Biomass Characteristics of 14 Switchgrass Cultivars Grown In Marginal Vs. Prime Soil.

The national strategy is to produce bioenergy crops on marginal cropland where there will be no competition with food production.  The characteristics of switchgrass (Panicum virgatum) make it an excellent candidate for sustainable biomass production on marginal land. However, few studies have evaluated switchgrass performance on marginal land.  The objectives of the project are to identify the best performing switchgrass cultivars on marginal land in specific locations and identify cultivars with broad adaptation across several regions. Fourteen switchgrass cultivars representing a range in adaptation, from southern lowland to northern upland ecotypes, were established in ‘paired’ field trials (on marginal soil and on prime farmland soil) in NJ, NY, WI, SD, PA, and MD at a seeding rate of 11.2 kg PLS ha^-1. Two nitrogen treatments (0, 120 kg ha^-1) were applied in the spring of each year. Biomass, tiller density and plant height were collected across locations in 2009 and/or 2010. Significant differences were observed for location, soil type, nitrogen treatment and cultivar for all characteristics.  All upland cultivars and northern lowland cultivars, except Kanlow had higher tiller densities than all southern lowland cultivars across locations. Lowland types exhibited the highest plant heights across locations. Highest biomass yield were observed in prime soil in NJ, SD and WI (9.47 – 8.41 Mg ha^-1) while lowest yields were observed in marginal soil in NJ and prime soil in NY (2.82- 2.13 Mg ha^-1).  Interestingly, marginal soil types were not always lower yielding than prime farmland sites.  At every location, except MD and NY, nitrogen treatments resulted in higher biomass yields in both prime and marginal soil types. Across the locations evaluated, the northern lowland cultivar, Timber, and all upland cultivars, except HighTide and KY 1625, out yielded southern lowland types, Bomaster, Alamo and Performer.