Methane yield from switchgrass harvested at different stages of development in Eastern Canada Daniel Massé a, * , Yan Gilbert a , Philippe Savoie b , Gilles Bélanger b , Gaétan Parent b , Daniel Babineau c a Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, 2000, College St., Sherbrooke, QC, Canada J1M 0C8 b Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada, 2560, Hochelaga Blvd., Quebec City, QC, Canada G1V 2J3 c Groupe EBI, 61, Montcalm St., Berthierville, QC, Canada J0K 1A0 article info Article history: Received 29 April 2010 Received in revised form 2 July 2010 Accepted 6 July 2010 Available online 17 August 2010 Keywords: Switchgrass Anaerobic digestion Methane Energy crops Green energy abstract Mesophilic methane yield of ensiled switchgrass grown in Eastern Canada was assessed. Switchgrass was harvested at three stages of development, corresponding to mid-summer, late summer and early fall in 2007. The regrowth of plots harvested in mid-summer was also harvested in early fall as a two-cut strat- egy. Specific methane yields decreased significantly with crop maturity from 0.266 to 0.309 N L CH 4 g 1 VS in mid-summer to 0.191–0.250 N L CH 4 g 1 VS in early fall; values were similar for the first harvest in late July and the second harvest (regrowth) in October. Approximately 25% more methane was produced by hectare for the two-cut strategy (2.90–3.44  10 6 N L CH 4 ha 1 ) compared to the one-cut strategy with a harvest in late summer (2.28–2.77  10 6 N L CH 4 ha 1 ). Methane yields from switchgrass grown under the cool humid climate of Eastern Canada suggest that this crop remains an interesting renewable alternative energy source. Crown Copyright Ó 2010 Published by Elsevier Ltd. All rights reserved. 1. Introduction Methane produced by anaerobic digestion can be a significant energy source for the generation of heat and power. Various bio- masses have been considered to generate renewable methane gas, notably municipal solid wastes (Hartmann and Ahring, 2006), animal and agricultural wastes (Sakar et al., 2009), sewage (Lettinga, 1995), animal carcasses (Massé et al., 2008) and dedi- cated energy crops (Amon et al., 2007a). Several perennial grasses have been identified as promising energy crops, such as Miscan- thus (Miscanthus  giganteus), reed canarygrass (Phalaris arundina- cea L.), and switchgrass (Panicum virgatum L.). Perennial grasses require less nutrient (McLaughlin and Walsh, 1998) and pesticide (Lewandowski et al., 2003) inputs than annual crops. The C4 grasses have been recognized as more promising energy crops than C3 grasses because of a more efficient photosynthetic pathway (Lewandowski et al., 2003). C4 switchgrass has additional advanta- ges such as superior above-ground biomass yield across a wide geographical range, adaptability to marginal quality land, and low water and nutrient requirements (Heaton et al., 2008; Wright and Turhollow, 2010). Moreover, switchgrass roots enhance soil structural stability and require relatively low inputs of energy, water and agrochemicals per unit of energy produced (McLaughlin and Walsh, 1998). Methane yield of crops can be assessed intrinsically, i.e. in litres of gas per unit of biomass (Chynoweth et al., 1993; Mähnert et al., 2005; Amon et al., 2007a; Amon et al., 2007b) but it should also be estimated per unit area because crop yield varies among plant spe- cies, varieties and geographical location (Weiland, 2003; Amon et al., 2007a). Some studies have investigated crops produced in colder climates, such as in Finland (Lehtomäki et al., 2008; Seppälä et al., 2009) or in the northern part of North America (Madakadze et al., 1999a). The harvest period may also influence methane yield of anaer- obically digested crops since plant chemical composition varies with stage of development (Cherney et al., 1986; Gunaseelan, 1997; Lehtomäki et al., 2008). Lehtomäki and colleagues (2008) established that for most grasses, methane yield per unit of volatile solids (VS) increased with delayed harvest, as opposed to a reduced methane yield for some grasses and clover (Kaparaju et al., 2002; Prochnow et al., 2005). No information is available regarding the effect of harvest time and strategy on methane yields per unit of VS of switchgrass under the relatively cool and humid climatic conditions of the north-east- ern part of North America. The objective of this project was to determine methane yields of anaerobically digested switchgrass harvested at different times and under different harvesting strategies. 0960-8524/$ - see front matter Crown Copyright Ó 2010 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2010.07.018 * Corresponding author. Tel.: +1 418 565 9174; fax: +1 418 564 5507. E-mail addresses: daniel.masse@agr.gc.ca (D. Massé), yan.gilbert@agr.gc.ca (Y. Gilbert), philippe.savoie@agr.gc.ca (P. Savoie), gilles.belanger@agr.gc.ca (G. Bélan- ger), ygaetan.parent@agr.gc.ca (G. Parent), babineaudaniel@hotmail.com (D. Babi- neau). Bioresource Technology 101 (2010) 9536–9541 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech