Miscanthus Yield Research Articles

Comprehensive Analysis of Miscanthus Research: Sustainable Biomass and Bioenergy Through Knowledge Mapping

Miscanthus grass species have gained global research attention in the fields of biomass and bioenergy, witnessing remarkable advancements in the 21st century. This study systematically searched and selected relevant literature on primary research involving Miscanthus species, published between 2007 and 2023, from the China National Knowledge Infrastructure and Web of Science core databases. Utilizing CiteSpace as a bibliometric tool, the study generated quantitative statistics and performed data analysis on the selected articles. The examination covered publication trends, national and author publication outputs, author and journal co-citations, keyword research hotspots, and the temporal evolution of research topics in the Miscanthus research field, offering empirical support for future in-depth investigations and innovation in Miscanthus spp. The research findings reveal the following insights: (1) Publication trends can be divided into two phases (stable growth and fluctuating decline), with recent trends maintaining a relatively high level. (2) A collaborative publication network, led by core authors such as Zili Yi, John Clifton-Brown, and Iris Lewandowski, has been established, characterized by a diverse research focus and close cooperation. (3) Research hotspots encompass several aspects, including biomass production yield, efficiency, and energy products of Miscanthus spp., ecological restoration, genetics, plant physiological research, and chemical components. The primary species investigated are Miscanthus×giganteus, Miscanthus sinensis, Miscanthus floridulus, and Miscanthus lutarioriparius.

The effects of organic waste materials on Miscanthus × giganteus yield and Zn and Ni content

The aim of the experiment was to determine the yield of Miscanthus × giganteus M 19 in the first three years of cultivation and its bioaccumulation of Zn and Ni in aboveground and underground parts in response to different doses of sewage sludge and substrate left after the production of white mushrooms. Miscanthus × giganteus is a grass species that adapts to different environmental conditions and can be grown in various climatic zones of Europe and North America. In April 2018 the experiment was established in a randomized block design and with four replications in central-eastern Poland. Waste organic materials (municipal sewage sludge and mushroom substrate) were applied to the soil in 2018 in the spring before the rhizomes of giant miscanthus were planted. Each year (from 2018 to 2020) biomass was harvested in December. The yield of fresh and dry matter and the total content of Zn and Ni, after wet mineralization of plant samples, were determined by optical emission spectrometry (ICP-OES). After the third year of cultivation, the content of Zn and Ni in rhizomes and in the soil was determined again. In relation to control, an increase in the yield of miscanthus biomass in response to organic waste materials was noted. Plants responded to mushroom substrate (SMS) with the highest average yield (16.89 Mgha−1DM), while on the control plot it was 13.86 Mg ha−1DM. After the third year of cultivation, rhizomes of Miscanthus x giganteus contained higher amounts of Zn (63.3 mg kg−1) and Ni (7.54 mg kg−1) than aboveground parts (40.52 and 2.07 mg kg–1), which indicated that heavy metals were retained in underground parts.

Nitrogen fertilization effects on aged Miscanthus × giganteus stands: Exploring biomass yield, yield components, and biomass prediction using in‐season morphological traits

AbstractFor sustainable biomass production of Miscanthus × giganteus (hereafter miscanthus), understanding the impact of stand age and nitrogen (N) fertilization on biomass yield is crucial. This study investigated the effects of varying N fertilization rates (0, 56, 112, and 168 kg N ha−1) on yield components (tiller height, density, and weight) and their correlations with end‐of‐season biomass yield in miscanthus. We also explored end‐of‐season biomass yield prediction using in‐season traits (canopy height, leaf area index, and leaf chlorophyll content [LCC]). The study was conducted at two sites in Illinois: a previously unfertilized 10‐year‐old miscanthus research stand at Urbana and a 16‐year‐old commercial stand at Pesotum with a history of annual 56N application. Results from 2018 to 2021 in Urbana and 2020 to 2021 in Pesotum showed increased biomass yields with N fertilization, varying by rate, year, and location. Biomass yield in Pesotum peaked at 56N, while in Urbana, it increased significantly at 112 kg N ha−1. Biomass yield was strongly correlated with tiller height and weight measured at Urbana across N rates. Morphological traits measured every 2–3 weeks during the 2020 and 2021 growing seasons showed that canopy height was the strongest single predictor of miscanthus biomass yield, followed by LCC. Mid‐August to September measurements of these traits were the best predictors of biomass yield. Multiple regressions involving the canopy height and LCC further improved yield predictions. We conclude that while N enhances biomass yields of aging miscanthus, the optimum rate depends on the site, environmental conditions, and management history.

Modelling the Yield and Estimating the Energy Properties of Miscanthus x Giganteus in Different Harvest Periods

This research aims to use artificial neural networks (ANNs) to estimate the yield and energy characteristics of Miscanthus x giganteus (MxG), considering factors such as year of cultivation, location, and harvest time. In the study, which was conducted over three years in two different geographical areas, ANN regression models were used to estimate the lower heating value (LHV) and yield of MxG. The models showed high predictive accuracy, achieving R2 values of 0.85 for LHV and 0.95 for yield, with corresponding RMSEs of 0.13 and 2.22. A significant correlation affecting yield was found between plant height and number of shoots. In addition, a sensitivity analysis of the ANN models showed the influence of both categorical and continuous input variables on the predictions. These results highlight the role of MxG as a sustainable biomass energy source and provide insights for optimizing biomass production, influencing energy policy, and contributing to advances in renewable energy and global energy sustainability efforts.

Biomass yield potential on U.S. marginal land and its contribution to reach net‐zero emission

AbstractBioenergy with carbon capture and geological storage (BECCS) is considered one of the top options for both offsetting CO2 emissions and removing atmospheric CO2. BECCS requires using limited land resources efficiently while ensuring minimal adverse impacts on the delicate food‐energy‐water nexus. Perennial C4 biomass crops are productive on marginal land under low‐input conditions avoiding conflict with food and feed crops. The eastern half of the contiguous U.S. contains a large amount of marginal land, which is not economically viable for food production and liable to wind and water erosion under annual cultivation. However, this land is suitable for geological CO2 storage and perennial crop growth. Given the climate variation across the region, three perennials are major contenders for planting. The yield potential and stability of Miscanthus, switchgrass, and energycane across the region were compared to select which would perform best under the recent (2000–2014) and future (2036–2050) climates. Miscanthus performed best in the Midwest, switchgrass in the Northeast and energycane in the Southeast. On average, Miscanthus yield decreased from present 19.1 t/ha to future 16.8 t/ha; switchgrass yield from 3.5 to 2.4 t/ha; and energycane yield increased from 14 to 15 t/ha. Future yield stability decreased in the region with higher predicted drought stress. Combined, these crops could produce 0.6–0.62 billion tonnes biomass per year for the present and future. Using the biomass for power generation with CCS would capture 703–726 million tonnes of atmospheric CO2 per year, which would offset about 11% of current total U.S. emission. Further, this biomass approximates the net primary CO2 productivity of two times the current baseline productivity of existing vegetation, suggesting a huge potential for BECCS. Beyond BECCS, C4 perennial grasses could also increase soil carbon and provide biomass for emerging industries developing replacements for non‐renewable products including plastics and building materials.

Plant testing with hemp and miscanthus to assess phytomanagement options including biostimulants and mycorrhizae on a metal-contaminated soil to provide biomass for sustainable biofuel production

The need of biofuels from biomass, including sustainable aviation fuel, without using agricultural land dedicated to food crops, is in constant demand. Strategies to intensify biomass production using mycorrhizal fungi, biostimulants and their combinations could be solutions for improving the cultivation of lignocellulosic plants but still lack well-established validation on metal-contaminated soils. This study aimed to assess the yield of Miscanthus x giganteus J.M. Greef & Deuter and Cannabis sativa L. grown on a metal-contaminated agricultural soil (11 mg Cd, 536 mg Pb and 955 mg Zn kg−1) amended with biostimulants and/or arbuscular mycorrhizal fungi, and the shoot Cd, Pb and Zn uptake. A pot trial was carried out with soil collected from a field near a former Pb/Zn smelter in France and six treatments: control (C), protein hydrolysate (a mixture of peptides and amino acids, PH), humic/fulvic acids (HFA), arbuscular mycorrhizae fungi (AMF), PH combined with AMF (PHxAMF), and HFA combined with AMF (HFAxAMF). Metal concentrations in the soil pore water (SPW), pH and electrical conductivity were measured over time. Miscanthus and hemp shoots were harvested on day 90. Both PH and PHxAMF treatments increased SPW Cd, Pb, and Zn concentrations (e.g. by 26, 1.9, and 22.9 times for miscanthus and 9.7, 4.7, and 19.3 times for hemp in the PH and PHxAMF treatments as compared to the control one, respectively). This led to phytotoxicity and reduced shoot yield for miscanthus. Conversely, HFA and HFAxAMF treatments decreased SPW Cd and Zn concentrations, increasing shoot yields for hemp and miscanthus. Shoot Cd, Pb, and Zn uptakes peaked for PH and PHxAMF hemp plants (in μg plant-1, Cd: 310–334, Pb: 34–38, and Zn: 232–309 for PHxAMF and PH, respectively), while lowest values occurred for PH miscanthus plants mainly due to low shoot yield. Overall, this study suggested that humic/fulvic acids can be an effective biostimulant for increasing shoot biomass production in a metal-contaminated soil. These results warrant further investigations of the HFAxAMF in field trials.

Comparative productivity of six bioenergy cropping systems on marginal lands in the Great Lakes Region, United States

AbstractGrowing lignocellulosic crops on marginal lands is a promising solution for sustainable biofuel production. We evaluated the productivity of bioenergy cropping systems (switchgrass [Panicum virgatum L., var. Cave‐In‐Rock], miscanthus [Miscanthus × giganteus, ‘Illinois clone’], hybrid poplar [Populus nigra × P. maximowiczii A. Henry ‘NM6’], native grasses [five species], early successional vegetation, and restored prairie vs. historical vegetation [as reference control]) with and without nitrogen fertilization on low‐fertility former cropland at five sites in the Great Lakes Region, United States. We reported biomass yields for the first 7 years after establishment. Switchgrass was most consistently productive across all sites but miscanthus was more productive at three of the five sites. When averaged across sites, years, and nitrogen (N) treatments, biomass yields followed the order miscanthus > switchgrass > hybrid poplar ≈ native grasses > restored prairie > early successional vegetation ≈ historical vegetation, but varied substantially by crop and site, with a significant crop by site interaction. Yields of miscanthus and switchgrass peaked after four–five growing seasons and declined thereafter, while yields of both native grasses and restored prairie increased throughout 6 years with no sign of follow‐on decline, suggesting that polycultures may outperform monocultures over the long term. Yields of early successional vegetation—similar in composition to historical vegetation at each site—did not improve with time. Nitrogen fertilization increased the yields of all cropping systems at all sites. Our results demonstrate the viability of low‐productivity former cropland for long‐term bioenergy production and suggest there is no single crop best suited for all low fertility soils.

Improving field establishment and yield in seed propagated Miscanthus through manipulating plug size, sowing date and seedling age.

Biomass crops provide significant potential to substitute for fossil fuels and mitigate against climate change. It is widely acknowledged that significant scale up of biomass crops is required to help reach net zero targets. Miscanthus is a leading biomass crop embodying many characteristics that make it a highly sustainable source of biomass but planted area remains low. Miscanthus is commonly propagated via rhizome, but efficient alternatives may increase uptake and help diversify the cultivated crop. Using seed-propagate plug plants of Miscanthus has several potential benefits such as improving propagation rates and scale up of plantations. Plugs also provide an opportunity to vary the time and conditions under protected growth, to achieve optimal plantlets before planting. We varied combinations of glasshouse growth period and field planting dates under UK temperate conditions, which demonstrated the special importance of planting date on yield, stem number and establishment rates of Miscanthus. We also propagated Miscanthus in four different commercial plug designs that contained different volumes of substrate, the resulting seedlings were planted at three different dates into field trials. In the glasshouse, plug design had significant effects on above and belowground biomass accumulation and at a later time point belowground growth was restricted in some plug designs. After subsequent growth in the field, plug design and planting date had a significant effect on yield. The effects of plug design on yield were no longer significant after a second growth season but planting date continued to have a significant effect. After the second growth year, it was found that planting date had a significant effect on surviving plants, with the mid-season planting producing higher survival rates over all plug types.Establishment was positively correlated with DM biomass produced in the first growth season. Sowing date had a significant effect on establishment but the impacts of plug design were more nuanced and were significant at later planting dates. We discuss the potential to use the flexibility afforded by seed propagation of plug plants to deliver significant impacts in achieving high yield and establishment of biomass crops during the critical first two years of growth.

Supply costs, energy use, and GHG emissions of biomass from marginal lands in Brittany, France

Growing energy crops on marginal lands is an option to increase current bioresources while avoiding the food vs fuel dilemma. Yet, little is known about the extent and characteristics of marginal lands, and about how growing energy crops on such lands will impacts productivity, supply chains, and the environment. This study combined a geographic information system, a crop growth model, life cycle assessment, and a logistics model to (i) quantify and map marginal lands (ii) estimate the yields of miscanthus grown thereon (iii) assess the impact on supply chain and the environment of miscanthus from marginal lands in Brittany. Three miscanthus harvest forms (chips, bundles, and bales) and three logistics scenarios (no storage, one storage point, and two storage points) were studied. It showed that 57544 ha of marginal lands are available in Brittany and that rooting (55%) and salinity (34%) were the dominant marginality factors of these lands. Miscanthus yields on these lands varied from 0 to 21 t DM ha−1 y−1, depending on marginality constraints. Despite the low energy use (311–604 MJ t−1 DM) and GHG emissions (6–19 kg CO2-eq t−1 DM), the delivery costs were too high (81–108 € t−1 DM). Bales were the cheapest and most environmental-friendly biomass form, as was the logistics configuration with no storage point. Sourcing biomass from marginal lands offers a solution for sustainable biofuel production in Brittany. However, economic incentives are needed to encourage production on marginal lands given the high delivery costs of biomass.

The effect of silage additive on the kinetics of biogas production from lignocellulosic perennial crops

The aim of the study was to assess the effect of silage additive containing heterofermentative lactic acid bacteria (LAB) strain of Lactobacillus buchneri species on ensiling quality, as well as methane yield and the kinetics of biogas production from ensiled perennial energy grasses: Miscanthus × giganteus (miscanthus), Spartina pectinata (cordgrass), Panicum virgatum (switchgrass) and Andropogon gerardii (big bluestem). The listed plants are not commonly used for biogas production, their susceptibility to ensiling is also little known, hence the need to investigate their suitability for these processes. Effective methods for increasing the biogas yield from biomass are still demand, hence the research on the use of LAB for this purpose. After harvesting the grasses were cut and ensiled in barrels with and without (controls) the usage of commercial silage inoculant containing Lactobacillus buchneri LN40177. After 90 days of ensiling obtained silages were analysed in order to compare their chemical composition: organic acids content, the loss of dry matter, the differences in particular fibres composition. The silages were then subjected to methane fermentation using OxiTop® sensors and exposed to air in order to check their aerobic stability. The silages prepared with LAB additive had higher concentration of acetic acid than the control silages prepared without LAB addition, which contributed to increased aerobic stability but had no effect on the methane yield of miscanthus, switchgrass and big bluestem. Using the microbial inoculant during ensiling had beneficial effect in terms of reducing the duration of biogas production process from obtained silages: lag phase was shortened, daily biogas production rate was increased and 90% of biogas was produced in a shorter period of time compared to the control silages from investigated grasses. The modified Gompertz model well reflected the kinetics of biogas production process.

The effect of nitrogen fertilization and foliar application of fertilizers on yield and energy efficiency of giant miscanthus plantations

Purpose. To improve the technology of caring for giant miscanthus plantations and establish the features of its productivity formation with the use of different types of fertilizers, starting from the second year of crop vegetation.
 Methods. The research was carried out in the years 2020–2021 in the Bila Tserkva Experimental and Breeding Station of the Institute of Bioenergy Crops and Sugar Beet of the National Academy of Agrarian Sciences of Ukraine, which is located in the zone of unstable moisture of the Right Bank Forest Steppe of Ukraine. The design of the experiment included application of mineral fertilizers [ammonium nitrate + ammonium sulfate (N24 + S6 kg/ha a.i.), ammonium nitrate (N24 kg/ha a.i.)] in a row zone in spring, foliar application of humates (Vermisol, 8.0 l/ha, Humifield BP-18, 0.4 l/ha) and complex fertilizer with amino acids (Quantum Aminomax, 0.5 l/ha). Mineral fertilizers were applied before the emergence of miscanthus sprouts; foliar application of fertilizers was carried out in the 5-leaf stage and the second time after two weeks.
 Results. Giant miscanthus plants in second year of vegetation formed from 18 to 37 shoots with an average weight of 76.3 to 111.0 g, with the maximum weight of one plant reaching 4091 g. In the next year of research, the number of stems per plant and their average weight increased by 1.5–2 times, and the maximum weight of one plant was 7016 g. Biomass yield of giant miscanthus in the third year of vegetation was 31.0–74.6 t/ha, the estimated yield of solid biofuel was 19.2–41.6 t/ha and energy 315.5–683.2 GJ/ha.
 Conclusions. Application of mineral fertilizers (ammonium nitrate + ammonium sulfate, ammonium nitrate) in spring contributed to significant increase in the indicators of raw biomass yield, solid biofuel output, and energy yield per hectare. Foliar application of Humifield BP-18 has a significant positive effect on the productivity of giant miscanthus. The best indicators of crop productivity were obtained in treatments combining spring fertilization with ammonium nitrate and ammonium sulfate (N24 + S6) followed by two-time foliar application of humates (Vermisol, 8.0 l/ha, Humifield BP-18, 0.4 l/ha) and complex fertilizer with amino acids Quantum Aminomax, 0.5 l/ha.

Biomass dry matter yield of willow and Miscanthus in low‐input cropping on heavy clay soils in Ukraine

AbstractIn Ukraine, 6.5 million hectares of agricultural land characterized by heavy clay soil could be available for sustainable bioenergy crop cultivation because they are considered marginal for food crop cultivation. This study investigated the biomass dry matter yield (DMY) of willow (Salix triandra L. and Salix viminalis L.) and Miscanthus (Miscanthus × giganteus Greef et Deuter) at two experimental sites with heavy clay in Ukraine. To promote plant rooting and adaptation in the first year of cultivation under low‐input conditions, tillage, moisture‐retaining agents, foliar fertilization, planting density and row spacing were varied. Willow obtained notable DMY on hard clay soils (clay >50%). The variety ‘Tora’ revealed the best DMY performance, indicated by the highest increment (4.1–4.6 m) in the first year of the second cycle. The highest biomass DMY (28.8 Mg ha−1) was obtained at a planting density of 15 000 plants ha−1 and a row spacing of 0.75 × 1.50 m. However, neither willow nor Miscanthus allow for a feasible biomass production at clay contents above 64%, because the young roots are damaged and deprived of nutrients as the soil dries out. For Miscanthus, plowing provided better soil loosening and easier sprouting of rhizomes compared with mini‐till. The application of moisture‐retaining agent Aquasorb (200 kg ha−1) supported Miscanthus plants with moisture in the first year of vegetation, but it did not maintain soil moisture in the long term. Therefore, growing willow and Miscanthus on soils with clay contents above 64% is not feasible because the soil texture and tendency to crack significantly reduce the DMY. © 2022 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

Third and fourth year biomass yields of Miscanthus x giganteus, switchgrass, big bluestem, and prairie cordgrass in southern Manitoba, Canada: Latitude of origin affects biomass yield among native grasses

Warm season perennial grasses that use C4 photosynthesis can provide a reliable supply of bioenergy and biomaterials, achieving the greatest annually harvestable biomass of any crop in most temperate regions. Short growing seasons bookended by cold temperatures and snow cover challenge the productivity of C4 perennial grasses at high latitudes. Cultivars from higher latitudes also often flower and senesce before fully realizing the late summer and fall growing season, compounding the productivity limitations of a shorter growing season. In contrast, cultivars from southern locations planted at higher latitudes may flower later in the growing season, extending their vegetative growth and productivity. At a common field site in southern Manitoba, Canada we compare first-, third-, and fourth-year biomass yields of Miscanthus x giganteus, and cultivars of switchgrass, prairie cordgrass, and big bluestem, spanning latitudes from southern Manitoba to Illinois/Indiana, USA. In addition, we compared spring canopy closure, plant height, and reproductive development during the fourth growing season. Miscanthus x giganteus (M114) and cultivars Sunburst (switchgrass) and Prairie View (big bluestem) consistently achieved ≥10 Mg ha−1 in their third and fourth years, with M114 achieving 13 Mg ha−1 both years. Both prairie cordgrass cultivars (Red River and IL-102) also achieved ≥10 Mg ha−1 the third year, but their yields were halved in the drier fourth growing season. Among native North American grasses, cultivars originating from higher latitudes showed more vigorous spring growth, but flowered earlier, thus reducing their biomass yields compared to cultivars originating further south of our field site.

Aerial Imagery Can Detect Nitrogen Fertilizer Effects on Biomass and Stand Health of Miscanthus × giganteus

Miscanthus × giganteus (Miscanthus) is a warm-season perennial grass grown for bioenergy feedstock production. Nitrogen (N) fertilizer management is crucial for the sustainability of Miscanthus production. In our two-year study (2018 and 2019), we investigated the role of vegetation indices (VIs) in evaluating N fertilization (0 N, 56 N, 112 N, and 168 N kg ha−1) impacts on Miscanthus biomass yield and stand health. The flight campaigns were conducted early, middle, and late during the summer growing season. Among the VIs, mid-summer growing season NDRE provided the best prediction of fresh biomass (R2 = 0.87 and 0.97) and dry biomass (R2 = 0.89 and 0.97) in 2018 and 2019, respectively. The VIs generally showed that it was possible to distinguish between 0 N and 168 N treatments, but neither 0 N and 56 N kg ha−1 nor 112 N and 168 N kg ha−1 could be separated. The results from this study highlight the importance of moderate application of N (112 kg N ha−1) in improving and maintaining the stand health and biomass yield of Miscanthus over time and suggest that mid-summer growing season VIs, NDRE in particular, can be useful for assessment of Miscanthus stand health and biomass yield.

Assessment of the Impact of Soil Contamination with Cadmium and Mercury on Leaf Nitrogen Content and Miscanthus Yield Applying Proximal Spectroscopy

The research objective was to use proximal spectroscopy in visible and near infrared (VNIR) spectra to determine the total leaf nitrogen (TN) content and the above-ground biomass of Miscanthus × giganteus (MxG) grown in the open-roof greenhouse experiment on soil contaminated with cadmium and mercury (100 mg Cd/kg soil; 20 mg Hg/kg soil), in dependence of different soil amendments in four treatments (I-soil without amendment; II-sludge; III-mycorrhizae; IV-MxG ash). Leaf reflectance was acquired using a field spectroradiometer (350–1050 nm) at the end of the vegetation period between 2018 and 2019 (n = 24). TN content was determined using the dry combustion method, while biomass was weighted immediately after the harvest. In terms of the treatment effect, sludge showed the greatest contribution in TN content. Regarding the biomass quantity, MxG ash revealed the best results as soil amendment. Applying the partial least squares regression, complete correlation and low root mean squared error (RMSE) were obtained between predicted and measured values for the validation dataset of TN content (R2 = 0.87, RMSE = 0.139%), while a strong correlation was calculated for biomass (R2 = 0.53, RMSE = 0.833 t/ha). As an additional tool with analytical methods, proximal spectroscopy is suitable to integrate the optical and physiological properties of MxG, and to assess nutrient stress in crop grown on contaminated soils.

Methods of Increasing Miscanthus Biomass Yield for Biofuel Production

The lignocellulosic perennial crop miscanthus, especially Miscanthus × giganteus, is particularly interesting for bioenergy production as it combines high biomass production with low environmental impact. However, there are several varieties that pose a hazard due to susceptibility to disease. This review contains links showing genotype and ecological variability of important characteristics related to yield and biomass composition of miscanthus that may be useful in plant breeding programs to increase bioenergy production. Some clones of Miscanthus × giganteus and Miscanthus sinensis are particularly interesting due to their high biomass production per hectare. Although the compositional requirements for industrial biomass have not been fully defined for the various bioenergy conversion processes, the lignin-rich species Miscanthus × giganteus and Miscanthus sacchariflorus seem to be more suitable for thermochemical conversion processes. At the same time, the species Miscanthus sinensis and some clones of Miscanthus × giganteus with low lignin content are of interest for the biochemical transformation process. The species Miscanthus sacchariflorus is suitable for various bioenergy conversion processes due to its low ash content, so this species is also interesting as a pioneer in breeding programs. Mature miscanthus crops harvested in winter are favored by industrial enterprises to improve efficiency and reduce processing costs. This study can be attributed to other monocotyledonous plants and perennial crops that can be used as feedstock for biofuels.

Identifying Factors Explaining Yield Variability of Miscanthus x giganteus and Miscanthus sinensis Across Contrasting Environments: Use of an Agronomic Diagnosis Approach

Miscanthus is a perennial C4 crop whose lignocellulose can be used as an alternative to the production of biosourced material. Miscanthus x giganteus (M. x giganteus) has demonstrated high maximum yields but also high yield variability across farmers’ fields. Miscanthus sinensis (M. sinensis) can be an alternative to M. x giganteus because it is considered to be more tolerant to water stress and to produce more stable yields. This study aimed to identify the main factors explaining the variability of yields across site-years for M. x giganteus and M. sinensis. A multi-local and multi-year trial network was set up in France (Ile de France and Center regions). Four treatments were established on seven sites, from spring 2013 to winter 2019: at each site, two treatments of M. x giganteus (a treatment from rhizome and a treatment from rhizome-derived plantlets) and two treatments of M. sinensis (a treatment from seed-derived plantlets established in single density and a treatment from seed-derived plantlets established in double density). We experienced 5 years of harvest because miscanthus was not harvested in 2014. First, we characterized yield variations across site-years for both genotypes. Second, we defined and calculated a set of indicators (e.g., water stress indicator, sum of degree-days of the previous year, number of frost days) that could affect miscanthus yields. Finally, we performed a mixed model with re-sampling to identify the main indicators that explained yield variability for each genotype specifically. Results showed that water stress and crop age mainly explained yield variability for both genotypes. M. sinensis yields were also affected by the sum of degree-days of the previous year of growth. Hence, genotype choice must take into account environmental characteristics. M. sinensis could indeed achieve higher and more stable yields than those of M. x giganteus in shallow sandy soils or in locations with a higher risk of low rainfall.

Energy Properties and Biomass Yield of Miscanthus x Giganteus Fertilized by Municipal Sewage Sludge.

The application of municipal sewage sludge as fertilizer in the production of non-food energy crops is an environmentally and economically sustainable approach to sewage sludge management. In addition, the application of municipal sewage sludge to energy crops such as Miscanthus x giganteus is an alternative form of recycling nutrients and organic material from waste. Municipal sewage sludge is a potential source of heavy metals in the soil, some of which can be removed by growing energy crops that are also remediation agents. Therefore, the objective of the research was to investigate the effect of municipal sewage sludge applied at three different rates of 1.66, 3.22 and 6.44 t/ha on the production of Miscanthus. Based on the analyses conducted on the biomass of Miscanthus fertilized with sludge from the wastewater treatment plant in three fertilization treatments, it can be concluded that the biomass of Miscanthus is a good feedstock for the process of direct combustion. Moreover, the application of the largest amount of municipal sewage sludge during cultivation had no negative effect on the properties of Miscanthus biomass. Moreover, the cellulose and hemicellulose content of Miscanthus is ideal for the production of second-generation liquid biofuels. Fertilizer treatments had no effect on the content of cellulose and lignin, while a significant statistical difference was found for hemicellulose.

Life Cycle Assessment of Biomass Production from Lignocellulosic Perennial Grasses under Changing Soil Nitrogen and Water Content in the Mediterranean Area

Low iLUC risk feedstocks, such as lignocellulosic no-food crops, have been indicated as sustainable crops for the transition to a bio-based economy. Given the high output to input ratio and the environmental benefits that can be obtained from renewable heat production replacing fossil fuels, the present study addressed the biomass yield, CO2-sequestration, and life cycle assessment of giant reed (Arundo donax L.) and miscanthus (Miscanthus × giganteus Greef et Deuter) growing under different soil water availability and nitrogen fertilization for three consecutive growing seasons in a semiarid Mediterranean environment. Giant reed outperformed miscanthus, showed a higher CO2-sequestration and a lower overall environmental impact. In case of both crops, the irrigation effect was significant, while the one of nitrogen fertilization was not apparent. While giant reed responded positively to reduced irrigation, compared to its highest level, as the plantation became older, miscanthus needed high water volume to get most out its potential yield. Nonetheless, the growing season had also a significant effect on both crops, mainly when low yields were achieved following the establishment year. Unlike the environmental benefits in the impact categories “non-renewable energy use” and “global warming potential”, environmental burdens concerning ozone depletion, acidification, and eutrophication were observed, indicating that further improvements of the evaluation of impact assessment associated with bioenergy production might be necessary.

Application of Hydrochar, Digestate, and Synthetic Fertilizer to a Miscanthus x giganteus Crop: Implications for Biomass and Greenhouse Gas Emissions

Miscanthus x giganteus (miscanthus), a perennial biomass crop, allocates more carbon belowground and typically has lower soil greenhouse gas (GHG) emissions than conventional feedstock crops, but best practices for nutrient management that maximize yield while minimizing soil GHG emissions are still debated. This study evaluated the effects of four different fertilization treatments (digestate from a biodigester, synthetic fertilizer (urea), hydrochar from the hydrothermal carbonization of digestate, and a control) on soil GHG emissions and biomass yield of an established miscanthus stand grown on abandoned agricultural land. Soil GHG fluxes (including CH4, CO2, and N2O) were sampled in all treatments using the static chamber methodology. Average biomass yield varied from 20.2 Mg ha−1 to 23.5 Mg ha−1, but there were no significant differences among the four treatments (p > 0.05). The hydrochar treatment reduced mean CO2 emissions by 34% compared to the control treatment, but this difference was only statistically significant in one of the two sites tested. Applying digestate to miscanthus resulted in a CH4 efflux from the soil in one of two sites, while soils treated with urea and hydrochar acted as CH4 sinks in both sites. Overall, fertilization did not significantly improve biomass yield, but hydrochar as a soil amendment has potential for reducing soil GHG fluxes.