Switchgrass as a biofuels feedstock in the USA

Switchgrass (Panicum virgatum L.) has been identified as a model herbaceous energy crop for the USA. In this review, we selectively highlight current USDA-ARS research on switchgrass for biomass energy. Intensive research on switchgrass as a biomass feedstock in the 1990s greatly improved our understanding of the adaptation of switchgrass cultivars, production practices, and environmental benefits. Several constraints still remain in terms of economic production of switchgrass for biomass feedstock including reliable establishment practices to ensure productive stands in the seeding year, efficient use of fertilizers, and more efficient methods to convert lignocellulose to biofuels. Overcoming the biological constraints will require genetic enhancement, molecular biology, and plant breeding efforts to improve switchgrass cultivars. New genomic resources will aid in developing molecular markers, and should allow for marker-assisted selection of improved germplasm. Research is also needed on profitable management practices for switchgrass production appropriate to specific agro-ecoregions and breakthroughs in conversion methodology. Current higher costs of biofuels compared to fossil fuels may be offset by accurately valuing environmental benefits associated with perennial grasses such as reduced runoff and erosion and associated reduced losses of soil nutrients and organic matter, increased incorporation of soil carbon and reduced use of agricultural chemicals. Use of warm-season perennial grasses in bioenergy cropping systems may also mitigate increases in atmospheric CO2. A critical need is teams of scientists, extension staff, and producer-cooperators in key agro-ecoregions to develop profitable management practices for the production of biomass feedstocks appropriate to those agro-ecoregions. Key words: Bioenergy, biomass conversion technologies, Panicum virgatum L., stand establishment, switchgrass improvement, USDA-ARS

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Effects of Selection Regime on Invasive Characteristics in an Emerging Biomass Crop, Switchgrass (Panicum virgatum L.)

Sustainability ◽

10.3390/su13095045 ◽

2021 ◽

Vol 13 (9) ◽

pp. 5045

Author(s):

Shelby A. Flint ◽

Ruth G. Shaw ◽

Nicholas R. Jordan

Keyword(s):

Biomass Production ◽

Panicum Virgatum ◽

Environmental Benefits ◽

First Year ◽

Biomass Feedstock ◽

Young Stand ◽

Panicum Virgatum L ◽

Plant Densities ◽

Biomass Yields ◽

Invasive Traits

Production of biomass feedstock crops could produce substantial environmental benefits, but these will be sharply reduced if these crops become invasive. Switchgrass (Panicum virgatum L.) is being bred for biomass production; these selective efforts may enhance invasive traits. To inform the assessment of invasive risk, undomesticated switchgrass strains were used as a baseline for comparison with strains bred for biomass production. In a three-year field experiment, we compared juvenile plant densities and survival, persistence of established plants, and aboveground biomass between selectively bred (cultivar) and undomesticated switchgrass strains. Cultivars had modestly greater third-year biomass and first-year plant densities than commercial ecotypes but lower survival and persistence; consequently, third-year plant densities did not significantly differ between cultivars and commercial ecotypes. Higher initial establishment and subsequent self-thinning in cultivars resulted in stands that were similar to those of commercial ecotypes. Therefore, our results do not suggest that the breeding of current cultivars of switchgrass enhanced juvenile and young-stand traits associated with invasiveness. Because biomass yields were not greatly different between cultivars and commercial ecotypes, use of the latter in biomass grasslands could provide functional benefits, including an enhanced habitat for native biodiversity and reduced pathogen loads, without incurring large losses in biomass production.

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Distribution of recently fixed photosynthate in a switchgrass plant-soil system

Plant Soil and Environment ◽

10.17221/532/2011-pse ◽

2012 ◽

Vol 58 (No. 6) ◽

pp. 249-255 ◽

Cited By ~ 12

Author(s):

D.R. Chaudhary ◽

J. Saxena ◽

N. Lorenz ◽

R.P. Dick

Keyword(s):

Panicum Virgatum ◽

Rhizosphere Soil ◽

Microbial Biomass Carbon ◽

Bulk Soil ◽

Energy Crop ◽

Marginal Lands ◽

Soil System ◽

Plant Soil ◽

Panicum Virgatum L ◽

Maintenance Requirements

The use of switchgrass (Panicum virgatum L.) as an energy crop has gained great importance in past two decades due to its high biomass yields on marginal lands with low agricultural inputs and low maintenance requirements. Information on the allocation of photosynthetically fixed C in the switchgrass-soil system is important to understand the C flow and to quantify the sequestration of C in soils. The allocation of 13C labeled photosynthates in shoot, root, soil, and in microbial biomass carbon (MBC) of rhizosphere and bulk soil of 45 days old, greenhouse grown-switchgrass was examined during 20 days 13C-CO2 pulse labeling period. The total 13C recovered in the plant-soil system varied from 79% after 1 day to 42% after 20 days of labeling. After labeling, 54%, 40%, and 6% excess 13C resided in shoot, root and soil, respectively on day 1; 27%, 61% and 11%, respectively on day 5 and 20%, 63% and 17%, respectively day 20 after labeling. The maximum incorporation of 13C from roots into the MB of rhizosphere soil occurred within the first 24 h of labeling. The excess 13C values of rhizosphere soil and rhizosphere MBC were significantly higher than excess 13C values of bulk soil and the bulk soil MBC, respectively. The proportion of excess 13C in soil as MBC declined from 92 to 15% in rhizosphere soil and from 79 to 18% in bulk soil, for 1 day and 20 days after labeling, respectively. The present study showed the effectiveness of 13C labeling to examine the fate of recently photosynthesized C in soil-plant (switchgrass) system and dynamics of MBC.

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Long-Term Productivity of Thirteen Lowland and Upland Switchgrass Ecotypes in the Mediterranean Region

Agronomy ◽

10.3390/agronomy10070923 ◽

2020 ◽

Vol 10 (7) ◽

pp. 923

Author(s):

Efthymia Alexopoulou ◽

Federica Zanetti ◽

Eleni G. Papazoglou ◽

Konstantinos Iordanoglou ◽

Andrea Monti

Keyword(s):

Panicum Virgatum ◽

Mediterranean Climate ◽

Biomass Crop ◽

The North ◽

Panicum Virgatum L ◽

The Usa ◽

Biomass Yields ◽

The Mediterranean ◽

Marginal Soil

Switchgrass (Panicum virgatum L.) has been identified in the USA as an ideal biomass crop, in relation to its wide environmental suitability, mainly linked to the availability of both upland and lowland ecotypes, allowing the possibility of growing this species in most of the North American region. Switchgrass is conventionally grown for forage, but more recently, it has been considered as a model biofuel crop. Early European studies on switchgrass as a bioenergy crop started in the late 1990s, when a multi-location field trial was established in Greece (Aliartos) and Italy (Ozzano) to compare the productivity of 13 switchgrass genotypes, including upland (Carthage, Blackwell, Caddo, CIR, Forestburg, SU 94-1, Summer) and lowland (Alamo, Kanlow, Pangburn, SL 93-2, SL 93-3, SL94-1) genotypes. The scope was to identify the most suitable ecotype within each environment and, possibly, the best performing variety. The trials lasted 17 years (1998–2014) in Greece and 13 years (1998–2010) in Italy. While in Italy the trial was rainfed and unfertilized, in Greece, where the soil was marginal, drip irrigation was always applied, and the plots were fertilized regularly. The biomass yields in Greece, as averages across the 17 years, were similar for the lowland and upland varieties (11.5 vs. 11.1 Mg ha−1, respectively), while in Italy, as averages across the 13 years, the differences were relevant: 15.4 vs. 11.3 Mg ha−1 for lowland and upland, respectively. Alamo (lowland) was the most productive variety, both in Greece and Italy, with average annual yields of 12.7 and 16.6 Mg ha−1, respectively; CIR in Greece (10.1 Mg ha−1) and Forestburg in Italy (9.1 Mg ha−1) (both upland) were the least productive genotypes. The present results demonstrate the good suitability of switchgrass as biomass crop for the Mediterranean climate. Despite the very marginal soil (i.e., very shallow and with a sandy texture) in the Greek trial, the application of regular fertilization and irrigation produced biomass yields above 11 Mg ha−1 (grand mean) in the present 17-year-long study.

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Profitability of organic and conventional soybean production under ‘green payments’ in carbon offset programs

Renewable Agriculture and Food Systems ◽

10.1017/s1742170511000408 ◽

2011 ◽

Vol 27 (4) ◽

pp. 266-277 ◽

Cited By ~ 2

Author(s):

Ariel Singerman ◽

Kathleen Delate ◽

Craig Chase ◽

Catherine Greene ◽

Michael Livingston ◽

...

Keyword(s):

Management Practices ◽

Clean Energy ◽

Organic Production ◽

Environmental Benefits ◽

Economic Research ◽

Agricultural Markets ◽

Cap And Trade ◽

Soybean Production ◽

Conventional Production ◽

The Usa

AbstractEmphasis on reducing emissions from the greenhouse gases (GHG), carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) has increased in recent years in the USA, primarily for industry, transportation, energy and agricultural sectors. In this study, we utilized on-farm data collected by the USDA-National Agricultural Statistics Service (NASS) Agricultural Resource Management Survey (ARMS), secured under an agreement with the USDA-Economic Research Service (ERS) to analyze the profitability of organic and conventional soybean production, based on changes that ‘green payments’ in a cap-and-trade system would introduce in agricultural markets in the USA. In particular, the analysis focused on establishing whether organic producers would be better positioned to sequester carbon (C) and reap the benefits of the C-offset scheme compared to conventional producers, given the differences in costs, management practices and environmental benefits between organic and conventional production methods. We estimated several changes in profitability of soybean producers according to management practices, incentives for the generation of offset credits, and increase in energy input prices that a potential cap-and-trade system may introduce in future agricultural markets in the USA. Survey data suggested that even with lower yields, conventional producers could profit from converting to organic agriculture, given organic price premiums. In addition, taking into consideration both direct and indirect costs, average cost for conventional-till (CT) organic soybean production was approximately 9% lower than no-till (NT) conventional production. With a C market and payments for soil C sequestration through potential Clean Energy legislation, additional profit could be accrued by organic producers, because organic production would have 28% greater ton CO2 eq. acre−1 yr−1 sequestration than conventional NT. Thus, the environmental benefits from GHG reduction could incentivize increased conversion from conventional to organic production across the USA.

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Suspected Selective Herbivory of Bioenergy Grasses by Meadow Voles (Microtus pennsylvanicus)

The Canadian Field-Naturalist ◽

10.22621/cfn.v127i1.1406 ◽

2013 ◽

Vol 127 (1) ◽

pp. 44 ◽

Cited By ~ 5

Author(s):

Heather A. Hager ◽

Frances E. C. Stewart

Keyword(s):

Panicum Virgatum ◽

Large Scale ◽

Management Practices ◽

Microtus Pennsylvanicus ◽

Substantial Effect ◽

Perennial Grasses ◽

Scale Production ◽

Meadow Voles ◽

Bioenergy Grasses ◽

Selective Herbivory

Highly productive native and non-native perennial grasses are being grown for bioenergy purposes in North America, and ecological risks of their large-scale production are being assessed to inform breeding and management practices. Giant Miscanthus (Miscanthus × giganteus) and Switchgrass (Panicum virgatum) were introduced into an old-field habitat in Guelph, Ontario, in 2012. Seedlings of these species suffered severe selective herbivory, being severed at the plant base by an unknown herbivore. We therefore performed a live-trapping survey and mark-recapture analysis of the small mammal community in 2012 to identify the probable herbivore and estimate its population density. Meadow Voles (Microtus pennsylvanicus) were the most abundant herbivore in the area, with an estimated population of 265 individuals/ha, a relatively high density. This and other evidence indicate that Meadow Voles were likely responsible for herbivory of >80% of the transplants. Such herbivory could have a substantial effect on the establishment and survival of these grasses, suggesting that future crop breeding programs and ecological risk assessments should take this into consideration.

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Switchgrass (Panicum virgatum L.) Cultivar Adaptation, Biomass Production, and Cellulose Concentration as Affected by Latitude of Origin

ISRN Agronomy ◽

10.5402/2012/763046 ◽

2012 ◽

Vol 2012 ◽

pp. 1-9 ◽

Cited By ~ 7

Author(s):

Paul G. Jefferson ◽

W. Paul McCaughey

Keyword(s):

Biomass Production ◽

Panicum Virgatum ◽

Nutritive Value ◽

Stand Density ◽

Canadian Prairie ◽

Grazing Cattle ◽

Northern Latitudes ◽

Panicum Virgatum L ◽

The Usa ◽

Cellulose Concentration

Ten cultivars of switchgrass (Panicum virgatum L.) of northern and southern origins that had demonstrated adaptation to North Dakota were evaluated for biomass production, cellulose concentration, and nutritive value in the southern Canadian prairie region: Saskatchewan and Manitoba. In this region, cultivars adapted to northern latitudes present interest for biomass production. Latitude of origin of the cultivars was positively correlated to stand density (r=0.83, P<0.01), biomass production (r=0.69, P<0.01), and cellulose (r=0.84, P<0.01), and negatively correlated with organic matter digestibility (r=−0.86, P<0.01) and N (r=−0.85, P<0.01). Dacotah and ND 3743, the northern origin cultivars, were more persistent in Brandon, MB (94 to 100% stand density) and exhibited higher cellulose and hemicellulose concentrations than southern cultivars. Southern cultivars produced higher biomass than northern-origin cultivars until they suffered significant stand and biomass decline. Cave-in-Rock, the southern origin cultivar, did not persist in the third year after seeding. However, southern-adapted cultivars exhibited better nutritive value for grazing cattle. We conclude that switchgrass production in the southern Canadian prairie should utilize the USA cultivars from northern latitudes or adapted Canadian cultivars should be developed.

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The Challenges of Using Reclaimed Asphalt Pavement for New Asphalt Mixtures: A Review

Materials ◽

10.3390/ma13184052 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4052

Author(s):

Giulia Tarsi ◽

Piergiorgio Tataranni ◽

Cesare Sangiorgi

Keyword(s):

Management Practices ◽

Asphalt Pavement ◽

Asphalt Mixtures ◽

Environmental Benefits ◽

Reclaimed Asphalt Pavement ◽

Recycled Asphalt ◽

Reclaimed Asphalt ◽

The Usa ◽

Pavement Construction ◽

A Minor

Reclaimed Asphalt Pavement (RAP) material mainly consists of removed asphalt concretes from existing infrastructures and, to a minor extent, of wasted or rejected mixes during the production processes. Being composed of two valuable non-renewable resources, i.e., aggregates and bituminous binder, its conscious use can ensure the sustainability of asphalt pavement construction. Thanks to the use of RAP material in new asphalt products, the USA saved 4.1 million tons of virgin binder and 78 million tons of virgin aggregates in 2018. Therefore, the use of RAP for the production of new asphalt formulations at the top of the recycling hierarchy is preferable instead of being down-cycled in low-value applications. The RAP material represents one of the most re-used construction products worldwide; in 2018, approximately 88% wt. and 72% wt. of RAP were used in USA and Europe, respectively, as aggregates for Hot, Warm and Cold Asphalt Mixtures and for unbound layers. Several studies have revealed positive responses of the recycled asphalt mixtures with high or very high content of RAP. However, the common practices of many countries still limit the RAP content to a 15–20% wt., on average, in the recycled asphalt mixes. The amount of RAP in asphalt concretes can be significantly increased by applying good management practices of the RAP, either processed or not, as well as novel production technologies and advanced mix design approaches. This manuscript aims to summarize the state-of-the-art of use of RAP aggregates in new asphalt mixtures. The economic and environmental benefits are also discussed.

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Managing Water Resources, Past and Present

10.1093/oso/9780199267644.001.0001 ◽

2004 ◽

Keyword(s):

Water Management ◽

Middle Ages ◽

Southern Africa ◽

Management Practices ◽

Social Groups ◽

Water Politics ◽

European Water ◽

The Usa ◽

British Experience ◽

Over Exploitation

A multi-disciplinary analysis of the evolution of water politics and policy by an international team of distinguished experts. Water management in the Middle Ages in Europe, its evolution in the USA, the elaboration of the European Water Framework Directive, the British experience of water management, the over-exploitation of African aquifers, and the evolution of the water situation in Southern Africa are all examined. This volume underlines the fact that only an integrative and interdisciplinary understanding can lead to genuinely improved water management practices that will not benefit some social groups at the expense of others.

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