Efficient Methods of Estimating Switchgrass Biomass Supplies

Agronomy Journal, 2014

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Biomass and Bioenergy, 2002

Renewable bioenergy could be supplied by high yielding grass crops, such as switchgrass (Panicum virgatum L.). Successful development of a bioenergy industry will depend on identifying cultivars with high yield potential and acceptable biofuel quality. The objective of this study was to evaluate 20 switchgrass populations in a ÿeld study planted in May 1997 in southern Iowa, USA. The populations included released cultivars and experimental germplasm of both upland and lowland ecotypes. Yield, plant height, stand, lodging, leaf:stem ratio, cell wall ÿber, total plant nitrogen, and ash were determined on all entries between 1998 and 2001. Ultimate and proximate analyses together with chlorine and major oxide determinations were made on three cultivars in 2000 and 2001. Biomass yield was determined from a single autumn harvest each year. The lowland cultivars 'Alamo' and 'Kanlow' produced the most biomass, exceeding the production of the widely recommended upland cultivar 'Cave-In-Rock'. Other traits di ered among the cultivars, although the range was less than that for yield. The di erences among years were substantially greater for the ultimate, proximate, and major oxide analyses than di erences among cultivars. The highest yielding cultivars had low ash, slightly lower ÿber concentrations, and moderate levels of important minerals, suggesting that excellent germplasm is available for biofuel production. The persistence of the lowland cultivars in southern Iowa may need more research because the winters during the experiment were mild. ? (E.C. Brummer). through crop diversiÿcation, decreased erosion, and improved water quality compared with a traditional annual row crop system . The perennial nature of these crops makes their cultivation desirable on highly erosive land, particularly if they can produce acceptable yields on poor quality soils. In order to be profitably grown, energy crops need to produce high yields of biomass, low concentrations of water, nitrogen, and ash, and high concentrations of lignin and cellulose . Switchgrass, a warm-season (C 4 ) grass native to 0961-9534/02/$ -see front matter ? 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 1 -9 5 3 4 ( 0 2 ) 0 0 0 7 3 -9

Biogeochemistry, 1992

Agronomy Journal, 2010

Fundamental to deriving a sustainable supply of cellulosic feedstock for an emerging biofuels industry is understanding how biomass yield varies as a function of crop management, climate, and soils. Here we focus on the perennial switchgrass (Panicum virgatum L.) and compile a database that contains 1190 observations of yield from 39 fi eld trials conducted across the United States. Data include site location, stand age, plot size, cultivar, crop management, biomass yield, temperature, precipitation, and information on land quality. Statistical analysis revealed the major sources of variation in yield. Frequency distributions of yield for upland and lowland ecotypes were unimodal, with mean (±SD) biomass yields of 8.7 ± 4.2 and 12.9 ± 5.9 Mg ha -1 for the two ecotypes, respectively. We looked for, but did not fi nd, bias toward higher yields associated with small plots or preferential establishment of stands on high quality lands. A parametric yield model was fi t to the data and accounted for one-third of the total observed variation in biomass yields, with an equal contribution of growing season precipitation, annual temperature, N fertilization, and ecotype. Th e model was used to predict yield across the continental United States. Mapped output was consistent with the natural range of switchgrass and, as expected, yields were shown to be limited by precipitation west of the Great Plains. Future studies should extend the geographic distribution of fi eld trials and thus improve our understanding of biomass production as a function of soil, climate, and crop management for promising biofuels such as switchgrass.

Crop Science, 2014

U se of lignocellulosic plant biomass as bioenergy feedstock has emerged as a viable alternative for meeting global energy demand while mitigating the impact of an elevated greenhouse-gas emission. Switchgrass was selected as a model herbaceous species for lignocellulosic bioenergy feedstock development (Bouton, 2007; McLaughlin et al., 1999; Vogel and Jung, 2001). Switchgrass is a native, perennial, warm-season grass of the North American tall-grass prairie adapted to a wide range of environments, and it has high biomass-yield potential with relatively low inputs and water use (

BIOTROPIA

Agronomy Journal, 2002

quirement of switchgrass is N. Switchgrass usually grows in association with mycorrhizae and is a very efficient Information on optimal harvest periods and N fertilization rates user of many soil nutrients, including P (Brejda et al., for switchgrass (Panicum virgatum L.) grown as a biomass or bioen-1998; Brejda, 2000; Muir et al., 2001). The N requireergy crop in the Midwest USA is limited. Our objectives were to determine optimum harvest periods and N rates for biomass produc-ment of switchgrass used for hay or grazing largely detion in the region. Established stands of 'Cave-in-Rock' switchgrass pends on the yield potential of the site, productivity at Ames, IA, and Mead, NE, were fertilized 0, 60, 120, 180, 240, or of the switchgrass cultivar, and management practices 300 kg N ha Ϫ1. Harvest treatments were two-or one-cut treatments being used. In the central Great Plains and Midwest per year, with initial harvest starting in late June or early July (Harvest states, optimum N rates for switchgrass managed for 1) and continuing at approximately 7-d intervals until the latter part pasture or hay range from about 50 to 120 kg ha Ϫ1 of August (Harvest 7). A final eighth harvest was completed after a (Brejda, 2000). In Texas, the optimum N fertilization killing frost. Regrowth was harvested on previously harvested plots rate for 'Alamo' switchgrass managed for biomass proat that time. Soil samples were taken before fertilizer was applied in duction was 168 kg ha Ϫ1 (Muir et al., 2001). the spring of 1994 and again in the spring of 1996. Averaged over Limited research information is available on harvest years, optimum biomass yields were obtained when switchgrass was harvested at the maturity stages R3 to R5 (panicle fully emerged from schedules for switchgrass managed as a bioenergy crop. boot to postanthesis) and fertilized with 120 kg N ha Ϫ1. Biomass yields In a previous study in Iowa, the greatest total switchgrass with these treatments averaged 10.5 to 11.2 Mg ha Ϫ1 at Mead and yields were achieved when the first harvest was taken 11.6 to 12.6 Mg ha Ϫ1 at Ames. At this fertility level, the amount of at the stem elongation stage when the fourth and fifth N removed was approximately the same as the amount applied. At nodes were palpable and when the regrowth was harrates above this level, soil NO 3-N concentrations increased. vested 6 wk later (George and Obermann, 1989). In Georgia, greater yields were achieved when plants were harvested once during the growing season when they S witchgrass is a perennial warm-season C 4 photosynreached either 61 or 91 cm in height and the regrowth thetic system grass that is native to the tallgrass harvested in the fall after a killing frost compared with prairie regions of North America (Moser and Vogel, a single harvest in the fall after a killing frost (Beaty 1995). Based on a series of evaluation trials, the U.S. and Powell, 1976). In Tennessee, Reynolds et al. (2000) Department of Energy has identified switchgrass as the evaluated two harvest treatments (early summer and most promising species for development into an herbalate autumn vs. late autumn) for switchgrass grown at ceous biomass fuel crop (Vogel, 1996). It has an array a constant N fertilization rate of 50 kg ha Ϫ1 yr Ϫ1 for 5 yr. of desirable attributes for use as a bioenergy crop, in-Treatments with the highest biomass yields varied with cluding broad adaptation and high yields on marginal years. Total N concentration of switchgrass herbage was and erosive croplands, and it can be harvested with significantly lower in biomass in late autumn compared conventional hay-making equipment. Major costs assowith summer harvests. ciated with producing switchgrass biomass include N Information on the interaction of N rates and harvest fertilization, harvesting, and transportation (Keeney and regimes is not available for managing switchgrass for DeLuca, 1992). The number of harvests and the yields biomass production in the Midwest. The main objectives per harvest affect the economics of harvesting switchof this research were to determine optimum harvest grass biomass. periods and N fertilization rates for the production of Research has been conducted on fertilizer requireswitchgrass as a biomass crop in the Midwest. The treatments of native warm-season grasses, including switchments resulted in plots that differed significantly in soil grass when managed for hay or grazing. The results of NO 3 concentrations, which provided us an opportunity these trials have recently been reviewed and summato determine the response of switchgrass biomass yields rized by Brejda (2000). In brief, the main fertilizer reto residual NO 3 concentrations in the year following completion of the main study. Utility of soil tests depend on significant response of the crop to soil nutrient con

Agronomy Journal, 2012

2013

If switchgrass harvest is delayed until after senescence, some nutrients will translocate to the plant's crown and roots. Biomass yield and fertilizer requirements depend on harvest date. The objective is to determine switchgrass biomass yield, nutrient concentration in biomass, fertilizer requirements, and expected production cost by month of harvest.