Browsing by Subject "Miscanthus"

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    Agrarökonomische Analyse von Verfahren zur Erzeugung lignozellulosehaltiger Biomasse und deren Akzeptanz in der Landwirtschaft Baden-Württembergs
    (2018) Gillich, Caroline Sophie-Theresia; Lippert, Christian
    In a future bio-based economy, agricultural production of renewable raw materials for the production of plant biomass is supposed to play a central role. This also includes the perennial crops short rotation coppice (SRC) and miscanthus. A material utilization, particularly of the produced lignocellulose, in chemical industry can contribute to a bio-based economic activity. However, the cultivation of SRC and miscanthus is not yet widespread. For a variety of reasons, such as lack of knowledge or low profitability, farmers have not strongly implemented these crops so far. To find out, which factors do have an impact on the cultivation of SRC and miscanthus, farmer workshops with surveys were conducted in selected regions of Baden-Wuerttemberg. Additionally, by means of a choice experiment, the preferences of the farmers for the cultivation of SRC and miscanthus were elicited. As the introduction of new production methods is often linked to increased risks, in addition the risk attitude of the farmers was determined by means of a “Holt and Laury” lottery. The surveys took place in the Vergleichsgebietsgruppen (VGG) „Unterland / Gaeue“, „Rhine / Lake Constance“ and „Bauland / Hohenlohe“ in Baden-Wuerttemberg. For all VGG site specific profitability and risk analyses were performed. The mentioned VGG were identified as most suitable for SRC and miscanthus. In total, 117 farmers participated in nine organized workshops. In the surveyed sample more farmers are cultivating SRC than in the entire farmer population. For the analysis of the choice experiment Random Parameter Logit Models were used. The following results are to be interpreted under ceteris paribus conditions. Generally, the part-worth utility of the cultivation of SRC and miscanthus is negative. Additionally to the opportunity costs of land, the expected average compensation payments amount to € 460 and € 400 per hectare and year for SRC and miscanthus. However, in this context farmers do not significantly distinguish between the two perennial crops. As expected an increasing profitability of these production activities increases the utility, whereas an increasing variability of contribution margins and increasing investment costs reduce the utility. It should be noted that a guaranteed purchase contract for the harvested crop over the whole cultivation period increases the utility of the permanent crops at a significant level. Through this the negative part-worth utility of SRC or miscanthus could be compensated almost completely. If colleagues in the near surrounding already cultivate these crops, this also increases the utility. Among the respondents a significant preference heterogeneity exists for both production activities and all attributes considered in the choice experiment. Further model estimations with interaction terms to explain part of the heterogeneity show that, among other things, an increasing farm size has a negative impact on the probability of cultivating SRC. An increasing age of the farm manager also reduces the utility of the cultivation of SRC and miscanthus. An increasing work experience has a positive effect on the probability of choosing SRC. Moreover, an increase of the initial investment cost reduces the utility of the participants the more, the more risk averse they are. In this context, the implicitly assumed interest rates, deduced from the model and assuming a farmer with average risk attitude, are in a realistic range between 2.3 % and 4.1 %. Based on the estimated part-worth utility distribution parameters of the model without interaction terms, finally supply functions were derived by means of Monte Carlo simulations, to illustrate cultivation potentials of SRC and miscanthus at various wood chip prices and for different scenarios. The potentials of SRC and miscanthus estimated this way are more realistic than former GIS-based potentials as not only location factors but also empirically found preferences of the farmers and opportunity costs of farmland were taken into account. Under the assumptions made, the maximum expectable potential of SRC and miscanthus on arable land in the surveyed region amounts in each case to 30,000 hectares. It should be noticed, that this cultivation potential is relatively low. The results of the choice experiment show that - as long as this is considered to be justified from an economic point of view - either a direct subsidy by the government, the cultivation in clusters or purchase guarantees for the farmers by the processing industry can strongly promote the cultivation of perennial lignocellulose containing crops.
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    Approaches to improve the implementation and expansion of Miscanthus production
    (2016) Xue, Shuai; Lewandowski, Iris
    Several species within the miscanthus genus (Miscanthus spp.) are characterized by high biomass yields and low production input requirements. This raised increasing interests in their applications for bioenergy. However, to date, only small areas of Miscanthus × giganteus (approximately 40,000 ha) are commercially grown and used for generating electricity and heat in Europe, where miscanthus has been developed as bioenergy crop for more than decade. Reviewing state-of-the-art revealed four main factors limiting the implementation of miscanthus production. These are inefficient and expensive propagation techniques, land use dilemma (i.e. lack of land available for growing miscanthus), lack of varieties/genotypes adapted to various and especially to stressful environmental conditions and lack of efficient agronomic practices for miscanthus establishment. Against these limiting factors, this thesis aims to (1) evaluate the different propagation systems with regard to technologies and costs, and improve the preferred rhizome propagation techniques; (2) address the land use dilemma through exploring marginal land (i.e. non-arable land with ability to grow plants with tolerance to environmental stresses) for miscathus production; (3) and screen optimal genotypes and effective practices for establishing and managing miscanthus on marginal land in a case study on grassland. To achieve the first objective, a review, our own field trials and farmer surveys were performed. Direct seed sowing was found to be the cheapest propagation method (1,508.5 € ha-1 overall establishment costs) and micro-propagation the most expensive (6,320.8 € ha-1). Direct rhizome planting is the farmers’ most preferred and most applied establishment method and has moderate establishment cost of 1,904-3,375.7 € ha-1. However, it goes along with the lowest propagation efficiency (1:10) and consequently restricts the availability of propagation material for large-scale plantations. However, the multiplication ratio can be increased by reducing the rhizome size. Field trial results showed that 6-cm length is close to the minimum size of rhizome that can germinate after directly planting into field. Compared to the traditionally used macro-rhizome, the multiplication ratio of the improved rhizome propagation (using 6-cm rhizomes) is tripled. In addition, the multiplication ratio can also be increased by transplanting rhizome- or stem-derived plantlets. However, due to higher labour and energy inputs required for the pre-growing of plantlets, their establishment cost reduction potential is limited, with estimated costs of 4,240.8-4,400.8 € ha-1. Direct seed sowing as the cheapest method is presently only possible for Miscanthus sinensis and not yet practical under German conditions. In addition, the seed-setting rate of M. sinensis is very low (0.0-28.7%) under the climatic conditions of south-west Germany, making commercial seeds production difficult. For all the propagation methods considered, more research efforts are still required to reduce the material production costs and simultaneously increase the multiplication ratio. For the second objective, the production potential of miscanthus on marginal land in China was assessed. Because China has limited agricultural land resources and its non-food bioenergy policy (it is only allowed to grow energy crops on marginal land) is adamant, there is a desideration for exploiting its marginal land potential. In this study, Geographic Information System (GIS) techniques, model simulation were adopted to identify the productive marginal areas for miscanthus and to estimate their biomass and bioenergy production potentials. The results show that in China there are large marginal land areas of 17,163.54 × 104 ha available for growing miscanthus. However, due to limitation by low winter temperatures and low precipitation levels in some areas, the total marginal area suitable for growing miscanthus is only 769.37 × 104 ha. The Monteith radiation yield model was used to determine the potential miscanthus yield in Chinese climatic conditions. The simulation gave the actual harvestable yield levels on arable land of 18.1-44.2 odt ha-1 yr-1. Taking the environmental stresses of marginal conditions into account an achievable miscanthus yield potential on marginal land of 2.1-32.4 odt ha-1 yr-1 was calculated (varying between different marginal land types). Based on these achievable yield levels, the total miscanthus production potential on the entire suitable marginal land areas is 13,521.7 × 104 odt yr-1; the corresponding bio-electricity generation and total greenhouse gas saving potentials are 183.9 TW h yr-1 and 21,242.4 × 104 t CO2 eq. yr-1, respectively. The spatial distribution of the suitable marginal areas shows that they are mainly concentrated in the central part of Northeast China and the Loess Plateau. Both regions are recommended as priority development zones for the Chinese miscanthus-based bioenergy industry. However, implementation of this huge marginal land potential is currently constrained by many barriers, e.g. concerns on potential ecological effects, competition for marginal land from other uses, lack of high yield varieties in marginal conditions. Lack of varieties with suitability to marginal conditions and efficient agronomic practices for the establishment on marginal land are the main barriers that limit using marginal land for miscanthus production. Therefore, stress tolerant varieties need to be selected and methods of effective establishment of miscanthus on marginal land need to be developed. Worldwide, grassland is the most important marginal land type because it has the largest terrestrial area and mild environmental stresses for growing energy crops (including miscanthus). However, it is undesirable or even legally prohibited to convert grassland into bioenergy cropland to avoid biodiversity loss and soil carbon being reduced by tilling practices. Hence, no-till establishment practices for miscanthus establishment and maintenance on grassland are investigated here under the third objectives. Our study demonstrates that miscanthus can be successfully cultivated on both good (nutrient-rich) and marginal (nutrient-poor) grassland using the proposed agronomic practices and an increased grassland productivity may be achieved through the establishment of suitable miscanthus genotypes. The recommended agronomic practices are summarized as following. Miscanthus genotypes with tall, thick shoots perform better than those with short, thin shoots. Better establishment is achieved when rhizome-derived plantlets are transplanted into pre-disturbed grassland. The grassland pre-disturbance of low vegetation cutting (5 cm) and herbicide spraying in narrow stripes is recommended for its beneficial effect on miscanthus establishment without significant negative effects on grassland productivity. Two harvests, one in late spring and one in late autumn, are optimal to achieve a high grassland yield. In this thesis, the limitation of the inefficient propagation technique was mitigated through minimizing the rhizome size and exploring the seeds propagation potential. The land-use dilemma was alleviated by exploring the marginal land production potential. Additionally, constrains of lack of genotypes and agronomic practices for the miscanthus establishment on marginal land were improved by field trials on grassland (the most important marginal land type with a huge potential).These results can improve the implementation and expansion of miscanthus production. However, in addition to constrains improved in this thesis, the miscanthus production is currently constrained by many other technical, economic and financial, social and political, environmental issues. It is unlikely that the implementation and expansion will achieve without mitigating these constrains. Further research and support should address these barriers in an integrate manner.
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    Biomass quality of miscanthus genotypes for different bioconversion routes
    (2017) Iqbal, Yasir; Lewandowski, Iris
    Currently, a wide range of biomass based resources (wood, agricultural residues, municipal waste, perennial dedicated energy crops) are being tested for different bioconversion routes such as combustion and ethanol production. In Europe, combustion is the most prevalent bioconversion route being adopted to produce heat and electricity. By 2020, in Europe out of 139 Mtoe biomass based energy production, 110.4 Mtoe will be heat and electricity. Along with combustion, EU (European Union) focuses on increasing the share of biofuels production to achieve the EU 2020 target to reach 10% share of renewables in the transportation sector. For both aforementioned bioconversion routes, large amount of feedstocks, produced in a sustainable way, are required. Miscanthus, being a perennial dedicated energy crop has the potential to deliver high yields by using the soil resources efficiently. However, the per unit energy yield depends not only on biomass yield but also quality of biomass relevant for a specific end use. For miscanthus based combustion, high lignin contents increase the energy yield of the biomass. The main challenges are high emissions (e.g. NOx) and combustion relevant problems such as corrosion, fouling and low ash melting temperature. Other than for combustion, the high lignin content is the main problem during miscanthus based ethanol production. Presently, M. x giganteus is the only commercially grown genotype, however a wide range of genotypes are being tested under the European conditions to select the most promising ones for both combustion and ethanol production. Therefore, the focus of this study is to evaluate the biomass quality of different miscanthus genotypes for combustion and ethanol production and relevant measures for each bioconversion route to optimize biomass quality at field level to fit the user demand. To realise the aim of this study, two different field trials were used: 1) long term field trial with 15 miscanthus genotypes (four M. x giganteus, one M. sacchariflorus, five M. sinensis hybrids and five M. sinensis genotypes) was established as randomized block design with three replications; 2) field trial with M. x giganteus and switchgrass was established as a randomized split plot design with different crops as main plots, divided into three subplots with different N levels (0, 40, and 80 kg N ha-1a-1). The biomass samples collected from these field trials were processed and analysed in laboratory to test the biomass quality parameters for combustion (mineral analysis, silicon, chloride, ash, moisture and ash melting behaviour) and ethanol production (fiber analysis, acid/base based pre-treatment). The outcomes of this study show that at biomass production level, crop management practices such as selection of appropriate genotypes, fertilization and time of harvesting determine the yield, biomass quality, overall cost of production and environmental performance of the crop for a specific bioconversion route (combustion, ethanol production). The ash melting behavior during combustion process can be improved through appropriate genotype selection from an ash deformation temperature of 800 °C up to 1100 °C. For ethanol production, fiber composition can be improved up to 16% through appropriate genotype selection by decreasing the lignin content and improving the cellulose content. This improvement will not be completely translated to increase in ethanol yield. However, it can improve the overall efficiency of conversion process by decreased the lignin content and subsequently lowering the energy and chemical inputs required for pre-treatment. In this study, no quantification is made about improvement in final ethanol yield. In fertilization, N fertilization is very important because it constituted up to 72% of the emissions in the conducted LCA described in chapter-1. Therefore, in case of high N fertilization, it not only affects the biomass quality but also increases the cost of biomass production and decreases the environmental performance of the crop. Based on the outcomes of this study, it can be concluded that at this location 40 kg N ha-1a-1 fertilization is sufficient to achieve good yield and quality biomass under late harvest regimes (March). At 40 kg N ha-1a-1 fertilization, the N content in the harvested biomass was still well below the threshold level set (0.3-1%) for biomass by the ENplus wood pellets. The other important factor which offers opportunity to optimize biomass quality is time of harvesting. Through appropriate harvesting time, biomass combustion quality can be improved up to 30% through decreasing the mineral, chloride and ash content whereas for ethanol production, fiber composition can be improved up to 12% by decreasing the lignin content. In practical terms, the delay in harvest will help to meet the set quality standards and counter the relevant challenges for each bioconversion route. In current study, none of the biomasses harvested from the different miscanthus genotypes, except for M. sinensis, could meet the ENplus-B wood pellet standards. For combustion, early ripening thin stemmed genotypes such as M. sinensis are recommended under late harvest regime (March). However, the low yield of these genotypes is a major concern because low biomass quantity decreases the final energy yield. Considering the high dry matter yield, cellulose and hemicellulose content, M. x giganteus and M. sacchariflorus are recommended for ethanol production under early harvest regimes (September-October). However, the high lignin content of M. x giganteus and M. sacchariflorus reduces the efficiency of overall process. Therefore, in this study recommendations were given to breeders about development of new genotypes for combustion by combining interesting traits such as high yield and lignin content of M. x giganteus, low ash content of M. sacchariflorus, low mineral content especially K and Cl of M. sinensis, whereas for ethanol production low lignin content of M. sinensis can be combined with high yield of M. x giganteus. This study suggests that optimization of biomass quality for a specific end use can be achieved through adoption of appropriate crop management practices such as selection of appropriate genotype and time of harvesting. This is the most cost-effective way with least environmental implications.
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    Continuous synthesis of 5‐hydroxymethylfurfural from biomass in on‐farm biorefinery
    (2022) Świątek, Katarzyna; Olszewski, Maciej P.; Kruse, Andrea
    5‐hydroxymethylfurfural (HMF) is the object of extensive research in recent times. The challenge in the industrial production of HMF is the choice of cheap, hexose feedstock. This study compares continuous HMF synthesis from hexoses—fructose and glucose, and biomass—Miscanthus × giganteus and chicory roots. The experiments were conducted in technical‐scale biorefinery (TRL 6/7). In the first stage, optimal conditions for the production of HMF from hexoses were selected using sulfuric acid as a catalyst in an aqueous medium. The following conditions were chosen for fructose: temperature of 200°C, the reaction time of 18 min, and pH = 2, and for glucose: 210°C, 18 min, and pH = 3. Under these conditions, the HMF yield was 56.5 mol% (39.6 wt.%) from fructose and 18.1 mol% (12.6 wt.%) from glucose. From the biomass, the HMF yields were 36.7 and 16.2 wt.% for miscanthus and chicory roots, respectively. Some results from the conversion of biomass solutions are unexpected and show a need for further investigations. This work has demonstrated the capacity to produce HMF from biomass as part of an environmentally friendly process in a biorefinery. Further research in this field and process optimization will be a step forward in the sustainable production of bioplastics.
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    How can miscanthus be integrated most efficiently into agricultural production systems?
    (2019) Mangold, Anja; Lewandowski, Iris
    The demand for biomass is increasing steadily, as fossil resources are gradually being replaced by biomass within the context of a developing bioeconomy. Plant-based feedstocks currently used for this replacement virtually all come from annual crops. However, perennial crops such as miscanthus are expected to be more environmentally benign due to their generally low-input requirements and high yield potential. Despite these advantages, the current cultivation area of miscanthus in Europe is quite low. One reason for this is that the cultivation and utilization of miscanthus faces several challenges. For example, the most common propagation method via rhizomes is very labour-intensive and thus expensive, leading to high establishment costs. Seed propagation is a promising option to reduce costs, but is not suitable for sterile genotypes. Another challenge to be overcome is the problem of re-integrating former miscanthus fields into crop rotations. The crop following miscanthus needs to be highly competitive in order not to be impaired by resprouting miscanthus shoots and thus able to achieve high yields. Additionally, there is only little information available on the effect of miscanthus cultivation and its subsequent removal on soil N content. This information is however crucial, for example to avoid environmental problems being caused by a potential nitrogen leaching after a miscanthus removal. If miscanthus is to be utilized as a biogas substrate, there are further challenges to be overcome. Firstly, the optimal harvest date needs to be defined with regard to the methane hectare yield and resilience of the crop to green cutting. Secondly, as a continuous supply of biomass throughout the year is necessary, ensiling will become a relevant topic. However, information is still required on the optimal harvest date to achieve a sufficient silage quality and the effects of ensiling on methane hectare yield. Finally, the suitability of miscanthus for biogas production is also influenced by biomass quality such as the proportions of leaf and stem. This has already been established for miscanthus utilization in combustion but has not yet been sufficiently investigated for anaerobic digestion. In summary, there are a number of uncertainties involved in miscanthus establishment, removal and utilization, which currently hamper its integration into agricultural production systems. From a bioeconomic point of view, this integration needs to be conducted as efficiently as possible in terms of nutrient-use, environmental and land-use efficiency. The aim of this study was to contribute to the filling of these knowledge gaps. To answer these knowledge gaps, several miscanthus field trials and laboratory experiments were conducted: a novel propagation method was tested; the re-integration of miscanthus fields into a crop rotation was analysed; and the effect of genotype, harvest date and ensiling on the digestibility and methane hectare yield was investigated. The results illustrate some possibilities of improving the nutrient-use, environmental and land-use efficiency of miscanthus biomass production along its supply chain: It was shown that miscanthus propagation via collars is feasible and a promising alternative to rhizome propagation, as the multiplication rate of collars is comparable to that of rhizome propagation. As the harvesting of collars is likely to be less labour-intensive and is less destructive for the mother field than rhizome propagation, this method is more favourable for both economic and ecological reasons. The re-integration of miscanthus into crop rotations revealed maize to be a suitable crop after miscanthus, as it coped with the prevailing soil conditions and suppressed resprouting miscanthus efficiently, resulting in satisfactory yields. The soil mineral nitrogen (Nmin) content was found to increase during the vegetation period following a miscanthus removal, but was generally on a low level (average: 17.3 kg Nmin ha-1). Additionally, it was found that, in Germany, miscanthus should be harvested in mid-October to maximize methane yields and nutrient recycling but minimize yield reduction. In addition, silage quality was best when miscanthus was harvested on this date. As leaf proportion correlated positively with substrate-specific methane yield (SMY) and thus genotypes with a higher leaf proportion were found to have a higher SMY, methane hectare yields could be increased even further by using genotypes with a high leaf proportion. In summary, the approaches developed in this study allow to considerably improve the ecological and economic performance of miscanthus production by increasing nutrient-use,environmental impact and land-use, and thus simplifying implementation into practice.
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    Integrating perennial biomass crops into crop rotations: How to remove miscanthus and switchgrass without glyphosate
    (2023) Lewin, Eva; Kiesel, Andreas; Magenau, Elena; Lewandowski, Iris
    Perennial energy grasses have gained attention in recent years as a promising resource for the bioeconomy because of their benign environmental profile, high stress tolerance, high biomass yields and low input requirements. Currently, strong breeding efforts are being made to extend the range of commercially available miscanthus and switchgrass genotypes. In order to foster farmers' acceptance of these crops, and especially of novel hybrids, more information is required about how they can be efficiently integrated into cropping rotations, how they can be removed at the end of their productive lifespan, and what effect they have on subsequently grown crops. Farmers in Europe are meanwhile increasingly constrained in the methods available to them to remove these crops, and there is a risk that the herbicide glyphosate, which has been used in many studies to remove them, will be banned in coming years. This study looks at the removal of seven‐year‐old stands of miscanthus and switchgrass over 1 year at an experimental site in Southern‐Germany. Three novel miscanthus genotypes were studied, alongside one variety of switchgrass, and the impact of each crop's removal on the yield of maize grown as a follow‐on crop was examined. A combination of soil tillage and grass herbicides for maize cultivation was successful in controlling miscanthus regrowth, such that yields of maize grown after miscanthus did not differ significantly from yields of maize grown in monoculture rotation (18.1 t dry biomass ha−1). Yields of maize grown after switchgrass (14.4 t dry biomass ha−1) were significantly lower than maize in monoculture rotation caused by insufficient control of switchgrass regrowth by the applied maize herbicide. Although some regrowth of miscanthus and switchgrass was observed in the follow‐on crop maize, complete eradication of both crops was achieved by subsequent winter wheat cultivation.
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    Interactions of nitrogen-related, growth promoting bacteria with Miscanthus × giganteus : impact and mechanism
    (2020) Liu, Yuan; Ludewig, Uwe
    The highly nitrogen-use efficient biomass grass Miscanthus is a host of the bacterial endophyte Herbaspirillum frisingense. While Herbaspirillum frisingense has the genetic competence to fix nitrogen, the plant-associated microbiome may also contribute to this nitrogen efficiency. Furthermore, the costly field establishment of the sterile perennial Miscanthus × giganteus from rhizomes is a severe constraint for expanding the production area of this commercial biomass crop. In this study, the effect of Herbaspirillum frisingense inoculation on stem-cutting sprouting, shoot biomass and other yield parameters was investigated. I studied how the inoculation impacts on the M. × giganteus associated microbiome and how the long term differences in nitrogen fertilizer amount modulated the M. × giganteus associated microbiome. This was studied in a 14 year-old field trial of M. ×giganteus fertilized with various amounts of nitrogen. Stem cutting inoculation improved the shoot sprouting and establishment success of Miscanthus × giganteus in the greenhouse. In a small field trial, plant height and biomass from inoculated sites were significantly larger in the second year after establishment, but already after one year after inoculation, the bulk soil, rhizosphere, root and rhizome microbiomes were almost devoid of Herbaspirillum. This beta-proteobacterium may colonize the shoot of Miscanthus × giganteus more efficiently. Major differences between bacterial communities were determined by plant-soil compartments and less by the plant organs, while both inoculation and nitrogen had little effects on these communities. Compared to the little effect on the soil, rhizosphere and root microbiomes, the rhizome microbiome was massively modulated by both inoculation and nitrogen level. In the rhizome, several proteobacteria, which are associated with plant growth promoting functions, were enriched by inoculation, while N2-fixing-related bacterial families were favored by long-term nitrogen-deficiency plots, but denitrifier-related families were depleted. The studies suggest that H. frisingense inoculation may improve establishment of Miscanthus stem cuttings and has long-lasting effects on the rhizome microbiome diversity, despite low rhizocompetence and low root abundance. Meanwhile, the rhizome could be a potential nitrogen fixation factory. The organ-specific, nitrogen-related bacterial communities are modulated by long-term different nitrogen supply and are mainly shaped by the plant, which provides guidance for optimizing Miscanthus sustainable cultivation.
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    Introducing new miscanthus hybrids into the European bioeconomy : the effect of environment and management on biomass quantity and quality
    (2023) Magenau, Elena; Lewandowski, Iris
    Miscanthus has been identified as a promising lignocellulosic perennial biomass crop for temperate climates and different (marginal) soils in terms of yield and ecological benefits. The cultivation of miscanthus brings numerous ecological advantages, such as a reduction in soil erosion, protection of aquatic ecosystems from alteration through eutrophication, and increasing heterogeneity in annual arable landscapes leading to increased biodiversity compared to annual crops. Reasons for this are its perenniality, the long period of time it stands on the field, and its low fertiliser and plant protection demands. Nevertheless, the area under cultivation in Europe is limited. The reasons are that the scientific yield levels are not reached commercially, and the only commercially cultivated hybrid Miscanthus × giganteus (M×g) is sterile. Miscanthus is therefore currently propagated and established via rhizomes, which limits upscaling. However, the seed-based hybrids tested so far do not reach the potential of M×g in terms of yield, quality, and ecological impact under a wide range of climatic conditions. To improve the integration of miscanthus as a biomass crop in the growing European bioeconomy, it is required to reach high and stable yields over several years (security of biomass supply) and a low ecological impact by low nutrient offtakes under different European climates. Therefore, it is essential to gain agronomic knowledge on how genetic (G), location-specific environment (E), and management (M) factors and the interactions between them affect the security of biomass supply and ecosystem services of novel seed-based hybrids. Against this background, the research objectives of this study are: 1) to investigate the effect of the onset of the growing season on biomass supply security and how it is affected by late spring frosts, 2) to assess G × E interaction effects on miscanthus biomass security, and 3) to assess G × E × M interaction effects on nutrient offtake, yield and quality of miscanthus biomass. For this purpose, new seed- and rhizome-based miscanthus hybrids were compared with the commercially grown M×g and evaluated for biomass yield, quality, and nutrient offtakes (a key parameter defining the ecological impact) under different European conditions to determine biomass supply security and ecological effects. The effect of the management parameters cutting height and harvest time was also analysed. The results show that to reach a high biomass supply security, avoiding damage by late spring frosts is essential. An effective mechanism is a low frost sensitiveness of the emerging shoots and to produce new shoots over the whole growth period, as observed for the seed-based M. sinensis × sinensis (M sin×sin). By contrast, a late emergence and producing fewer, thicker but frost-susceptible shoots at the beginning of the growing season, as observed for rhizome-based M×g and rhizome- and seed-based M. sacchariflorus × sinensis (M sac×sin), endangers the biomass supply security in case of frost after emerging. Over the first three years, the establishment process of miscanthus depended on location and hybrid. The M sin×sin hybrids flowered and senesced earlier than the taller M sac×sin hybrids. Active senescence, probably initiated by flowering, increases biomass quality by reducing the moisture and nutrient content. Following the third growing season, the highest yields were recorded at the low-altitude site in northern Italy and the lowest on a industrially damaged marginal land site in northern France. Moisture contents at spring harvest were lowest in Croatia and highest in Wales, United Kingdom. A lower moisture content is highly desirable for transport, storage and most end-use applications. Overall, lower moisture contents at harvest were found in M sin×sin hybrids than in M sac×sin. As expected, delaying the harvest until spring reduced yield and nutrient contents. At lower latitudes, the late-ripening M sac×sin combined high yields with low nutrient contents when harvested in spring. At the most elevated latitude location (Wales), the early-ripening M sin×sin combined high biomass yields with low nutrient offtakes. The M×g clone with intermediate flowering and senescence showed similarly low nutrient contents at all locations. An increased cutting height at spring harvest decreased yields by 270 kg ha-1 (0.83%) with each 1-cm increase in cutting height up to 40 cm. Although whole shoot mineral concentrations were significantly influenced by both hybrid and year interactions, total nutrient contents did not differ significantly from those in the lower basal sections. In years with wet conditions before harvest, an increase in cutting height of 10 cm decreased moisture content by up to 8%, whereas the effect during dry conditions was marginal. To achieve high biomass supply security and increased ecological benefits in miscanthus cultivation, the results of this study lead to the recommendation to cultivate M sin×sin hybrids at locations with a high risk of late spring frosts, as observed in northern European sites, and M sac×sin hybrids at locations where the risk is low, as observed in southern Europe. In southern Europe, M sac×sin hybrids achieved high yields with low nutrient and moisture contents as they made use of the long vegetation period. In general, M sin×sin has a shorter growth period than M sac×sin hybrids, making it the perfect hybrid for northern Europe, where the vegetation period is short. To ensure biomass supply in regions with extreme minimum winter temperatures and late spring frosts, miscanthus should be harvested in spring due to the thicker mulch layer, which functions as insulation. To ensure biomass supply security, a successful establishment is essential. Therefore, during the establishment phase, harvest should generally take place in spring, as the establishment period is crucial for securing biomass yield throughout the cultivation period. Weakening or even loss of plants during this period will lead to higher weed pressure and lower than optimal yields. The harvest cutting height should be as low as possible to achieve a higher yield without an over-proportional increase in nutrient offtake. However, cutting height needs to be adapted according to local conditions by finding an optimum between biomass loss and the risk of damage to harvest machinery and contamination of the biomass by soil. Should the moisture content of the biomass be too high for safe storage due to wet conditions during harvest, the cutting height can be increased to avoid costly post-harvest drying procedures. This study recommends hybrids for specific locations in Europe, provides important data for determining harvest timing and height, and key data on the ecological impact. It shows that the cultivation of miscanthus in Europe, taking into account the G × E × M interactions, has the potential to secure the biomass supply for the growing bioeconomy while positively influencing the provision of ecosystem services. Furthermore, integrating miscanthus into the agricultural system increases its resilience by diversifying the crops grown, the structure of the agricultural landscape and farmers income.
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    Methodological approaches for assessing the environmental performance of perennial crop-based value chains
    (2017) Wagner, Moritz; Lewandowski, Iris
    In a developing bioeconomy, the demand for biomass for industrial purposes is expected to increase significantly. This demand needs to be met in a sustainable way and without compromising food security. With this goal in mind, resource-efficient lignocellulosic crops, such as perennial energy grasses, are often cited as a biomass source with low negative impacts on the environment. Under European conditions, miscanthus is the leading perennial energy grass because of its high biomass and energy yield potential. It is a C4 plant, which achieves dry matter biomass yields of up to 20 Mg ha−1 yr−1 when harvested in later winter, and up to 30 Mg ha−1 yr−1 when harvested green in October. Currently the main utilization route of miscanthus is direct combustion for heat generation, but the biomass can also be used for various other applications, such as biofuels and insulation material. Several studies have analysed the environmental performance of perennial crop-based value chains, but most of these only assessed the Global Warming Potential (GWP). However, the GWP alone is not an adequate indicator for the holistic assessment of the environmental performance of such value chains. In addition, these studies often used generic data and applied varying assumptions, which makes a comparison of different value chains difficult. The main goal of this thesis is to draw up recommendations for future assessments of the environmental performance of perennial crop-based value chains. For this purpose, five research objectives were formulated: 1) to identify the key parameters influencing the environmental performance of perennial crop-based value chains; 2) to analyse which impact categories are most relevant when assessing the environmental performance; 3) to assess the differences between various perennial-crop based value chains; 4) to assess the environmental performance of the utilization of marginal land to grow perennial crops for industrial purposes; and 5) to analyse and compare the environmental performance of annual and perennial crops in the example value chain ‘biogas production’. To achieve these research objectives, the environmental performance of several perennial crop-based value chains was analysed in various impact categories applying the same underlying assumptions and using field data obtained under ceteris paribus conditions. The analysis was carried out using the globally recognised Life Cycle Assessment (LCA) methodology, which is standardized by two ISO norms (14040/44). The results revealed that biomass yield is one of the most important parameters influencing the environmental performance of perennial crop-based value chains. An increase in yield of 50%, for instance, leads to an increase in carbon mitigation potential in a comparable range (46%). Furthermore, the marked influence on the environmental impact mitigation potential of both fertilizer-induced emissions and selection of the reference system was demonstrated. For example, if the reference system is changed from light fuel oil to natural gas, the substituting by heat generated from the combustion of miscanthus biomass increases the net impact in the category ‘particulate matter formation’ by 220%. The relevance of different impact categories was analysed for various perennial crop-based value chains using a normalisation approach. The results clearly indicated that a holistic assessment of the environmental performance of perennial crop-based value chains should at least include the impact categories ‘marine ecotoxicity’, ‘human toxicity’, ‘agricultural land occupation’, ‘freshwater eutrophication’ and ‘freshwater ecotoxicity’. In future assessments, it is recommended to include the impacts of land-use on both biodiversity (using species richness as an indicator) and soil quality (using SOM as an indicator). The comparison of the environmental performance of different perennial crop-based value chains revealed clear environmental advantages of the cascade use of biomass. An example is the production of miscanthus-based insulation material, which is first used as a building material and then incinerated to generate heat and electricity. The results also demonstrate that, despite low biomass yield on marginal land, miscanthus-based value chains have a substantial environmental impact mitigation potential when substituting a fossil-based reference system. Furthermore, the comparison of annual and perennials crops as biogas substrates showed that perennial crops, and in particular miscanthus, have a considerably better environmental performance in the impact categories ‘climate change’ (up to -73%), ‘fossil fuel depletion’ (up to -79%), ‘freshwater eutrophication’ (up to -69%), ‘marine eutrophication’ (up to -67%), and ‘terrestrial acidification’ (up to -26%). In all four studies included in this thesis, it was observed that the data used for the biomass cultivation in particular, such as yield and fertilizer-induced emissions, have a considerable influence on the environmental performance. This data is highly site- and crop-specific and is strongly dependent on the agricultural management system applied. Based on the results of this thesis, the common practice of using generic data in assessments of the environmental performance of perennial crop-based value chains should be rejected. In order to obtain realistic results, the use of site- and crop-specific data is highly recommended.
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    Site impacts nutrient translocation efficiency in intraspecies and interspecies miscanthus hybrids on marginal lands
    (2022) Magenau, Elena; Clifton‐Brown, John; Awty‐Carroll, Danny; Ashman, Chris; Ferrarini, Andrea; Kontek, Mislav; Martani, Enrico; Roderick, Kevin; Amaducci, Stefano; Davey, Chris; Jurišić, Vanja; Kam, Jason; Trindade, Luisa M.; Lewandowski, Iris; Kiesel, Andreas
    Miscanthus, a C4 perennial rhizomatous grass, is capable of growing in varied climates and soil types in Europe, including on marginal lands. It can produce high yields with low nutrient inputs when harvested after complete senescence. Senescence induction and rate depend on complex genetic, environmental, and management interactions. To explore these interactions, we analysed four miscanthus hybrids (two novel seed‐based hybrids, GRC 3 [Miscanthus sinensis × sinensis] and GRC 14 [M. sacchariflorus × sinensis]; GRC 15, a novel M. sacchariflorus × sinensis clone; and GRC 9, a standard Miscanthus × giganteus clone) in Italy, Croatia, Germany and the UK. Over all trial locations and hybrids, the average aboveground biomass of the 3‐year‐old stands in August 2020 was 15 t DM ha−1 with nutrient contents of 7.6 mg N g−1 and 14.6 mg K g−1. As expected, delaying the harvest until spring reduced overall yield and nutrient contents (12 t DM ha−1, 3.3 mg N g−1, and 5.5 mg K g−1). At lower latitudes, the late‐ripening M. sacchariflorus × sinensis GRC 14 and GRC 15 combined high yields with low nutrient contents. At the most elevated latitude location (UK), the early‐ripening M. sinensis × sinensis combined high biomass yields with low nutrient offtakes. The clonal Miscanthus × giganteus with intermediate flowering and senescence attained similar low nutrient contents by spring harvest at all four locations. Seasonal changes in yield and nutrient levels analysed in this study provide: (1) a first step towards recommending hybrids for specific locations and end uses in Europe; (2) crucial data for determination of harvest time and practical steps in the valorization of biomass; and (3) key sustainability data for life cycle assessments. Identification of trade‐offs resulting from genetic × environment × management interactions is critical for increasing sustainable biomass supply from miscanthus grown on marginal lands.
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    Social assessment of miscanthus cultivation in Croatia: Assessing farmers' preferences and willingness to cultivate the crop
    (2023) Marting Vidaurre, Nirvana A.; Jurišić, Vanja; Bieling, Claudia; Magenau, Elena; Wagner, Moritz; Kiesel, Andreas; Lewandowski, Iris
    Social aspects of miscanthus cultivation have been investigated in a limited way in the scientific literature. Adopting existing frameworks for social life‐cycle assessment enables assessments to include numerous social aspects; however, the relevance of these aspects depends on the local context. This study aims to identify the most relevant social aspects from the farmers' perspective using a previously proposed framework for the assessment of the stakeholder ‘farmer’. It is based on a case study for miscanthus production in Sisak Moslavina in Croatia. The existence of abandoned lands in Croatia presents an opportunity for the cultivation of miscanthus as a potential source of biomass for the production of bio‐based materials and fuels. The study seeks to assess the feasibility of cultivating miscanthus in the region, taking into account potential challenges and opportunities, as well as farmers' willingness to adopt the crop, and to understand the reasons behind land abandonment. We conducted a survey among 44 farmers in the region and used a scoring method to identify the most relevant social aspects. The aspects most valued by the farmers were health and safety, access to water, land consolidation and rights, income and local employment, and food security. Responses to the question of whether they would adopt the crop highlight the importance of an established market, good trading conditions and profitability of cultivation. The survey also enabled an understanding of farmers' preferences with respect to the production conditions of crops. The farmers regarded the provision of subsidies as one of the main factors that render a crop attractive. Opportunities for the adoption of the miscanthus cultivation include high yields and low input requirements. Barriers include land conflicts and land availability. Despite the opportunities for miscanthus development in the region, there are important challenges to consider for successful implementation of the crop.
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    Spring emergence and canopy development strategies in miscanthus hybrids in Mediterranean, continental and maritime European climates
    (2023) Magenau, Elena; Clifton‐Brown, John; Parry, Catherine; Ashman, Chris; Awty‐Carroll, Danny; Ferrarini, Andrea; Kontek, Mislav; Martani, Enrico; Amaducci, Stefano; Davey, Chris; Dolstra, Oene; Jurišić, Vanja; Kam, Jason; Trindade, Luisa M.; Lewandowski, Iris; Kiesel, Andreas
    Due to its versatility and storability, biomass is an important resource for renewable materials and energy. Miscanthus hybrids combine high yield potential, low input demand, tolerance of certain marginal land types and several ecosystem benefits. To date, miscanthus breeding has focussed on increasing yield potential by maximising radiation interception through: (1) selection for early emergence, (2) increasing the growth rate to reach canopy closure as fast as possible, and (3) delayed flowering and senescence. The objective of this study is to compare early season re‐growth in miscanthus hybrids cultivated across Europe. Determination of differences in early canopy development on end‐of‐year yield traits is required to provide information for breeding decisions to improve future crop performance. For this purpose, a trial was planted with four miscanthus hybrids (two novel seed‐based hybrids M. sinensis × sinensis [M sin × sin] and M. sacchariflorus × sinensis [M sac × sin], a novel rhizome‐based M sac × sin and a standard Miscanthus × giganteus [M × g] clone) in the UK, Germany, Croatia and Italy, and was monitored in the third and fourth growing season. We determined differences between the hybrids in base temperature, frost sensitivity and emergence strategy. M × g and M sac × sin mainly emerged from belowground plant organs, producing fewer but thicker shoots at the beginning of the growing season but these shoots were susceptible to air frosts (determined by recording 0°C 2 m above ground surface). By contrast, M sin × sin emerged 10 days earlier, avoiding damage by late spring frosts and producing a high number of thinner shoots from aboveground shoots. Therefore, we recommend cultivating M sac × sin at locations with low risk and M sin × sin at locations with higher risk of late spring frosts. Selecting miscanthus hybrids that produce shoots throughout the vegetation period is an effective strategy to limit the risk of late frost damage and avoid reduction in yield from a shortened growing season.
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    The potential of miscanthus as biogas feedstock
    (2020) Kiesel, Andreas; Lewandowski, Iris
    Of all renewable energy forms, biomass accounts for the by far largest proportion of gross inland energy consumption in Europe. As the biogas sector in particular can provide demand-driven electricity generation, energy storage and flexible utilization options including biofuels, it is likely to play an important role in future energy systems in future. In Germany, the largest biogas market in Europe, energy crops provide the highest proportion of biogas input substrates, with maize being the most dominant. The environmental impact of biogas production is mainly attributed to energy crop production, with the risks of maize cultivation being particularly criticized. Perennial biomass crops have the potential to reduce the environmental impact of the biogas sector and miscanthus is an especially promising candidate crop due to its high yields. However, preliminary observations have indicated that the green harvest of miscanthus necessary for biogas production leads to a strong yield depression in the subsequent year. The aim of this thesis was to determine and understand the mechanisms influencing the green-cut tolerance of miscanthus and to assess the potential of different green-harvest regimes for biogas production. Here, ‘green-cut tolerance’ is defined as the crop’s ability to regrow in the year after the green harvest is performed without yield depression. A further aim of this thesis was to investigate the environmental performance of miscanthus-based biogas production and to determine its energy efficiency compared to other utilization options. Field trials were conducted to assess the potential of miscanthus hybrids for biogas production, the green-cut tolerance of Miscanthus x giganteus (Mxg), and how both are influenced by management practices (harvest regime x nitrogen fertilization). A Life-Cycle Assessment was performed to evaluate the environmental impact of biogas production from perennial C4 grasses, including miscanthus, and to assess the optimization potential compared to the standard biogas crop maize. The suitability of miscanthus biomass was investigated for the utilization options bioethanol, biogas and combustion, and the energy efficiency of these was compared based on their net energy yield. The results revealed that Mxg harvested in October showed the highest average biomass yield, the highest methane yield (approx. 6000 m3 methane ha-1) of all harvest regimes, and a higher substrate-specific methane (SMY) yield than for biomass harvested after winter. An earlier green harvest (July, August) improved the SMY, but led to a sharp biomass and thus methane yield decline in the second year and was identified as unsuitable for Mxg. As increased nitrogen fertilization showed no effect on the yield in any of the harvest regimes, it can be disregarded as a management practice for improving green-cut tolerance. Instead, harvest date was found to have a strong influence on green-cut tolerance and sufficient time for relocation of carbohydrates needs to be allowed before a green cut is performed. This finding is crucial for the utilization of miscanthus biomass harvested green and also for the breeding of new varieties with improved green-cut tolerance. Breeding targets for optimized biogas varieties should include to increase the SMY and biomass yield and to widen the possible harvest window. Selecting genotypes that relocate carbohydrates to the rhizomes earlier would allow an earlier green harvest without yield decline the following year, but this may involve a trade-off with the SMY. The suitability of miscanthus for the utilization options assessed was found to be influenced by biomass composition, which in turn was affected by genotype and harvest date. Lignin content had a negative effect on biomass quality for biogas and bioethanol production and increased with later harvest dates. Hemicellulose had a positive effect on biomass quality for bioethanol production through the improvement of the saccharification potential. Low ash, potassium and chloride content enhanced biomass quality for combustion by increasing the ash melting temperatures and decreased with a delay in harvest to after winter. For the biogas and bioethanol utilization pathways, novel miscanthus varieties with low lignin content need to be developed, whereas for combustion varieties with a high lignin content are more favourable. The Life Cycle Assessment revealed that the use of miscanthus has a high potential to reduce the environmental impacts of biogas crop production and thus the biogas sector. Miscanthus had a more favourable performance than the annual biogas crop maize in each impact category considered and the highest reduction potential compared to the fossil reference in the impact categories climate change, fossil fuel depletion and marine eutrophication. The choice of biomass utilization pathway had a considerable effect on the energy yield per unit area, with combustion showing the overall highest energy yield potential for electricity production. However, for the combustion pathway, miscanthus is generally harvested after winter and this is accompanied by biomass yield losses of 35% compared to peak yield. In the biogas pathway, miscanthus can be harvested close to peak yield, leading to an only 10% lower energy yield than that of combustion. When considering the use of miscanthus for biofuel production, the highest area efficiency was found for the direct use of biomethane, followed by battery electric vehicles fuelled by electricity from biomass combustion, and the lowest for the direct use of bioethanol. However, the low conversion efficiency of bioethanol production did not consider energy generation from by-products. In this thesis it was determined that the green-cut tolerance of miscanthus is influenced by the carbohydrate relocation to the rhizomes and thus by harvest date. Miscanthus harvested in October shows a high potential as feedstock for biogas production due to its high yield and sufficient digestibility, can help improve the biogas sector’s environmental performance and contribute to an increase in greenhouse gas mitigation. The digestibility of miscanthus biomass for biogas production could be improved by breeding and selecting genotypes with low lignin contents and by applying suitable pretreatment methods. Increased digestibility could also help to overcome potential trade-offs between early carbohydrate relocation and SMY. The efficiency of biomass utilization greatly depends on the utilization option, with a high efficiency being identified for biomethane as a transportation fuel and for peak-load power generation. It was shown that miscanthus is a suitable crop for the provision of sustainably produced biomass as a feedstock for the growing European bioeconomy that provides additional ecosystem services, e.g. groundwater and surface water protection.