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Napier grass (Pennisetum purpureum Schumach) has been identified as a potential energy crop in Thailand. However, information regarding the biomass production characteristics of napier grass in response to K and N fertilization is required to guide management decisions for biofuel feedstock. Our objective was to determine the effects of K and N rates on biomass yield, developmental morphology, nutrient content and removal. This experiment was conducted during 2016 and 2017 at Kamphaeng Saen (KPS), Thailand. The experimental design was a split plot arranged in a randomized complete block (RCB) with four replications. Three K fertilization rates (0, 250, and 500 kg ha−1) were used for the main plots and four N fertilization rates (0, 250, 500, and 1000 kg ha−1) were arranged as subplots. With increasing N fertilization rate, most growth parameters increased, except leaf to stem ratio and dry matter concentration decreased. Total dry matter yield (TDMY) increased from 16.6 to 43.0 t ha−1 and from 15.2 to 41.6 t ha−1 in 2016 and 2017, respectively, as N rate increased from 0 to 1000 kg ha−1. However, growth and TDMY were not affected by K fertilizer. Increased TDMY resulted from an increase in the proportion of elongating tillers leading to advancing mean stage by count (MSC) from 2.35 to 2.45. Therefore, although napier grass demonstrated large biomass production under multiple harvest regimes, its higher removal rates (285.0–1615. kg K ha−1 and 86.7–422.2 kg N ha−1) were varied with fertilization rates indicating a potential for higher fertilizer requirements and production costs over time. [ABSTRACT FROM AUTHOR]

Biomass yield and adaptability to a broad range of environments are important characteristics of dedicated energy crops for sustainable bioenergy feedstock production. In addition to yield potential, the role of species diversity on ecosystem services is also growing in importance as we seek to develop sustainable feedstock production systems. The objective of this study was to compare the biomass yield potential of the commercially available germplasm of native warm-season grasses in monocultures and in blends (mixture of different cultivars of the same species) or mixtures of different species across an environmental gradient (temperature and precipitation) in the Midwest, USA. Warm-season grasses including switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii Vitman), indiangrass (Sorghastrum nutans [L.] Nash), sideoats grama (Bouteloua curtipendula [Michx.] Torr.) and Miscanthus × giganteus (Greef and Deu.) were planted in 2009. Biomass was annually harvested from 2010 through 2015 for Urbana, IL and Mead, NE but only in 2010 and 2011 for Ames, IA. The effect of species in monocultures and mixtures (or blends) on biomass yields was significant for all locations. In monocultures, the annual biomass yields averaged over a 6-year period were 11.12 Mg ha−1 and 10.98 Mg ha−1 at Urbana and Mead, respectively, while the annual biomass yield averaged over a 2-year period was 7.99 Mg ha−1 at Ames, IA. Also, the annual biomass yields averaged across the different mixtures and blends at each location were 10.25 Mg ha−1, 9.88 Mg ha−1, and 7.64 Mg ha−1 at Urbana, Mead, and Ames, respectively. At all locations, M. × giganteus and 'Kanlow N1' produced the highest biomass yield in monocultures while mixtures containing switchgrass and big bluestem had the greatest mixture yield. The results from this multi-environment study suggest mixtures of different species provided no yield advantage over monocultures for bioenergy feedstocks in Illinois and Nebraska and both systems consistently produced biomass as long as April–July precipitation was near or above the average precipitation (300 mm) of the regions. [ABSTRACT FROM AUTHOR]

Biofuels and bio-based products can be produced from a wide variety of herbaceous feedstocks. To supply enough biomass to meet the needs of a new bio-based economy, a suite of dedicated biomass species must be developed to accommodate a range of growing environments throughout the USA. Researchers from the US Department of Agriculture's Agricultural Research Service (USDA-ARS) and collaborators associated with the USDA Regional Biomass Research Centers have made major progress in understanding the genetics of switchgrass, sorghum, and other grass species and have begun to use this knowledge to develop new cultivars with high yields and appropriate traits for efficient conversion to bio-based products. Plant geneticists and breeders have discovered genes that reduce recalcitrance for biochemical conversion to ethanol and drop-in fuels. Progress has also been made in finding genes that improve production under biotic and abiotic stress from diseases, pests, and climatic variations. [ABSTRACT FROM AUTHOR]

High yielding, native warm-season grasses could be used as renewable bioenergy feedstocks. The objectives of this study were to determine the effect of warm season grass monocultures and mixtures on yield and chemical characteristics of harvested biomass and to evaluate the effect of initial seeding mixture on botanical composition over time. Switchgrass ( Panicum virgatum L.), indiangrass [ Sorghastrum nutans (L.) Nash], and big bluestem ( Andropogon gerardii Vitman) were planted as monocultures and in all possible two- and three-way mixtures at three USA locations (Brookings and Pierre, SD and Morris, MN) during May 2002. Biomass at each location was harvested after a killing frost once annually from 2003 to 2005. Total biomass yield significantly increased with year at all locations. Switchgrass monocultures or mixtures containing switchgrass generally out-yielded big bluestem or indiangrass in monocultures or the binary mixture. Cellulose and hemicellulose concentrations were higher in 2004 and 2005 compared with 2003. Switchgrass or mixtures containing switchgrass tended to have less cellulose than either big bluestem or indiangrass. Results were more variable for total N, lignin, and ash. Switchgrass was the dominant component of all mixtures in which it was present while big bluestem was dominant when mixed with indiangrass. Indiangrass was maintained only in monocultures and declined over years when grown in mixtures at all locations. Our results indicated if biomass yield in the northern Great Plains is a primary objective, switchgrass should be a component of binary or tertiary mixtures that also contain big bluestem and/or indiangrass. [ABSTRACT FROM AUTHOR]

Perennial grasses may provide a renewable source of biomass for energy production. Biomass yield, nutrient concentrations, and nutrient removal rates of switchgrass ( Panicum virgatum L.), giant miscanthus ( Miscanthus x giganteus), giant reed ( Arundo donax L.), weeping lovegrass [ Eragrostis curvula (Shrad.) Nees], kleingrass ( Panicum coloratum L.), and Johnsongrass ( Sorghum halepense (L.) Pers.) were evaluated at four N fertilizer rates (0, 56, 112, or 168 kg N ha) on a Minco fine sandy loam soil in southern Oklahoma. Species were established in 2008 and harvested for biomass in winter of 2009 and 2010. Biomass yield (dry matter basis) did not show a strong relationship with N fertilizer rate ( p = 0.08), but was affected by year and species interactions ( p < 0.01). Weeping lovegrass and kleingrass produced 29.0 and 16.0 Mg ha in 2009, but only 13.0 Mg ha and 9.8 Mg ha in 2010, respectively. Biomass yields of giant reed, switchgrass, and Johnsongrass averaged 23.3, 17.8, and 6.0 Mg ha, respectively. Giant miscanthus established poorly, producing only 4.7 Mg ha. Across years, giant reed had the highest biomass yield, 33.2 Mg ha at 168 kg N ha, and the highest nutrient concentrations and removal rates (162 to 228 kg N ha, 23 to 25 kg P ha, and 121 to 149 kg K ha) among the grasses. Although giant reed demonstrated tremendous biomass production, its higher nutrient removal rates indicate a potential for increased fertilization requirements over time. Switchgrass had consistently high biomass yields and relatively low nutrient removal rates (40 to 75 kg N ha, 5 to 12 kg P ha, and 44 to 110 kg K ha) across years, demonstrating its merits as a low-input bioenergy crop. [ABSTRACT FROM AUTHOR]