for the leaves was confirmed in the field. This leads to the formation of an important thick layer of mulch(2 to 4cm) and quantitatively (6-7 t C ha-1). Finally, a high N availability increases the C mineralization rate in the short term which was reflected by an increase in microbial C, fungal ergosterol, and enzymatic activities related to C and N degradation of (xylanase, leucine aminopeptidase). However, this high N availability suppresses laccase activity. We also showed that decreasing N availability for decomposers by adding increasing amounts of leaves in the soil leads toslow microbial and fungal growth. However, this situation favors an early installation of fungal biomass (increased ergosterol / microbial C ratio) and their activity (laccase).This work showed that the cultivation of Miscanthus potentially allows a large accumulation of organic C which is favorable to the maintenance of soil fertility in the long term. It is now essential to predict the fate of underground C parts of Miscanthus, in the perspective of change in land use, i.e.when the Miscanthus stands is to be replaced in field by another crop.

Herbicide treatments were tested on mature stands of Miscanthus in 2013 and 2014 in Winston and Oktibbeha counties Mississippi. Twenty-one different herbicide treatments and two application timings, summer and fall, were evaluated. Glyphosate at 4,500 g ae ha-1 applied in the summer provided the best Miscanthus control at each location. Control with fall applications of glyphosate varied between locations. Two greenhouse studies were conducted in 2014 and 2015 at Mississippi State, MS to evaluate the effects of mowing on seedling Miscanthus, as well as the time period between seed germination and rhizome initiation. Rhizomes were visible on seedling plants 15 or 13 weeks after germination in 2014 and 2015, respectively. Removal of the Miscanthus terminal reduced the number of rhizomes produced compared to plants with intact terminals. However, terminal removal increased the number of shoots produced compared to plants with intact terminal.

This thesis focused on the fate of nitrogen and trace metals species from combustion and gasification of biomass. The effect of process parameters on the release of these species during pilot-scale combustion and gasification of biomass was investigated and the information used to identify methods for the reduction of these species. The investigation focused on Miscanthus and Dried distillers’ grains with solubles (DDGS). The pilot-scale test rigs used were a fluidised-bed combustor and a fixed-bed downdraft gasifier. The two fuels were analysed by means of proximate, ultimate and ash analysis. The process parameters monitored were temperatures, gas flow, gas composition and ash composition and the process parameters studied are bed temperature and equivalence ratio. The different nitrogen content of the two fuels plays an important role in the emission. Both bed temperature and air to fuel ratio have demonstrated to have an important influence in the release of nitrogen oxides in combustion and ammonia in gasification, therefore they can be used to mitigate the emission of these species in the flue gas. Both processes are affected by the high alkali metals content of the fuels for the tendency to form low melting composites. Differences have been highlighted in the metal distribution between combustion and gasification. The different nitrogen and ash content of the two fuels make the results of the present thesis applicable to predict the behaviour of other biomass fuels according to the fuel characteristics. The scale of the tests performed allowed highlighting which methods can be used to control the emission of nitrogen and trace metal species. Moreover, the investigation highlighted major drawbacks in the use of biomass fuels in both fluidised bed and fixed bed technology due to ash properties.

Bioenergy crops have attracted increasing interest over the last two decades as their potential to 1) improve national energy security, 2) substitute finite fuels with renewable alternatives, 3) reduce carbon (C) intensity of energy generation, and 4) remove CO2 from the atmosphere and sequester it in soils. In light of climate change predominantly caused by rising atmospheric greenhouse gas concentrations, the potential importance and value of bioenergy cannot be underestimated. This research used data from a single site in Lincolnshire, UK, in combination with new experimental techniques to examine the C dynamics associated with Miscantus x giganteus. The net C budgets were examined using long term eddy-covariance data alongside measurements of C stocks within the soil and litter layer. Results indicated that using a cradle-to-grave lifecycle analysis, and based on the productivity of this site, Miscanthus as an energy feedstock was marginally better than coal but more C intensive than natural gas. Further, soil C stocks were not seen to change significantly over the first 7 years of cropping. Consequently, a combination of soil fractionation and in combination with natural abundance stable C isotope techniques allowed rates of soil C gain or loss to be estimated over time. Soil C was observed to accumulate at fast rates in stable fractions, those that relate to model pools with turnover times well beyond the lifetime of a Miscanthus plantation – a result not predicted by model simulations performed with the systems models ECOSSE and DayCent. A review of six models parameterised for Miscanthus showed a number of factors that contribute to model uncertainty. The results from this thesis are a crucial first step to helping to define model parameters and improve model performance, and therefore to accurately predict the impacts of Miscanthus on C sequestration in a given location for given environmental conditions.

Nitrogen fertilization has the potential to significantly affect yield, nutrient concentration and removal and overall stand longevity of C4 grasses grown for bioenergy production. While most studies report that these grasses need little to no fertilizer inputs to maximize yield, no specific recommendations have been given for fertilizer requirements across a wide range of C4 perennial grass species, cultivars, harvest timings and N application rates. Two field trials were established in the summer of 2008 in Ridgetown and Elora, Ontario to compare 4 Miscanthus (M. sinensis and M. sacchariflorus crosses; Nagara-116 and Amuri-114, and Miscanthus x giganteus; M1 Select and Polish), 2 switchgrass (Panicum virgatum L.; Cave-in-rock and Shelter) and 2 big bluestem varieties (Andropogon gerardii Vitman; Prairie view and Southlow), 4 nitrogen fertilization rates (0, 40, 80, and 160 kg N ha-1) and 2 harvest timings (fall vs. spring harvest). Plots were harvested in the fall of 2009 and spring and fall of 2010. Yield response to N fertilization varied by location, species and year. In general, increasing N fertilization rates generated an increased yield response in all tested species. Different rates of N fertilization resulted in variable responses to N, P and K tissue concentrations and removal in switchgrass and Miscanthus. Tissue N concentrations and removal both increased with added N fertilization at both locations. In most cases N removal was the highest at the highest N application rate. Nitrogen concentrations were highest in the leaves and seed heads across species, N rates and locations. P and K concentrations and removal with increasing N fertilization in the whole plant and in individual plant parts did not follow clear trends in either Miscanthus or switchgrass in both locations. Delaying harvest to spring reduced yield at both locations by 35-42% and 62-65% for Miscanthus and switchgrass, respectively. Yield losses by delaying harvesting to the spring were increased with higher rates of N fertilization. Delaying harvesting decreased N, P and K concentration and removal in most grasses and locations.

Zugl.: Innsbruck, Univ., Diss., 2007 / Hergestellt on demand